A consistent finite displacement and rotation formulation of the Linear Elastic Brittle Interface Model for triggering interlaminar damage in fiber-reinforced composites

Abstract

In this study, a novel procedure enabling the computation of the relative displacements (normal δn, shear δss and in-plane δsl) that are needed to evaluate a traction-separation law (TSL) under finite displacement and rotation hypotheses within the framework of interface modelling is investigated. This kind of procedure is required when rigid body motions appear along the interface that links two solids or along an adhesive joint. The implementation of this procedure into a general purpose Finite Element (FE) code is also described. In this context, the displacements associated with a coordinate system with an axis coincident with the midplane of an interface in presence of rigid body motions are obtained for two types of element formulations: cohesive elements and continuum or solid elements. In particular, the FE commercial code ABAQUS® is used to perform two dimensional analyses. Firstly, normal and shear relative displacements, δn and δss respectively, are calculated using the strain field for COH2D4 cohesive elements. Secondly, relative displacements are determined for standard continuum elements by means of the plane strain elements CPE4. In the second case, a description of the element enhancement is detailed, using an enriched displacement field thanks to the computation of the in-plane jump δsl. Subsequently, some representative benchmark problems involving 1-element tests with prescribed node displacements are shown in order to validate the proposed procedure. Finally, the Horizontal Drum Peel test which includes finite displacements and rotations is modelled together with the Linear Elastic Brittle Interface Model (LEBIM). This test allows the fracture toughness of a bonded joint to be evaluated.