Design of Quasi-zero Stiffness Vibration Isolator Based on Motion Singularity Characteristics of Parallel Mechanism

Abstract

A new quasi-zero stiffness isolator based on the motion singularity characteristics of parallel mechanism in the passage is proposed, which can solve the problems of poor low-frequency vibration isolation performance and small vibration isolation bandwidth of linear passive vibration isolation technology. The planar horizontal 2-RRR parallel mechanism and the vertical single-degree of freedom mobile mechanism in parallel to construct a P/2(2-RRR)RR parallel vibration isolation mechanism. The quasi-zero stiffness characteristics of the system are constructed by the superposition of the following two characteristics that the planar 2-RRR parallel mechanism can output the negative stiffness near the motion singular point and the positive stiffness generated by the spring in the vertical direction. Firstly, the nonlinear force–displacement model of planar 2-RRR parallel mechanism is established, and the stiffness characteristics of P/2(2-RRR)RR parallel vibration isolation mechanism are analyzed. Then the dynamic model of P/2(2-RRR)RR parallel vibration isolation mechanism is established, and the influence of excitation force amplitude and system damping on the vibration isolation performance of the system is analyzed by harmonic balance method. The results show that the P/2(2-RRR)RR parallel vibration isolation mechanism has lower resonance peak and wider vibration isolation bandwidth than the traditional linear vibration isolation system when the amplitude of vibration excitation force is small and the damping ratio is appropriate.