Study of influence of periodic defects on the propagation of wedge waves using laser ultrasound technique and finite element analysis

Wedge wave is a kind of elastic wave propagation along the tip of a wedge. In this study, a brass wedge with an apex angle of 60° was used as the substrate test piece and periodic defects were designed at the wedge tips. Laser ultrasonic technique and finite element analysis were used to investigate the influence of periodic defects at the wedge tip. The influence of different periodic defect parameter changes on the guided wave of the wedge body was studied. After obtaining the time-domain signal of the experiment and numerical analysis, the result was compared with the signal processing of Fast Fourier Transform. Result showed that the frequency domain signals would be effected by periodic defects on wedge tips, basic frequency would be downgraded by increase in defect width or increase in number of defects. But, the results did not reflect on the frequency channel phenomenon of phononic crystals. The wedge guided wave passing through three periodic defects and four periodic defects showed an error percentage of 1.4–2.9, which confirm the convergence of the results. The experimental measurement agreed well with the finite element simulation results. The results of this study can be applied to estimate the defect width and penetration wave.