FATIGUE CRACK PROPAGATION AND CRACK CLOSURE BEHAVIOR IN POLYCARBONATE AND FIBER REINFORCED POLYCARBONATE.

Fatigue crack propagation was investigated in polycarbonate and glass fiber reinforced polycarbonate and the effect of stress ratio and glass fiber content determined. The addition of glass fiber increases the tensile strength, but does not always contribute to an increase in fatigue crack propagation resistance. For polycarbonate, the effect of stress ratio can be partly explained by using crack closure concepts as other researchers have suggested, but for glass fiber reinforced polycarbonate this was not possible. Fractography revealed a void growth process, which occurred by decohesion at the interface of the glass fibers and the base material, which was dependent on the maximum stress intensity factor.