Dr Li is currently a Senior Lecturer in the School of Civil and Environmental Engineering and Core Member of Centre for Built Infrastructure Research at the University of Technology Sydney.
Dr. Li has published around 110 peer-reviewed journal and conference papers on the topic of smart materials and structures, and vibration control. He serves as Associate Editor of Journal of Intelligent Material Systems and Structures (SCI, IF; 2.410) and member of Editorial Board for Frontiers in Materials (SCI, IF; 2.705).
Associate Editor, Journal of Intelligent Material Systems and Structures (SCI, IF; 2.410), 2020-
Member of Editorial Board, Frontiers in Materials (SCI, IF; 2.705), since 2017-
Can supervise: YES
Smart Materials and Structures, Passive and semiactive vibration control, Negative stiffness device, Deep learning based crack detection.
PhD positions available for motivated HDR candidates in the following topics:
- Inerter-based passive control devices: This projects will explore the mechanism and experimental validation of various inerter based structural control devices, e.g., Tuned inerter damper and Tuned mass damper inerter, for vibration control of engineering structures under diversified dynamic loadings. It contains theoretical analysis, analytical modelling and experimental testing.
- Rail track corrugation mitigation: This project aims to understand the cause of the rail track corrugation and form effective method to attenuate the high-frequency vibration. It involves analytical analysis and case study.
- Behaviour of magneto-active composite materials: The projects will investigate the nonlinear behaviour of magneto-active composite materials, such as MR elastomer, MR plasttomer, MR gel and MR grease, and hysteresis modelling of the material behaviours. It contains theoretical analysis, analytical modelling and experimental testing.
- Use of magnetic field in construction materials: This project explore the new idea of using magnetic field in the consturction material development, including self-sensing cemententitious composit and high performance concrete, to improve its physical properties. It requires skills in finite element analysis, numerical modelling and experimental testing.
- Rheology of fresh-state cement paste: This research examines the rheological behaviour of fresh cement paste and establishes the constitutive model based on experiental data. It involves rheology, experimental testing and constitutive modelling.
- Deep learning-based crack detection using UAV images: This project utilises deep learning based image processing to detect crack in the structure surface captured by UAV images. It involves advanced coding, analytical and experimental verification.
- Multi-objective structural optimisation of untrasonic food processor: as part of collaboration with CSIRO, this project conducts multi-objective optimisation for a new type of ultrasonic food processor. It contains analytical modelling and experimental testing.
As subject coordinator:
Computer Modelling and Design (48389)
Advanced Engineering Computing (48371)
Also serve as Coursework Project Coordinator for School of Civil and Environmental Engineering
Li, S, Liang, Y, Li, Y, Li, J & Zhou, Y 2020, 'Investigation of dynamic properties of isotropic and anisotropic magnetorheological elastomers with a hybrid magnet shear test rig', Smart Materials and Structures.View/Download from: Publisher's site
Zhang, G, Li, Y, Yu, Y, Wang, H & Wang, J 2020, 'Modeling the nonlinear rheological behavior of magnetorheological gel using a computationally efficient model', Smart Materials and Structures.View/Download from: Publisher's site
Zheng, J, He, X, Li, Y, Zhao, B, Ye, F, Gao, C, Li, M, Li, X & E, S 2020, 'Viscoelastic and magnetically aligned flaky Fe-based magnetorheological elastomer film for wide-bandwidth electromagnetic wave absorption', Industrial & Engineering Chemistry Research.View/Download from: Publisher's site
Gu, X, Li, J & Li, Y 2020, 'Experimental realisation of the real-time controlled smart magnetorheological elastomer seismic isolation system with shake table', Structural Control and Health Monitoring, vol. 27, no. 1.View/Download from: Publisher's site
© 2019 John Wiley & Sons, Ltd. Traditional base isolation protects structures against severe seismic events by providing a designated lateral flexibility at the base level of the structures. Due to its inherent passive nature, in the design process, compromises have to be made among performance of different design targets (displacements, interstorey drifts, accelerations, etc.). In addition, as the working principle, the effectiveness of a base isolation relies on the degree of "decoupling" between ground excitation and superstructure. However, a higher degree of decoupling compromises the stability of the structures. In other words, for a base solation system, it possesses inherent conflicts between the effectiveness of the isolation and the lateral stability of the structure. A concept of new smart base isolation system is proposed, in which real-time controllable decoupling for a base isolation structure is achieved by employing magnetorheological elastomer (MRE) base isolators. With controllable lateral stiffness, the smart base isolation system can achieve an optimal decoupling by instantly shifting the structure's natural frequencies to a nonresonant region. This paper aims at experimentally proving and validating this innovative concept, including designing a three-storey shear building model equipped with MRE base isolators, demonstrating the feasibility and evaluating the performance of the proposed system by a series of shake table testing. The comprehensive experimental design and results of shake table testing have concept-proved the proposed smart MRE base isolation system for future development in practical applications.
Li, H, Li, Y & Li, J 2020, 'Negative stiffness devices for vibration isolation applications: A review', Advances in Structural Engineering, vol. 23, no. 8, pp. 1739-1755.View/Download from: Publisher's site
© The Author(s) 2020. In recent years, negative stiffness vibration isolation device with nonlinear characteristic has become an emerging research area and attracted a significant amount of attentions in the community due to the promising potentials it brought into the field. Its high-static-low-dynamic stiffness property endows the capacity to realize effective vibration isolation and in the meantime to maintain the system stability. This article presents a comprehensive review of the recent research and developments on negative stiffness vibration isolation device. It begins with an introduction on the concept of negative stiffness and then provides a summary and discussion regarding the realization and characteristics of negative stiffness vibration isolation device. The article places its special interest on the principles, structure design, and device characterisation of different types of negative stiffness vibration isolation devices, including spring type, pre-bucked beam type, magnetism type, geometrically nonlinear structural type, and composite structural type. Besides, the applications of negative stiffness vibration isolation device, as well as negative stiffness damper, are summarized and discussed based on the current state-of-the-art. Finally, the conclusions and further discussion provide highlights of the investigation.
Li, S, Tian, T, Wang, H, Li, Y, Li, J, Zhou, Y & Wu, J 2020, 'Development of a four-parameter phenomenological model for the nonlinear viscoelastic behaviour of magnetorheological gels', Materials & Design, pp. 108935-108935.View/Download from: Publisher's site
Li, S, Watterson, P, Li, Y, Wen, Q & Li, J 2020, 'Improved magnetic circuit analysis of a laminated magnetorheological elastomer devices featuring both permanent magnets and electromagnets', Smart Materials and Structures.View/Download from: Publisher's site
Tian, Z, Li, Y, Zheng, J & Wang, S 2019, 'A state-of-the-art on self-sensing concrete: Materials, fabrication and properties', Composites Part B: Engineering, vol. 177.View/Download from: Publisher's site
Wang, H, Li, Y, Zhang, G & Wang, J 2019, 'Effect of temperature on rheological properties of lithium-based magnetorheological grease', Smart Materials and Structures, vol. 28, no. 3.View/Download from: Publisher's site
© 2019 Zhang, Li, Wang and Wang. The paper tests the influence of mass fractions of carbonyl iron particles (CIPs) on the rheological properties of magnetorheological (MR) gels. Polyurethane-based MR gels with different weight fraction of CIPs, i.e., 40, 60, and 80%, were firstly prepared by mechanical mixing, respectively. The changes of shear stress and viscosity with shear rate under different magnetic flux density were tested and analyzed. It was found that the shear stress increases with mass fraction under magnetic flux density. The viscoelastic properties of MRGs were achieved by oscillatory shear measure. The effects of strain amplitude and frequency on viscoelastic of MRGs under different magnetic flux density were measured and analyzed. The study results shown that the elastic characteristics become more obvious with the increase of CIPs mass fraction. However, it has opposite effect on the viscous properties of materials.
Gu, X, Yu, Y, Li, Y, Li, J, Askari, M & Samali, B 2019, 'Experimental study of semi-active magnetorheological elastomer base isolation system using optimal neuro fuzzy logic control', Mechanical Systems and Signal Processing, vol. 119, pp. 380-398.View/Download from: Publisher's site
In this paper, a "smart" base isolation strategy is proposed in this study utilising a semi-active magnetorheological elastomer (MRE) isolator whose stiffness can be controlled in real-time and reversible fashion. By modulating the applied current, the horizontal stiffness of the MRE isolator can be controlled and thus the control action can be generated for the isolated structure. To overcome the inherent nonlinearity and hysteresis of the MRE isolator, radial basis function neural network based fuzzy logic control (RBF-NFLC) was developed due to its inherent robustness and capability in coping with uncertainties. The NFLC was optimised by a non-dominated sorting genetic algorithm type II (NSGA-II) for better suited fuzzy control rules as well as most appropriate parameters for the membership functions. To evaluate the effectiveness of the proposed smart base isolation system, four scenarios are tested under various historical earthquake excitations, i.e. bare building with no isolation, passive isolated structure, MRE isolated structure with Bang-Bang control, MRE isolated structure with proposed NFLC. A three-storey shear building model was adopted as the testing bed. Through the testing results, limited performance of passive isolation system was revealed. In contrast, the adaptability of the proposed isolation strategy was demonstrated and it is proven that the smart MRE base isolation system is able to provide satisfactory protection for both structural and non-structural elements of the system over a wide range of hazard dynamic loadings.
Li, Y & Li, J 2019, 'Overview of the development of smart base isolation system featuring magnetorheological elastomer', Smart structures and systems, vol. 24, no. 1, pp. 37-52.View/Download from: Publisher's site
Yu, Y, Li, J, Li, Y, Li, S, Li, H & Wang, W 2019, 'Comparative Investigation of Phenomenological Modeling for Hysteresis Responses of Magnetorheological Elastomer Devices.', International Journal of Molecular Sciences, vol. 20, no. 13.View/Download from: Publisher's site
Magnetorheological elastomer (MRE) is a type of magnetic soft material consisting of ferromagnetic particles embedded in a polymeric matrix. MRE-based devices have characteristics of adjustable stiffness and damping properties, and highly nonlinear and hysteretic force-displacement responses that are dependent on external excitations and applied magnetic fields. To effectively implement the devices in mitigating the hazard vibrations of structures, numerically traceable and computationally efficient models should be firstly developed to accurately present the unique behaviors of MREs, including the typical Payne effect and strain stiffening of rubbers etc. In this study, the up-to-date phenomenological models for describing hysteresis response of MRE devices are experimentally investigated. A prototype of MRE isolator is dynamically tested using a shaking table in the laboratory, and the tests are conducted based on displacement control using harmonic inputs with various loading frequencies, amplitudes and applied current levels. Then, the test results are used to identify the parameters of different phenomenological models for model performance evaluation. The procedure of model identification can be considered as solving a global minimization optimization problem, in which the fitness function is the root mean square error between the experimental data and the model prediction. The genetic algorithm (GA) is employed to solve the optimization problem for optimal model parameters due to its advantages of easy coding and fast convergence. Finally, several evaluation indices are adopted to compare the performances of different models, and the result shows that the improved LuGre friction model outperforms other models and has optimal accuracy in predicting the hysteresis response of the MRE device.
Yu, Y, Li, Y, Li, J & Gu, X 2019, 'Characterizing nonlinear oscillation behavior of an MRF variable rotational stiffness device', SMART STRUCTURES AND SYSTEMS, vol. 24, no. 3, pp. 303-317.View/Download from: Publisher's site
Zheng, J, Li, Y, Hu, M, Wen, J, Wang, J & Kan, J 2018, 'Feasibility study of a miniaturized magnetorhological grease timing trigger as safety and arming device for spinning projectile', Smart Materials and Structures, vol. 27, no. 11.View/Download from: Publisher's site
Safety and arming (S&A) device is to keep the fuze for projectile unarmed during shipping, handling and storage, while arming the firing section at a proper time via sensing external conditions such as pressure, position, etc. With the increasing need for smaller S&A devices, miniature design with a compact configuration and high reliability is on demand. This paper proposes a miniaturized timing trigger as S&A device for a spinning projectile by utilizing the "locking" and "unlocking" properties of magnetorheological (MR) grease with/without the presence of magnetic field. The design and arming mechanism of the timing trigger are firstly introduced in which the MR grease is locked by a magnetic field generated by two permanent magnets (PMs). Under sufficient firing acceleration, the PMs disengage to unlock the contraction flow of MR grease, which enables its triggering function. A theoretical analysis was conducted to interpolate the delayed time against the geometry of the device, shear/extensional characteristics of MR grease and the spinning rate of a projectile. A series of tests have been conducted to measure the delayed times by tuning the physical parameters, including particle concentration, spinning rate and orifice diameter, etc. The experimental results showed that this theoretical model is capable of well calculating the delayed time of MR grease timing trigger.
