An analytical model for debonding of composite cantilever beams under point loads

Abstract

The paper presents an analytical model to study the shear driven debonding of a composite cantilever beam subjected to a point load. The composite structure consists of two elastic beams connected by an interface layer, and the model uses cohesive zone models to simulate the degradation process at the joint. These cohesive zone models are characterized by non-continuous and linear softening in the relationship between shear stress and relative tangential displacement. The results are expressed using non-dimensional parameters, and the model yields quasi-static equilibrium paths that demonstrate snap-back responses in both force and displacement values. The significance of the research lies in its application to structural engineering, where composite materials are extensively used. The study emphasizes the critical role of the interface layer strength in maintaining the structural integrity of composites. The proposed model advances the understanding of debonding by introducing a constitutive relation for the interface that accounts for the step-wise change in mechanical properties. The governing equations for the cantilever beam are derived, considering the equilibrium of forces and moments, and the relative tangential displacement at the interface. The model delineates three stages of interface degradation: no relative slip, plastic deformation, and progressive debonding. The analytical solutions for each stage provide insights into the beam deflection, shear stress, and axial force distribution. This research contributes to the field by offering a more refined analytical approach to study debonding in composite beams, which is essential for improving the design and analysis of composite structures.