Scientific paper ID 989 : 2014/3

The Rayleigh wave is used for the diagnosis of defects on the surfaces of machine elements. As parameter for diagnostics are used most often amplitude and time propagation of the wave. If there are discontinuities the wave dissipates by their surfaces. It is appropriate additional experiments of the signal parameters to be carried out in order to improve equivalent evaluation of discontinuity.

Aim of this paper is to present experimental investigation for propagation of Rayleigh wave trough bulk discontinuities in order to substantiate additional data parameters for diagnosis of machine elements’ surfaces.

Dispersion of Rayleigh wave around a discontinuity when displace probes in angular and axial direction has been investigated. There is a wave radiation from the surface of discontinuities. That changes the spectrum of the surface waves signal. The change of the spectrum is proportional to the size of the reflecting surface around discontinuities. Its resonance frequency and amplitude decrease and the specter becomes wider. This is a reason for Q factor reduction of the signal. A phase change of the signal is found, as well. These additional parameters are appropriate to be d in the non-destructive evaluation of surface bulk discontinuities by Rayleigh wave.