Pseudo-elastic cavitation model—part II: extension to cyclic behavior of transparent silicone adhesives

Abstract

This study investigates the cyclic structural behaviour of adhesive joints of glass and metal using thin, structural silicone adhesives in heavily constrained applications. Based on cyclic uniaxial tensile tests on dog-bone and pancake test samples, the pseudo-elastic cavitation model from part I of this publication will be extended to describe two phenomenons: stress softening due to Mullins effect, as well as a mechanical hysteresis occurring under hydrostatic loading of rubber-like materials. This mechanical hysteresis under hydrostatic loading is associated with the growth and shrinkage of microscopic voids in the materials structure, and shows distinctive differences to the mechanical hysteresis known from isochoric test samples. In order to transfer the already presented pseudo-elastic cavitation model to describe the cyclic material behaviour, the isochoric part of the cavitation model is extended according to the classical theory of pseudo-elasticity to numerically describe stress softening under isochoric deformations. In addition, the volumetric part is provided with a special material formulation so that it can numerically reproduce the void growth hysteresis under cyclic volumetric tests, e.g. pancake tests. For validation, three-dimensional simulations of both cyclic tensile tests (dog-bone and pancake tests) are carried out.