title: Nonlinear elastic wave tomography for the imaging of corrosion damage.
abstract: This paper presents a nonlinear elastic wave tomography method, based on ultrasonic guided waves, for the image of nonlinear signatures in the dynamic response of a damaged isotropic structure. The proposed technique relies on a combination of high order statistics and a radial basis function approach. The bicoherence of ultrasonic waveforms originated by a harmonic excitation was used to characterise the second order nonlinear signature contained in the measured signals due to the presence of surface corrosion. Then, a radial basis function interpolation was employed to achieve an effective visualisation of the damage over the panel using only a limited number of receiver sensors. The robustness of the proposed nonlinear imaging method was experimentally demonstrated on a damaged 2024 aluminium panel, and the nonlinear source location was detected with a high level of accuracy, even with few receiving elements. Compared to five standard ultrasonic imaging methods, this nonlinear tomography technique does not require any baseline with the undamaged structure for the evaluation of the corrosion damage, nor a priori knowledge of the mechanical properties of the specimen.
authors.affiliation: Department of Mechanical Engineering, University of Bath, Bath BA2 7AY, UK.
authors.forename: Francesco
authors.initials: F
authors.lastname: Ciampa
authors.affiliation: Department of Engineering for Innovation, University of Salento, via per Monteroni, Lecce 73100, Italy.
authors.forename: Gennaro
authors.initials: G
authors.lastname: Scarselli
authors.affiliation: Department of Mechanical Engineering, University of Bath, Bath BA2 7AY, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Pickering
authors.affiliation: Department of Mechanical Engineering, University of Bath, Bath BA2 7AY, UK. Electronic address: m.meo@bath.ac.uk.
authors.forename: M
authors.initials: M
authors.lastname: Meo
keywords: Bispectral analysis; Nonlinear imaging methods; Structural health monitoring; Ultrasonic guided waves