A tunable stiffness and damping vibration isolator based on magnetorheological elastomers (MREs) is developed. In this isolator, four MRE elements are used as the tunable springs, whose stiffness can be controlled by varying the magnetic field. A voice coil motor, which is controlled by the relative velocity feedback of the payload, is used as the tunable damper of the isolator. Under the combined ON–OFF control, the proposed vibration isolator shows satisfying isolation effect. The experimental results indicate that the responses of the payload are suppressed significantly in comparison to the passive system. The transmissibility of the payload around the resonant frequency is decreased by 61.5%. The root mean square (RMS) value and the maximum value of the displacement responses of the payload are decreased by 36.0% and 50.0%, respectively. In addition, the RMS values and maximum values of the velocity responses are decreased by 45.4% and 52.5%, respectively.

In this paper, semi-active H∞ control with magnetorheological (MR) dampers for railway vehicle suspension systems to improve the lateral ride quality is investigated. The proposed semi-active controller is composed of a H∞ controller as the system controller and an adaptive neuro-fuzzy inference system (ANFIS) inverse MR damper model as the damper controller. First, a 17-degree-of-freedom model for a full-scale railway vehicle is developed and the random track irregularities are modelled. Then a modified Bouc-Wen model is built to characterise the forward dynamic characteristics of the MR damper and an inverse MR damper model is built with the ANFIS technique. Furthermore, a H∞ controller composed of a yaw motion controller and a rolling pendulum motion (lateral motion + roll motion) controller is established. By integrating the H∞ controller with the ANFIS inverse model, a semi-active H∞ controller for the railway vehicle is finally proposed. Simulation results indicate that the proposed semi-active suspension system possesses better attenuation ability for the vibrations of the car body than the passive suspension system.

In this paper, a magneto-rheological (MR) damper-based semi-active controller for vehicle suspension is developed. This system consists of a linear quadratic Gauss (LQG) controller as the system controller and an adaptive neuro-fuzzy inference system (ANFIS) inverse model as the damper controller. First, a modified Bouc-Wen model is proposed to characterise the forward dynamic characteristics of the MR damper based on the experimental data. Then, an inverse MR damper model is built using ANFIS technique to determine the input current so as to gain the desired damping force. Finally, a quarter-car suspension model together with the MR damper is set up, and a semi-active controller composed of the LQG controller and the ANFIS inverse model is designed. Simulation results demonstrate that the desired force can be accurately tracked using the ANFIS technique and the semi-active controller can achieve competitive performance as that of active suspension.

The magnetic-field-induced normal force of magnetorheological elastomer (MRE) under compression status is studied in this paper. The influence of monotonic loading of the magnetic field, particle distribution, temperature, and cyclic loading of the magnetic field are investigated. The experimental results show that the normal force increases with increasing magnetic field and precompression force. For aligned MRE, the change of the magnetic-field-induced normal force is larger than that of isotropic MRE due to the special chainlike structure. When the temperature increases, the maximum change of the magnetic-field-induced normal force first increases and then decreases, due to the interaction of iron particles and the decreasing of the saturation magnetization of the carbonyl iron particles. If the magnetic field is circularly applied on the MRE, the normal force during unloading is smaller than that during loading due to the stress relaxation.

A 9-kN magneto-rheological (MR) damper for lateral suspension control of a railway vehicle is created in this paper. The twin-tube style is adopted in order to obtain a long damper stroke and guarantee the symmetry of the output damping force. A bypass MR valve with a radial flow path is utilised to control the generated damping force. Three-dimensional finite element analysis studies are performed to determine the magnetic field strength inside the MR valve region. The MR damper is mathematically modelled for the situation of a unidirectional fluid flow in the chamber and valve. The test results indicate that the MR damper can produce a considerable range of dynamic force and can operate as a fail-safe device. Sedimentation is detected in the damper; however, the response time is acceptable for real-world deployment.