Multistage Frequency-Domain Transient-Based Method for the Analysis of Viscoelastic Parameters of Plastic Pipes

Plastic/viscoelastic pipes such as polyvinyl chloride (PVC), polyethylene (PE), and high-density polyethylene (HDPE) pipes have been increasingly applied in fluid piping systems. The understanding of the hydrodynamic behavior and features of such pipe materials are important in their practical applications. This paper develops an effective frequency-domain transient-based method (FDTBM) for the efficient and accurate identification of viscoelastic parameters of plastic pipes. The analytical expression of transient frequency response in a typical viscoelastic pipeline system is first derived to describe the dependence relationship among different factors and coefficients in the system (e.g., pipe and fluid properties). The obtained result is then applied to inversely identify the viscoelastic parameters of plastic pipes under different flow and operational conditions. A multistage analysis framework is proposed to enhance the robustness and effectiveness of the proposed FDTBM to obtain accurate and unique solutions of viscoelastic parameters for the plastic pipes used in this study. The proposed method and analysis framework have been validated and evaluated through various experimental tests and numerical simulations.