MATERIAL FRACTURE-TOUGHNESS DETERMINATION FOR POLYETHYLENE PIPE MATERIALS USING SMALL-SCALE TEST-RESULTS

The Small-Scale Steady State (S4) test has been recently developed in order to assess the fracture behaviour of polyethylene (PE) gas distri bution pipe material during rapid axial crack propagation. Based on an investigation of the S4 test, a simulation model of S4 test has been developed. This paper describes the use of the results obtained from t he S4 test and program modified from PFRAC (Pipeline Fracture Analysis Code) to evaluate the fracture toughness of the material, G(d), which could not be directly obtained from the test, and to predict critical pressure, p(c), for rapid crack propagation (RCP) in a full scale PE pipe. The algorithms for contact conditions are developed to consider the opening pipe wall impact against a series containment rings and th e capabilities of PFRAC are also extended. When G(d) is evaluated, inv estigations are made on the effect of temperature, wall thickness and crack velocity. In addition, procedures to evaluate the critical press ure for the S4 test pipe are also discussed.