Effects of adherend notching on the bonding performance of composite single-lap joints

The use of adhesively bonded joint is a mainstream and effective approach for solving connection problems of composite materials. Single-lap joint (SLJ) is one of the most frequently used joint types in the industry due to its simple geometry and easy applicability. The main factors in designing SLJ are the notch geometrical configurations (depths and lengths), the bond overlap lengths, and the types of adhesives. However, the influence of the notch geometrical configura-tions (depths and lengths) on joint bonding performances under different adhesive types (brittle and ductile adhesives) is still not fully understood. In this study, both the un-notched and notched 2D finite element models of SLJs have been developed and verified by comparison with literature -reported data and self-performed experiments, respectively. Subsequently, this validated 2D modeling approach is used to evaluate the influence of notch geometrical configurations and overlap lengths on the SLJs bonding performances in terms of failure loads, peel stresses and shear stresses distributions under two different brittle and ductile adhesives. In addition, a three-point bending resistance numerical analysis of SLJs has been carried out to investigate their flexural properties. The research conclusions will serve as a guide for the SLJs to choose proper adhesive types and notching configurations to increase joint strength and decrease stress concentrations.