NONDESTRUCTIVE EVALUATION OF PRECURSORY STAGE OF FRACTURE ON POLYMER BY ETFuM Elastic-wave Transfer Function Method

Abstract Polymer is popularly used for the housing or parts of machine and equipment. However, the mechanical properties, especially the fracture process has not been clarified. It is the reason why polymer has not been used for the parts required reliability By the way, it is well known that fracture process of polymer under monotonic tensile test occurs Molecular chains locally orient in a very fine area, then the area grow up with increasing load and strain. The grown up area is called “craze”. After then, the craze grow up and coalescent each other, and the fibril is broken in some craze and becomes micro crack. However, we can only monitor the craze optically, and it is difficult to monitor the precursory stage of craze dynamically In this paper, the precursory stage of craze during tensile test was monitored by ETFuM (Elastic-wave Transfer Function Method), and evaluated quantitatively. In this study, clarification of the relation between mechanical degradation process and the transfer function in Polymethylmethacrylate (PMMA) and Polycarbonate (PC) was conducted, and also, it is found the amplitude change in some frequency range of transfer function during tensile test is strongly related to the nucleation and growth of craze. The results suggested that the ETFuM is useful and a powerful method for monitoring and evaluating nondestructively the conditions of polymer.