Assessment of Polycarbonate Toughness by Creep Test

摘要

The problems associated with fracture toughness as a material parameter is addressed through studies of the crack and associated process zone developed under creep loading with polycarbonate. Fracture toughness, G_(1C), increased 40% with a 5% decrease in creep load, which shows it is not a material parameter. The time interval from steady crack growth to ultimate failure is even more sensitive to the creep stresses. It was found that a gradient of shear band density exists within the process zone which plays a strong role in the above measures of fracture toughness and lifetime. This finding is incorporated into a model for crack and process zone interaction, the crack-layer model.