Rayleigh wave interaction with surface-breaking cracks

Abstract

This paper investigates Rayleigh wave interaction with simulated, surface breaking cracks using a finite element method, in which the scattered wave modes giving rise to the in-plane and out-of-plane displacements are presented. By looking at the contribution from all of the transmitted, reflected, and mode-converted signals at the crack, the magnitude of signal enhancement in the near field and the mechanism by which this occurs can be fully explained. Furthermore, oscillations in the Rayleigh wave reflection and transmission coefficients with crack depth in the far field can be explained by means of multiple reflected and transmitted wave modes at the crack, whose relative amplitudes are dependent on the crack depth. Results agree with previously published experimental measurements.

Enhancement of ultrasonic surface waves at wedge tips and angled defects

“…Rayleigh waves are a good probe of surface-breaking defects 8,9 and the far-field transmission coefficient varies with depth and angle to the surface 10,11 .…”

Electromagnetic acoustic transducers for in- and out-of plane ultrasonic wave detection

“…The capability of selective detection of the in-plane or out-of-plane particle velocity is sometimes very useful for defect evaluation using guided waves such as Rayleigh waves or Lamb waves [7][8] . However, for more general applications, receiving EMATs are designed to pick up both in-plane and out-of-plane particle velocities to enhance the detection sensitiveness of the receiving EMATs.…”

“…The ratio of the amplitude of the in-plane particle velocity to that of the out-of-plane particle velocity is dependent on the material elastic properties (and particular wave mode for the Lamb wave). It has been reported that the responses from defects for in-plane and out of-plane ultrasonic wave displacements are different [7] . Thus it is reasonable to speculate that a particular particle velocity component may have an optimal sensitivity for specific defect inspection and sizing applications.…”

“…The in-plane and out-of-plane components of the particle velocity of bulk waves (longitudinal and shear) are always in phase. However, the in-plane and out-of-plane particle velocities of guided waves such as Rayleigh waves or Lamb waves are not in phase [7,8] . The ratio of the amplitude of the in-plane particle velocity to that of the out-of-plane particle velocity is dependent on the material elastic properties (and particular wave mode for the Lamb wave).…”

“…Ultrasonic field measurements are of great interest in transducer development, material evaluation and non-destructive testing (NDT) [1][2][3][4][5][6][7] . The in-plane and out-of-plane components of the particle velocity of bulk waves (longitudinal and shear) are always in phase.…”