Zheng, J, Li, Y, Wang, J, Shiju, E & Li, X 2018, 'Accelerated thermal aging of grease-based magnetorheological fluids and their lifetime prediction', MATERIALS RESEARCH EXPRESS, vol. 5, no. 8.View/Download from: Publisher's site
Chen, X, Li, Y, Li, J & Gu, X 2018, 'A dual-loop adaptive control for minimizing time response delay in real-time structural vibration control with magnetorheological (MR) devices', Smart Materials and Structures, vol. 27, no. 1, pp. 1-20.View/Download from: Publisher's site
Time delay is a challenge issue faced by the real-time control application of the magnetorheological (MR) devices. Not to deal with it properly may jeopardize the effectiveness of the control, even lead to instability of the control system or catastrophic failure. This paper proposes a dual-loop adaptive control to address the response time delay associated with MR devices. In the proposed dual-loop control, the inner loop is designed to compensate the time delay of MR device induced by the PWM current driver. While the outer loop control can be any structural control algorithm with aims to reducing structural responses of a building during extreme loadings. Here an adaptive control strategy is adopted. To verify the proposed dual-loop control, a smart base isolation system employing magnetorheological elastomer base isolators is used as an example to illustrate the control effect. Numerical study is then conducted using a 5 -storey shear building model equipped with smart base isolation system. The result shows that with the implementation of the inner loop, the control current can instantly follow the control command which reduce the possibility of instability caused by the time delay. Comparative studies are conducted between three control strategies, i.e. dual-loop control, Lyapunov's direct method based control and optimal passive base isolation control. The results of the study have demonstrated that the proposed dual-loop control strategy can achieve much better performance than the other two control strategies.
Yu, Y, Li, Y, Li, J, Gu, X & Royel, S 2018, 'Nonlinear Characterization of the MRE Isolator using Binary-Coded Discrete CSO and ELM', International Journal of Structural Stability and Dynamics, vol. 18, no. 8.View/Download from: Publisher's site
© 2018 World Scientific Publishing Company Magnetorheological elastomer (MRE) isolator has been proved as a promising semi-active control device for structural vibration control. For its engineering application, developing an accurate and robust model is definitely necessary and also a challenging task. Most of the present models, belonging to parametric models, need to identify various model parameters and sometimes are not capable of perfectly capturing the unique characteristics of the device. In this work, a novel nonparametric model is proposed to characterize the inherent dynamics of the MRE isolator with the features of hysteresis and nonlinearity. Initially, dynamic tests are conducted to evaluate the performance of the isolator under various loading conditions, including harmonic, random, and seismic excitations. Then, on the basis of the captured experimental results, a hybrid learning method is designed to forecast the nonlinear responses of the device with known external inputs. In this method, a type of single hidden layer feed-forward network, called extreme learning machine (ELM), is developed to forecast the nonlinear responses (shear force) of the device with captured velocity, displacement, and current level. To obtain optimal performance of the developed model, an improved binary-coded discrete cat swarm optimization (BCDCSO) method is adopted to select optimal inputs and neuron number in the hidden layer for the network development. The performance of the proposed method is verified through the comparison between experimental results and model predictions. Due to the noise influence in the practical condition, the robustness of the proposed method is also validated via adding noise disturbance into the supplying currents. The results show that the proposed method outperforms the standard ELM in terms of characterization of the MRE isolator, even though the captured responses are polluted with external measurement noises.
Du, G, Huang, X, Li, Y, Ouyang, Q & Wang, J 2017, 'Performance of Semi-active/Passive Integrated Isolator based on Magnetorheological Elastomer and Spring', Smart Materials and Structures, vol. 26, no. 9.View/Download from: Publisher's site
This paper reports an investigation on a semi-active/passive integrated vibration isolator utilizing a magnetorheological elastomer (MRE) and spring. To overcome the main shortcoming of passive isolation systems, i.e. lack of adaptability, the semi-active/passive integrated isolator (SAPII) based on an MRE and spring is designed and prototyped. The magnetic circuit is optimized by finite element analysis to fully unlock the unique features of the MRE. The dynamic response characteristic of the SAPII is experimentally investigated under a sweep frequency test. A dynamic model of the SAPII vibration isolation system is established on the basis of the Kelvin model. The model parameters, such as equivalent stiffness and equivalent damping, are identified from experimental data. An ON-OFF control law based on the minimal displacement transmissibility is designed for isolation control of the sinusoid excitation. Two control laws, i.e. ON-OFF control and fuzzy logic control, are designed for vibration isolation of random excitation. Finally, the effectiveness of these control laws is verified by numerical simulation and experiment.
Zheng, J, Li, Y & Wang, J 2017, 'Design and multi-physics optimization of a novel magnetorheological damper with a variable resistance gap', Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, vol. 231, no. 17.View/Download from: Publisher's site
This paper presents the design and multi-physics optimization of a novel multi-coil magnetorheological (MR) damper with a variable resistance gap (VRG-MMD). Enabling four electromagnetic coils (EMs) with individual exciting currents, a simplified magnetic equivalent circuit was presented and the magnetic flux generated by each voltage source passing through each active gap was calculated as vector operations. To design the optimal geometry of the VRG-MMD, the multi-physics optimization problem including electromagnetics and fluid dynamics has been formulated as a multi-objective function with weighting ratios among total damping force, dynamic range, and inductive time constant. Based on the selected design variables (DVs), six cases with different weighting ratios were optimized using Bound Optimization BY Quadratic Approximation (BOBYQA) technique. Finally, the vibration performance of the optimal VRG-MMD subjected to sinusoidal and triangle displacement excitations was compared to that of the typical multi-coil MR damper.
Gu, X, Yu, Y, Li, J & Li, Y 2017, 'Semi-active control of magnetorheological elastomer base isolation system utilising learning-based inverse model', Journal of Sound and Vibration, vol. 406, pp. 346-362.View/Download from: Publisher's site
© 2017 Magnetorheological elastomer (MRE) base isolations have attracted considerable attention over the last two decades thanks to its self-adaptability and high-authority controllability in semi-active control realm. Due to the inherent nonlinearity and hysteresis of the devices, it is challenging to obtain a reasonably complicated mathematical model to describe the inverse dynamics of MRE base isolators and hence to realise control synthesis of the MRE base isolation system. Two aims have been achieved in this paper: i) development of an inverse model for MRE base isolator based on optimal general regression neural network (GRNN); ii) numerical and experimental validation of a real-time semi-active controlled MRE base isolation system utilising LQR controller and GRNN inverse model. The superiority of GRNN inverse model lays in fewer input variables requirement, faster training process and prompt calculation response, which makes it suitable for online training and real-time control. The control system is integrated with a three-storey shear building model and control performance of the MRE base isolation system is compared with bare building, passive-on isolation system and passive-off isolation system. Testing results show that the proposed GRNN inverse model is able to reproduce desired control force accurately and the MRE base isolation system can effectively suppress the structural responses when compared to the passive isolation system.
Ahamed, R, Ferdaus, MM & Li, Y 2016, 'Advancement in energy harvesting magneto-rheological fluid damper: A review', Korea-Australia Rheology Journal, vol. 28, no. 4, pp. 355-379.View/Download from: Publisher's site
In this paper, a comprehensive review of the present literature on energy generated magnetorheological (MR) fluid based damper, modeling and applications of the MR damper are presented. The review starts with an introduction of the basic of MR fluid and their different modes, consequences with different types of MR fluids based devices, and their relevant applications. Besides, various forms of MR damper and its applications are presented. Following this, the modeling of the MR fluids and the modeling of the MR fluid based damper are deliberated according to arrangement and configurations. Finally, the review ends with the design and advancement issues, performance analysis matters, and analytical modeling of energy generated magnetorheological fluid damper systems.
Ubaidillah, U, Imaduddin, F, Li, Y, Mazlan, SA, Sutrisno, J, Koga, T, Yahya, I & Choi, S-B 2016, 'A new class of magnetorheological elastomers based on waste tire rubber and the characterization of their properties', Smart Materials and Structures, vol. 25, no. 11.View/Download from: Publisher's site
This paper proposes a new type of magnetorheological elastomer (MRE) using rubber from waste tires and describes its performance characteristics. In this work, scrap tires were utilized as a primary matrix for the MRE without incorporation of virgin elastomers. The synthesis of the scrap tire based MRE adopted a high-temperature high-pressure sintering technique to achieve the reclaiming of vulcanized rubber. The material properties of the MRE samples were investigated through physical and viscoelastic examinations. The physical tests confirmed several material characteristics—microstructure, magnetic, and thermal properties–while the viscoelastic examination was conducted with a laboratory-made dynamic compression apparatus. It was observed from the viscoelastic examination that the proposed MRE has magnetic-field-dependent properties of the storage modulus, loss modulus, and loss tangent at different excitation frequencies and strain amplitudes. Specifically, the synthesized MRE showed a high zero field modulus, a reasonable MR effect under maximum applied current, and remarkable damping properties.
Zheng, J, Ouyang, Q, Li, Z, Li, Y & Wang, J 2016, 'Experimental analysis of separately controlled multi-coils on the performance of magnetorheological absorber under impact loading', Journal of Intelligent Material Systems and Structures, vol. 27, no. 7, pp. 887-897.View/Download from: Publisher's site
A magnetorheological absorber is capable of actively adapting any gun recoil condition by means of controlled Coulomb force. The objective of multi-coil magnetorheological absorber with individual input currents is to mitigate the peak force transferred to the buffer structure during bullet firing, and thus to increase the structural fatigue life. This article
investigates various cases by applying random combinations of input currents to the magnetic coils. The impact tests were conducted by obtaining and analyzing the force, displacement, and velocity. As a reference, input currents with equivalent magnitude are considered statistically, in terms of average peak force and occurrence time. The experimental results show that separately controlled multi-coils contribute to the magnitude and occurrence time of peak force significantly. Furthermore, to reduce peak forces, a simple open-loop control strategy was proposed and validated effectively by the experimental results.
Chen, X, Li, J, Li, Y & Gu, X 2016, 'Lyapunov-based Semi-active Control of Adaptive Base Isolation System employing Magnetorheological Elastomer base isolators', Earthquake and Structures, vol. 11, no. 6, pp. 1077-1099.View/Download from: Publisher's site
One of the main shortcomings in the current passive base isolation system is lack of adaptability. The recent research and development of a novel adaptive seismic isolator based on magnetorheological elastomer (MRE) material has created an opportunity to add adaptability to base isolation systems for civil structures. The new MRE based base isolator is able to significantly alter its shear modulus or lateral stiffness with the applied magnetic field or electric current, which makes it a competitive candidate to develop an adaptive base isolation system. This paper aims at exploring suitable control algorithms for such adaptive base isolation system by developing a close-loop semi-active control system for a building structure equipped with MRE base isolators. The MRE base isolator is simulated by a numerical model derived from experimental characterization based on the Bouc-Wen Model, which is able to describe the forcedisplacement response of the device accurately. The parameters of Bouc-Wen Model such as the stiffness and the damping coefficients are described as functions of the applied current. The state-space model is built by analyzing the dynamic property of the structure embedded with MRE base isolators. A Lyapunov-based controller is designed to adaptively vary the current applied to MRE base isolator to suppress the quakeinduced vibrations. The proposed control method is applied to a widely used benchmark base-isolated structure by numerical simulation. The performance of the adaptive base isolation system was evaluated through comparison with optimal passive base isolation system and a passive base isolation system with optimized base shear. It is concluded that the adaptive base isolation system with proposed Lyapunov-based semi-active control surpasses the performance of other two passive systems in protecting the civil structures under seismic events.
Gu, X, Li, J, Li, Y & Askari, M 2016, 'Frequency control of smart base isolation system employing a novel adaptive magneto-rheological elastomer base isolator', Journal of Intelligent Material Systems and Structures, vol. 27, no. 7, pp. 849-858.View/Download from: Publisher's site
In the past decades, base isolation techniques have become increasingly popular for seismic protection of civil structures owing to its capability of decoupling buildings from harmful ground motion. However, it has been recognised recently that the traditional passive base isolation technique could encounter a serious problem during earthquakes due its incapability in adjusting the isolation frequency to cope with the unpredictability and diversity of earthquakes. To address this challenge, a great deal of research efforts have been conducted to improve traditional base isolation systems, most of which focused on hybrid supplementary devices (passive, active and semi-active types) for the isolators to control displacement or to dissipate seismic energy. On the other hand, the most effective approach to address the aforementioned challenge should lay on varying isolator stiffness in real-time to achieve real-time spontaneous decoupling. A recent advance of the development of an adaptive magneto-rheological elastomer base isolator has brought such idea to reality as the new magneto-rheological elastomer base isolator is capable to alter its stiffness significantly in real-time. In this article, an innovative smart base isolation system employing such magneto-rheological elastomer isolator is proposed and a novel frequency control algorithm is developed to shift the fundamental frequency of the structure away from the dominant frequency range of earthquakes. Such design enables the building to avoid resonant state in real-time according to the on-coming spectrum of the earthquakes. Extensive simulation has been conducted using a five-storey benchmark model with the isolation system, and testing results indicate that the proposed control system is able to significantly suppress both the floor accelerations and inter-storey drifts simultaneously under different earthquakes.
Gu, X, Li, Y & Li, J 2016, 'Investigations on response time of magnetorheological elastomer isolator for real-time control implementation', Smart Materials and Structures, vol. 25, no. 11.View/Download from: Publisher's site
Utilising the unique features of MRE materials for vibration isolators has been intensively studied over the last several years. Real-time control of the MRE isolators holds the key to unlock MRE materials' unique characteristics, i.e. instantly changeable shear modulus in continuous and reverse fashion. However, one of the critical issues for the applications of real-time control is the response time delay of MRE vibration isolators, which has not yet been fully addressed and studied. This paper identified the inherent response time of the MRE isolator and explored two feasible approaches to minimise the response time delay. Experiments were designed and conducted to evaluate the effectiveness of the proposed approaches on minimising time delay on: (i) the transient response of current of a large coil that generates magnetic field and (ii) the transient response of shear force from the MRE isolator. The results show that the proposed approaches are effective and promising. For example, the proposed approach is able to reduce the force response time from 421 ms to 52 ms at rising and from 400 ms to 48 ms falling edges respectively. Such level of short response time of the MRE isolators demonstrates the feasibility of application of real-time control and hence is the essential step on the realisation of real-time control of vibration suppression system based on MRE isolator.
