Performance and residual strength of metal-faced composite corrugated sandwich structure under multiple impacts

The metallic-faced composite corrugated sandwich structure, which combines the impact resistance of metals with the high specific strength and stiffness of composites, represents an exemplary form of innovative construction. During its service life, the sandwich structure is subjected to multiple impact conditions, yet the patterns of damage from repeated impacts and the post-damage residual strength are not yet clearly understood. To address this, a comprehensive study was conducted through a series of impact tests and CT non-destructive scanning analyses, delving into the dynamic response to low-velocity impacts, internal failure modes, load-displacement characteristics, and energy absorption features. Furthermore, based on these findings, plane compression tests were carried out on impacted specimens to analyze the residual compressive strength and failure modes after multiple impacts. The findings indicate that the initial impact inflicts the most damage, and with increasing impact frequency, the energy-absorbing capacity and impact resistance of the sandwich structure diminish. In multiple impacts, the predominant damage modes in the sandwich structure include matrix cracking, delamination, and fiber breakage in the core material, with higher energy impacts invariably causing more extensive damage. Moreover, as the number of impacts increases, the accumulation of damage approaches saturation, and the residual compressive strength trends towards a threshold value.