Volume 21, Issue 5 (September 1993)
Lifetime Predictions of uPVC Pipes from Short Time Tests
Fracture mechanics tests according to British Standard 3505 have been made on two unplasticized polyvinyl chloride (uPVC) pressure pipes. The applied load was varied and time to failure was measured as a function of load. The results were fitted to an empirical power law, using the concepts of linear elastic fracture mechanics, relating crack growth rate, v, to the stress intensity factor, K1, according to v = A K∞1, where , where A and α are α constants. The parameters A and α were then applied to uPVC pipes provided with assumed Flaws of different sizes and shapes, and lifetime was calculated as a function of internal pressure.
Close agreement with published ductile failure data of uPVC pipes were obtained for elongated, axial flaws on the inside wall, between 0.8 and 1.0 mm in size.