Hygrothermal effects on the dynamic compressive properties of graphite/epoxy composite material

The effects of temperature and moisture on the response of graphite/epoxy laminated composites to high strain rate penetration loading using the Split Hopkinson Pressure Bar apparatus was investigated. The results show that in the thickness direction loading under extreme temperature, moisture and combined moisture and temperature conditions, the compressive strength, elastic modulus, and energy absorbed decrease exponentially. Failure strain and displacement increase linearly with temperature and moisture with particle velocity increasing linearly with temperature but independent of moisture content. The combined effect of temperature and moisture on the damage process was more apparent than the effect of temperature or moisture acting alone. At the same impact energy, the results show the failure properties to be sensitive to the strain rate, with energy absorbed increasing linearly with strain rate at low temperature and remaining relatively constant at high temperature. The compressive yield strength increases as the strain rate increases both at low and high temperatures while the ultimate strength (maximum strength) decreases slightly with strain rate.