Gu, X, Yu, Y, Li, J, Li, Y & Alamdari, M 2016, 'Semi-active storey isolation system employing MRE isolator with parameter identification based on NSGA-II with DCD', Earthquake and Structures, vol. 11, no. 6, pp. 1101-1121.View/Download from: Publisher's site
Base isolation, one of the popular seismic protection approaches proven to be effective in practical applications, has been widely applied worldwide during the past few decades. As the techniques mature, it has been recognised that, the biggest issue faced in base isolation technique is the challenge of great base displacement demand, which leads to the potential of overturning of the structure, instability and permanent damage of the isolators. Meanwhile, drain, ventilation and regular maintenance at the base isolation level are quite difficult and rather time- and fund- consuming, especially in the highly populated areas. To address these challenges, a number of efforts have been dedicated to propose new isolation systems, including segmental building, additional storey isolation (ASI) and mid-storey isolation system, etc. However, such techniques have their own flaws, among which whipping effect is the most obvious one. Moreover, due to their inherent passive nature, all these techniques, including traditional base isolation system, show incapability to cope with the unpredictable and diverse nature of earthquakes. The solution for the aforementioned challenge is to develop an innovative vibration isolation system to realise variable structural stiffness to maximise the adaptability and controllability of the system. Recently, advances on the development of an adaptive magneto-rheological elastomer (MRE) vibration isolator has enlightened the development of adaptive base isolation systems due to its ability to alter stiffness by changing applied electrical current. In this study, an innovative semi-active storey isolation system inserting such novel MRE isolators between each floor is proposed. The stiffness of each level in the proposed isolation system can thus be changed according to characteristics of the MRE isolators. Nondominated sorting genetic algorithm type II (NSGA-II) with dynamic crowding distance (DCD) is utilised for the optimisation of the para...
Pokhrel, A, Li, J, Li, Y, Maksis, N & Yu, Y 2016, 'Comparative Studies of Base Isolation Systems featured with Lead Rubber Bearings and Friction Pendulum Bearings', Applied Mechanics and Materials, vol. 846, pp. 114-119.View/Download from: Publisher's site
Due to the fact that safety is the major concern for civil structures in a seismic active
zone, it has always been a challenge for structural engineers to protect structures from earthquake.
During past several decades base isolation technique has become more and more popular in the
field of seismic protection which can be adopted for new structures as well as the retrofit of existing
structures. The objective of this study is to evaluate the behaviours of the building with different
seismic isolation systems in terms of roof acceleration, elastic base shear and inter-storey drift
under four benchmark earthquakes, namely, El Centro, Northridge, Hachinohe and Kobe
earthquakes. Firstly, the design of base isolation systems, i.e. lead rubber bearing (LRB) and
friction pendulum bearing (FPB) for five storey RC building was introduced in detail. The nonlinear
time history analysis was performed in order to determine the structural responses whereas
Bouc-Wen Model of hysteresis was adopted for modelling the bilinear behaviour of the bearings.
Both isolation systems increase the fundamental period of structures and reduces the spectral
acceleration, and hence reduces the lateral force cause by earthquake in the structures, resulting in
significant improvement in building performance; however the Lead Rubber Bearing provided the
best reduction in elastic base shear and inter-storey drift (at first floor) for most of the benchmark
earthquakes. For the adopted bearing characteristics, FPB provided the low isolator displacement.
Yu, Y, Li, Y, Li, J & Gu, X 2016, 'A hysteresis model for dynamic behaviour of magnetorheological elastomer base isolator', Smart Materials and Structures, vol. 25, no. 5, pp. 1-15.View/Download from: Publisher's site
In recent years, an adaptively tuned magnetorheological elastomer (MRE) isolator for a base isolation system has been designed and tested with the benefits of low power cost, fail safe manner and fast responses. To make full use of this striking device for design of smart structures, a highly precise model should be developed to effectively and accurately forecast the shear force of the device in real-time so as to adopt a proper control strategy to improve the responses of the protected structures. In this work, a novel mechanical model is presented to characterize this nonlinear hysteresis for its implementation in structural vibration control. This model employs the displacement and velocity of the device as well as the applied current as the inputs and just has the limited constant parameters to be identified compared with some classical hysteretic models such as Bouc–Wen, improved Dahl and LuGre models. Performance evaluation of this novel hysteresis model has been conducted based on the testing data from an MRE base isolator. The results show that the proposed model has high modelling accuracy and is able to perfectly portray the unique and complicated behaviours of the device with various excitations.
Yu, Y, Li, Y, Li, J & Gu, X 2016, 'Self-adaptive step fruit fly algorithm optimized support vector regression model for dynamic response prediction of magnetorheological elastomer base isolator', Neurocomputing, vol. 211, pp. 41-52.View/Download from: Publisher's site
Parameter optimization of support vector regression (SVR) plays a challenging role in improving the generalization ability of machine learning. Fruit fly optimization algorithm (FFOA) is a recently developed swarm optimization algorithm for complicated multi-objective optimization problems and is also suitable for optimizing SVR parameters. In this work, parameter optimization in SVR using FFOA is investigated. In view of problems of premature and local optimum in FFOA, an improved FFOA algorithm based on self-adaptive step update strategy (SSFFOA) is presented to obtain the optimal SVR model. Moreover, the proposed method is utilized to characterize magnetorheological elastomer (MRE) base isolator, a typical hysteresis device. In this application, the obtained displacement, velocity and current level are used as SVR inputs while the output is the shear force response of the device. Experimental testing of the isolator with two types of excitations is applied for model performance evaluation. The results demonstrate that the proposed SSFFOA-optimized SVR (SSFFOA_SVR) has perfect generalization ability and more accurate prediction accuracy than other machine learning models, and it is a suitable and effective method to predict the dynamic behaviour of MRE isolator.
Yu, Y, Li, Y, Li, J, Gu, X, Royel, S & Pokhrel, A 2016, 'Nonlinear and hysteretic modelling of magnetorheological elastomer base isolator using adaptive neuro-fuzzy inference system', Applied Mechanics and Materials, vol. 846, pp. 258-263.View/Download from: Publisher's site
Magnetorheological elastomer (MRE) base isolator is a semi-active control device which has currently obtained increasing attention in the field of vibration control of civil structures. However, the inherent nonlinear and hysteretic response of the device is regarded as a challenge
aspect for using the smart device to realize the high performance. Therefore, an accurate and robust
model is essential to make full use of these unique features for its engineering applications. In this
paper, to solve this issue, adaptive neuro-fuzzy inference system (ANFIS) is utilized to characterize
the dynamic behavior of the device. In this proposed model, the inputs are historical displacements
and applied current of the device while the output is the shear force generated. To validate its forecast performance, the ANFIS model is also compared with some conventional models. Finally, the result verifies that ANFIS has the best perfection ability among existing MRE-based device models.
Ha, Q, Sayed, R, Li, J & Li, Y 2016, 'Hysteresis Modeling of Smart Structure MR Devices using Describing Functions', IEEE-ASME Transactions on Mechatronics, vol. 21, no. 1, pp. 44-50.View/Download from: Publisher's site
Magneto-rheological (MR) devices have been quite promising for semi-active control thanks to their capability of adjusting structural parameters, under a low-power control signal, to effectively withstand severe dynamic loadings including seismic events. MR devices, using visco-elastic and ferromagnetic materials, are subject to hysteresis, which may degrade the performance of smart structures. Therefore, this multi-valued nonlinearity needs to be properly modelled and characterized for control and health monitoring. As engineering structures operate as low-pass filter in normal conditions, it is suitable to use the classical describing function (DF) method for modelling and analysis of the hysteretic behaviors in MR device-based smart structures. Data obtained from characterizing tests are recorded in look-up tables to obtain the DFs for these devices, using a curve-fitting technique. The proposed DFs are then useful in structural frequency analysis. Experimental results are reported for a steel beam with MR pin joints subject to quake-induced vibrations provided by a shake table.
Yu, Y, Royel, S, Li, J, Li, Y & Ha, Q 2016, 'Magnetorheological elastomer base isolator for earthquake response mitigation on building structures: modeling and second-order sliding mode control', Earthquake and Structures, vol. 11, no. 6, pp. 943-966.View/Download from: Publisher's site
Recently, magnetorheological elastomer (MRE) material and its devices have been developed and attracted a good deal of attention for their potentials in vibration control. Among them, a highly adaptive base isolator based on MRE was designed, fabricated and tested for real-time adaptive control of base isolated structures against a suite of earthquakes. To perfectly take advantage of this new device, an accurate and robust model should be built to characterize its nonlinearity and hysteresis for its application in structural control. This paper first proposes a novel hysteresis model, in which a nonlinear hyperbolic sine function spring is used to portray the strain stiffening phenomenon and a Voigt component is incorporated in parallel to describe the solid-material behaviours. Then the fruit fly optimization algorithm (FFOA) is employed for model parameter identification using testing data of shear force, displacement and velocity obtained from different loading conditions. The relationships between model parameters and applied current are also explored to obtain a current-dependent generalized model for the control application. Based on the proposed model of MRE base isolator, a second-order sliding mode controller is designed and applied to the device to provide a real-time feedback control of smart structures. The performance of the proposed technique is evaluated in simulation through utilizing a three-storey benchmark building model under four benchmark earthquake excitations. The results verify the effectiveness of the proposed current-dependent model and corresponding controller for semi-active control of MRE base isolator incorporated smart structures.
Zheng, J, Li, Y, Li, Z & Wang, J 2015, 'Transient multi-physics analysis of a magnetorheological shock absorber with the inverse Jiles-Atherton hysteresis model', Smart Materials and Structures, vol. 24, no. 10.View/Download from: Publisher's site
This paper presents multi-physics modeling of an MR absorber considering the magnetic hysteresis to capture the nonlinear relationship between the applied current and the generated force under impact loading. The magnetic field, temperature field, and fluid dynamics are represented by the Maxwell equations, conjugate heat transfer equations, and Navier?Stokes equations. These fields are coupled through the apparent viscosity and the magnetic force, both of which in turn depend on the magnetic flux density and the temperature. Based on a parametric study, an inverse Jiles?Atherton hysteresis model is used and implemented for the magnetic field simulation. The temperature rise of the MR fluid in the annular gap caused by core loss (i.e. eddy current loss and hysteresis loss) and fluid motion is computed to investigate the current?force behavior. A group of impulsive tests was performed for the manufactured MR absorber with step exciting currents. The numerical and experimental results showed good agreement, which validates the effectiveness of the proposed multi-physics FEA model.
Zheng, J, Wang, X, Ouyang, Q, Li, Y & Wang, J 2015, 'Modeling and characterization of novel magnetorheological (MR) cell with individual currents', Journal of Central South University, vol. 22, no. 7, pp. 2557-2567.View/Download from: Publisher's site
Jiang, X, Wang, J, Li, Y, Li, J & Yao, J 2015, 'Energy harvesting for powering wireless sensor networks in low-frequency and large-force environments', PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE, vol. 229, no. 11, pp. 1953-1964.View/Download from: Publisher's site
Li, Y & Li, J 2015, 'A Highly-Adjustable Base Isolator Utilizing Magnetorheological Elastomer: Experimental Testing and Modeling', Journal of Vibration and acoustics -Transactions of the ASME, vol. 137, no. 1.View/Download from: Publisher's site
This paper presents a recent research advance on the development of a novel adaptive seismic isolation system to be used in seismic protection of civil structures. A highly-adjustable laminated magneto-rheological elastomer (MRE) base isolator was developed and experimental results show that the prototypical MRE base isolator provides amazing increase of lateral stiffness up to1630%. To facilitate the structural control development using such adaptive MRE base isolator, an analytical model was developed to simulate its behaviors. Comparison between the analytical model and experimental data proves the effectiveness of such model in reproducing the behavior of MRE base isolator.
Li, Y & Li, J 2015, 'Finite element design and analysis of adaptive base isolator utilizing laminated multiple magnetorheological elastomer layers', Journal of Intelligent Material Systems and Structures, vol. 26, no. 14, pp. 1861-1870.View/Download from: Publisher's site
Available magnetorheological elastomer devices normally consist one to two layers of small-size magnetorheological elastomer materials. To be used in large-scale structures, magnetorheological elastomer devices with multiple larger magnetorheological elastomer materials are expected. This article addresses the critical issue in designing a large-scale device with multiple layers of low magnetic conductive magnetorheological elastomer materials, that is, magnetic circuit
design. The primary target in magnetic circuit design for magnetorheological elastomer devices is to provide sufficient and uniform magnetic field to all magnetorheological elastomer layers in the device. In this article, finite element investigations are conducted. An innovative magnetic circuit design is proposed for magnetorheological elastomer base isolator with multi-layer of magnetorheological elastomer materials. In the design, laminated magnetorheological elastomer and
steel structure is adopted as part of the magnetic core together with two steel blocks. Cylindrical steel tube is used as the yoke of the magnetic circuit. Two plates are placed on the top and bottom of the device to form enclosed magnetic path in the device. Finite element results showed that such innovative magnetic design is able to provide sufficient and uniform magnetic field to all magnetorheological elastomer layers, that is, 25 magnetorheological elastomer layers with thickness of 1 mm and diameter of 120 mm in this case. Finally, the influence of lateral deformation of the magnetorheological elastomer base isolator on the magnetic field is investigated. It is found that the magnetic field in magnetorheological elastomer materials deteriorates when the deformation of the device increases.
