Semi-actively controlled magnetorheological (MR) fluid dampers offer rapid variation in damping properties in a reliable fail-safe manner using very low power requirements. Their characteristics make them ideal for semi-active control in structures and vehicle applications in order to efficiently suppress vibration. To take advantage of their exceptional characteristics, a high fidelity model is required for control design and analysis. Perfect understanding of the dynamic characteristics of such dampers is necessary when implementing MR struts in applications. Different models have been proposed to simulate the hysteresis phenomenon of MR dampers. The Bouc-Wen model has been extensively used to simulate the hysteresis behavior of MR dampers. However, considerable differences still exist between the simulation and experimental results. Moreover, the characteristic parameters in the traditional Bouc-Wen model are not functions of the frequency, amplitude and current excitations; therefore, the estimated parameters can characterize the behavior of the tested MR damper under specific excitation conditions and must be re-evaluated if a different combination of excitation parameters is desired. This can be extremely cumbersome and computationally expensive. In this work, a new hysteresis model based on the Bouc-Wen model has been developed to better characterize the hysteresis phenomenon of the MR damper. The proposed model incorporates the frequency, amplitude and current excitation as variables and thus enables us to predict efficiently and accurately the hysteresis force for changing excitation conditions. The proposed modified Bouc-Wen model has been validated against the experimental results through graphical and quantitative analysis in time, displacement and velocity domains and an excellent correlation has been found.

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Recently, magnetorheological (MR) dampers have emerged as a potential technology to implement semi-active control in structures and vehicle applications in order to efficiently suppress vibration. Perfect understanding about the dynamic characteristics of such dampers is necessary when implementing MR struts in application. One of the important factors to successfully attain desirable control performance is to have a damping force model which can accurately capture the inherent hysteresis behavior of MR dampers. Different models have been proposed to simulate the hysteresis phenomenon in such a kind of damper. The Bouc–Wen model has been extensively used to simulate the hysteresis behavior of MR dampers. However, considerable differences still exist between the simulation and experimental results. In this work, a methodology to find the characteristic parameters of the Bouc–Wen model in the attempt to better characterize the hysteresis phenomenon of MR dampers has been proposed. The methodology takes into consideration the effect of each individual term of the Bouc–Wen model over the hysteretic loop to estimate the appropriate values of the parameters. The Bouc–Wen model in which the new established characteristic parameters have been used has been validated against experimental data and an excellent agreement has been shown between the simulation and experimental results. Moreover, the findings pointed towards the fact that linear or exponential relationships exist between the estimated parameters and the current excitation. Considering this, a new model based on the Bouc–Wen model has been proposed in which the excitation current has been incorporated as a variable. This proposed modified Bouc–Wen model has also been validated against the experimental results and a good correlation has been found.

During past four decades, applications of magnetorheological and electrorheological fluids in adaptive sandwich structures have been widely studied, primarily for the purpose of vibration control. The rapid response time of controllable magnetorheological/electrorheological fluids to an applied magnetic/electric field and reversible variations in their stiffness and damping properties have been the key motivations for adaptive structures applications. This article presents a comprehensive review of the reported studies on applications of magnetorheological/electrorheological fluids for realizing active and semi-active vibration suppression in sandwich structures. The review focuses on methods of characterizing the magnetorheological/electrorheological fluids in the pre-yield region, magnetic/electric field-dependent phenomenological models describing the storage and loss moduli of fluids, experimental and analytical methods developed for vibration analysis of sandwich structures with magnetorheological/electrorheological fluid treatments, analysis of structures with partial magnetorheological/electrorheological fluid treatments and optimal treatment locations, and developments in control strategies for vibration suppression of magnetorheological/electrorheological sandwich structures. The studies on dynamic responses of fully and partially treated magnetorheological/electrorheological-based sandwich beams, plates, shells, and panels are also discussed, including the mathematical modeling methods and associated assumptions, methods of solutions, and experimental methods.

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