Hybridization of face sheet in sandwich composites to mitigate low temperature and low velocity impact damage

In this study, the impact response and damage mechanisms of carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) hybrid face sheet sandwich composites are investigated with the aim to provide an understanding and solution to mitigate the coupling effects of low temperature and low velocity impact damage. Hybridization of face sheet is achieved by stacking CFRP and GFRP in different thickness configurations. Samples are subjected to low-velocity impact at 23 degrees C and -70 degrees C to compare and understand the effect of cold temperature in the Arctic environment. Results show that hybridization improves the impact performance at -70 degrees C. CFRP layers and foam core become extremely brittle at low temperature, but GFRP layers maintain a certain extent of ductility and enhanced laminate strength at low temperature. Moreover, different damage modes (delamination, fiber breakage, core crushing, core shear, face sheet debonding, back face fiber splitting) are observed and characterized by X-ray micro-computed tomography. The additions of GFRP layers to CFRP face sheet mitigated the increased brittle fiber failure observed at low temperatures, however the impact characteristics and damage size was found to be dependent on the hybridization configuration.