Yu, Y, Li, Y & Li, J 2015, 'Forecasting hysteresis behaviours of magnetorheological elastomer base isolator utilizing a hybrid model based on support vector regression and improved particle swarm optimization', Smart Materials and Structures, vol. 24, no. 3, pp. 1-15.View/Download from: Publisher's site
Due to its inherent hysteretic characteristics, the main challenge for the application of a magnetorheological elastomer- (MRE) based isolator is the exploitation of the accurate model, which could fully describe its unique behaviour. This paper proposes a nonparametric model for a MRE-based isolator based on support vector regression (SVR). The trained identification model is to forecast the shear force of the MRE-based isolator online; thus, the dynamic response from the MRE-based isolator can be well captured. In order to improve the forecast capacity of the model, a type of improved particle swarm optimization (IPSO) is employed to optimize the parameters in SVR. Eventually, the trained model is applied to the MRE-based isolator modelling with testing data. The results indicate that the proposed hybrid model has a better generalization capacity and better recognition accuracy than other conventional models, and it is an effective and suitable approach for forecasting the behaviours of a MRE-based isolator.
Yu, Y, Li, Y & Li, J 2015, 'Nonparametric modeling of magnetorheological elastomer base isolator based on artificial neural network optimized by ant colony algorithm', Journal of Intelligent Material Systems and Structures, vol. 26, no. 14, pp. 1789-1798.View/Download from: Publisher's site
Laminated magnetorheological elastomer base isolator is regarded as one of the most promising candidates for realizing adaptive base isolation for civil structures. However, the intrinsic hysteretic and nonlinear behavior of magnetorheological elastomer base isolators imposes challenge for adopting the device to accomplish high-accuracy performance in structural control. Therefore, it is essential to develop an accurate model for symbolizing this unique characteristic before designing a feedback controller. So far, some classical parametric models, such as Bouc–Wen, Dahl, and LuGre, have been proposed to depict the hysteretic response of magnetorheological devices, that is, magnetorheological damper, which may also be used for describing the nonlinear behavior of magnetorheological elastomer base isolator. However, the parameter identification is difficult to implement due to the nonlinear differential equations existing in these models. Considering this problem, this article proposes a nonparametric model, that is, an artificial neural network–based model with 3 input neurons, 18 hidden neurons, and 1 output neuron, to predict the magnetorheological elastomer isolator behavior. In this model, the ant colony algorithm is employed for model training to obtain the optimal weights based on the force–displacement/velocity data sampled from the magnetorheological elastomer isolator. Finally, experimental data are used to validate the effectiveness of the proposed artificial neural network–based model with the good forecasting results.
Yu, Y, Li, Y & Li, J 2015, 'Parameter identification and sensitivity analysis of an improved LuGre friction model for magnetorheological elastomer base isolator', Meccanica, vol. 50, no. 11, pp. 2691-2707.View/Download from: Publisher's site
The recently designed magnetorheological elastomer (MRE) base isolator can provide a fast change in the shear modulus and damping property, which makes it as an ideal device for the semi-active control in buildings and bridges. Previous studies show that this new device is featured with its nonlinear and hysteretic responses, and it is necessary to sufficiently understand its behaviour when adopting this device in operation connected with a control system. Although there are several models presented to predict the hysteresis of MRE base isolator, they are always suffered from some application limitations. To better interpret this complicated feature of the device, this work presents an improved LuGre friction model, which has been successfully used in modelling other magnetorheological (MR) device i.e. MR damper. In addition, an improved fruit fly optimization algorithm (IFFOA) is also proposed to identify the model parameters. In the improved algorithm, a transfer factor based on a self-adaptive step is added together with a three-dimensional searching space. This improvement can enhance the convergence rate of the algorithm and avoid falling into the local optimum. Furthermore, to reduce the complexity of the model, the local and global parameter sensitivity analyses are conducted for model simplification. Eventually, the experimental measurements of device displacement, velocity and shear force are used to evaluate the performance of the proposed model and IFFOA.
Yu, Y, Li, Y & Li, J 2015, 'Parameter identification of a novel strain stiffening model for magnetorheological elastomer base isolator utilizing enhanced particle swarm optimization', Journal of Intelligent Material Systems and Structures, vol. 26, no. 18, pp. 2446-2462.View/Download from: Publisher's site
This article presents a novel model to describe the nonlinear relationships between shear force and displacement/velocity in a magnetorheological elastomer base isolator. The proposed model, containing a strain stiffening element, is able to portray the distinct dynamic behaviors of magnetorheological elastomer base isolator. To identify the model parameters, an enhanced particle swarm optimization is used on force–displacement/velocity data sampled under different loading conditions. In this algorithm, a self-adaptive inertia weight replaces the general linear weight, enhancing the convergence rate of iteration process. Besides, the mutation operator in genetic algorithm is adopted for finding global optimum. Testing data of the device displacement, velocity and force from magnetorheological elastomer base isolator are utilized to validate the proposed model and corresponding parameter identification algorithm.
Jiang, X, Li, Y, Li, J, Wang, J & Yao, J 2014, 'Piezoelectric energy harvesting from traffic-induced pavement vibrations', Journal of Renewable and Sustainable Energy, vol. 6.View/Download from: Publisher's site
This paper focuses on the development and experimental testing of a potential clean energy source for powering the remote equipment used in transportation infrastructure. Traditional power sources (i.e., power cables and batteries) are excessively expensive or infeasible in this type of application. A compression-based roadway energy harvester has been developed that can be embedded into pavement to scavenge electrical energy from traffic-induced vibrations. The proposed roadway harvester employs a group of piezoelectric harvesting units to convert traffic-induced vibrations into electrical energy, and each single harvesting unit contains three piezoelectric multilayer stacks. According to the linear theory of piezoelasticity, a two-degree-of-freedom electromechanical model of the piezoelectric harvesting unit was developed to characterize its performance in generating electrical energy under external excitations. Experimental testing in the laboratory was conducted to investigate the output power properties of the harvesting unit and shows good agreement with the theoretical analysis. Based on the testing results of the harvesting unit, the capability of the proposed roadway harvester has been theoretically evaluated and demonstrated that it has the ability to generate sufficient energy for driving common electrical equipment used in transportation infrastructure.
Jiang, X, Li, Y, Wang, J & Li, J 2014, 'Electromechanical modeling and experimental analysis of a compression-based piezoelectric vibration energy harvester', International Journal of Smart and Nano Materials, vol. 5, no. 3, pp. 152-152.View/Download from: Publisher's site
Over the past few decades, wireless sensor networks have been widely used in the field of structure health monitoring of civil, mechanical, and aerospace systems. Currently, most wireless sensor networks are battery-powered and it is costly and unsustainable for maintenance because of the requirement for frequent battery replacements. As an attempt to address such issue, this article theoretically and experimentally studies a compression-based piezoelectric energy harvester using a multilayer stack configuration, which is suitable for civil infrastructure system applications where large compressive loads occur, such as heavily vehicular loading acting on pavements. In this article, we firstly present analytical and numerical modeling of the piezoelectric multilayer stack under axial compressive loading, which is based on the linear theory of piezoelectricity. A two-degree-of-freedom electromechanical model, considering both the mechanical and electrical aspects of the proposed harvester, was developed to characterize the harvested electrical power under the external electrical load. Exact closed-form expressions of the electromechanical models have been derived to analyze the mechanical and electrical properties of the proposed harvester. The theoretical analyses are validated through several experiments for a test prototype under harmonic excitations. The test results exhibit very good agreement with the analytical analyses and numerical simulations for a range of resistive loads and input excitation levels.
Jiang, X, Wang, J, Li, Y & Li, J 2014, 'Design and modelling of a novel linear electromagnetic vibration energy harvester', International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 2, pp. 165-183.View/Download from: Publisher's site
This paper presents the design and evaluation of a novel permanent magnet (PM) energy harvesting system for scavenging electrical energy from ambient vibrations. A two-phase tubular linear PM vibration energy harvester consisting of a mover attached with permanent magnets and a slotted stator with built-in two-phase electromagnetic coils is proposed to convert vibrational kinetic energy into electrical energy. Aiming at maximizing the efficiency of vibration-to-electrical energy conversion under designated vibration and limited space requirement, a systematic research, including innovative device design, theoretical modelling and analysis, and finite element evaluation on the PM vibration energy harvester will be presented in this paper. In addition, the methodology of winding the two-phase coils in slotted stator is explicated in order to fully utilize the harvested electrical energy. A two-phase rectifier circuit is developed to convert the alternative voltage generated by the PM harvester into DC voltage that can be used directly by the external resistive load. Simulation results indicate that the proposed linear PM vibration energy harvesting system is able to generate about 100 watt DC electrical power under the vibration with the velocity of 0.4 m/s and the output electrical power is proportional to the levels of vibration excitations.
Li, Y & Li, J 2014, 'Dynamic characteristics of a magnetorheological pin joint for civil structures', Frontiers of Mechanical Engineering, vol. 9, no. 1, pp. 15-33.View/Download from: Publisher's site
Magnetorheological (MR) pin joint is a novel device in which its joint moment resistance can be controlled in real-time by altering the applied magnetic field. The smart pin joint is intended to be used as a controllable connector between the columns and beams of a civil structure to instantaneously shift the structural natural frequencies in order to avoid resonance and therefore to reduce unwanted vibrations and hence prevent structural damage. As an intrinsically nonlinear device, modelling of this MR fluid based device is a challenging task and makes the design of a suitable control algorithm a cumbersome situation. Aimed at its application in civil structure, the main purpose of this paper is to test and characterise the hysteretic behaviour of MR pin joint. A test scheme is designed to obtain the dynamic performance of MR pin joint in the dominant earthquake frequency range. Some unique phenomena different from those of MR damper are observed through the experimental testing. A computationally-efficient model is proposed by introducing a hyperbolic element to accurately reproduce its dynamic behaviour and to further facilitate the design of a suitable control algorithm. Comprehensive investigations on the model accuracy and dependences of the proposed model on loading condition (frequency and amplitude) and input current level are reported in the last section of this paper.
During the last few decades, magnetorheological (MR) elastomers have attracted a significant amount of attention for their enormous potential in engineering applications. Because they are a solid counterpart to MR fluids, MR elastomers exhibit a unique field-dependent material property when exposed to a magnetic field, and they overcome major issues faced in magnetorheological fluids, e.g. the deposition of iron particles, sealing problems and environmental contamination. Such advantages offer great potential for designing intelligent devices to be used in various engineering fields, especially in fields that involve vibration reduction and isolation. This paper presents a state of the art review on the recent progress of MR elastomer technology, with special emphasis on the research and development of MR elastomer devices and their applications. To keep the integrity of the knowledge, this review includes a brief introduction of MR elastomer materials and follows with a discussion of critical issues involved in designing magnetorheological elastomer devices, i.e. operation modes, coil placements and principle fundamentals. A comprehensive review has been presented on the research and development of MR elastomer devices, including vibration absorbers, vibration isolators, base isolators, sensing devices, and so on. A summary of the research on the modeling mechanical behavior for both the material and the devices is presented. Finally, the challenges and the potential facing magnetorheological elastomer technology are discussed, and suggestions have been made based on the authors' knowledge and experience.
Li, Y, Li, J, Tian, T & Li, W 2014, 'Corrigendum: A highly adjustable magnetorheological elastomer base isolator for applications of real-time adaptive control (2013 Smart Mater. Struct. 22 095020)', Smart Materials and Structures, vol. 23, no. 12.View/Download from: Publisher's site
Hu, H, Jiang, X, Li, Y, Wang, J & Qian, S 2013, 'Integrated design and controllability test of piezoelectric self-powered MR absorber', Zhendong Ceshi Yu Zhenduan/Journal of Vibration, Measurement and Diagnosis, vol. 33, no. 4, pp. 712-718.
Aiming at the piezoelectric self-powered MR absorber, the feasibility of structure composite and function integration is studied, by combining the semi-active vibration control device based on MR technology with energy harvesting equipment based on piezoelectric vibrator. A theory model of piezoelectric self-powered MR absorber is established. Then, its magnetic circuit structure of MR absorber is optimized and designed by using the numerical simulation method, its influences of piezoelectric vibrator's geometric parameters on the outputting voltage of the vibration energy harvesting equipment are also analyzed, and the vibration energy harvesting circuit is simulated and tested, respectively. The simulation results show that the current of 1.67 A could be provided into the coil of MR absorber once the ring-shaped piezoelectric vibrator is excited by AC voltage source. Finally, an experimental platform is constructed in order to test its controllability of the piezoelectric self-powered MR absorber. The experimental results show that the ring-shaped piezoelectric vibrator could provide an enough amount of electrical energy for the piezoelectric self-powered MR absorber's semi-active vibration control, and its damping force achieves 2.4 times before and after the on-off controlling strategy.
