Digital Image Correlation method for monitoring tensile tests at high temperature. Part 1: comparing the speckle quality produced by various methods at high temperature

Abstract : In order to improve the thermo-mechanical models proposed for hot forming processes, the identification and validation of the numerical simulations could take advantage of continuous kinematic full field measurements achieved during different production steps. This kind of measurements could especially be obtained by Digital Image Correlation. Although this method is relatively mastered at room temperature, it is more complex to implement at high temperature (typically from 600°C to 800°C). This is due to a number of factors, including the mirage effect (phenomena of gradient of refractive index), the loss of image contrast and the speckle flaking observed during thermo-mechanical experiments. This study focus on fabrication methods of speckle and its characteristics at high temperature. The first part introduces different techniques for creating the speckle (paint spraying, anodization, laser engraving and combination between anodization and laser engraving). In order to compare these methods, the same mask (prepared from a synthetic image) is systematically used. The pattern obtained therefore meets certain criteria (density, size, correlation length, etc.) and can be reproduced. Images of the speckled surface are then captured at different temperatures and compared in term of contrast, gray level distribution, etc. The first results show that the speckle obtained by combining laser marking and anodizing leads to better contrast when compared with other techniques at room temperature. However, this result is no more certain at high temperature because of the oxidation layer that develops. In the second part, the adhesion on the surface of a Ti-6Al-4V alloy of the speckles produced using different methods is evaluated. Tensile tests performed at high-temperature with large strain are then performed. In conclusion, a guideline for choosing an appropriate speckle deposition method for studying conditions of hot forming process is suggested.
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Conference papers
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https://hal-mines-albi.archives-ouvertes.fr/hal-02274455
Contributor : Imt Mines Albi Ecole Nationale Supérieure Des Mines d'Albi-Carmaux <>
Submitted on : Thursday, August 29, 2019 - 6:01:13 PM
Last modification on : Tuesday, October 22, 2019 - 5:20:45 PM

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  • HAL Id : hal-02274455, version 1

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Linh Phuong Luong, Rébecca Bonnaire, Jean-Noël Périé, Q Sirvin, Luc Penazzi. Digital Image Correlation method for monitoring tensile tests at high temperature. Part 1: comparing the speckle quality produced by various methods at high temperature. CFM 2019 - 24ème Congrès Français de Mécanique, Aug 2019, Brest, France. ⟨hal-02274455⟩

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