Vibration control of platform structures with magnetorheological elastomer isolators based on an improved SAVS law

This paper presents a study on the vibration control of platform structures with magnetorheological elastomer (MRE) isolators. Firstly, a novel MRE isolator design is put forward based on the mechanical properties of MREs, and subsequently a single-degree-of-freedom (SDOF) dynamic model and a multiple-degree-of-freedom (MDOF) dynamic model for platform systems incorporating such isolators are developed. In order to overcome the shortcomings of the conventional on–off control law, an improved semi-active variable stiffness (SAVS) control law is proposed. The proposed SAVS scheme makes full use of the continuously variable stiffness of MREs, and it takes into account the influence of the sampling interval such that the field-dependent restoring force is made to do negative work during the whole sampling interval as far as possible. The results of numerical simulations demonstrate that the improved SAVS control law can achieve better vibration-control effectiveness than the on–off control law. The comparative results are discussed through examining the mechanisms of these two control laws in light of the power spectral density and the energy input. For an MDOF platform a simplified approach is proposed to combine the local response signals with an equivalent SDOF representation to generate the control parameters for individual isolators, and the effectiveness of such a scheme is also verified through numerical simulation.