Characterization of Bending Strength in Similar and Dissimilar Carbon-Fiber-Reinforced Polymer/Aluminum Single-Lap Adhesive Joints

In recent years, the adhesive bonding method has gained increased attention, especially in the automotive industry, for constructing efficient body structures from dissimilar and lightweight materials such as aluminum and polymeric composites. Adhesively bonded automotive structures endure complicated loading conditions, including tensile and bending loading, during their service lives. To the best of the authors’ knowledge, there is no published work on the assessment of bending strength in single-lap adhesive joints (SLJs) when considering dissimilar adherends under three-point bending. In this study, three-point bend experiments were carried on the bending strength and the failure mechanisms of dissimilar SLJs made of carbon-fiber-reinforced polymer (CFRP) and aluminum substrates bonded with Araldite 2015 adhesive. Additional experiments were conducted individually on similar SLJs, including aluminum/aluminum and CFRP/CFRP, to investigate and compare the effects of adherend material type on the bending strength and failure behavior of SLJs. The results indicate that a CFRP/CFRP single-lap adhesive joint exhibits significantly higher joint strength in comparison to an aluminum/aluminum single-lap adhesive joint under three-point bending. The strength of dissimilar CFRP/aluminum single-lap joints usually falls between that of an aluminum/aluminum and that of a CFRP/CFRP single-lap adhesive joint. When the CFRP adherend is situated at the bottom of the joint in three-point bending, it imparts significantly greater joint strength and deformation compared to situations where the aluminum adherend is placed at the bottom.