Davis, Burn, Whittle
Posters - Additional Information # 2001 Munich
The C-ring test method is widely used by the water industry to determine the fracture toughness of poly(vinyl chloride) (PVC) pipes. The test currently forms a draft ISO standard (ISO/DIS 11673.2) and an interim Australian/New Zealand Standard (AS/NZS 1462.19(Int)) for fracture toughness assessment. Whilst results from the test can be processed using a modified linear elastic fracture mechanics approach, failure can occur after significant crack growth, and in some cases by plastic collapse of the C-ring section. Consequently, values of fracture toughness obtained from the test should be carefully interpreted. This paper investigates the failure process in the C-ring test, by isolating incubation time, slow crack growth period and eventual failure by a transition to unstable fracture or plastic collapse. A phenomenological simulation of the C-ring test is developed and used to assess failure in un-plasticised PVC and modified PVC materials. Actual failure times agree well with those predicted from test simulations, implying that for each material, failure occurs in the stages proposed.
