Strength analysis of metallic bonded joints containing defects

Finite element simulation has been utilized to study the overall strength of metallic single lap joints with defects in their adhesive layers. Three types of defects are taken into account respectively, which are local debonding, weak bonding and void. For the first two types of defects, a developed numerical method using the cohesive zone model modified by user-defined subroutines is carried out as to consider the influences of the defect size and location. Furthermore, a modified-Gurson model is employed to simulate the adhesive layer with voids, considering the influence of the void size. The results show that the overall strength of the joints diminishes as the defect size is increased. Especially, the adhesive fracture properties and the size of the weak bonding region have combined influences on the strength of the joints.