Anisotropic Thermal Diffusivity Measurement Using the Flash Method

A well-established method for determining the thermal diffusivity of materials is the laser flash method. The work presented here compares two analysis methods for flash heating tests on anisotropic carbon bonded carbon fiber. This material exhibits a higher conductivity in the direction in which th...

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Bibliographic Details
Published in:Journal of thermophysics and heat transfer 2014-07, Vol.28 (3), p.518-523
Main Authors: McMasters, Robert L, Dinwiddie, Ralph B
Format: Article
Language:English
Subjects:
Anisotropy
Bonding
Carbon
Carbon fibers
Diffusivity
Fiber orientation
Lasers
Pixels
Thermal diffusivity
Thermal imaging
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Summary:A well-established method for determining the thermal diffusivity of materials is the laser flash method. The work presented here compares two analysis methods for flash heating tests on anisotropic carbon bonded carbon fiber. This material exhibits a higher conductivity in the direction in which the fibers are oriented than in the direction perpendicular to the fiber orientation. Of the two analysis methods used, one method uses the temperature data from the entire surface of the sample by examining 201 temperature histories simultaneously, with each temperature history originating from an individual pixel within a line across the middle of the sample. The other analysis method uses only the temperature history from a single pixel in the center of the sample, similar to the data that is traditionally generated using the classical flash diffusivity method. Both analysis methods include accommodations for modeling the penetration of the laser flash into the porous surface of the carbon bonded carbon fiber material. The robustness of the method using the single-pixel temperature history shows that anisotropic thermal diffusivity can be measured using standard flash diffusivity instruments, if modeled properly, avoiding the additional complexity associated with the use of a thermal imaging camera.
ISSN:0887-8722
1533-6808
DOI:10.2514/1.T4189