Compliant quasi-zero-stiffness isolator for low-frequency torsional vibration isolation

The structures of traditional torsional quasi-zero-stiffness (QZS) vibration isolators are too complicated to achieve the desired vibration isolation performance as theoretically predicted. To resolve this issue, this study proposes a compliant quasi-zero-stiffness (CQZS) isolator to isolate low-frequency torsional vibrations in the shaft system. First, the configuration of the CQZS isolator is devised using a compliant mechanism, and the stiffness characteristics of the CQZS isolator are deduced analytically based on the energy method and verified using the finite element method. Subsequently, a dynamic model of the shaft system integrated with the CQZS isolator is established. The equation of motion for the shaft system is solved theoretically using the harmonic balance method. Finally, a prototype is fabricated using 3D printing technology with polylactic acid material, and static and dynamic experiments are conducted to verify the theoretical prediction. The results indicate that the CQZS isolator can achieve ideal torsional QZS characteristics and fulfil low-frequency torsional vibration isolation. The proposed CQZS isolator is much more compact, lightweight, and easier to manufacture than conventional QZS isolators.