Model reduction strategy applied to a problem of crack propagation in anisotropic materials

Abstract : Fatigue affects components subjected to cyclic loadings such as high pressure turbine blades that work under very aggressive environments. In order to predict their life, a damage tolerance approach must be set. This approach requires a study of crack propagation and encounters two main issues. The first one is the non-linear behavior of these components, especially under complex loadings where the definition of a cycle is no longer obvious. The second problem is running expensive elastic-plastic finite element computations on complex 3D structures over millions of cycles. In order to overcome the first problem a set of time-derivative equations were proposed as a replacement of the commonly used cycle-derivative equation. This incremental description of the fatigue crack growth is mainly based on the blunting of the crack tip assuming that the crack propagates due to plasticity. To address the second problem, a model reduction strategy was used to reduce the cost of finite element analysis and to obtain a condensed non-local model that will serve as an input for the incremental analysis. To do so, an elastic analysis is applied over the whole structure while a confined elastic-plastic one, fed by the previous, is processed on the K-dominance zone around the crack tip. Kinematic displacement fields from this region are projected on a reduced basis in order to obtain the non-local condensed model that gives the evolution of plasticity at the crack tip as a function of the loading given through stress intensity factors. Besides, the single crystal structure of some high pressure turbine blades creates a challenge into studying crack propagation in materials presenting direction-dependent behavior. The current work aims to identify the aforementioned kinematic basis for different aspects of anisotropy and to set an extended material model of the region near the crack tip.
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https://hal.archives-ouvertes.fr/hal-01903877
Contributor : Yoann Guilhem <>
Submitted on : Wednesday, October 24, 2018 - 4:45:42 PM
Last modification on : Friday, May 24, 2019 - 5:27:53 PM

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  • HAL Id : hal-01903877, version 1

Citation

Walid Tezeghdanti, Sylvie Pommier, Yoann Guilhem. Model reduction strategy applied to a problem of crack propagation in anisotropic materials. International Conference on Fatigue Damage of Structural Materials XII (FATDXII), Sep 2018, Hyannis, United States. ⟨hal-01903877⟩

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