Abstract：A 3D dynamic finite element model with stitching threads is described as the spatial truss element is proposed to predict the progressive damage of stitched laminates. Combined with the user-defined material constitutive program of ABAQUS/Explicit, the typical failure modes, such as fiber break, matrix crushing, matrix cracking and delamination are simulated by employing the strain-based Hashin and Yeh failure criterion The dynamic response and damage propagation of stitched/unstitched laminates were simulated with this method. The numerical results are well agreed with the measured results and verify the effectiveness of the model. The effects of the impact velocity, the component material systems and the main stitching parameters on the dynamic response and damage evolution of stitched composites were discussed in detail, and some valuable conclusions are drawn herein. The results indicate that the stitched threads are not broken during the low velocity impact. The failure modes and damage evolution of stitched laminates are similar to the unstitched laminates, but the former has smaller damage areas. With the stitching density and strength of threads increasing, the stitching threads restrain damage evolution more effectively.
2011, Vol. 32 