Li, Y, Li, J & Samali, B 2013, 'On the magnetic field and temperature monitoring of a solenoid coil for a novel magnetorheological elastomer base isolator', Journal of Physics: Conference Series, vol. 412, no. 1, pp. 1-7.View/Download from: Publisher's site
Following a successful experimental validation of a magnetorheological elastomer (MRE) base isolator, this study presents one of the major concerns, the heating of the magnetic coil, in the design and development of the adaptive MRE based isolator. In this research, the MRE materials, with a total thickness of nearly 150 mm, are placed as the magnetic core of the device to best utilize the magnetic energy provided by the coil. A series of tests are undertaken to investigate the magnetic fields inside the coil with or without the MRE materials. Thermocouples are used to monitoring the surface temperature of the coil when it is applied with various currents for 10 min. It is shown that the measurement of field inside the solenoid when no MRE is placed inside agrees with the theoretical analysis. It is also shown that the temperature of the coil increase dramatically when a current is applied. Cooling of the coil may takes even longer, about 4 h, till down to the room temperature. Dropping of the magnetic field is observed when the temperature goes high.
Li, Y, Li, J, Li, W & Samali, B 2013, 'Development and characterization of a magnetorheological elastomer based adaptive seismic isolator', Smart Materials and Structures, vol. 22, no. 3, pp. 1-12.View/Download from: Publisher's site
One of the main shortcomings in current base isolation design/practice is lack of adaptability. As a result, a base isolation system that is effective for one type earthquake may become ineffective or may have adverse effect for other earthquakes. The vulnerability of traditional base isolation systems can be exaggerated by two types of earthquakes, i.e. near-field earthquakes and far-field earthquakes. This paper addresses the challenge facing current base isolation design/practice by proposing a new type of seismic isolator for the base isolation system, namely an adaptive seismic isolator. The novel adaptive seismic isolator utilizes magnetorheological elastomer (MRE) for its field-sensitive material property. Traditional seismic isolator design with a unique laminated structure of steel and MRE layers has been adopted in the novel MRE seismic isolator. To evaluate and characterize the behavior of the MRE seismic isolator, experimental testing was conducted on a shake table facility under harmonic cycling loading. Experimental results show that the proposed adaptive seismic isolator can successfully alter the lateral stiffness and damping force in real time up to 37% and 45% respectively. Based on the successful development of the novel adaptive seismic isolator, a discussion is also extended to the impact and potential applications of such a device in structural control applications in civil engineering.
Li, Y, Li, J, Tian, T & Li, W 2013, 'A highly adjustable magnetorheological elastomer base isolator for applications of real-time adaptive control', Smart Materials and Structures, vol. 22, no. 9, pp. 1-18.View/Download from: Publisher's site
Inspired by its controllable and field-dependent stiffness/damping properties, there has been increasing research and development of magnetorheological elastomer (MRE) for mitigation of unwanted structural or machinery vibrations using MRE isolators or absorbers. Recently, a breakthrough pilot research on the development of a highly innovative prototype adaptive MRE base isolator, with the ability for real-time adaptive control of base isolated structures against various types of earthquakes including near- or far-fault earthquakes, has been reported by the authors. As a further effort to improve the proposed MRE adaptive base isolator and to address some of the shortcomings and challenges, this paper presents systematic investigations on the development of a new highly adjustable MRE base isolator, including experimental testing and characterization of the new isolator. A soft MR elastomer has been designed, fabricated and incorporated in the laminated structure of the new MRE base isolator, which aims to obtain a highly adjustable shear modulus under a medium level of magnetic field. Comprehensive static and dynamic testing was conducted on this new adaptive MRE base isolator to examine its characteristics and evaluate its performance. The experimental results show that this new MRE base isolator can remarkably change the lateral stiffness of the isolator up to 1630% under a medium level of magnetic field. Such highly adjustable MRE base isolator makes the design and implementation of truly real-time adaptive (e.g. semi-active or smart passive) seismic isolation systems become feasible.
Yang, J, Du, H, Li, W, Li, Y, Li, J, Sun, S & Deng, H 2013, 'Experimental study and modeling of a novel magnetorheological elastomer isolator', Smart Materials and Structures, vol. 22, no. 11, pp. 1-14.View/Download from: Publisher's site
This paper reports an experimental setup aiming at evaluating the performance of a newly designed magnetorheological elastomer (MRE) seismic isolator. As a further effort to explore the field-dependent stiffness/damping properties of the MRE isolator, a
Zeng, J, Guo, Y, Li, Y, Zhu, J & Li, J 2013, 'Two-dimensional magnetic property measurement for magneto-rheological elastomer', JOURNAL OF APPLIED PHYSICS, vol. 113, no. 17.View/Download from: Publisher's site
Hu, H, Jiang, X, Wang, J & Li, Y 2012, 'Design, modeling, and controlling of a large-scale magnetorheological shock absorber under high impact load', Journal of Intelligent Material Systems and Structures, vol. 23, no. 6, pp. 635-645.View/Download from: Publisher's site
In this article, an MRD50 type of large-scale magnetorheological shock absorber was designed and manufactured in Smart Materials and Structures Laboratory of Nanjing University of Science and Technology. Upon providing a brief background on magnetorheological dampers, the detailed structure of this developed large-scale magnetorheological shock absorber was depicted. A suit of hardware-in-the-loop simulation platform under high impact load excitation was introduced for a weapon system. A series of tests were conducted to establish the dynamic behaviors of magnetorheological shock absorber under impact loads. The test results show that the inertia damping force should not be ignored like a common magnetorheological damper because of the large acceleration from the impact load. Based on the theory model and the experimental data, index parameters of magnetorheological fluid and other structural parameters in Herschel-Bulkley-Inertia model were identified by using the least square algorithm. In order to evaluate the controllability of large-scale magnetorheological shock absorber applied into high impact loads, three control algorithms, including on-off control, proportional-integral-derivative control, and fuzzy control algorithm, were used in tests to control the dynamic behavior of magnetorheological shock absorber, and some results of the controllability tests were exhibited in this article. In conclusion, the results indicated that the developed large-scale magnetorheological shock absorber was indeed able to effectively control the recoil dynamics.
Hu, H, Wang, J, Qian, S, Li, Y, Shen, N & Yan, G 2011, 'Dynamic Modeling And Its Sliding Controller Of MR Shock Absorber Under Impact Load', Chinese Journal of Mechanical Engineering, vol. 47, no. 13, pp. 84-91.View/Download from: Publisher's site
An MR shock absorber under impact load is investigated. A single-rod long-stroke impact absorber is developed. Based on Bingham model and its structure of MR damper under impact load, a dynamic model of MR damper under impact load is derived, which is composed of annular damping hole's friction damping force, coulomb damping force, inertia damping force, throttle damping force, structure additional damper force and other friction forces. By applying the least square algorithm, important parameters in the dynamic model are identified. Experimental results confirm the accuracy of the derived and fitted dynamic model. According to its strong nonlinearity, wide frequency range and high peak-value of acceleration characteristics of impact load, an output target tracer using sliding control strategy is designed and simulated on the basis of constructing hardware-in-the-loop platform. The control effects of three control strategies, namely, On-Off strategy, PID strategy and sliding mode control strategy, are compared and analyzed. The results show that the vibration peak value of MR impact absorber under sliding mode control strategy is reduced by 27.33%, and its piston stroke is reduced by 48.75% , thus being the most ideal control effect.
Magnetorheological fluid (MRF) has received significant attention lately and MRF based devices have been proposed for structural control applications in recent years. The unique characteristics of MR fluid lies in its abilities to reversibly, repeatedly and instantly change from a free flowing liquid to a semi-solid state when exposed to a magnetic field. The electric power required to drive the MR devices can be easily provided by a battery. Possessing such unique properties, MR fluid based devices, such as MR damper, have become promising candidates in the semi-active control for civil structure applications. However, most of the published research has focused on application of MR dampers instead of exploring other type of MR devices. In addition, MR based devices exhibit complex nonlinear hysteresis behaviour and thus making their modelling a challenging task. In this paper, a novel MR fluid based device, namely MR pin joint, is proposed as a smart structural member in development of an intelligent civil structure that can suppress unwanted vibrations to ensure safety and serviceability of the structure. After design and fabrication, experiments have been conducted to characterise dynamic behaviours of the new device under different harmonic excitations with various input currents. Response time of the MR pin joint is compared when the MR pin joint is driven under different applied currents and moving speeds. Test data shows that the MR pin joint possesses a unique behaviour in the moment-angular velocity plot. A hyperbolic hysteresis model is proposed to model such unique behaviour. The investigation presented in the paper explores dynamic performance of MR pin joint. Finally, a parametric model is developed following the investigation on the correlation of coefficients in the proposed model with the loading conditions and applied currents.
Lin, Z, Li, Y, Zhu, J, Wang, X, Dou, SX, Guo, Y, Lei, G, Wang, Y, Phillips, M, Cortie, MB, Li, Y, Choi, K & Shi, X 2011, 'Visualization Of Vortex Motion In Feas-Based Bafe(1.9)Ni(0.1)As(2) Single Crystal By Means Of Magneto-Optical Imaging', Journal Of Applied Physics, vol. 109, no. 7, pp. 0-0.View/Download from: Publisher's site
Superconductivity has been found in newly discovered iron-based compounds. This paper studies the motion of magnetic vortices in BaFe(1.9)Ni(0.1)As(2) single crystal by means of the magneto-optical imaging technique. A series of magneto-optical images re
Hu, HS, Wang, J, Jiang, XZ, Li, YC & Li, ZC 2010, 'Design and controllability analysis of a gun magnetorheological recoil damper', Zhendong yu Chongji/Journal of Vibration and Shock, vol. 29, no. 2, pp. 184-188.
According to gun magnetorheological (MR) recoil damper's characteristics, aiming at the recoil part of a gun system under high impact and high-speed environment, the recoil resistance force's effect on the quiescence and firing stability of the gun was studied. The controllability of a magnetorheological damper to the gun recoil part's movement was also studied. A new gun magnetorheological recoil damper was designed and developed. And a suit of real-time measuring and controlling simulation experimental platform including hardware and software for dynamic response of a gun MR recoil damper under impact load was developed. Considering the dynamic behavior of the MR damper under impact load, an inertia factor was introduced into the dynamic model of the recoil part of the gun system. A shock test was done to measure the designed long-stroke MR damper's dynamic performance under impact load. To evaluate the control effect of the MR damper on the gun recoil movement during recoiling, a hardware-in-loop simulation and a test were performed. The testing results showed that the recoil's resistance and stroke of the designed gun MR recoil damper under impact load can be controlled by changing the applied current. The results lay a foundation for the integrated design and engineering application of the gun recoil force and stroke control.
Hu, H, Li, Y & Wang, J 2009, 'Structural design and dynamic characteristics analysis for a magneto-rheological gun recoil shock absorber under impact load', Zhongguo Jixie Gongcheng/China Mechanical Engineering, vol. 20, no. 4, pp. 389-393.
A full-scale mock-up for MR shock absorber characterized with multistage slotted and smoothness disposal under impact load was firstly established. Considering the dynamic of MR shock absorber under impact load, an inertia factor was introduced to Herschel-Bulkley model, which led to two revised models, named as Herschel-Bulkley-Inertia model. And a suit of real-time measuring and controlling simulation experimental platform including hardware and software for dynamic response of MR gun recoil shock absorber under impact load was developed. The parameters in Bingham-Inertia model and Herschel-Bulkley-Inertia model were identificated by using the testing data. Further, the testing results prove that the designed MR gun recoil long-stroke shock absorber's dynamic performance under impact load can be well controlled by changing the applied current, and the dynamic response models for MR gun recoil shock absorber under impact load are proved.
Hu, HS, Wang, J & Li, YC 2009, 'Design and magnetic analysis of a gun recoil magneto-rheological damper', Dandao Xuebao/Journal of Ballistics, vol. 21, no. 2, pp. 78-82.
A gun recoil magneto-rheological (MR) damper under impact load was researched. A full-scale gun recoil MR damper with long-stroke, multistage slotted and smoothness disposal was designed. The coupling problem between structure and magnetic circuit for MR recoil damper was solved by the electromagnetic field finite element analysis software, and the electromagnetic field distribution of the designed gun recoil MR damper was also analyzed under different conditions, such as coil ringing direction, plunger and steel cylinder part's material selection, dampen channel, smoothness and chamfering disposal, etc. The magnetic circuit design rules of MR recoil damper under high impact load were also concluded. The simulation results indicate that the performance of the designed gun recoil damper satisfy the design requirements.
Li, Y, Li, J, Samali, B & Wang, J 2009, 'Design Considerations and Experimental Studies on Semi-Active Smart Pin Joint', Frontiers of Mechanical Engineering in China, vol. 4, no. 4, pp. 363-370.View/Download from: Publisher's site
Hostile dynamic loadings such as severe wind storms, earthquakes, and sudden impacts can cause severe damage to many civil engineering structures. An intelligent structural system equipped with smart structural members that are controllable in real-time is an effective solution to structural damage and failure during such situations. Civil intelligent structures with controllable properties to adapt to any changes due to dynamic loadings can lead to effective protection of structures and their occupants. In this paper, design and testing of a semi-active magnetorheological (MR) pin joint, in which the moment resistance can be controlled in real-time by altering the magnetic field, is reported with the view of using it as a potential candidate for smart members in the development of intelligent structures. Design of prototype smart pin joints includes theoretical analysis related to the radius of the rotary plate, the property of MR fluids and the gap between the rotary plate and the casing based on the requirements of the dynamics of MR pin joints. FEM analysis was deployed to study the distribution of the magnetic field along the gap. It is found, from the theoretical analysis and experimental verification, that the MR pin joint with a diameter of 180 mm can produce a torque of up to 30 Nm, which meets requirements for semi-active members in a multi-storey prototype building model in the next stage of research and development.
