Dynamic Fracture Criteria for Polycarbonate and Polymide

摘要

The report describes the results of a study of the dynamic fracture characteristics of polymers. The main objective of the study was to develop the capability to predict quantitatively the level of damage produced in polymeric materials under known dynamic loads. To accomplish this objective, disk-shaped specimens of polycarbonate, a relatively tough polymer, and polyimide, a brittle high temperature polymer, were subjected to flat-plate impact in a light gas gun under well-controlled and well-monitored conditions. For polycarbonate the stress-volume loading and unloading paths were determined under both static and dynamic conditions. Static stress-volume loading and unloading curves, an approximate constitutive relation, and the shock damage threshold stress for stress durations of about a microsecond were obtained for polyimide. A detailed study of the fracture mechanism was made for both materials. (Author Modified Abstract)