On the toughness measurement for ductile polymers by orthogonal cutting

The fracture toughness, Gc, of three commercial polymers (HDPE, PP and PEEK) has been determined using a cutting test method. The traditional linear elastic fracture mechanics tests were conducted for comparison. The results showed that the cutting analysis is capable of giving valid fracture data for ductile polymers. However, when the cut depth is small, e.g. less than 100 μm, an inverse size effect on Gc was observed in cutting, i.e. the measured toughness of the polymers tends to decrease with the decrease of the cutting depth. Possible mechanisms for such a scale effect on fracture energy are discussed.