Rayleigh-Lamb wave detection of two-dimensional defects in metal plates

Nondestructive testing of engineering structures is essential to ensure safety. Ultrasonic C-scanning uses waves ropagating normal to a plane surface. This is accurate, but slow for planar structures. Longitudinal waves would allow quicker testing of such structtwes. This paper considers the reflection of low to moderate frequency Rayleigh­ Lamb waves by a through width lozenge-shaped defect in an isotropic plate. A numerical method is used. It is shown that such longitudinal ultrasonic waves can be used with success to detect and locate structural defects if care is exercies in frequency selection.