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Transient Vibro-Thermography and Nonlinear Resonant Modes

Kolappan Geetha, G and Roy Mahapatra, D and In, W and Raulerson, DA (2020) Transient Vibro-Thermography and Nonlinear Resonant Modes. In: Journal of Vibration and Acoustics, Transactions of the ASME, 142 (6).

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Official URL: https://doi.org/10.1115/1.4046860


Transient vibro-thermography for nondestructive evaluation and super-resolution imaging of material defects invariably employs nonlinear contact dynamics involving the ultrasonic actuator (horn) and the surface of the target structure. It produces nonlinear resonant modes of vibration in the target structural component. Vibration-induced heat generation is one phenomenon involved here. However, the contribution of nonlinear vibration on the thermal signature is poorly understood. In this study, we consider a metallic component with a thin-walled cavity as a representative sharp feature tuned to the main excitation frequency of the ultrasonic actuator. We have developed a mathematical model to simulate transient thermal signature of structural discontinuity/cavity/defect. The model incorporates a coupled thermo-viscoelastic heat generation process in the bulk material based on the Helmholtz free energy formulation. To capture the source of nonlinear resonant modes, we incorporate the stick-separation contact dynamics due to the ultrasonic horn and the target structural component. Commercial finite element simulation (comsol multiphysics) is used to quantitatively understand the nonlinear vibration response and the thermal transport behavior of the target structure with the cavity. The proposed model accounts for the effects of both the normal and the shear components of deformation contributing on heat generation and captures the nonlinear modal contribution on the heat flux map. The study shows how the geometric feature and material parameters produce an evolution of the nonlinear subsuper harmonics along with the primary harmonics tuned to the excitation frequency. Results obtained from numerical simulations are compared with the experimental results. © 2020 by ASME.

Item Type: Journal Article
Publication: Journal of Vibration and Acoustics, Transactions of the ASME
Publisher: American Society of Mechanical Engineers (ASME)
Additional Information: The copyright for this article belongs to American Society of Mechanical Engineers (ASME)
Keywords: Actuators; Free energy; Heat flux; Heat generation; Nondestructive examination; Shear flow; Thin walled structures; Ultrasonic testing, Excitation frequency; Finite element simulations; Non destructive evaluation; Non-linear vibrations; Structural component; Structural discontinuity; Super resolution imaging; Ultrasonic actuators, Thermography (imaging)
Department/Centre: Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited: 05 Nov 2021 10:57
Last Modified: 05 Nov 2021 10:57
URI: http://eprints.iisc.ac.in/id/eprint/65950

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