Evaluation of internal structure of self-contracting auxetic rubber material by finite element analysis

Abstract

In this study, the internal structure of auxetic materials was evaluated by finite element analysis. The auxetic materials have periodic voids. Volume of auxetic materials decreases and the density increases under compression. This kind of behavior is referred to as self-contraction. The structure does not necessarily exhibit self-contraction even materials have periodic voids. Finite element analysis showed the deformation behavior of the model on compression displacement. In this paper, the elliptical void model and the dumbbell void model were proposed. Multiple internal structures were created to change the elliptical void angle θ. Self-contractility was improved in the case of placing the elliptical void diagonally to the compression direction. From this results, rotation of internal structure is related to self-contraction. The dumbbell shaped void model composed more rotatable structure. The internal structure made of dumbbell shaped void gave the model high self-contractility. Auxetic materials consisting of periodic voids needs rotational mechanism in its internal structure. The self-contraction occurred stable in the case of rotation angle increases constant.