Interfacial debonding in a thin plate bonded to a rigid substrate with a circular hole

Abstract

Mode I fracture is a prevalent failure mode in adhesively bonded joints. This paper presents analytical and numerical solutions for the mechanical interaction of a thin plate bonded to a rigid substrate with a circular hole. Utilizing the bilinear cohesive law, the proposed solution is designed for the bonded joints subjected to uniformly distributed load and point load, respectively. The interfacial normal stress distribution and load-displacement response undergo three distinct stages: the initial elastic stage, followed by the elastic-softening stage, and culminating in the elastic-softening-debonding stage. The load-displacement response of the joints subjected to uniformly distributed load and point load diverges after debonding occurs. The load-carrying capacity of the former decreases rapidly, while the latter exhibits an opposite trend. Finite element (FE) simulation is conducted for numerical validation, demonstrating excellent agreement between the proposed model and FE results. The paper concludes by discussing the influences of hole radius, bond length, and the properties of the adhesive layer and thin plate on load-displacement response and the ultimate load. The findings suggest that higher bond strength and larger fracture energy of the adhesive, along with thicker and stiffer thin plates, contribute to achieving higher load-carrying capacity in bonded joints. Additionally, a longer bond length improves the load-carrying capacity for the joint subjected to the point load, with minimal impact for uniformly distributed loads once the bond length exceeds the effective bond length.