Numerical analysis of the dynamic response of C/C-PMI sandwich panels under low-velocity impact loading

Objectives This study aims to reveal the dynamic response and damage evolution mechanisms of sandwich structures composed of woven C/C laminates and PMI foam under low-velocity impact loading, and to clarify the influence of impact energy and key structural parameters on their mechanical performance. Methods A numerical simulation model was established, incorporating a progressive damage model for the composite laminates implemented via a VUMAT subroutine and a crushable foam plasticity model for the PMI foam considering strain rate effects. A systematic investigation was conducted on the dynamic response of the sandwich panels under low-velocity impact, quantitatively analyzing the influence of the foam core's strain rate effect on the simulation results. Furthermore, a sensitivity analysis was performed on the key structural parameters of the sandwich panel. Results The results indicate that neglecting the strain rate effect severely underestimates the dynamic load-carrying capacity of the sandwich structure. The primary failure mechanisms of the C/C-PMI sandwich panels include matrix tension, matrix compression, and foam core crushing. The plastic crushing of the PMI core acts as the primary pathway for energy dissipation, accounting for 83.2% of the total energy absorption. As impact energy increases, the expansion of localized failure leads to a decrease in energy absorption efficiency. The core-to-face sheet thickness ratio is identified as the primary parameter affecting the impact response; while increasing this ratio enhances energy absorption efficiency, an excessively high ratio leads to premature face sheet penetration and localized core crushing, which is detrimental to the overall load-bearing capacity.Conclusions This study elucidates the structural response characteristics of sandwich panels considering strain rate effects under dynamic impact, providing a valuable reference for the low-velocity impact resistance design and safety assessment of such composite structures in naval engineering applications.