Impact fracture toughness determination by Spb method

J. WAINSTEIN; L. FASCE; A. CASSANELLI; P. FRONTINI

Alexandropolis, Greece

Conferencia; European Conference of Fracture; 2006

European Structural Integrity Society

The evaluation of the impact fracture toughness of polymers is highly relevant, particularly because of the ongoing development of new polymeric blends, most of which are aimed at increasing the impact resistance of engineering plastics. The application of the currently available fracture mechanics methods under impact loading conditions for ductile polymers based on the J-Integral approach (ESIS ,Technical Committee 4) results still rather complicated. Under such a situation, the development of easier and lower time consuming methodologies sounds very attractive. To this end, impact toughness of two commercial grade tough polymers one  ABS and one PPBC was evaluated using  the essential work of fracture (EWF) and  a novel single specimen J-R resistance  curve technique known as  Spb . The EWF is a simple method useful for application on highly  ductile materials which only requires the determination of the total fracture energy of several samples differing in initial ligament length, and the linear regression of the data. On the other hand, the Spb method is capable of constructing J-R curves from one sharp and one blunt load-displacement traces without the need of knowing the final crack growth length. The fracture toughness values (J0.2 , taken at 0.2 mm crack growth) arisen from the determined J-R curves are compared with the specific essential work of fracture values (wIe). The suitability of both methodologies is also discussed.