Compression behavior of laminated composites subjected to damage induced by low velocity impact and drilling

摘要

Carbon fiber/epoxy composites are extensively used in aerospace due to their superior strength to weight ratio. But their strength awfully degrade, if experience some external and internal damage. The purpose of this study is to investigate the effect of two common damage types; impact and drilling on compression strength of woven carbon fiber reinforced epoxy composites. For this purpose, combined loading compression test (CLC) was carried out for the compression behavior of un-damaged composite laminate. Compression after impact test (CAI) and open-hole compressive test (OHC) were carried out for the compression behavior of impact damaged and drill damaged composite laminates respectively. The fracture surfaces obtained after CAI and OHC tests were studied under scanning electron microscope (SEM). Results showed that impact damage has more deleterious effect on the compression strength of composite laminate than drilling. The micro-buckling of fibers in the kink band found to be the dominant final failure mechanism for each type of failure under compressive loading. Whereas damage mechanisms such as interlaminar shearing, constituent (i.e., matrix and fiber) microcracking, and longitudinal splitting were found to play some role in the propagation of initial cracks/microcracks due to impact and drilling.