Amplitude-Modulation Vibro-Acoustic Technique for Damage Evaluation

This study proposes an amplitude-modulation vibro-acoustic (AMVA) technique to track the evolution of thermal damage in pristine graphene mortar. In the proposed amplitude-modulation technique, the pump wave is amplitude-modulated using three different methods: (1) the pure amplitude-modulated (PAM) method, (2) the suppressive amplitude-modulated (SAM) method and (3) the transmitted amplitude-modulated (TAM) method. The nonlinear parameters [Formula: see text], [Formula: see text] and [Formula: see text] corresponding to the PAM, SAM and TAM methods, respectively, are theoretically established and experimentally demonstrated that the nonlinear parameters associated with the material nonlinearity, and they can be used to quantitatively characterize different damage stages of thermal damage. Meanwhile, the resonant frequency (RF) and ultrasonic pulse velocity (UPV) tests are conducted. The linear measurements, dynamic elastic modulus [Formula: see text] obtained from RF test and ultrasonic pulse velocity [Formula: see text] collected by UPV test, are used to compare with the nonlinear parameters. The results show that the proposed AMVA technique is more sensitive and feasible to serve as the tool for thermal damage detection in cement-based material compared with the conventional RF and UPV techniques.