Folding stress analysis of a sandwich plate based on transversely isotropic and rate-dependent constitutive relationship of adhesive

Abstract

ABSTRACT Flexible and foldable electronic products often contain adhesive layers, and failure generally initiates at the adhesive interfaces. To analyze the interfacial stress accurately, correct constitutive relationship of adhesive layers is necessary. However, soft adhesives used in foldable sandwich plates can show rate-dependent and anisotropic mechanical behaviors, which can hardly be implemented by traditional linear elastic and hyperelastic constitutive models in the folding process simulation. Through experiments in material’s principal axes and the strain energy equivalence principle, a transversely isotropic and rate-dependent constitutive relationship of adhesive has been developed in a three-dimensional form. By commercial finite element (FE) software ABAQUS and its user subroutine UMAT, the folding stress of a sandwich plate has been analyzed. The results of FE simulation show that folding time would affect stress distributions significantly due to the anisotropic and rate-dependent properties of adhesive.