On the Impact Essential Work of Fracture of Ductile Polymers

LAURA FASCE; CELINA BERNAL; PATRICIA FRONTINI; YIU-WING MAI

POLYMER ENGINEERING AND SCIENCE

JOHN WILEY & SONS INC

Lugar: New York; Año: 2001 p. 1 - 10

0032-3888

The essential work of fracture method (EWF) to evaluate the fracture toughnessof ductile materials in plane stress with prevalent gross yielding conditions wasoriginally developed by the Cotterell-Mai research group in Sydney University morethan ten years ago. Since then, the EWF method has been proven independently bymany researchers to be a valid tool for a range of ductile metals, polymers, papersheets and fibrous composites. The current interest in the technical community ofthe plastics industry is to extend the EWF methodology to high-rate impact testingof polymers and their blends and to determine the impact specific essential work offracture. Since the literatures related to the applicability of this methodology underdynamic loading conditions appear controversial, our purpose in this work is toclarify under what conditions the impact EWF method is applicable. The EWFmethodology was applied to the energy impact data obtained on two PP copolymersand one ABS polymer at different specimen thickness and geometry. The resultsshowed that the EWF method can be applied to high-rate testing provided the ligamentis fully yielded and the plastic zone is scaled with the square of the ligamentlength. When these conditions are fully satisfied, the impact specific EWF is a materialconstant independent of specimen geometry for a given sheet thickness inplane stress; and it is also invariant with specimen thickness when plane strainconditions are met.