Performance of a shock isolator inspired by skeletal muscles

Nonlinear vibration isolators with low dynamic stiffness have advantages compared to linear isolators, but they also have limitations in terms of the maximum allowable displacement around a chosen equilibrium position. To overcome this issue, a novel nonlinear isolator is proposed that outperforms the classical quasi-zero stiffness nonlinear isolator when large inputs are applied. In this paper, the response of the isolator when subject to shock excitation is investigated. The isolator suspension is designed to exhibit a quasi-static force-deflection curve with sigmoidal shape, which has been observed in many studies reporting the characteristics of skeletal muscles. The shape of the force-deflection curve is such that the suspension system can store greater elastic potential energy. Simulations show that the proposed four-spring system outperforms the classical nonlinear three-spring configuration, in terms of maximum displacement of a suspended mass, when the shock amplitude is relatively large. This is achieved by exploiting the softening effect for large deformations.