Plastic Pipes Conference Association # 2010 Vancouver
A.Frank
Lifetime prediction of pressurized pipes made of polyethylene (PE) under complex loading situations is of special interest. Methods of linear elastic fracture mechanics (LEFM) are suitable to characterize the relevant long-term failure mechanisms in such pipes, which is slow crack growth. However, these methods require the knowledge of the creep crack growth (CCG) kinetics and material specific fracture mechanics parameters at application near temperatures. As testing of CCG with common test methods is not possible in feasible times, an accelerated extrapolation procedure based on fatigue tests with cracked round bar (CRB) specimens was developed previously. Within the present work this test procedure was used to characterize the CCG behavior of two commercial available PE pipe grades. Lifetime predictions of these materials are correlated to real failure times of internal pressure tests. Furthermore, failure times of more complex loading conditions with external soil load and external point load were predicted with fracture mechanics tools.
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