Increase of quasi-zero stiffness region using two pairs of oblique springs

摘要

Quasi-zero stiffness (QZS) nonlinear isolation systems have demonstrated better performance than their linear counterparts. However, their optimal performance is achieved only in a small displacement range around the static equilibrium position. Based on the QZS system with one pair of oblique springs, this paper proposes a new limb-like QZS system with two pairs of oblique springs to enlarge the QZS range and thus improve its isolation performance. Two pairs of oblique springs are configured to provide the dynamic stiffness opposite to the vertical spring for generating QZS characteristics. In comparison with the corresponding QZS system with one pair of oblique springs, the proposed QZS system with two pairs of oblique springs can achieve a lower dynamic stiffness in a much wider region around the static equilibrium position. Based on the theoretical analysis, a prototype is designed and fabricated to physically realize the QZS isolation system. Experimental results are found to be in good agreement with the theoretical predictions which also confirm the proposed QZS system has better isolation performance than the corresponding QZS system with one pair of oblique springs. The proposed model can be adopted for isolating low frequency vibrations in practical applications.