The isolation performance of vibration systems with general velocity-displacement-dependent nonlinear damping under base excitation: numerical and experimental study

The study is concerned with isolation performance of a velocity-displacement-dependent (VDD) nonlinear damping, which has arbitrary nonnegative velocity exponent and displacement exponent. Displacement transmissibility of a single-degree-of-freedom (SDOF) vibration system with proposed damping under base excitation is investigated. The implicit amplitude-frequency equation is derived by using the averaging perturbation method. The stability analysis for both integer power law damping and rational powers less than unity in the nonlinearities is performed. The relative and absolute displacement transmissibility is obtained to evaluate the isolation performance. Parametric analysis is carried out to study the influence of damping parameters on the transmissibility. It shows that the proposed damping can not only suppress the response at resonance but also improve isolation performance at high frequencies if the velocity and displacement exponent as well as damping coefficient satisfy some conditions. The condition of a VDD damping that is independent on the excitation amplitude is obtained. Experimental investigation is performed by using a SDOF base excited vibration isolation system possessing a simple velocity feedback control active damper to reproduce the proposed nonlinear damping. The measured results are shown to be in good agreement with theoretical predictions thereby verifying the effects of VDD damping undergoing base excitation. The investigation is capable to enhance understanding of the effects of VDD damping, which will set a foundation for the design and exploitation on beneficial effects of this damping for vibration isolation in engineering systems.