KWON Sung Duk

(Dept. of Physics, Andong National University  P.O.Box 203, Andong, 760-749, Korea)

Received Oct. 27, 2009

Revised Dec. 5, 2009

Abstract Generalized Lamb surface waves are negated in a surface region when ultrasonic waves are incident to the layered substrates such as painted specimen in liquid. Then, backward radiated waves are returned to the direction of incidence by scattering and energy radiation of the surface waves. Hence, the backward radiation could be used in assessing the interfacial state between layer and substrate because the surface wave is sensitive to the change of physical properties in a surface region. Painting surface treatment of commercial produces and articles occasionally hide the surface region troubles such as roughness and crack. The evaluation of interfacial state under painting layer is very important in the prevention of great accidence, hence the evaluation technique should be nondestructive, fast and easy applicable to the fields. The backward radiations were measured for the painted glass with periodic interfacial roughness immersed in water tank. The effect of interfacial roughness on the angular pattern and frequency spectrum of ultrasonic backward radiation was investigated to develop the nondestructive technique for interfacial roughness evaluation. 　 　

PACS numbers: 43.35