Stage M2 – Frequency-Dependency of Nonlinear Acoustic Properties of Concrete: an experimental multi-physics approach
This internship provides a unique opportunity to take part in an international Franco-American collaboration involving a fundamental study of the nonlinear acoustic properties of concrete. Nonlinear acoustics/ultrasonics is an emerging field in nondestructive evaluation of cementitious materials, which promises higher sensitivity to incipient microscopic damage (microcracking) – compared to conventional (linear) acoustic/ultrasonic testing techniques e.g., (Jin et al., 2019). We will employ Dynamic Acoustoelastic Testing (DAET), one of the methods for local characterization of nonlinear acoustic parameters of concrete (Shokouhi et al., 2017), which are sensitive to microscopic defects. A pump and probe approach, this method relies on measuring the dynamic strain-dependency of materials elastic properties through monitoring the evolution of wave speed and amplitude during and after pumping. DAET can yield both classical and non-classical (or hysteretic) nonlinear acoustic properties. One fundamental question to answer is: How/why would the frequency of the dynamic strain pumping affect the measured acoustic proprieties? The answer to this question has significant implications in upscaling the laboratory observations to field applications concerning the nonlinear acoustic monitoring of concrete structures.
More informations on the link below.