Material state characterization methods sensitive to incipient damage provide new opportunities for managing the life cycle of structures. Finite element simulations of ultrasonic guided waves show the potential of nonlinear wave mixing to detect localized degradation invisible to both linear elastic stress-strain response and the eye. Correlation of material degradation to the generation of higher harmonics or combinational harmonics makes estimation of remaining life possible from material state data early in the service life.
Lissenden, C. J., Liu, Y., Chillara, V. K., Choi, G., & Cho, H. (2015). Nonlinear guided wave mixing for localized material state characterization. In Physics Procedia (Vol. 70, pp. 668–671). Elsevier. https://doi.org/10.1016/j.phpro.2015.08.074