Low-velocity impact performance and damage mechanisms of all-CFRP honeycomb sandwich shell

This study investigates the damage behavior of all-CFRP (carbon fiber reinforced polymer) honeycomb sandwich shells subjected to low-velocity impacts, utilizing both experimental methods and simulation results based on the modified Hashin criterion. The results reveal that both the initial damage load and peak load significantly increase with facesheet thickness, while the increase due to impact energy is relatively modest. Moreover, impacts at the honeycomb center produce distinct cross-shaped damage, while impacts along the honeycomb cell walls result in more chaotic damage patterns. A comparison of axial and circumferential damage volumes indicates that the inherent circumferential curvature and complex boundary of honeycomb sandwich shells leads to greater damage in the circumferential direction. Additionally, foam-reinforced honeycomb shells are fabricated using a winding-based method combined with foam infusion, demonstrating how facesheet thickness and impact energy influence damage failure. The analysis of specific energy absorption efficiency shows that increasing facesheet thickness and adding foam significantly enhance energy absorption capabilities. Finally, the effects of impactor diameter and shape on the resulting damage are investigated, providing a comprehensive understanding of the factors that influence the damage response of composite honeycomb sandwich shells under low-velocity impacts.