Numerical simulation research on impact response characteristics of M-type foldcore sandwich structure with different impact angles

To meet the growing demand for multifunctional structural materials in aerospace and other advanced fields, an improved M-type foldcore sandwich structure is proposed. Considering the scarcity of research on its dynamic response and energy absorption under multi-angle impacts, this research establishes an experimentally validated finite element model to conduct numerical impact simulations across five impact angles ranging from 0° to 40°. The results indicate that that the structure absorbed over 90 J of energy under all test conditions, demonstrating good energy-absorption potential. The impact angle significantly influenced the impact mechanical response, with the highest energy absorption of 98.5 J observed when the impact angle was 10°. This is likely because the impact force was able to act effectively on the corners of the folded core material, enabling the core to absorb and bear the impact in the most efficient manner. Energy absorption at the base position increased from 91.2 J at 0°to 102.7 J at 40°. As the impact angle increases, the horizontal component of the impact force becomes larger, causing the structure to undergo more complex deformations (such as bending and torsion) and absorb more energy. Regarding damage morphology, low-angle impacts caused localised circular damage (with a radius of approximately 25 mm) in the sandwich structure. The internal configuration of the sandwich structure determined its energy absorption performance. During high-angle impacts, damage predictions indicate a wider damage zone and accelerated overall collapse, suggesting that the failure mode shifts from local crushing to global buckling. This is particularly evident at an angle of 40°, where the base is subjected to enormous bending moments and secondary stresses. Although the base is located further from the impact point, the extent of damage is more severe than at the node. These will serve as a guide for future applications of the structure.