Design of a compliant lever-type passive vibration isolator using quasi-zero-stiffness mechanism

Abstract

In this thesis, design and analysis of a new passive vibration isolator using compliant lever-type and quasi-zero-stiffness (QZS) mechanisms is provided. At first, various systems are designed without QZS mechanism. It is aimed to create antiresonance frequency by using lever-type mechanism. Anti-resonance occurs when the inertial force generated by the levered mass cancels the spring force. Since the levertype mechanism increases the effect of the isolator mass, it is capable of isolating a relatively heavy body with little mass in itself. These designs are examined analytically, numerically and experimentally. First, the systems are modeled with lumped and distributed parameters. Then, the system is modeled by finite element method (FEM). Optimization of the design is made to get highest isolation in the widest frequency range. As a result, the optimized design with desired properties is found. At last, the optimized design is manufactured and tested. In the second part, QZS mechanism is attached to the design. This design consists of multiple parts which renders the system adjustable. The equations of negative stiffness mechanism are provided. FEM results are compared with the analytical results. The working principle of adjustable mechanisms are explained. As a result, design and analysis of a new compliant levertype passive vibration isolator using QZS mechanisms is provided. Finally, the design is manufactured and tested. This design can also be adjusted for the designed vibration isolation frequency range and good isolation levels can be acquired especially at low frequencies.