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Étude de l'endommagement de structures céramiques "nid d'abeilles" sous sollicitations thermomécaniques : application à la régénération des filtres à particules

Abstract : Diesel Particulate Filters (DPF) used in PSA Peugeot-Citroën vehicles consist in assembled silicon carbide honeycomb segments. These structures undergo strong thermal gradients during the regeneration (cleaning) phase, which consists in burning accumulated soot in the DPF. Mechanical damage, under the form of cracks, can appear for heavy loaded DPF. In the worst cases, the efficiency of the filtration can be affected by this cracking. This work mainly aimed to provide thermomechanical modelings of the regeneration phase, both numerically and experimentally. The thermomechanical properties of the honeycomb structure have been determined by experiments and an orthotropic equivalent homogeneous material, representative of the cellular structure, has been defined to perform finite element simulations. An analysis of the numerous temperature measurements carried out in engine test bench allowed the evolution versus time of the thermal gradients due to soot combustion to be determined. Instants of cracks initiations have been identified by acoustic emission. Locations and moments of cracking have been associated to strong, local thermal gradients. A simplified test bench based on resistive heating has been designed to reproduce on single DPF segments the thermal gradients encountered in engine test bench. From measured temperatures, the thermal fields have been built and further used to calculate the stress field in honeycombs, using finite elements calculations. The correlation of these stress fields with the locations and the instants of cracking allowed a simple criterion of crack initiation to be proposed. This criterion has been extrapolated to engine bench tests.
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Submitted on : Wednesday, March 7, 2012 - 12:25:56 PM
Last modification on : Thursday, September 24, 2020 - 6:30:07 PM
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  • HAL Id : pastel-00677124, version 1

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Arnaud Beurotte. Étude de l'endommagement de structures céramiques "nid d'abeilles" sous sollicitations thermomécaniques : application à la régénération des filtres à particules. Matériaux. École Nationale Supérieure des Mines de Paris, 2011. Français. ⟨NNT : 2011ENMP0063⟩. ⟨pastel-00677124⟩

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