Effect of T-stress on a Nickel base superalloy under mode I fatigue crack propagation

Abstract : Some aircraft components, such as turbine disks, are subjected to very strict certification stages. In order to predict their fatigue lifetime, it is necessary to treat this type of cracks and include it in a damage tolerance approach. Thus, other than the fact that the material has a non linear behaviour (Nickel base superalloy), the complex loading it experiences makes the definition of a fatigue cycle difficult. Otherwise, elasto-plastic simulations on 3D structures over millions cycles makes this approach difficult. However, in order to overcome the first difficulty, an incremental model, relying on plastic blunting, is used. Concerning the second, a model reduction is applied to reduce simulation costs. Moreover, during maintenance stages those components are exposed to the creation of defects such as impacts or scratchs. They create micro-cracks and an initial residual stress state which is multiaxial and with gradients. Taking in account those defects implies considering T stresses and modeling the initial residual state in the vicinity of the defect. Bi-axial tests with T stress transitories are currently held in order to highlight their effect on the propagation, and a determination of the relevant quantities at the defect tip linked with a model reduction will be led to model the residual stress. A propagation criterion containing those ingredients will be set and incorporated in the incremental model
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https://hal.archives-ouvertes.fr/hal-01580029
Contributor : Yoann Guilhem <>
Submitted on : Friday, September 1, 2017 - 1:27:07 AM
Last modification on : Friday, May 24, 2019 - 5:27:29 PM

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  • HAL Id : hal-01580029, version 1

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Besnik Sadriji, Bumedijen Raka, François Brugier, Yoann Guilhem, Sylvie Pommier. Effect of T-stress on a Nickel base superalloy under mode I fatigue crack propagation. European Conference on Fracture (ECF21), Jun 2016, Catania, Italy. ⟨hal-01580029⟩

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