Numerical Study on Signal Enhancement of the Rayleigh Wave in the Near-Field of Surface Defects

The near-field scattering of laser generated Rayleigh waves from surface slot, which serves as artificial defects, has been studied using finite element method. Distinct signal enhancements of in-and out-of-plane displacement waveforms are observed in the near field of the surface slot, which enhance the detectability of the surface defect. Furthermore, the four interference phonomina in the displacement signals of surface acoustic waves have been captured and analyzed by considering the acoustic reflections and mode conversion happened at the defect. The results illustrate the physical mechanism which is responsible for the signal enhancement in the near field and the oscillations of signal enhancement factors for two directions as a function of the separation of the observation point and the defect tip. (C) 2010 The Japan Society of Applied Physics DOI: 10.1143/JJAP.49.062502