Multi-spar composite box design and its post-buckling analysis

The post-buckling loading capability of the box was analyzed with the commercial software ABAQUS, focusing on the failure of skin/flange interface induced by post-buckling under bend-twist loading. Based on the FEM results, the skin/flange interface was enhanced by stitch which was simulated by using cohesive element, and the impact of stitch on failure mode and loading capability of the box was discussed. Moreover, the loading capability of reinforced box was studied by testing. The FEM results show that the multi-spar composite box has a long post-buckling period, and the post-buckling loading capability of the box reinforced by stitching technique could be improved significantly. The predicted results coincide well with experimental data, and the failure mode is also consistent with test results.