Elastic wave inverse scattering in nondestructive evaluation

Ultrasonic detection and characterization of flaws in metals and ceramics is of considerable technological interest. Scattering and inverse scattering theories have recently been applied to these tasks in a systematic manner and considerable progress has resulted. This paper first reviews briefly the development of scattering and inverse scattering methods in the AF/DARPA Program in Quantitative Nondestructive Evaluation.² Then one particular inverse method studied in that program, the inverse Born approximation, is discussed in detail. Progress is reviewed and the ability of the method to distinguish volumetric and crack-like flaws is demonstrated in simple cases.This work was sponsored by the Center for Advanced Nondestructive Evaluation, operated by the Ames Laboratory, USDOE, for the Air Force Wright Aeronautical Laboratories/Materials Laboratory under Contract No. W-7405-ENG-82 with Iowa State University.