Numerical analysis of crack initiation angles and propagation paths in adhesively bonded joints under mixed mode I/II loading using a novel test specimen

Abstract

In the present work, first, the effect of adherent type on the fracture parameters of a novel mixed mode I/II fracture specimen called bi-material inclined notch short bend beam (BI-SBB) is investigated by using the J-integral method. Then, the crack propagation path is obtained incrementally based on the maximum tangential stress (MTS) fracture criterion. In the next step, the crack propagation path is examined once again using the hybrid XFEM-CZM approach. To do that, in the adhesive region, the elements are enriched and in the adherent and adhesive interface, cohesive surface is used. The results showed that for the mode I loading, based on both methods, the crack propagation path is along the initial crack and inside the adhesive. But under mode II and mixed mode I/II loading, the crack kinks towards the adherent-adhesive interface. However, kinking slop obtain from the hybrid approach is steeper than the path obtained from the MTS criterion. According to the hybrid approach, once the crack reaches the adherent-adhesive interface, crack growth in the XFEM domain ceases and the damage appears on the cohesive surface. Then delamination propagates at the interfaces between the adhesive and adherents as the loading increases.