Li, YC, Wang, J & Qian, LF 2006, 'Magnetorheological technology and its latent applications to military field', Dandao Xuebao/Journal of Ballistics, vol. 18, no. 3, pp. 68-73.
The constitutions, characters, and late progress of the magnetorheological(MR) fluid were introduced. The applications of MR technology to military field were summarized. They are applications to military guard equipment, weapon buffer device, helicopter, military vehicle and fuze. The technology of applications was explained. The prospect of applications of MR technology to military field was recounted. The main factors that restrict the applications to military field include performance of MR fluid, the innovative structural design of MR device, control technology of MR device and system.
Li, YC, Wang, J & Qian, LF 2006, 'Nonlinear performance of MR damper under base excitation', Gongneng Cailiao/Journal of Functional Materials, vol. 37, no. 6, pp. 986-988.
Magnetorheological damper is a typical nonlinear device; it has the characters such as nonlinearity, time-delaying and uncertainty. Nonlinearity of MR damper is of great influence on its behaviors. In this paper, the dynamic responses of nonlinear MR damper under base harmonic excitation is obtained; Characters of MR damper is analyzed using MATLAB software. It is shown that a multi-value performance appears in transmissibility when the damping ration is below 1. Some advices are suggested in design of MR damper.
Wang, J & Li, Y 2006, 'Dynamic simulation and test verification of MR shock absorber under impact load', Journal of Intelligent Material Systems and Structures, vol. 17, no. 4, pp. 309-314.View/Download from: Publisher's site
The magnetorheological (MR) shock absorber is one of the most promising new devices for vibration reduction. Many investigations have been carried out on low velocity and frequency applications of MR devices. The use of the MR shock absorber under impact load is of great interest. The now widely used MR damper models, such as the Bingham model, cannot explain sufficiently the shear thinning behavior under impact loads. However, the HerschelBulkley model can be used to explain the same. The main purpose of this study is to analyze the behavior of the MR shock absorber under impact load and to verify the analytical conclusions and experiments. First, some dynamic simulations on the MR shock absorber under impact loads in Matlab and Simulink are carried out. The model describes the dynamic characteristics especially the shear thinning behavior of the shock absorber, based on this model, then analyzes the variations of piston acceleration and back cavity pressure of MR shock absorber at both same and different flow indices. A test rig is developed to test the characteristics of the long-stroke MR shock absorber under impact loads. Comparisons between the simulation and the test results are made to validate our conclusions. The results indicate that the peak acceleration value of the piston rod and the pressure of the back cavity are decided by the peak value and the duration of the impact force. The peak value of the acceleration and the cavity pressure cannot be changed, but the transitional time of the acceleration of the piston and the pressure of the back cavity of MR shock absorber can be controlled by changing the applied current in the electromagnetic coil. MR shock absorbers will be the most promising shock reduction device under an impact environment.
Wang, J, Zhang, G, Wang, H, Ouyang, Q, Zheng, J, Li, Y & Li, Z 2019, 'Use of magnetorheological shock absorber for impact loading mitigation with individually controllable coils' in Magneto-Rheological Materials and Their Applications, Institution of Engineering & Technology, pp. 93-133.View/Download from: Publisher's site
This book chapter presents comprehensive investigations on the use of magnetorheological (MR) shock absorber to mitigate the effect of impact loading, with emphasis on the recoil system. A physical model of the field gun is established and a long-stroke MR recoil absorber with four-stage parallel electromagnetic coils is designed to apply separate current respectively and generate variable magnetic field distributions in the annular flow channel. The response time and the compensation method are investigated to facilitate the application. Based on the dynamic analysis and firing stability condition during the process of shock, the ideal recoil force-stroke profiles of MR absorber at different limiting firing angles are obtained. The experimental studies are carried out on the impact test rig under different combinations of current loading: conventional unified control mode, separate control mode and timing control mode.
Li, Y & Li, J 2019, 'Development of smart base isolation system for civil structures utilising magnetorheological elastomer' in Magneto-Rheological Materials and Their Applications, Institution of Engineering & Technology, USA, pp. 355-394.View/Download from: Publisher's site
This chapter details the development of a smart base isolation system for seismic protection of civil structures utilising magnetorheological (MR) elastomer (MRE). Critical components of the development of the system, i.e. adaptive base isolator, control design and shake table testing, are described. Finally, shake table testing is conducted to verify the effectiveness of the proposed smart-base isolation system.
Yu, Y, Li, Y, Li, J, Nguyen, TN, Li, S & Erkmen, E 2019, 'Vibration control of MRE isolator-embedded smart building using genetic algorithm', Proceedings of 30th International Conference on Adaptive Structures and Technologies, ICAST 2019, International Conference on Adaptive Structures and Technologies, Montreal, Canada, pp. 9-10.
© copyright Environment and Climate Change Canada. This study developed the adaptive genetic algorithm (GA) for vibration control of building structures subjected to ambient hazard excitations. An innovative smart building system was designed based on magnetorheological elastomer (MRE) isolators under each storey of the structure instead of being only installed beneath the entire structure. Such innovative system allows high authority semi-active control of storey responses by instantly changing the stiffness of the isolator, the control process of which can be considered as solving a global multi-objective optimization problem. Finally, a numerical investigation was conducted using a 5-storey international benchmark model under four benchmark earthquakes.
Wang, H, Li, Y, Zhang, G, Wang, J & Li, J 2019, 'Behaviours of lithium-based magnetorheological grease under triangular quasi-static test', Proceedings of 30th International Conference on Adaptive Structures and Technologies, ICAST 2019, pp. 131-132.
© copyright Environment and Climate Change Canada. This paper investigates the behaviour of lithium-based magnetorheological (MR) grease under the triangular quasi-static test. Three types of MR grease are prepared with weight fractions of carbon iron particles (CIP) as 30%, 50% and 70%, respectively. Quasi-static test of periodical triangular inputs, with various shear strain and strain rates, are employed to evaluate the performance of the MR greases, figure 1 and 2. Further evaluations are conducted by cross-checking the behaviour of the MR grease under various strain rate at a given max strain and the cases under various shear strains at a fixed strain rate.
Yu, Y, Li, Y & Li, J 2017, 'Sigmoid function-based hysteresis modeling of magnetorheological pin joints', 2017 3rd International Conference on Control, Automation and Robotics, ICCAR 2017, International Conference on Control, Automation and Robotics, IEEE, Nagoya, Japan, pp. 514-517.View/Download from: Publisher's site
© 2017 IEEE. The magnetorheological (MR) pin joint is a semi-active control device which can be installed in the column-beam structures for structural vibration control. Nevertheless, the nonlinear response of the MR pin joint together with its unique rheological nature makes the device modeling difficult and impedes its engineering application. Although many complicated phenomenal models have been proposed to illustrate the dynamic behaviour of MR devices, a large number of model parameters and differential equations bring the challenges for model identification and controller design. In this study, we try to predict the dynamic response of a MR pin joint using a novel and simple phenomenal model, which is comprised of a rotary spring, a rotary damper and a sigmoid function-based hysteresis component. Then, the model parameters are identified using trust-region-reflective least squares algorithm in MATLAB optimization toolbox. Finally, the experimental results under various loading conditions are used to validate the performance of the proposed model.
Yu, Y, Li, Y, Li, J, Gu, X & Royel, S 2016, 'Dynamic modeling of magnetorheological elastomer base isolator based on extreme learning machine', Mechanics of Structures and Materials: Advancements and Challenges - Proceedings of the 24th Australasian Conference on the Mechanics of Structures and Materials, ACMSM24 2016, Australian Conference on the Mechanics of Structures and Materials, CRC press, Perth, Australia, pp. 703-708.
© 2017 Taylor & Francis Group, London. This paper presents a novel modeling method to describe the nonlinear and hysteretic characteristics of Magnetorheological Elastomer (MRE) isolator, which is a semi-active control device and used in vibration control of engineering structures such as vehicle suspension system, offshore platform and built infrastructure. In the proposed method, a new single-hidden-layer feed-forward neural network algorithm named Extreme Learning Machine (ELM) is adopted to set up the model, in which the captured responses such as displacement and velocity of the device together with applied current level are employed as model inputs while the model output is the shear force generated according to the external excitation. Finally, the experimental data are utilized to validate the performance of the proposed method.
Royel, S, Yu, Y, Li, Y, Li, J & Ha, QP 2015, 'A Hysteresis Model and Parameter Identification for MR Pin Joints using Immune Particle Swarm Optimization', Proceedings of the 2015 IEEE International Conference on Automation Science and Engineering., IEEE Conference on Automation Science and Engineering, IEEE, Gothenburg, Sweden, pp. 1319-1324.View/Download from: Publisher's site
A novel hybrid model is proposed in this paper to
describe the highly-nonlinear hysteretic relationship between
the torque and angular velocity in a magnetorheological pin
joint (MRP). The MRP's hysteresis loop is modelled by a mixture
of hyperbolic and Gaussian functions using the curve fitting
technique, resulting in a significant reduction of the model
parameters. To identify the model parameters, an immune
particle swarm optimization (IPSO) algorithm is employed
using torque-angular displacement/velocity experimental data
recorded under various loading conditions. To demonstrate
the accuracy of the proposed model and the effectiveness of
parameter identification process, characterization test data of
the smart pin torque and angular velocity are utilized for
Gu, X, Li, J & Li, Y 2014, 'Innovative semi-active storey isolation system utilising novel magnetorheological elastomer base isolators', Proceedings of the 23rd Australasian Conference on the Mechanics of Structures and Materials, Australasian Conference on the Mechanics of Structures and Materials, Southern Cross University, Byron Bay, Australia, pp. 925-930.
Seismic base isolation has been a widely adopted technique for earthquake protection of civil infrastructures. As the technology matures, new innovative designs of the base isolation systems become increasingly attractive to researchers, especially storey base isolation systems due to its design flexibility and better performance for seismic protection. Moreover, considering the unpredictable and diverse nature of earthquakes, the conventional base isolation systems have reached their limit due to their inherent passive nature which is incapable to adjust their isolation frequencies according to the characteristics of the earthquakes. A recent advance on the development of an adaptive magneto-rheological elastomer (MRE) base isolator provides an opportunity for the research and development on new adaptive base isolation systems. In this paper, an innovative semi-active storey isolation system utilising the novel magneto-rheological elastomer base isolator has been proposed. The proposed isolation system design incorporates adaptive magneto-rheological elastomer isolators under each storey of the structure instead of being only installed beneath of the entire structure. Such innovative system allows high authority semiactive control of storey responses by instantly changing stiffness of the isolator. Extensive simulation has been conducted to investigate such system using 5-storey international benchmark model under four benchmark earthquakes.
Li, Y & Li, J 2014, 'Base isolator with variable stiffness and damping: design, experimental testing and modelling', Proceedings of the 23rd Australasian Conference on the Mechanics of Structures and Materials, Australasian Conference on the Mechanics of Structures and Materials, Southern Cross University, Byron Bay, Australia, pp. 913-918.
Vulnerability in base isolation system of civil structures originated from passive nature of the rubber material raises the urgency of developing smart base isolation system with adaptive and controllable properties, i.e. variable stiffness and damping. To address this issue, this paper presents comprehensive investigations on a novel adaptive base isolator, including design, experimental testing and dynamic modelling. Smart rubber with field-dependent modulus and damping property is incorporated into the laminated base isolator design. Experimental testing is conducted utilising an advanced shake table facility to examine its performance under cycling loading. Results show that the adaptive base isolator possesses a stiffness increase of more than 16 times and damping ratio between 10% and 27%. With such features, it can be developed into a smart base isolation system to protect civil structures against any type of earthquake. Results also show that this device has high nonlinear hysteresis, i.e. shear stiffening behaviour. A mechanical model is thus required to describe the complex behaviour of new adaptive base isolator. A new strain stiffening element is proposed for this purpose. Comparison between the model and the experimental data verifies the fidelity and effectiveness of the proposed model.
Yu, Y, Li, Y & Li, J 2014, 'A New Hysteretic Model for Magnetorheological Elastomer Base Isolator and Parameter Identification Using Modified Artificial Fish Swarm Algorithm', The 31st International Symposium on Automation and Robotics in Construction and Mining (ISARC 2014), International Symposium on Automation and Robotics in Construction, University of Technology, Sydney, City campus, 15 Broadway, Ultimo NSW, Sydney, pp. 176-183.View/Download from: Publisher's site
Yu, Y, Li, Y & Li, J 2014, 'A Novel Strain Stiffening Model for Magnetorheological Elastomer Base Isolator and Parameter Estimation Using Improved Particle Swarm Optimization', Proceedings of the 6th edition of the World Conference of the International Association for Structural Control and Monitoring (IACSM), Sixth World Conference on Structural Control and Monitoring (6WCSCM), International Center for Numerical Methods in Engineering (CIMNE), Barcelona, Spain.
