Nondestructive detection of Rayleigh wave dispersion in beryllium

The presence of machining damage (MD) in beryllium may be determined nondestructively in the acoustic microscope via the acoustic material signature (AMS). Rayleigh wave dispersion is attributed to substantial modification of the macroelastic properties in the surface region due to the machining process. Comparison of acoustic material signatures at 35 MHz obtained from chemically etched (undamaged) and machining-damaged (MD) specimens show substantial (3%) Rayleigh velocity reduction in the latter. Damage variation with depth may be ascertained via AMS mesurements over a wide frequency range