Abstract
Elastic guided waves (GW) are used to inspect pipeworks in various industries. Modelling tools for simulating GW inspection are necessary to understand complex scattering phenomena occurring at specific features (welds, elbows, junctions...). In pipeworks, straight pipes coexist with elbows. GW propagation in the former cases is well-known, but is less documented in the latter. Their scattering at junction of straight and curved pipes constitutes a complex phenomenon. When a curved part is joined to two straight parts, these phenomena couple and give rise to even more complex wave structures. In a previous work, the SemiAnalytic Finite Element method extended to curvilinear coordinates was used to handle GW propagation in elbows, combined with a mode matching method to predict their scattering at the junction with a straight pipe. Here, a pipework comprising an arbitrary number of elbows of finite length and of different curvature linking straight pipes is considered. A modal scattering matrix is built by cascading local scattering and propagation matrices. The overall formulation only requires meshing the pipe section to compute both the modal solutions and the integrals resulting from the mode-matching method for computing local scattering matrices. Numerical predictions using this approach are studied and compared to experiments.
Highlights
Thanks to their ability to propagate over long distance without attenuation, elastic guided waves (GW) are used in efficient non-destructive testing (NDT) operations for the in-service inspection of industrial pipeworks
Because of the multi-modal and dispersive properties of GW, scattering phenomena involved when GW interact with specific features in the pipework are complex
A numerical model able to deal with curved guides is developed. This model is based on an extension of the Semi-Analytic Finite Element method (SAFE) method, commonly used to simulate the GW propagation in straight guides
Summary
Thanks to their ability to propagate over long distance without attenuation, elastic guided waves (GW) are used in efficient non-destructive testing (NDT) operations for the in-service inspection of industrial pipeworks. The aim of the present work is to study numerically and experimentally the GW propagation in a pipe elbow linked to straight parts using a modal approach in order to supplement capabilities of CIVA platform [3]. A numerical model able to deal with curved guides is developed This model is based on an extension of the SAFE method, commonly used to simulate the GW propagation in straight guides. Once the modal solution for GW in an elbow is obtained, the scattering at the junction between a straight and a curved guide is investigated. A numerical model based on the mode matching method is used to predict the modal decomposition of an incident mode scattered at such junction. 2. Semi-analytical model for guided waves propagations in pipe works comprising elbows the overall modelling approach is summarized. Readers interested in its detailed derivation are referred to Ref. 4
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