Failure mode of composite stiffened structures under explosive loading: Improved damage model and test verification

To investigate the dynamic damage response of fiber-reinforced polymer composites under explosion load, an improved explosion damage model of FRP was proposed. By introducing the dynamic enhancement factor to characterize the material strengthening at high strain rates, Hashin-Strain criterion is optimized to capture interfacial debonding and delamination damage mechanisms under multi-axial stress coupling, and a nonlinear exponential stiffness degradation model is proposed to describe the rapid accumulation and energy dissipation process of damage under explosion load. Based on ABAQUS/VUMAT subroutine, the prediction accuracy of five damage calculation schemes is compared and analyzed. The near-field explosion test of composite sandwich panel is carried out, and the optimized damage calculation method is extended to the near-field explosion damage prediction of composite sandwich panel. The results show that the optimized model significantly improves the prediction ability of damage morphology and fracture size. The area error of delamination damage and perforation damage predicted against Gargano , s test simulation are all within 10%, and the damage energy dissipation curve agree well with the test results. The corresponding results provide theoretical and experimental support for the anti-explosion design and evaluation of fiber reinforced composites in marine armor and other protection projects.