Strength and damage evolution of mid-thick composite laminates with countersunk bolt joints

Comparison analysis on bearing strength of two thickness composite laminates with countersunk bolt joint or protruding bolt joint was conducted using experimental method to deal with the strength and damage evolution of mid-thick composite laminates with countersunk bolt joints. The results provide sufficient evidence that the decrease of bearing strength caused by the laminates thickness increase of countersunk bolt is less than that of protruding bolt connection structure. To investigate the damage evolution and failure strength of countersunk bolt joint, a new continuum damage failure model with the combination of continuum damage evolution and 3D mixed failure criterions was proposed. The model takes the advantages of consideration of matrix shear nonlinearity, using the improved fiber failure criterion and improvement in the convergence of the composite structure. The predicted results agree well with the experimental results and the deviation of the failure strength is no more than 8.62%.