Relationships between fracture parameters and fracture surface roughness of brittle polymers

Fracture parameters such as crack velocity à, stress intensity factor K _d and a specific crack extension resistance R ^* were measured for Homalite-100, PMMA and epoxy in the course of fast crack propagation using a Cranz-Schardin type high speed camera. Fracture surface roughness was evaluated as a function of crack length a so that it could be correlated with the fracture parameters above. The results showed that none of those parameters could be uniquely related to . Instead, there was a good correlation between and a product R ^* à.