Design and analysis of novel negative stiffness structures with significant energy absorption

Negative stiffness structures (NSS) are a type of mechanical metamaterials that absorb energy via buckling of negative stiffness members. However, these structures have limitations in energy absorption and reusability. Therefore, this study aimed to design, simulate, fabricate, and perform experimental tests on novel designed negative stiffness (NS) structures and improve the performances of negative stiffness structures in terms of energy absorption and keeping their original configuration under cyclic loading. First, the finite element method (FEM) and parametric study of the geometrical dimensions of NS members were considered to investigate the activation/non-activation snap-through mechanisms in the designed structures under quasi-static compression loading. Subsequently, two designed structures were manufactured via the Fused deposition modeling (FDM) printing method and one cyclic loading with a quasi-static state was carried out. The results of the FE simulation and experimental tests were compared, and good agreements were found between them. Afterward, the dissipated energy values and loss factor values of the designed structures under two cyclic loading (two loading/unloading processes) were investigated. Considering both the parameters of the energy absorption values and the remaining members in the elastic region, the proposed NSS was presented for energy absorber structures.