A novel 3D assembled negative stiffness metamaterial: Experimental and numerical studies

In recent years, the negative stiffness (NS) structure has been widely studied because of its unique mechanical response and large geometric deformation during stress. Most of the existing NS structures are made by additive manufacturing technology. With further research, the high cost of structural applications has become one of the obstacles to their popularity. In this case, fabricating metamaterials via an assembled process is a novel and economical method. A new assembled negative stiffness metamaterial is designed in this work. Inspired by traditional wooden structures, two kinds of clasp joints similar to mortise and tenon joints were designed. The negative stiffness frame structure can be freely assembled in three-dimensional direction by adding these two kinds clasp in the rigid frame. The quasi-static compression test and numerical simulation are used to study the mechanical properties of the structure. Comparison between assembled and integrated specimens, mechanical response under cycle loading and parametric analysis is also mentioned. Finally, a certain explanation has been made for the mechanical customization behavior exhibited in the structure. This strategy of assembly can reduce the costs of manufacturing and improve transportation efficiency. The proposed assembled structures provide practical solutions for the design and manufacture of negative stiffness metamaterials and expand the application of metamaterials.