Stress Analysis in Single-Lap Adhesive Joints: Comparison of Unreinforced, Reinforced and Prestressed Configurations Assembled with Brittle Structural Adhesives

Adhesive joints provide an effective and lightweight solution for the assembly of structures and offer both mechanical and operational advantages over conventional mechanical fastening systems. In this study, a new single-layer adhesive joint is investigated in which a thin, pretensioned textile reinforcement is inserted into the adhesive layer. In the first part, a simplified analytical model is proposed to describe the distribution of axial stresses in the adhesives and the reinforcement as well as the shear stresses in the adhesive layer. In the second part, the effects of geometric, mechanical and loading variables are investigated in a parametric analysis, focussing on the role of the initial pre-compression on the tensile response of the joint. The third part of this study compares the theoretical results with experimental data obtained with static tests on specimens made of unreinforced GFRP and epoxy resin. The results show small deviations (3-8%) between model and test. Finally, a simplified method for estimating the load-bearing capacity of brittle joints, both conventional and reinforced, is proposed. It is shown how the introduction of reinforcement and prestressing can modulate the stiffness and improve the stability of the joint without significantly affecting the load-bearing capacity.