基于全向性SH₀模态磁致伸缩贴片型传感器阵列的 铝板缺陷成像研究

During the process of production, transportation and application, plates can easily appear damages which influence the performance of plates and cause potential safety hazard. Transducer array imaging technique lays the foundation for damage visualization. Damage information can be displayed through transducer array imaging technology intuitively and clearly. SH₀ mode spreads in the aluminum plate with the characteristics of non-dispersion and constant velocity. The impact of dispersion cannot be considered during the signal processing which is helpful to damage location and imaging. A kind of magnetostrictive patch transducer based on the magnetostriction mechanism is made for generating and receiving the lowest mode of SH waves, i.e., SH₀ mode, in plates. Furthermore, the omnidirectivity of magnetostrictive patch transducer is tested. Aluminum plates which are popular in engineering applications are taken as research objects. Omnidirectional SH₀ mode magnetostrictive patch transducers are arranged as distributed transducers array. Imaging detection of simulated damages with different diameters in aluminum plates are realized by using ellipse algorithm. Furthermore, the detectability of omnidirectional SH₀ mode magnetostrictive patch transducers array is studied and imaging common threshold is set for improving the damage imaging quality based on ROC curve.