Design and testing of a parabolic cam-roller quasi-zero-stiffness vibration isolator

• The condition of the PCR QZS isolator outperforming the CCR one is derived. • The optimal design of the parabolic-cam-roller QZS isolators is investigated. • A prototype of the proposed PCR QZS isolator is fabricated and tested. • The present PCR QZS isolator has lower transmissibility than the CCR one. • The proposed isolator can withstand larger amplitude excitations than the CCR one. Circular cam-roller (CCR) quasi-zero stiffness (QZS) vibration isolators have been extensively studied. As the CCR isolator can only achieve low stiffness in a very small range and cannot withstand excitation with large amplitude, study on other cam profiles has become interests. This paper investigates a parabolic cam-roller (PCR) QZS vibration isolator. Theoretical formulations of the PCR QZS isolator are derived in detail and the condition of PCR isolator outperforming CCR one is obtained. Design parameters are analyzed and then the optimal design is presented. A prototype of the PCR QZS vibration isolator is fabricated and tested; the corresponding CCR QZS and linear isolators are also experimentally evaluated. In comparison with CCR QZS isolators, the proposed PCR QZS isolators can withstand force and displacement excitations with larger amplitudes in the QZS region. The experimental results validate the present formulation and show that vibration isolation performance of the proposed PCR QZS isolator is much better than that of the CCR QZS isolator and that of the corresponding linear isolator. In comparison with the CCR QZS isolator, the present PCR QZS isolator can have lower stiffness in a wider region around the equilibrium position and lower transmissibility.