Impact resistance and damage mechanism of polyurea coated CFRP laminates under quasi-static indentation and low velocity impact

In this study, polyurea coating has been applied to improve the impact resistance of carbon fiber reinforced plastics (CFRP) battery pack housing under automotive crash condition. The quasi-static indentation test and low velocity impact test were carried out to study the impact response of polyurea coated unidirectional and plain woven CFRP laminates with three coating methods. The impact velocity was selected from 10−4 m/s to 4.5 m/s. In addition, damage mechanism and failure modes of the laminates were analyzed, focusing on the identification of dominant damage modes and crack evolution. It was demonstrated that thin polyurea coating can improve the impact resistance of both unidirectional and plain woven CFRP, while the former was more significant than the latter. The specific energy absorption had 94% and 51% increment under low velocity impact and quasi-static indentation. The front coating method was the best polyurea coating method. Results also revealed that the polyurea coating increased the damage area and fracture crack of polyurea coated CFRP laminates with different damage mechanisms. This study confirms that the use of polyurea coated CFRP laminates is an interesting and promising structure candidate for crash safety design and lightweight design of battery pack housing.