Numerical Investigation of the Influence of Viscoelastic Deformation on the Pressure-Leakage Behavior of Plastic Pipes
Publication: Journal of Hydraulic Engineering
Volume 142, Issue 3
Abstract
It has been well established that leakage from pipes is more sensitive to changes in pressure than the square root relationship predicted by the orifice equation. The main reason for this is that leak areas are not static, but vary with changes in system pressure. While previous studies have shown that the leak area is a linear function of pressure for elastic materials, the effect of the viscoelastic behavior of plastic pipes on the pressure-leakage response is not yet well understood. In this study, finite element analysis was used to investigate the effect of viscoelastic behavior on round holes and longitudinal cracks in both high density polyethylene (HDPE) and polyvinylchloride (PVC) pipes. The standard differential equation for linear viscoelastic deformation was then calibrated to the finite element results, resulting in equations that accurately describe the viscoelastic variation in leak areas as functions of time. The results also showed that the time-dependent behaviors of both pipe materials are proportional to their elastic behavior, and stabilize after about 12 h. The total deformations of HDPE and PVC pipes were found to be approximately 220 and 122% of their respective elastic deformations.
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Published In
Journal of Hydraulic Engineering
Volume 142 • Issue 3 • March 2016
Copyright
© 2015 American Society of Civil Engineers.
History
Received: Jan 19, 2015
Accepted: Aug 25, 2015
Published online: Oct 14, 2015
Published in print: Mar 1, 2016
Discussion open until: Mar 14, 2016
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