Analysis and design improvement of composite bolted π-joints under bending load

A 3D progressive model with better convergence property is established to capture the mechanical properties and damage mechanism of a composite bolted π-joint under bending load and shown to closely match experimental results. This model is then used to investigate the effect of internal laminate stacking sequence and surface layers thickness on the bending performance of the joint. It was found that the stacking sequence and the surface layers thickness have a significant effect on the matrix crack and delamination distributions in the joint, respectively. Local surface layer thickness can be designed to control the delamination damage around the bolt hole. Finally, volume fraction of 0° layer in the internal laminate and surface layer thickness are used to improve the joint bending performances by proper design.