Impact damage and compression after impact on the CFRP-GFRP hybrid composite materials applied to aero-smart-skins

The newly developed smart skins for aircraft urgently need to integrate load-bearing and wave-transmitting functions. The hybrid wave-transmitting structure, composed of wave-transmitting layers and load-bearing layers, can be employed in aircraft as smart skins. In this study, the low-energy impact and compression after impact (CAI) performance of carbon fiber reinforced plastic-glass fiber reinforced plastic (CFRP-GFRP) hybrid structures were investigated experimentally and numerically. Subsequently, C-scan and CAI tests were conducted on the specimens after impact. The results show that interface delamination between GFRP and CFRP is the primary damage mode. An exponential relationship between residual compression capacity (RCC) and impact energy was established. It was also observed that the hybrid specimens exhibited higher residual compression load-bearing capacity and damage strain, indicating superior CAI performance. The hybrid configurations led to significant increases in RCC by 43.47% and 32.2% under impact energies of 20 J and 33.5 J, respectively. A slight buckling was also detected when comparing the strain values at the same locations on both sides of the specimens. In addition, a finite element method (FEM) model, incorporating 0-thickness cohesive elements and a VUMAT subroutine, was developed to simulate the impact behavior of hybrid specimens.