ACCELERATED INVESTIGATION OF CREEP CRACK GROWTH IN POLYETHYLENE PIPE GRADE MATERIALS BY THE USE OF FATIGUE TESTS ON CRACKED ROUND BAR SPECIMENS

摘要

For lifetime and safety assessment of pressurized polyethylene (PE) pipes the knowledge of the crack growth behavior is of essential importance. With common test methods the investigation of creep crack growth (CCG) in modern PE-pipe materials under static loading conditions is not possible in a feasible time. In the present research work fatigue tests on cracked round bar (CRB) specimens at different R-ratios (min. load/max. load) were used to extrapolate to the case of static loading. By comparing these results with already existing data it was verified, that the applied method is qualified to generate CCG-curves at service-near loading and temperature conditions in relatively short times.