In order to fully utilize the advantages of magnetorheological elastomer (MRE) base isolator for seismic protection of civil structures, a high fidelity model should be established to characterize its nonlinear hysteresis for its implementation in structural control. In this paper, a novel strain stiffening model is developed to capture this unique characteristic. In this model, a strain stiffening component, which described the unique viscos-elastic behavior of the device, is incorporated with a Voigt element, which portrays the solid-material behavior. The new model, as an attractive feature, maintains a relationship between the isolator parameters and physical force-displacement nonlinear phenomenon and decreases the complexity in other existing models. In addition to the proposed model, an improved optimization algorithm based on particle swarm optimization (IPSO) is designed to identify the model parameters by utilizing experimental force-displacement-velocity data acquired from various loading conditions. In this new algorithm, the mutation operation in genetic algorithm is utilized for helping the model solution avoiding the local optimum. The superiority of the proposed model and parameter solving algorithm is validated by comparing them with the classical Bouc-Wen model and other optimization algorithms through the error analysis, respectively. The comparison results show that the proposed model can exactly predict the force-displacement and force-velocity responses at both small and large displacements, and has a smaller root-mean-square (MSE) error than the Bouc-Wen model. Compared with other optimization algorithm, the IPSO not only has a faster convergence rate, but also obtains the satisfactory parameters identification results.
Yu, Y, Li, Y & Li, J 2014, 'Parameter Identification Of An Improved Dahl Model For Magnetorheological Elastomer Base Isolator Based On Enhanced Genetic Algorithm', Proceedings of the 23rd Australasian Conference on the Mechanics of Structures and Materials, Australasian Conference on the Mechanics of Structures and Materials, Southern Cross University, Byron Bay, Australia, pp. 931-936.
In view of the problems of high nonlinearity and multiple parameters in existing models of magnetorheological elastomer (MRE) base isolator, this paper proposes an improved Dahl model and an enhanced genetic algorithm (GA) for model parameter identification. In this model, the Dahl hysteresis operator is employed to depict the Coulomb force to avoid the estimation of many parameters and this model can perfectly capture the hysteretic behavior of the MRE base isolator at both small and large displacements. To improve the searching efficiency of identification process, adaptive crossover and mutation operators are introduced into the GA to avoid the algorithm falling into the local optimum, achieving faster convergence rate for optimal solutions. Furthermore, an appropriate stopping criterion is designed to reduce the calculation cost. Testing data from a practical MRE base isolator are utilized to validate the proposed algorithm with satisfactory parameter identification results.
Li, J, Li, Y, Askari, M & Ha, QP 2014, 'Future Intelligent Civil Structures: Challenges and Opportunities', The 31st International Symposium on Automation and Robotics in Construction and Mining (ISARC 2014), International Symposium on Automation and Robotics in Construction, International Association for Automation and Robotics in Construction (IAARC), Sydney, pp. 72-79.View/Download from: Publisher's site
An intelligent civil structure offers ultimate protection to its structure, contents and occupants in terms of safety and functionality against undesired dynamic loadings and structural deficiency. In this paper, the concept of the future intelligent civil structure featuring self-adaptive, selfprognostic, self-sensing, self-powering and self-repairing abilities, is proposed. A decade research efforts from Centre for Built Infrastructure Research, University of Technology Sydney, towards the development and concept proof of such intelligent structure is reviewed.
Gu, X & Li, Y 2013, 'Comprehensive Investigations on Magnetic Field Distribution in a Solenoid', ASME 2013 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, Conference on Smart Materials, Adaptive Structures and Intelligent Systems, ASME, Snowbird, Utah, USA, pp. 1-7.View/Download from: Publisher's site
Finding engineering applications for a new class of smart material, magnetorheological elastomer (MRE), has been a major task for researchers in this field. Novel MRE devices, such as vibration absorbers and vibration isolators, have been proposed and fabricated to pioneer its engineering applications. In civil engineering, the author has proposed a novel MRE based isolator to be used in the base isolation system for mitigating the devastating effects of earthquakes on civil structures. For any MRE-based device, electromagnetic coil is evitable involved to provide magnetic field for the MRE materials. Comparing with magnetic circuit design in magnetorheological fluid (MRF) device, i.e. MR damper, MRE devices normally need a larger coil to energize the MRE materials, particularly for a large-scale MRE device. Therefore, investigation of the solenoid on the magnetic field distribution is of great importance for the design and development of MRE based device. In particular, provision of sufficient and uniform magnetic field is essential towards the success in designing MRF/MRE devices. To understand the mechanism of magnetic field generation in a solenoid is the key for device design and optimization. The main objective of this paper is to analytically investigate and experimentally validate the magnetic field distribution in a solenoid. The theoretical investigation starts from the analysis on an ideally thin cylindrical solenoid in order to obtain analytical results.
Jiang, X, Li, Y & Li, J 2012, 'A novel piezoelectric wafer-stack vibration energy harvester', From materials to structures: Advancement through innovation, Australasian Conference on the Mechanics of Structures and Materials, CRC press/Balkema, Sydney, Australia, pp. 399-404.
Piezoelectric vibration-based energy harvesters are attractive as inexhaustible replacements for batteries in low-power requirement wireless electronic devices and thus have received increasing research interest in the last few years. This paper presents a novel piezoelectric harvester based on the wafer-stack configuration to convert the external vibration into usable electrical energy for this purpose. Both analytical and experimental investigations are undertaken at University of Technology Sydney. Firstly, an electromechanical model with a rectified circuit, considering both the mechanical and electrical factors of the harvester, is built to characterise the harvested electrical power across the external loadings. Exact closed-form expressions of the electromechanical model have been given to analyse conditions for maximum harvested power. Finally, a shake table experimental testing was conducted to evaluate the feasibility of the presented PZT wafer stack harvester under standard sinusoidal loadings. Test results show that the harvester can generate a maximum 16mW electrical power for sinusoidal loading with 40mm amplitude and 2 Hz frequency.
Jiang, X, Li, Y & Li, J 2013, 'A piezoelectric wafer-stack vibration energy harvester for wireless sensor networks', Proceedings of SPIE - The International Society for Optical Engineering - Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2013, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems, SPIE, San Diego, USA, pp. 1-9.View/Download from: Publisher's site
Over the past few decades, wireless sensor networks have been widely used in civil structure health monitoring application. Currently, most wireless sensor networks are battery-powered and it is costly and unsustainable for maintenance because of the requirement for frequent battery replacements. As an attempt to address such issue, this paper presents a novel piezoelectric vibrational energy harvester to convert the structural vibration into usable electrical energy for powering wireless sensor networks. Unlike the normal cantilever beam structure, the piezoelectric harvester presented in this paper is based on the wafer-stack configuration which is suitable for applications where large force vibration occurs, and therefore can be embedded in civil structures to convert the force induced by vibration of large structures directly into electrical energy. The longitudinal mode of the piezoelectric wafer-stack was developed firstly to illustrate the force-to-voltage relationship of piezoelectric materials and to find the inter-medium force that will be used to convert vibration energy into electrical energy. Then, two electromechanical models (without and with a rectified circuit), considering both the mechanical and electrical aspects of the harvester, were developed to characterize the harvested electrical power under the external load. Exact closed-form expressions of the electromechanical models have been derived to analyze the maximum harvested power and the optimal resistance. Finally, a shake table experimental testing was conducted to prove the feasibility of the presented piezoelectric-wafer-stack harvester under standard sinusoidal loadings. Test results show that the harvester can generate a maximum 45mW (AC) or 16mW (DC) electrical power for sinusoidal loading with 40mm amplitude and 2Hz frequency, and the harvested electrical power is proportional to the levels of exciting vibrational loading.
Jiang, X, Li, Y & Li, J 2013, 'Design of a Novel Linear Permanent Magnet Vibration Energy Harvester', 2013 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM2013) - Conference Proceedings, IEEE/ASME International Conference on Advanced Intelligent Mechatronics, IEEE, Wollongong, Australia, pp. 1090-1095.View/Download from: Publisher's site
This paper presents a novel linear tubular permanent magnet (PM) energy harvester to scavenge energy from ambient vibrations. The proposed linear PM energy harvester consists of a mover attached with PMs and a slotted stator with build-in two-phase electromagnetic coils to induce the electromagnetic induction for converting vibrations into useful electrical energy. The magnetic circuit model of the PM harvester is built to analyze the parameters about scavenging energy and used to optimize the non-dimensional geometry factors and the structural parameters in order to maximize harvested energy under given vibration and space conditions. To confirm the design, dynamic FE simulations were conducted and compared with the analytical results. Simulation results indicate that the proposed PM harvester is able to scavenge about 100 W DC power when the RMS of vibration velocity equals to 0.4 m/s. Also, the harvested power increases as the vibration velocity increasing.
Li, J, Li, Y, Li, W & Samali, B 2013, 'Development of adaptive seismic isolators for ultimate seismic protection of civil structures', Proceedings of SPIE - The International Society for Optical Engineering - Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2013, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems, SPIE, San Diego, USA, pp. 1-12.View/Download from: Publisher's site
Base isolation is the most popular seismic protection technique for civil engineering structures. However, research has revealed that the traditional base isolation system due to its passive nature is vulnerable to two kinds of earthquakes, i.e. the near-fault and far-fault earthquakes. A great deal of effort has been dedicated to improve the performance of the traditional base isolation system for these two types of earthquakes. This paper presents a recent research breakthrough on the development of a novel adaptive seismic isolation system as the quest for ultimate protection for civil structures, utilizing the field-dependent property of the magnetorheological elastomer (MRE). A novel adaptive seismic isolator was developed as the key element to form smart seismic isolation system. The novel isolator contains unique laminated structure of steel and MR elastomer layers, which enable its large-scale civil engineering applications, and a solenoid to provide sufficient and uniform magnetic field for energizing the field-dependent property of MR elastomers. With the controllable shear modulus/damping of the MR elastomer, the developed adaptive seismic isolator possesses a controllable lateral stiffness while maintaining adequate vertical loading capacity. In this paper, a comprehensive review on the development of the adaptive seismic isolator is present including designs, analysis and testing of two prototypical adaptive seismic isolators utilizing two different MRE materials. Experimental results show that the first prototypical MRE seismic isolator can provide stiffness increase up to 37.49%, while the second prototypical MRE seismic isolator provides amazing increase of lateral stiffness up to1630%. Such range of increase of the controllable stiffness of the seismic isolator makes it highly practical for developing new adaptive base isolation system utilizing either semi-active or smart passive controls.
Li, Y & Li, J 2013, 'Development and Modeling of a Highly-Adjustable Base Isolator Utilizing Magnetorheological Elastomer', ASME 2013 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, Conference on Smart Materials, Adaptive Structures and Intelligent Systems, ASME, Snowbird, Utah, USA, pp. 1-8.View/Download from: Publisher's site
This paper presents a recent research breakthrough on the development of a novel adaptive seismic isolation system as the quest for seismic protection for civil structures, utilizing the field-dependent property of the magnetorheological elastomer (MRE). A highly-adjustable MRE base isolator was developed as the key element to form smart seismic isolation system. The novel isolator contains unique laminated structure of steel and MRE layers, which enable its large-scale civil engineering applications, and a solenoid to provide sufficient and uniform magnetic field for energizing the field-dependent property of MR elastomers. With the controllable shear modulus/damping of the MR elastomer, the developed adaptive base isolator possesses a controllable lateral stiffness while maintaining adequate vertical loading capacity. Experimental results show that the prototypical MRE base isolator provides amazing increase of lateral stiffness up to 1630%. Such range of increase of the controllable stiffness of the base isolator makes it highly practical for developing new adaptive base isolation system utilizing either semi-active or smart passive controls. To facilitate the structural control development using the adaptive MRE base isolator, an analytical model was developed to stimulate its behaviors. Comparison between the analytical model and experimental data proves the effectiveness of such model in reproducing the behavior of MRE base isolator, including the observed strain stiffening effect.
Li, Y, Li, J & Li, W 2013, 'Design and Experimental Testing of an Adaptive Magneto-Rheological Elastomer Base Isolator', 2013 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM2013) - Conference Proceedings, IEEE/ASME International Conference on Advanced Intelligent Mechatronics, IEEE, Wollongong, Australia, pp. 381-386.View/Download from: Publisher's site
Magnetorheological elastomer (MRE) is known for its field-sensitive shear modulus and damping property when it is exposed to a magnetic field. It has a great potential for the development of vibration reduction devices. Many research, mostly in mechanical engineering, have been focused on different kinds of vibration absorbers and vibration isolators, however few research addresses its potential in base isolation system in civil engineering application. The objective of this paper is to pilot the design and experimental testing of a novel device, an adaptive MRE base isolator, for the development of smart base isolation system. A large-scale design of the novel device with unique laminated structure of steel and MR elastomer layers is adopted. Detailed procedures on designing such adaptive base isolator are introduced. An innovative design on the magnetic circuit, with aim to provide strong and uniform magnetic field to the multi-layer MRES, is proposed to incorporate into the device design. Experimental investigation is conducted to examine its behavior under various cycling loadings when it is applied with different current inputs. Experimental results indicated that the force increase and the stiffness increase of the novel device are about 45% and 37%, respectively. To conclude, the MR elastomer base isolator will be a promising candidate to facilitate the development of adaptive base isolation system for civil structures.
