Failure of Adhesively Bonded Joints. Analysis of Experimental Results by Nominal and Local Approaches

The failure in structural adhesively bonded lap joints can be analyzed following different approaches: using a nominal stress state typically given by Strength of Material models, a local singular stress state induced at the mutimaterial corners of the joint, or using cohesive constitutive laws for the adhesive layer or other damage progression models. The aim of this paper is to analyze the suitability of models based on nominal and local stress states to predict a failure in metal-to-composite double-lap joints and their capability to predict a failure when the geometrical parameters such as overlap length, adherent thickness or stacking sequence change. For that objective, a preliminary test program have been carried out, which has shown limitations in approaches using local stress states when gross yielding takes place inside the adhesive layer.