Numerical parametric study of Nonlinear Coda Wave Interferometry sensitivity to microcrack size in a multiple scattering medium

This paper reports a numerical study of the sensitivity and applicability Nonlinear Coda Wave Interferometry (NCWI) method in heterogeneous material with localized microcracked zone. We model influence strong pump wave on zone as small average increase length each crack. Further probing this multiply scattered ultrasonic induces changes to coda-type signal, which are quantified coda interferometry. A parametric CWI observables respect crack is established via simulations problem using 2D spectral element (SEM2D). The stretching proportional relative variation effective velocity, found be linearly global change length, while other parameter, remnant decorrelation coefficient, quadratically change. NCWI shown relevant for detection different damaged states complex solids. reported results especially significant context quantitative nondestructive evaluation micro-damage level materials nonlinear ultrasound signals.