Abstract: Ultrasonic guided waves detecting technology has shown a good prospect in non-destructive testing and health monitoring of industrial pipelines, thanks to its advantages such as long detection range and high detection efficiency, but very few researches have been conducted on guided waves inspection of multilayered pipes, which is widely used in industrial circle. The semi-analytical finite element method is used to formulate the governing equation for guided waves propagating in multilayered pipes on the basis of the virtual work principle, dispersive characteristics including phase velocity, energy velocity, attenuation and wave structures are extracted by solving governing equation, which provide the basis for selecting mode and frequency during application. The effect of viscoelastic material on guided waves propagating in multilayered pipes is taken into consideration, and the dispersive solutions for multilayered pipes are obtained in terms of attenuation curves, which can be used to supervise the inspection of multilayered pipes, furthermore, the theoretical result is partly verified by numerical simulation as well as detecting single-layered pipe and lining plastic pipe by using MSGW guided waves detecting instrument.

Key words: guided waves;multilayered pipes;semi-analytical finite element method(SAFE);dispersive characteristics;viscoelasticity