Mechanical Response of <scp>FMLs</scp> / <scp>CFRP</scp> Honeycomb Sandwich Structures Under Low‐Velocity Impact

ABSTRACT Honeycomb sandwich structures are favored in the aerospace industry for their excellent energy absorption and impact resistance. In this paper, a honeycomb sandwich structure with FMLs as skin panels and CFRP as the honeycomb core was manufactured. The effects of structural parameters, including panel thickness (2/1, 3/2, 4/3), honeycomb cell wall thickness (0.2, 0.4, 0.6 mm), and core cell sizes (5, 10, 15 mm), on the energy absorption ability of the sandwich structures were investigated by drop hammer impact tests under different impact energies (15, 40, 90 J). The results show that the peak impact force and absorbed energy increase significantly with the increase of panel thickness. Other parameters have minimal effects. It is worth noting that the energy absorption ability of the honeycomb core is significantly improved when the cell size is 5 mm under higher energy impact. Then the damage process and energy absorption characteristics of honeycomb sandwich structures under 90 J impact were investigated by finite element simulation. Subsequently, the energy absorption of honeycomb sandwich structures with different core sizes was systematically analyzed. An energy absorption formula for honeycomb cores with cell size smaller than 6 mm is derived to provide guidance for the design of the high impact‐resistant sandwich structures.