Nonlinear Scattering of Acoustic Waves by Discontinuity-like Defects in Application to Crack Detection

Abstract

Nonlinear sound scattering into higher or combination frequency harmonics on a crack-type dis continuity in a solid due to the intrinsic nonlinearity of the crack is considered. Characteristics of the nonlin early scattered sound are estimated, taking into account the micro-roughness of crack surfaces. Possibilities of the effect of usage for crack detection are discussed, comparison with conventional linear approaches is performed, and the main expected advantages of the nonlinear methods are pointed out.

Nonlinear acoustics for fatigue crack detection – experimental investigations of vibro-acoustic wave modulations

“…This includes the analysis of modulation intensity. Section 'Vibrothermographic experimental Stick-slip friction between crack surfaces, adhesion hysteresis 20 Crack-induced nonlinearity (variation in elastic moduli) Hertzian type nonlinearity (contact between crack surfaces) [21][22][23] High compliant elastic inclusion with an arbitrary weak deviation from the linear model (rheological model) 24 Local stiffness reduction leading to natural frequency shift 16,25 Bi-linear stiffness (closing-opening crack) 23,26 Clapping mechanism 27,28 Wave modulation due to impedance mismatch (discontinuity due to closing-opening crack) 11,17,29…”

Damage imaging in composites using nonlinear vibro-acoustic wave modulations

“…Recent years have shown, an increasing interest in novel, the so‐called non‐classical nonlinear damage detection methods . This is mainly because the nonlinear damage detection methods are usually much more sensitive to detect small damage severities than are their linear counterparts . One of the most promising techniques that can be used for damage detection is a method that utilizes nonlinear vibro‐acoustic wave modulations .…”

“…[2,9] This is mainly because the nonlinear damage detection methods are usually much more sensitive to detect small damage severities than are their linear counterparts. [10][11][12] One of the most promising techniques that can be used for damage detection is a method that utilizes nonlinear vibro-acoustic wave modulations. [13][14][15] The method has been successfully applied to detect damage in metallic structures [16][17][18][19] as well as for impact damage detection in composites.…”