Cushion performance of cylindrical negative stiffness structures: Analysis and optimization

This paper focused on the analysis and optimization of the cushion performance of the cylindrical negative stiffness (NS) structure, which was designed to satisfy some special application scenarios. The basic mechanical properties, NS behaviors, and deformation mechanisms of the cylindrical NS structure were investigated through the combination of experimental and numerical approaches. Herein, a behavior, global asymmetric instability, was observed when the structure was under uniaxial compression. Also, the mechanism was analyzed. To prevent the asymmetric instability behavior, a gradient cylindrical NS structure was proposed and investigated. Subsequently, impact tests were conducted to investigate the cushion performance of the normal and gradient cylindrical NS structures. Research results indicated that the NS cylindrical structure could threshold the acceleration response, and the global asymmetric instability would weaken its cushion performance. Furthermore, the whole shock response process and deformation mechanism of the NS structure under impact were systematically analyzed. Based on the analysis of cylindrical NS structure's impact response characteristics and related deformation modes, two optimization approaches to improve structure's cushion performance, including introducing lattice supporting walls and filling foam materials, were presented. Experimental results suggested that these two optimization approaches could improve structure's cushion performance when certain requirements were satisfied.