An energy-based 2D model for predicting mechanical behavior of adhesively bonded CFRP laminates

Abstract

This paper presents a two-dimensional energy-based model for the mechanical behavior of adhesively bonded carbon fiber-reinforced polymer (CFRP) joints subjected to tensile loading. The proposed energy model is better suited than available discrete models to capture failure modes in adhesively bonded CFRP joints of different configurations having complex geometries. The governing equations are first developed for a three-stepped lap joint configuration by employing the minimum potential energy theorem and then solved using the finite element method (FEM). The disbond behavior of the joint configuration is modeled using the bilinear cohesive law. Subsequently, the developed model is extended to capture the mechanical response of adhesive joints for simple lap and scarf joint configurations. The proposed energy model is verified against 3D-FEA and experimental studies. Thereafter, a comparative analysis is undertaken for the three configurations of adhesive joints studied here. This is followed by a parametric study for the three-stepped lap joint to understand the influence of geometric and material properties of the adhesive and adherends on the stiffness and load-carrying capacity of the adhesively bonded CFRP joint. Finally, a design criterion is proposed for the three-stepped lap joint configuration, aimed at improving its load-carrying capacity/strength by reducing the peak stress levels at joint corners/overlap edges.