An energy-based analytical model for adhesively bonded stepped and simple-lap joined CFRP laminates

Abstract

An energy-based analytical model is proposed here to investigate the mechanical behavior of adhesively bonded simple-lap and stepped-lap joints (SLJ) with carbon fiber-reinforced polymer (CFRP) adherends subjected to tensile loading. In this study, the CFRP uni-directional (UD) adherends of \([0]_{16}\) and quasi-isotropic (QI) layup sequence of \([45/-45/0/90]_{2s}\) are considered to be joined. The governing differential equations (GDEs) of equilibrium are derived for the adhesively bonded adherends in stepped lap joint configuration following an energy-based approach. Additionally, this model is reduced for GDEs of the simple-lap joint configuration. The finite difference scheme is employed to obtain the numerical solution of the proposed analytical model. The field distributions of strain and displacement over the specimen surfaces are captured in the experimental investigation using the full field technique of 2D digital image correlation (DIC). The analytical model generates the load–displacement curve, validated against experimental and finite element (FE) predictions. Additionally, a sensitivity analysis is conducted to assess the influence of the design parameters of the adhesive joint, including the thickness of the adhesive layer, length of overlap region, and elastic modulus. Finally, the analytical model prediction of the peak load for damage in adhesively bonded joints under shear loading is compared with experimental results. The developed analytical model provides an understanding of the mechanical behavior, including possible failure/critical locations of the adhesive joints from the design perspective.