Cut-off frequency analysis of SH-like guided waves in the three-dimensional component with variable width

The component with variable width (such as railway turnout) is one of the most critical configurations in infrastructure. Guided waves have already been employed for flat plates, however, the influence of cross-section width change for guided waves can’t be ignored. In this study, the theoretical cut-off frequency of shear-horizontal (SH)-like guided waves in rectangular plate was analysed. The dispersion curves of rectangular plate with different widths were calculated by the periodic finite element (FE) method. Theoretical calculations and dispersion curves both show that the cut-off frequency of SH-like guided waves decreases when the width of rectangular plate increases. A periodic-permanent-magnet (PPM) electromagnetic-acoustic-transducer (EMAT) at the excitation frequency of 200 kHz was constructed and used in the experiments to generate SH-like guided waves on rectangular plates with the widths of 12 mm and 20 mm, respectively. Experimental results show that multiple wave modes of SH-like guided waves appear as the width of the rectangular plate increases. When the SH-like guided waves propagates in a rectangular plate with variable width, the high-order modes will be cut-off and reflected as the width decreases.