Numerical study on the onset of initiation of debond growth in adhesively bonded composite joints

Adhesively bonded composite joints plays, an important role in the modern composite structures assembly to realize light weight structures than the mechanical fastening. However, in the process of adhesive bonding of composite components can result in manufacturing flaws namely debonds. Debonds can change the structural response of adhesively bonded joints significantly in compressively loaded aerospace structures. In general, the prediction of the maximum load that composite structures can withstand is very crucial due to the anisotropic nature of the composite material. The presence of manufacturing defects like debonds adds further complexity to the prediction of failure mechanisms of the composite joints. The present study is focused to ascertain the effective load carrying capacity of the adhesively bonded composite joints in the presence of closed debonds. The finite element method (FEM) is used to predict the onset of initiation of debond growth in conjunction with virtual crack closure technique (VCCT). The studies are carried out for various bonded laminate configurations in the frame work of VCCT using general purpose FE code (ABAQUS). The influence of parameters such as laminate sequence, debond location, size and its shapes (square and circular) are investigated.