Moisture and Temperature Effects on the Mixed-Mode Delamination Fracture of Unidirectional Graphite/Epoxy

摘要

The critical strain energy release rates for interlaminar fracture of unidirectional graphite/epoxy, both from a sharp notch and as a function of crack extension, were determined experimentally for combined tensile/shear loadings. Based on well founded compliance techniques a substantial data base was generated over the temperature range -50 C to 100 C for both dry and moisture saturated states. The fracture energy of the unreinforced epoxy matrix material was also measured. Initiation energies for delamination were found to incease as the proportion of shear loading increased and as the temperature was lowered but were insensitive to moisture content. The Fracture resistance to crack extension was found to increase under tensile dominated loadings with both temperature and moisture content but remained constant for high shear loadings. The applicability of various mixed-mode fracture criteria to both the present data and to available literature data is examined.