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Fatigue thermique d'un alliage pour aubes de turbopompe astronautique : le Superwaspaloy

Abstract : In this study, we evaluate the thermal fatigue resistance of Superwaspaloy and we model its damage in such loading to provide the industrial partner (SEP) "tools" to evaluate the lifetime of blades of turbo engine VULCAIN. First, the damage of Superwaspaloy was studied by considering a volume element subjected to various critical mechanical and thermal loads. Life material is discussed considering the influence of various parameters: type of stress, temperature, frequency of loading and environment. From micrographic observations, we identify the damage mechanisms and explain their dependence on parameters of test conditions. Comparing the results of isothermal and anisothermal low cycle fatigue tests allows us to better understand the mechanisms involved in anisothermal fatigue and identify some trends to model life. Then the Superwaspaloy is studied by thermal fatigue on a specially design thermal fatigue rig. We exhibit the results for two specimen geometries with emphasis on mechanisms of cracks initiation and propagation. On the basis of metallographic observations, we propose a description of material damage in the case of cyclic thermal loading. Finally, we outline the damage modelling of Superwaspaloy under thermal fatigue. We suggest two models based on damage mechanics to describe the life of thermal fatigue test. The first one is based on the theory of internal variable of damage (Chaboche model) and evaluates the rupture of specimens considering the cumulative fatigue damage and creep. The second one describes the progress of a crack in the rupture of a microstructural element considering the interaction of fatigue damage, creep and oxidation. These two models are identified and tested using the results obtained with isothermal tests and anisothermal low cycle fatigue. Finally, they are applied to thermal fatigue of structures to verify their ability to assess the damage of the material.
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https://pastel.archives-ouvertes.fr/pastel-00521854
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Submitted on : Tuesday, September 28, 2010 - 4:46:09 PM
Last modification on : Thursday, September 24, 2020 - 6:30:04 PM
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  • HAL Id : pastel-00521854, version 1

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Alain Köster. Fatigue thermique d'un alliage pour aubes de turbopompe astronautique : le Superwaspaloy. Matériaux. École Nationale Supérieure des Mines de Paris, 1997. Français. ⟨pastel-00521854⟩

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