Dynamic characteristics analysis of bilayer bio-inspired X-shaped vibration isolation structure

Abstract

Based on the vibration isolation properties of the coupled toe-leg structure of the biped bird, a bilayer bio-inspired X-shaped vibration isolation structure (BBXVI) considering the coordination function between skeleton type and muscle/tendon is proposed in this research. The mapping relationships of equivalent restoring force–displacement and equivalent stiffness–displacement with various parameters are analyzed by statics, the parameter condition and the modulation of nonlinear behavior of the BBXVI to achieve quasi-zero stiffness (QZS) are investigated. Based on establishing dynamic model of the bilayer X-shaped structure, the effects of initial angle, rod-length ratio and rod length on dynamic characteristics and vibration transmissibility of the BBXVI subjected to displacement excitation are studied by incremental harmonic balance method (IHBM). The study found that the BBXVI presents excellent low frequency vibration isolation performance. With increasing α1, the QZS characteristic, vibration isolation bandwidth and response amplitude of the BBXVI increase first and then decrease. The larger rod-length ratio and longer rod length can increase the vibration isolation bandwidth and improve the vibration isolation performance. In addition, longer rod length could make the equivalent stiffness of the BBXVI gradually evolve from hardening spring to softening spring properties, and the vibration transmission property of the vibration isolation system is changed.