Experimental and numerical failure analyses of dissimilar material joints between aluminium and thermoplastic

In the automotive industries, joining of dissimilar materials has extensively attracted interest, because combinations of various lightweight materials in car bodies becomes more significant in order to achieve the most optimum design. On the other hand, several techniques for hybrid assembly have been continuously developed. In this work, aluminium sheets A5052 were joined with PBT-30GFR using two different methods, namely, hot pressing and adhesive bond. Then, resulted load carrying capacities were evaluated by means of single-lap joint (SLJ) specimens and occurred failure mechanisms were examined. Effects of surface treatments for aluminium samples on the strength of SLJ samples were also studied. Furthermore, FE simulations of single-lap shear tests were performed, in which cohesive zone (CZ) model was applied for representing the separation and subsequent failure behaviour of SLJ specimens. The parameters of the traction-separation law were individually determined for each joining techniques by mode-I and mode-II fracture toughness tests. Afterwards, force-displacement curves, maximum loads and failure occurrences of SLJ specimens with different overlap lengths were predicted. It was found that the proposed FE models and CZ parameters could correctly describe the experimental results of both joining methods.