Sliding-boundary-constrained cantilever structure for vibration isolation via nonlinear stiffness modulation

Abstract

In this paper, a novel sliding-boundary-constrained cantilever structure with nonlinear stiffness modulation (SCS-NSM) is proposed and systematically investigated for vibration isolation. The SCS-NSM is composed of a hemisphere-constrained cantilever structure (HCCS) and a pair of repulsive magnets. The nonlinear stiffness modulation mechanism for achieving quasi-zero stiffness (QZS), that is, using the hardening stiffness of the magnets to modulate the negative stiffness of HCCS, is fully revealed by static analysis. Furthermore, the QZS is adjustable to respond to different loads, and the modulation principle is clarified. Compared with conventional QZS isolators (paralleling negative and linear stiffness), the proposed SCS-NSM shows the advantages of wide load range and small static deflection. Static tests are performed to verify the effectiveness of the nonlinear stiffness modulation mechanism. Dynamic analysis shows that the SCS-NSM has a low resonant frequency and a wide vibration isolation frequency band due to its low stiffness. Periodic, sweep and random excitation tests are implemented to evaluate the vibration isolation performance of SCS-NSM. Experimental results validate the dynamic model and demonstrate that the vibration with a frequency higher than 4.6 Hz can be effectively attenuated. The proposed SCS-NSM provides a new perspective on low-frequency vibration isolation, and the nonlinear stiffness modulation mechanism has reference significance for designing QZS isolators with wide-bearing capacity and high compactness.