Inversion of temperature dependence of elastic constants using SAWS dispersion by Floquet-Bloch theory

Abstract

In this paper, we propose a method grounded in Floquet-Bloch theory for calculating the SAW dispersion curve and invert temperature dependence of the elastic constant based on laser heating, where the temperature dependence is converted into a depth distribution. In our previous work, the computational method utilized perturbation theory, which becomes ineffective at high temperatures. We conduct a comparative analysis of SAW dispersion in TC4 with high surface temperatures and large temperature gradients induced by pulsed laser irradiation, utilizing both perturbation theory and Floquet-Bloch theory. The calculation results indicate that perturbation theory becomes ineffective in high-temperature environments, whereas Floquet-Bloch theory remains consistent with the simulation results. Furthermore, the temperature-dependent parameters of the material’s shear modulus are inverted using both methods. It was found that the inverted elastic properties exhibited an error of approximately 1% compared to the theoretical value when employing Floquet-Bloch theory, while the error reached 20% with perturbation theory.