Annular Wedge Wedge Wave Of Dispersion Characteristic Frequency

In this dissertation, ASF mode wedge waves which propagate along the cylindrical wedge tip have been researched in both experimental and numerical way. The influence of wedge wave transmission that is caused by the wedge angle and the radius of curvature is discussed.The theoretical model of laser irradiating on the tip of a cylindrical wedge which induce the wedge waves is constructed by using finite element method. By the2D-FFT method to do time-frequency analysis, the phase velocity of each anti-symmetric flexural mode is presented. In the figure the number of modes decreases with the increase of the wedge apex angle. Dispersion curves of the straight wedge and the cylindrical wedge have been compared in terms of the same wedge angle. The numerical calculation results indicate that the radius of curvature is the cause of dispersion. By changing the radius of curvature in the same wedge angle, the impact of the dispersion curves due to the radius of curvature is studied.For small-angle wedge, the dispersion magnitude of low-level mode is relatively large; under the same mode, the smaller radius of curvature is, the larger value of the phase velocity and dispersion amplitude are. For large-angle wedge, the change of the curvature radius has no influence on the dispersion amplitude.In the experimental aspect, the detection technology of ASF mode wedge waves is summarized. Based on optical interferometry method, the experimental setup is established. Through analyzing the time domain waveform and surface scanning image of the wedge wave, each mode of the corresponding wedge is separated clearly. Through the two-dimensional Fourier transform, the time domain signal is converted into a corresponding frequency domain signal, the dispersion graphs can be obtained. According to the Phase Velocity-Frequency graph, the phase velocity dispersion of each mode is gotten. Since the sample is non-ideal wedge tip with inevitable truncation, the dispersion magnitude in the experiment is significantly larger than the numerical simulation result. The experiment results match well with the conclusion of numerical calculation.The dispersion characteristics of ASF mode wedge waves in the theoretical study field can be proved by the research of this paper. The results also make it possible to apply the non-destructive evaluation to the cylindrical wedge-like engineering components.