Design of quasi-zero stiffness compliant shock isolator under strong shock excitation

Abstract

The quasi-zero stiffness (QZS) mechanism can rely on the combination of negative and positive stiffness elements to achieve very low dynamic stiffness while obtaining high static stiffness to support the isolated payload. It is a nonlinear shock isolation method with good shock isolation performance. In this paper, a new QZS compliant shock isolator is designed for shock isolation under strong acceleration shock excitation(>1000g), by paralleling a fixed-guided beam with negative stiffness and a Roberts configuration compliant beam with positive stiffness. The force-displacement characteristics of the QZS compliant shock isolator is analyzed and calculated theoretically using an elliptic integration method, and are verified by comparison using finite element simulation. The dynamic time-domain response characteristics of the QZS compliant shock isolator under the excitation of ideal shock excitation with different amplitudes, different periods, different payloads, and actual shock excitation are calculated, and compared with the performance of a general positive stiffness compliant shock isolator under the same excitation. The results show that the proposed QZS compliant shock isolator can be applied to shock isolation under strong shock excitation, and exhibits good constant force characteristics in the whole stroke during the shock isolation process, and is less affected by the amplitude and period of shock excitation. Compared with the general positive stiffness compliant shock isolator, the proposed QZS compliant shock isolator can significantly reduce the peak of the shock, reduce the maximum acceleration ratio and improve the shock isolation performance. It can provide some theoretical guidance for the design of the QZS compliant shock isolator under strong shock excitation.