State of the art of control schemes for smart systems featuring magneto-State of the art of control schemes for smart systems featuring magnetorheological materials rheological materials

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A new magnetorheological elastomer isolator in shear-compression mixed mode is designed in this article. Two pieces of magnetorheological elastomer fabricated with different dimensions are utilized in the isolator. One magnetorheological elastomer operates on shear mode, and the other operates on compression mode. Next, a finite element method magnetic package is used to analyze the designed magnetic circuit system, and a test system is established to obtain the frequency response of magnetorheological elastomer isolator with mixed mode. It is found that the natural frequency of magnetorheological elastomer isolator changes greatly with variable current applied, and the amplitude of vibration is attenuated widely. Compared with the natural frequency of 0 A, the increment of natural frequency is up to 103% with applied current reaches to 1.5 A. Finally, the dynamic model of isolator system is established, and the stiffness and damping coefficients of magnetorheological elastomer isolator are identified by the experimental method. Meanwhile, the variable range for stiffness and damping of magnetorheological elastomer isolator with mixed mode is greater than that of single mode, which has been proved in theory and experiments.

This paper addresses the problem of micro-vibration control of a precision vibration isolation system with a magnetorheological elastomer (MRE) isolator and fuzzy control strategy. Firstly, a polyurethane matrix MRE isolator working in the shear-compression mixed mode is introduced. The dynamic characteristic is experimentally tested, and the range of the frequency shift and the model parameters of the MRE isolator are obtained from experimental results. Secondly, a new semi-active control law is proposed, which uses isolation structure displacement and relative displacement between the isolation structure and base as the inputs. Considering the nonlinearity of the MRE isolator and the excitation uncertainty of an isolation system, the designed semi-active fuzzy logic controller (FLC) is independent of a system model and is robust. Finally, the numerical simulations and experiments are conducted to evaluate the performance of the FLC with single-frequency and multiple-frequency excitation, respectively, and the experimental results show that the acceleration transmissibility is reduced by 54.04% at most, which verifies the effectiveness of the designed semi-active FLC. Moreover, the advantages of the approach are demonstrated in comparison to the passive control and ON-OFF control.