Detection of defect parameters using nonlinear air-coupled emission by ultrasonic guided waves at contact acoustic nonlinearities

Steven Delrue; Koen Van Den Abeele

doi:10.1016/j.ultras.2015.07.001

Detection of defect parameters using nonlinear air-coupled emission by ultrasonic guided waves at contact acoustic nonlinearities

Ultrasonics. 2015 Dec:63:147-54. doi: 10.1016/j.ultras.2015.07.001. Epub 2015 Jul 15.

Authors

Steven Delrue¹, Koen Van Den Abeele²

Affiliations

¹ Wave Propagation and Signal Processing Research Group, KU Leuven Kulak, E. Sabbelaan 53, 8500 Kortrijk, Belgium. Electronic address: Steven.Delrue@kuleuven-kulak.be.
² Wave Propagation and Signal Processing Research Group, KU Leuven Kulak, E. Sabbelaan 53, 8500 Kortrijk, Belgium. Electronic address: Koen.VanDenAbeele@kuleuven-kulak.be.

PMID: 26208725
DOI: 10.1016/j.ultras.2015.07.001

Abstract

Interaction of ultrasonic guided waves with kissing bonds (closed delaminations and incipient surface breaking cracks) gives rise to nonlinear features at the defect location. This causes higher harmonic frequency ultrasonic radiation into the ambient air, often referred to as Nonlinear Air-Coupled Emission (NACE), which may serve as a nonlinear tag to detect the defects. This paper summarizes the results of a numerical implementation and simulation study of NACE. The developed model combines a 3D time domain model for the nonlinear Lamb wave propagation in delaminated samples with a spectral solution for the nonlinear air-coupled emission. A parametric study is conducted to illustrate the potential of detecting defect location, size and shape by studying the NACE acoustic radiation patterns in different orientation planes. The simulation results prove that there is a good determination potential for the defect parameters, especially when the radiated frequency matches one of the resonance frequencies of the delaminated layer, leading to a Local Defect Resonance (LDR).

Keywords: Comsol; Guided waves; Kissing bonds; NACE.