| Abstract Scope |
Material damage in structural components is driven by nano- and micro-scale defects that evolve early in the component’s life. In metals, the interaction of an ultrasonic wave with these nano- and micro-structural defects, such as dislocations, precipitates, and micro-cracks, generates a second harmonic wave that is proportional to the acoustic nonlinearity parameter, which is an absolute and measurable material parameter. These defects are known to cause measurable changes in the acoustic nonlinearity parameter, which changes as the nano- and micro-structural defects evolve in the material. This talk will discuss how these nonlinear ultrasound (NLU) techniques can be used as a nondestructive evaluation tool to monitor nano- and micro-scale defects in metals, and thus characterize early-stage damage. I will focus on our recent work using NLU to monitor: (1) neutron radiation-induced embrittlement in nuclear reactor steels, (2) precursors to fatigue damage in structural metals, and (3) microstructure of additively manufactured metals. |