In order to evaluate the in-plane thermal diffusivity of C/C brake, infrared thermography with periodic mask is used. The principal characteristic is that the thermal diffusion along in-plane must to be generated. Here, heat is still applied to the front face of the sample by flash lamps and the periodic mask is added between the specimen and the lamps. After flashing, the heat is distributed over the rear face with such a designed periodic pattern along principle in-plane direction. The thermography is then performed to record the entire transient temperature image on the rear face of the sample. The masks were specially designed to determine the radial and circumferential diffusivities by generating heat gradient along these two orthotropic directions on the carbon disk sample. The period was carefully chosen as a function of sample thickness and an estimation of the ratio of through-thickness and in-plane diffusivity. The in-plane thermal diffusivity profile is then obtained by doing a Fourier transform analysis over one period of the grid mask. The results represented the average diffusivity value in that one period area. The tests have been conducted for aluminum plate and half C/C specimen. The resulting in plane diffusivity then compared with the value obtained from conventional laser flash method and literatures.
In-plane thermal diffusivity measurements of C/C brakes using thermography
Messung der Thermodiffusion in der Ebene von C/C-Bremsen mittels Thermographie
2006
6 Seiten, 5 Quellen
Conference paper
English
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