Research topics on ultrasonic testing of materials and structures

Abstract

The presentation will discuss some recent research topics in the area of Ultrasonic Testing of materials and structures at UC San Diego. The first topic is the passive extraction of the Green’s function of the test piece subjected to an uncontrolled excitation. This concept is being utilized to detect, at high speed, internal defects in rail tracks using the train wheels as the acoustic excitation. The second topic deals with the nonlinear wave propagation regime and its increased sensitivity to material state awareness compared to the linear regime. Nonlinear wave propagation will be presented for the case of waveguides and the case of constrained solids subjected to thermal excursions. The third topic deals with ultrasonic Synthetic Aperture Focus (SAF) imaging and proposes some techniques to improve image quality in the cases of bulk-wave testing and guided-wave testing. The fourth topic is the identification of the elastic constants of multilayered composites based on the inversion of guided wave dispersion curves and optimization algorithms.