Li, Y, Li, J & Samali, B 2012, 'A novel adaptive base isolator utilising magnetorheological elastomer', From materials to structures: Advancement through innovation, Australasian Conference on the Mechanics of Structures and Materials, CRC press/Balkema, Sydney, Australia, pp. 763-767.View/Download from: Publisher's site
Base isolation is the most popular seismic protection technique for civil structures. However, research has revealed that the traditional base isolation system is vulnerable to two kinds of earthquakes, i.e. the near-fault and far-fault earthquakes, due to its passive nature.A great deal of effort has been dedicated to improve the performance of traditional base isolation systems for these two types of earthquakes. Controllable supplementary and energy-dissipation members, such as magnetorheological damper, friction damper or hydraulic fluid damper, have been proposed to reduce seismic responses of the building structures. However, with the introduction of additional control devices, the system complexity increases resulting difficulty in the system implementation and control system design. It would be ideal if a certain level of adaptability could be introduced into base isolation systems while maintaining the traditional outfit. This paper addresses the challenge facing the current base isolation practices and proposes a novel adaptive base isolator as a solution to the problem.A smart rubber, namely, magnetorheological elastomer (MRE), is utilised in this research for its magnetic field-sensitive material property as the main element in the novel device. The tradition base isolator design for a large-scale structure with laminated steel and MRE layers is adopted. To verify and characterise the performance of the MRE base isolator, experimental testing was conducted on UTS shake table facility. Experimental results show that after being energised with magnetic field, the maximum force and the stiffness of the novel device can increase by up to approximately 45% and 37%, respectively.With the field-dependent stiffness and damping, the proposed adaptive base isolator is very promising in meeting the challenges associated with the base isolation systems encountered in practice.
Jiang, X, Li, Y, Li, J & Wang, J 2012, 'Electromechanical Modeling of a PZT Disc-type Energy Harvester for Large Force Vibration', PROCEEDINGS OF THE FIRST INTERNATIONAL CONFERENCE ON MECHATRONIC SYSTEM AND MEASUREMENT TECHNOLOGY, 1st International Conference on Mechatronic System and Measurement Technology, SCIENCE PRESS USA INC, Nanjing, PEOPLES R CHINA, pp. 411-416.
Guo, Y, Zeng, J, Zhu, J, Lin, Z & Li, Y 2012, 'Magnetic Hysteresis of Magnetorheological Fluid under 2D Rotating Magnetic Field Excitation', the 13th International Conference on Electrorheological Fluids and Magnetorheological Suspensions: Book of Abstracts, Gazi University, Ankara, Turkey, pp. 1-2.
Zeng, J, Guo, Y, Zhu, J, Li, Y & Li, J 2012, 'Magnetic Hysteresis Properties Measurement for Magneto-Rheological Elastomer', the 13th International Conference on Electrorheological Fluids and Magnetorheological Suspensions: Book of Abstracts, Gazi University, Ankara, Turkey, pp. 1-2.
Hu, HH, Wang, J & Li, Y 2010, 'Investigation on its vibration-reduction and shock-resistant properties of a gun recoil mechanism based on MR damper', Electro-Rheological Fluids and Magneto-Rheological Suspensions - Proceedings of the 12th International Conference, International Conference on Electrorheological Fluids and Magnetorheological Suspensions, World Scientific, Philadelphia, Pennsylvania, USA, pp. 214-220.
MR damper has brought out new challenges for development of the recoil mechanisms and vibration stability control of weapons because of its good electromechanical coupling performances. At present, it has been an urgent task during automatic firing to ensure its dynamic performance and its reliability of gun recoil mechanism under continuous fastly impact. For recoil mechanisms applications, MR dampers are desired to provide optimal damping force to control the recoil dynamics, so that large peak of recoil forces can be avoided with a certain limited stroke, and the firing stillness and stability are ensured. According to its vibration and shock mechanics process of gun recoil mechanism, the measurement method of its vibration-reduction and shock-resistant properties of gun recoil mechanism based on MR damper is analyzed. The results show that a gun recoil mechanism based on MR damper is quite a good vibration-reduction and shock-resistant equipment when the vibration and shock energy dissipation by damp is considered.
Li, Y, Li, J & Samali, B 2010, 'Design of new generation magnetorheological pins', Incorporating Sustainable Practice in Mechanics of Structures and Materials - Proceedings of the 21st Australasian Conference on the Mechanics of Structures and Materials (ACMSM21), Australasian Conference on the Mechanics of Structures and Materials, CRC Press/Balkema, Melbourne, Australia, pp. 807-812.
Recently, research and development of smart materials and structures for civil engineering applications have attracted increasing attentions from researchers around the world. Smart devices can be incorporated into civil structures as smart structural members with intelligent and controllable capacities for optimally detecting and reacting to the internal and external changes. Within the smart devices, magnetorheological (MR) based devices are one of the most promising smart devices to be considered for civil structures. Tills paper presents a novel design of a new-generation MR pin joint with high-torque capacity. An innovative design and analysis of MR pin with radial slots at the surface of the rotary plate is proposed. Theoretical modelling is undertaken based on the material, mechanical and magnetic analyses. Parametric analysis is conducted to optimise the shape, width and depth of the slots to best accommodate the design objectives.
Hongsheng, H, Juan, W, Jiong, W, Suxiang, Q & Yancheng, L 2009, 'Investigation on modeling and controability of a magnetorheological gun recoil damper', SECOND INTERNATIONAL CONFERENCE ON SMART MATERIALS AND NANOTECHNOLOGY IN ENGINEERING.View/Download from: Publisher's site
Hu, H, Wang, J, Qian, S, Li, Y & Jiang, X 2009, 'Investigation on controllability of a magnetorheological gun recoil damper', 2009 IEEE International Conference on Information and Automation, ICIA 2009, pp. 1044-1049.View/Download from: Publisher's site
Its primary purpose of this study is to provide a comprehensive investigation on the controllability of a Magnetorheological (MR) gun recoil damper. Performances of MR damper under random load, mainly in the transportation applications, seismic protection in civil engineering and windrain- induced load in Cable Bridge, have been well investigated by many researchers. However, little research has been focused on the dynamic performance and its controllability of MR damper under impact load. At present, a systematic architecture has still not been formed, including its structure design, dynamicmodelling and controlling method of a MR damper subjected to impact load. In this paper, the research is developed and aims at the MR gun recoil damper. To evaluate its controllability of a MR gun recoil damper, a test rig which uses a closed bump to produce an impact load is developed. A novel large-scale singleended MR damper without the accumulator is used as the specimen. First, impact tests were done to evaluate the response time of the special designed long-stroke MR gun recoil damper, corresponding to the step signal of the operating current. Then, three revised control strategies, including on-off control method, PID control method, adaptive fuzzy control method, were investigated to confirm its controllability of the MR damper under impact load. Compared with on-off control and PID control policy, it is indicated by test results that this developed MR gun recoil damper has a bette r controllability using the adaptive fuzzy control policy. © 2009 IEEE.
Hu, H, Wang, J, Wang, J, Li, Y & Jiang, X 2009, 'Investigation on its properties for MR damper under high impact load', ISTM/2009: 8TH INTERNATIONAL SYMPOSIUM ON TEST AND MEASUREMENT, VOLS 1-6, 8th International Symposium on Test Measure, INTERNATIONAL ACADEMIC PUBLISHERS LTD, Chongqing, PEOPLES R CHINA, pp. 2186-2189.
Hu, H, Wang, J, Wang, J, Qian, S & Li, Y 2009, 'Investigation on modeling and controability of a magnetorheological gun recoil damper', SECOND INTERNATIONAL CONFERENCE ON SMART MATERIALS AND NANOTECHNOLOGY IN ENGINEERING, 2nd International Conference on Smart Materials and Nanotechnology in Engineering, SPIE-INT SOC OPTICAL ENGINEERING, Weihai, PEOPLES R CHINA.View/Download from: Publisher's site
Li, Y, Li, J, Samali, B & Wang, J 2008, 'Theoretical and Experimental Studies on Semi-Active Smart Pin Joint', Future in Mechanics of Structures and Materials, Proceedings of the 20th Australasian Conference on the Mechanics of Structures and Materials, Australasian Conference on the Mechanics of Structures and Materials, Taylor & Francis Group, Toowoomba, Queensland, Australia, pp. 723-736.
An intelligent structural system equipped with smart structural members that are controllable in real-time is one effective solution to prevent structural damage and failure during hostile dynamic loadings, thereby leading to effective protection of structures and their occupants. The primary purpose of this study is to design, fabricate and characterise a prototype smart member, namely a semi-active magnetorheological (MR) pin joint, through theoretical modelling and experimental investigation. Design of prototype smart pin joints includes theoretical analysis relating to the rotary plate radius, the property of MR fluids and the gap between the rotary plate and the casing based on the requirements of the dynamics of MR pin joints. It is verified that an MR pin joint with a diameter of 180mm can produce a torque of up to 30 Nm, which is deemed adequate for realisation of the semi-active control for multi-storey building models in the next stage of research.
Li, Y & Wang, J 2008, 'Experimental study on PID control of MagnetoRheological shock absorber under impact load', 15th International Congress on Sound and Vibration 2008, ICSV 2008, pp. 3022-3028.
Magneto-Rheological fluids (MRF), with their fast, reversible and repeatable change of rheological behaviour in response to an external applied magnetic field, have for about a decade been the most fascinating subject of widespread interest. Many investigations have been fulfilled and prototypes have also been fabricated to undertake experiments, mainly in the transportation application such as automobile suspensions, heavy truck seats, and racecar suspensions and seismic protection in civil engineering and wind-rain-induced load mitigation in Cable Bridge. In recent years, the applications of MR devices under high shock and impact load have got increasing attentions because of its widely potentials in the engineering. Although there are researches focusing on the structure design and the dynamics of impact-use MR shock absorber, still very few investigations concerning the semi-Active control of the MR shock absorber under impact load have been explored. The primary purpose of this paper is to experimentally investigate the effectiveness of PID control policies on large-scale Magneto-Rheological (MR) shock absorber subjected to impact load. In this paper, three pre-estimated controllers, which are PID controller, PI controller and P controller, are developed to mitigate the peak shock response of MR shock absorber when it subjected to high impulsive load. An impulsive test rig that uses a fixed amount powder to produce the impact force is introduced. Comparative test results show that the P control has the best control results to restrain the peak response of damping force and inner pressure of MR shock absorber.
Li, Y, Wang, J & Hu, H 2007, 'Comprehensive study on controllablity of a large-scale MR shock absorber under high impact load', PROCEEDINGS OF THE ASME INTERNATIONAL DESIGN ENGINEERING TECHNICAL CONFERENCE AND INFORMATION IN ENGINEERING CONFERENCE, VOL 1, PTS A-C, ASME International Design Engineering Technical Conferences/Computers and Information in Engineering Conference, AMER SOC MECHANICAL ENGINEERS, Las Vegas, NV, pp. 1803-1808.
Li, Y, Wang, J & Hu, H 2008, 'Effect of fluted flow channel on magnetic field in Magneto-Rheological damper', Proceedings of the World Forum on Smart Materials and Smart Structures Technology, SMSST'07, p. 574.
Li, Y, Wang, J & Qian, L 2006, 'A new methodology of modeling a novel large-scale magnetorheological impact damper', NONLINEAR SCIENCE AND COMPLEXITY, Conference on Nonlinear Science and Complexity, WORLD SCIENTIFIC PUBL CO PTE LTD, Beijing, PEOPLES R CHINA, pp. 382-+.View/Download from: Publisher's site
Li, Y, Wang, J & Qian, L 2006, 'Nonlinear characteristics of magnetorheological damper under base excitation', NONLINEAR SCIENCE AND COMPLEXITY, Conference on Nonlinear Science and Complexity, WORLD SCIENTIFIC PUBL CO PTE LTD, Beijing, PEOPLES R CHINA, pp. 388-+.View/Download from: Publisher's site
Liu, X, Li, Y, Gu, Y & Tang, K 2006, 'Enhanced stochastic taps NLMS filter with efficient sparse taps localization', 2006 8TH INTERNATIONAL CONFERENCE ON SIGNAL PROCESSING, VOLS 1-4, 8th International Conference on Signal Processing, IEEE, Guilin, PEOPLES R CHINA, pp. 3241-+.
Li, YC, Wang, J & Qian, LF 2005, 'Comparative analysis of the dynamic characteristics of MR shock absorber under impact loads', PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON MECHANICAL ENGINEERING AND MECHANICS 2005, VOLS 1 AND 2, International Conference on Mechanical Engineering and Mechanics, SCIENCE PRESS BEIJING, Nanjing Univ Sci & Technol, Nanjing, PEOPLES R CHINA, pp. 927-931.
Wang, J, Wang, QL & Li, YC 2004, 'Finite element analysis of magnetorheological damper', Electrorheological Fluids and Magnetorheological Suspensions (ERMR 2004), Proceedings, 9th International Conference on Electorheological (ER) Fluids and Magnetorheological (MR), WORLD SCIENTIFIC PUBL CO PTE LTD, Beijing, PEOPLES R CHINA, pp. 722-727.
Wang, JN & Li, YC 2004, 'The dynamic simulation and test verification of MR shock absorber under impact load', ELECTRORHEOLOGICAL FLUIDS AND MAGNETORHEOLOGICAL SUSPENSIONS (ERMR 2004), PROCEEDINGS, 9th International Conference on Electorheological (ER) Fluids and Magnetorheological (MR), WORLD SCIENTIFIC PUBL CO PTE LTD, Beijing, PEOPLES R CHINA, pp. 822-828.