Finite element analysis of interfacial crack propagation based on local shear. I: Near tip deformation; II: Fracture (Q1282667)

In the first part, full-field plane-strain elastoplastic solutions for an interface crack in adhesive bonds deforming in shear are obtained from a finite element analysis. The analysis, which considers very large strains and includes the effect of contact and friction between the debonded interfaces, is particularized to a nearly elastic ideally-plastic interlayer obeying \(J_2\) flow, which is sandwiched between either rigid or compliant substrates. Guided by experimental evidence, the analysis focuses on the interface ahead of the crack tip, where crack propagation occurs. The mechanics of fracture of a stably extending interface crack in polymeric adhesive bonds undergoing very large shear deformation is studied in the second part using a rate-dependent finite element analysis. Plane-strain and \(J_2\) plasticity conditions are considered. Based on recent experimental observations, it is assumed that the local engineering shear strain at a certain distance (i.e., for the polymer adhesive studied, approximately one tenth of bond thickness) straight ahead of the crack tip remains constant during the crack propagation. This critical strain is rate-dependent, being a function of the crack velocity. The proposed fracture criterion is applied to several experimental crack growth histories pertaining to different specimen geometries, bond thicknesses and crack velocities.