Sonic assessment of physical ageing of plastic pipes

This article explores the potential of vibro-acoustics to detect physical ageing plastic pipes. For this purpose, two different topics are combined: ability estimate storage modulus a pipe, and sensitivity estimated changes due ageing. Concerning first topic, vibro-acoustic method was applied water-filled HDPE pipes, one surrounded by air another sand. The excitation achieved via an impact hammer propagating signal recorded with aid hydrophones. Signal analysis led estimation axial wavenumber axisymmetric fluid-borne wave. value used in dispersion equation for mode evaluate pipe material given experimental setup. Results revealed that gives consistent reliable estimations modulus. second samples from PVC pipes age difference 41 years were subjected dynamic mechanical study behaviour as function frequency. showed it is feasible distinguish discrepancies magnitude ageing, provided measurement uncertainty small. highlighted parameters need be more accurately known order lower overall when proposed used. Irrespectively medium surrounding (air or soil), distance between points recording signals should sufficiently long measure phase accurately. It found accurate knowledge pipe’s geometry, i.e. wall thickness internal radius, equally important controlling than soil. • Low frequency water-borne wave can quantify pipe. An must known. sensors kept possible. High accuracy geometry offers uncertainty. Accurate soil properties beneficial but not necessary.