A comparison of failure prediction methods for an adhesively bonded composite beam

In this paper, three different techniques are proposed to predict the failure load in two adhesively bonded composite I-beams. These methods are analytical solutions, finite element analyses (FEAs) and hybrid methods (combination of FEA and closed-form solutions). The two I-beams were tested in the three-point bending and four-point bending configurations. In the analytical solutions, simple stress analysis and fracture mechanics, based on beam theory, are used. Failure in the adhesive layer as well as failure in the skin or spar caps is considered. In the finite element (FE) approach a submodelling technique is adopted, in which a coarse model and a submodel are required. A circular flaw of 6 mm radius is initiated in the adhesive layer and the strain energy release rates are extracted from the FEA results using a modified crack closure technique. In the hybrid method, a global FE model is constructed and the stresses are calculated; then an analytical solution for a circular crack is applied. Comparison between the three techniques is presented