Simultaneous measurement of ultrasonic velocity and sample thickness and its application to NDE of composites. Free

Ultrasonic velocity is widely used for nondestructive evaluation of material properties. In cases where the thickness of the test piece is not precisely known or varies spatially, it is desirable to be able to determine the ultrasonic velocity and the sample thickness simultaneously. In immersion tests, the velocity and the thickness may be determined simultaneously by measuring a number of times‐of‐flight [cf. Kuo et al., J. Acoust. Soc. Am. 88, 1679–1682 (1990)]. In this work the ‘‘simultaneous’’ method was tested in four different configurations of pulse echo and through transmission and was applied to the characterization of porosity in graphite polyimide and graphite–epoxy composites. In addition, the velocity‐thickness method was also implemented with water squirters. [Work supported by Center for NDE, Iowa State University.]