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Forward models for extending the mechanical damage evaluation capability of resonant ultrasound spectroscopy.
- Source :
-
Ultrasonics [Ultrasonics] 2017 May; Vol. 77, pp. 183-196. Date of Electronic Publication: 2017 Feb 08. - Publication Year :
- 2017
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Abstract
- Finite element (FE) modeling has been coupled with resonant ultrasound spectroscopy (RUS) for nondestructive evaluation (NDE) of high temperature damage induced by mechanical loading. Forward FE models predict mode-specific changes in resonance frequencies (Δf <subscript>R</subscript> ), inform RUS measurements of mode-type, and identify diagnostic resonance modes sensitive to individual or multiple concurrent damage mechanisms. The magnitude of modeled Δf <subscript>R</subscript> correlate very well with the magnitude of measured Δf <subscript>R</subscript> from RUS, affording quantitative assessments of damage. This approach was employed to study creep damage in a polycrystalline Ni-based superalloy (Mar-M247) at 950°C. After iterative applications of creep strains up to 8.8%, RUS measurements recorded Δf <subscript>R</subscript> that correspond to the accumulation of plastic deformation and cracks in the gauge section of a cylindrical dog-bone specimen. Of the first 50 resonance modes that occur, ranging from 3 to 220kHz, modes classified as longitudinal bending were most sensitive to creep damage while transverse bending modes were found to be largely unaffected. Measure to model comparisons of Δf <subscript>R</subscript> show that the deformation experienced by the specimen during creep, specifically uniform elongation of the gauge section, is responsible for a majority of the measured Δf <subscript>R</subscript> until at least 6.1% creep strain. After 8.8% strain considerable surface cracking along the gauge section of the dog-bone was observed, for which FE models indicate low-frequency longitudinal bending modes are significantly affected. Key differences between historical implementations of RUS for NDE and the FE model-based framework developed herein are discussed, with attention to general implementation of a FE model-based framework for NDE of damage.<br /> (Copyright © 2017 Elsevier B.V. All rights reserved.)
Details
- Language :
- English
- ISSN :
- 1874-9968
- Volume :
- 77
- Database :
- MEDLINE
- Journal :
- Ultrasonics
- Publication Type :
- Academic Journal
- Accession number :
- 28254563
- Full Text :
- https://doi.org/10.1016/j.ultras.2017.02.002