Effect of Impact Damage and Open Hole on Typical Mechanical Properties of CYCOM 7701/7781 Fiberglass Epoxy Composite Lamina

CYCOM 7701/7781 fiberglass epoxy fabric prepreg was used to fabricate the composite lamina specimens through medium temperature curing process. The specimens were categorized into three groups. The tensile strength of unnotched and open-hole specimens, the compressive strength of unnotched and open-hole specimens, and the compressive strength after impact were respectively tested under three conditions of cold temperature dry (CTD), room temperature dry (RTD), and elevated temperature wet (ETW). The effects of impact and open hole on typical mechanical properties of CYCOM 7701/7781 composite lamina were studied. The results show that the open-hole makes the average tensile strength decrease by about 50% under the CTD, RTD and ETW conditions, and decreases the coefficients of variation of the tensile strength. Impact damage and open-hole have similar disadvantageous effects on the average compressive strength under CTD and RTD environment conditions, which decrease the average compressive strength by about 45%-55%, while the impact damage and open-hole have different effects on the compressive strength under ETW condition. The compressive strength is decreased about 50% by the open-hole and about 30% by the impact damage under ETW condition. It is indicating that the effect of open-hole condition is more severe than that of impact damage condition under ETW condition