Nonlinear resonant ultrasound spectroscopy (NRUS) for nondestructive evaluation

Nonlinear Resonant Ultrasound Spectroscopy (NRUS) is a simple yet effective technique for nondestructive evaluation of incipient damage in a wide range of materials. NRUS combines the advantages of resonance-based testing and nonlinear ultrasonic or acoustic testing in that it can be used for testing complex-shaped objects and detection of microscopic defects. In this talk, I describe several applications of NRUS in: (1) monitoring of microcracking in concrete materials due to various damage processes; (2) monitoring the growth of microscopic fatigue cracks in aluminum; and (3) predicting the fatigue life of additively manufactured metallic alloys. In addition, I provide a snapshot of our ongoing research in developing non-contact NRUS test set up and using NRUS for in-process monitoring of additively manufactured parts. I close with describing the limitations of NRUS and possible directions for future research to realize NRUS potential in nondestructive evaluation (NDE) applications.