Negative stiffness materials for vibration damping: a material realization of a nonlinear bistable element

This paper addresses material and shape design of a prototype exhibiting a negative stiffness over a finite range of global strains. The objective is to define a design loop, where, starting from the actual material realization, a corresponding finite element model is developed and associated to a bistable discrete one-dimensional mechanical system composed of precompressed springs, a stabilizing spring and a damper. The discrete model can easily be analyzed and optimized for improved vibration damping properties. This will allow the determination of an alternative specification of a new optimized prototype. If confirmed by finite element analysis, then an improved prototype can be produced accordingly. This paper presents the first results: the material realization and the corresponding discrete model identification exploring also the finite element model. Optimization will be subject of further research. It is concluded that the specimen behaves according to the expectations, i.e. the negative stiffness region is well-formed and the discrete correspondence is easily obtainable. Such a structure can be used as a negative-stiffness element to achieve extreme mechanical properties of a composite or as a structure with improved damping properties.