Wave absorption control of a lumped mass system using a dynamic absorber with variable stiffness property

Abstract

Severe vibration may occur in structures such as high-rise buildings and bridges according to wind and seismic excitations, and in large space structures due to their lightweight and flexible constitution. Generally, when several vibration modes are simultaneously excited, application of the model-based control strategies become difficult. In this study, we propose a wave absorption control method for reducing vibrations in multi-degree-of-freedom systems semi-actively using a magnetorheological elastomer-based dynamic absorber. The stiffness of the absorber is changeable according to the applied magnetic field strength. The value is tuned adaptively so that the mechanical impedance at the boundary meets an absorptive boundary requirement. Analytical investigation clarified relationship between the excitation frequency and absorber stiffness that could eliminate the wave reflection from the boundary and maintain no resonant state in the system. Based on this stiffness condition, numerical simulation and experiment for the wave absorption control were performed. The proposed absorber to be used with the wave control scheme was found to significantly reduce structural vibrations within the stiffness variable range.

Keywords

• wave absorption control
• lumped mass system
• dynamic absorber
• variable stiffiness
• magnetorheological elastomer
• semi-active control