Failure analysis and experimental study on bolted composite joints based on continuum damage mechanics

This study focuses on the numerical analysis and experimental evaluation of failures and damages in the bolted joints of CFRP composite laminates under tensile loads. Firstly, failure criteria for fiber and matrix are established based on the Puck/LaRC failure criteria and in-situ strength theory. A mechanical model for composite damage analysis is established by adopting the nonlinear stiffness degradation method. Secondly, the tensile properties of composite laminates and perforated plates are analyzed using a mechanical model developed above. Finally, we conducted an experimental investigation of the composite joints and finite element analysis of their failure and damage evolution. The comparison between the calculated and experimental results demonstrated that the employed mechanical model and calculation method could accurately predict the strength and damage of carbon fiber composite joints under tensile loads. Moreover, to evaluate the fracture angle in matrix failures, we proposed a new method, which is found to be beneficial in improving the accuracy and efficiency of evaluating fracture angles.