Generalized pulse equations for through-transmission evaluation of arbitrary multilayered structures

Generalized transit-time and pulse-amplitude equations have been derived for modeling the ultrasonic through-transmission wave propagation of an arbitrary n-layered structure. The equations can be programmed into an expert system and used to identify and predict the through-transmission pulse signals from the critical interfaces of a multilayered structure. To test the formulas, the through-transmission responses from one- and three-layered configurations were measured in the laboratory and compared with computer-generated data that were determined using the derived equations. The results verify the validity of the formulas.