An experimental and numerical study on the behaviors of adhesively-bonded steel double-hat section components under axial impact loading

Abstract

A significant consideration in the deployment of adhesively-bonded joints in applications such as automotive body structures is their performance under impact loading. Due to the distinct behaviors of an epoxy-based structural adhesive under normal and shear loads combined with its propensity to undergo brittle fracture in cohesion and adhesion, special care needs to be taken in the constitutive modeling of such an adhesive as traditional Von Mises type yielding and elastoplastic material behavior do not seem to be applicable. In the current study, to start with, experimental load-displacement behaviors till failure of single lap shear and T-peel joints with steel substrates are predicted with the aid of a cohesive zone material model using LS-DYNA, an explicit nonlinear finite element analysis solver. With confidence established on cohesive zone modeling of the joints mentioned, the procedure is extended to robust prediction of the load-displacement responses and deformed shapes of steel double-hat section components subjected to axial impact loading. Three variants of steel hat section components have been considered from the viewpoint of joining of flanges with conventional discrete spot-welds, only continuous adhesive bonding, and a hybrid configuration with a combination of adhesive bonding and sparse spot-welds. The study reported here provides insights into mechanical behaviors of adhesively-bonded steel double-hat sections under impact loading, and demonstrates an efficient finite element modeling approach for adhesively-bonded steel hat sections using cohesive zone elements with fracture mechanics-based criteria for failure.