[3A1] Magnetostrictive patch transducers for guided wave non-destructive testing and condition monitoring
O Trushkevych and S Dixon
University of Warwick, UK
Guided waves are highly promising for non-destructive testing and condition monitoring as they allow large areas to be inspected, including inaccessible regions such as pipes under supports. Magnetostrictive patch transducers are highly efficient in generating guided waves. They are already commercially available, however the patch materials used are often very brittle and the cost of systems is very high. Here, we explore the benefits and limitations of the use of lower-cost soft magnetostrictive (MS) patches and patch transducers (MPT) and lower-cost supporting electronics, from the point of view of industrial applications. FeCo soft patches are explored because of their relatively low cost and high promise for high-temperature applications (Curie temperature up to 780ºC). We obtain highly efficient SH wave generation in magnetically (and physically) soft MS patches and demonstrate defect detection capabilities in industrially relevant samples using MPTs. We explore MPT geometry in terms of patch size, field directions and wavelength and consider MPT performance without using the normally required applied magnetic fields. We also compare MPTs with electromagnetic acoustic transducers (EMATs) and explore the reasons behind EMAT efficiency enhancement when on a magnetostrictive patch. We demonstrate SH wave generation using an EMAT with an unprecedented 50 mm lift-off above a magnetostrictive patch. High efficiency and the potential low cost of patches and coils means they may be left in situ and interrogated frequently. This is enabling for condition monitoring and NDT.
