Progressive damage analysis of an adhesively bonded composite T-joint under bending, considering micro-scale effects of fiber volume fraction of adherends

In this study, a numerical study on failure assessment and stress distribution on the adhesive region in a composite T-joint under bending load case is investigated using cohesive zone method (CZM). The Finite Element Model (FEM) has been verified with experimental results. To study the load transfer capability of the T-joint, five different adhesives are considered in the adhesive region and the effect of geometrical parameters such as stringer thickness, corner radius, and adherend thickness as well as micromechanical properties of reinforced fiber composite adherends are investigated. Effective properties of two composite adherends including Carbon-Epoxy (IM7/8552) and Glass-Epoxy (E-glass/Epon 828) with various fiber volume fractions are estimated using a 3D representative volume element (RVE) and employing period boundary conditions (PBC) through Python scripts in ABAQUS. The results show that the fiber volume fraction of composite adherends has a significant effect on failure behavior. For instance, increasing fiber volume fraction of carbon/epoxy composite from 0.4 to 0.7 resulted in a 78% increase in elastic stiffness and a 41% enhancement in maximum load-bearing capacity. Among different adhesive types used in this study, FM300 resulted in the strongest structure and S7752 led to a more ductile T-joint.