Strength and failure analysis of adhesive single-lap joints under shear loading: Effects of surface morphologies and overlap zone parameters

Abstract

ABSTRACT The adhesive bonding process is widely used in the automobile industry because of sealing, insulation and good mechanical properties. In this study, the effects of surface treatments and joint parameters on shear strength and failure mode were investigated. Four different sandpaper treatments, overlap length and adhesive thickness were selected to carry out quasi-static shear test. The failure behaviour of aluminium alloy single-lap adhesive joints was analysed and a dimensionless parameters δ was introduced to quantitatively evaluate the effect of overlap length on joint strength. Results showed that the joint strength was enhanced by sandpaper grinding due to the change of surface roughness. The specimens with 90°/0° grinding direction using P360 sandpaper had the best performance rather than an excessively rough surface. The joint shear strength decreased with the increase of adhesive thickness but the effect of overlap length on joint strength was limited. The adhesive thickness had little impact on joint shear strength when the overlap length over 40 mm. In addition, the joint strength could be improved by increasing overlap length until δ below 0.95. However, with the decrease of δ, there was almost no effect on joint strength because of high peeling stress at the both ends of the long joints.