期刊
MECHANICS OF MATERIALS
卷 85, 期 -, 页码 16-37出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.mechmat.2015.01.020
关键词
Crystal slipping; Cyclic plasticity; Statistical RVE model; Inhomogeneous strain; Symmetrical strain cycle; Low-cycle fatigue life
资金
- National Natural Scientific Foundation of China [90815001, 11072064, 11272094, 11472085]
- Key Project of Guangxi Science and Technology Lab Center [LGZX201101]
The fatigue-life of a polycrystalline superalloy under symmetrical cyclic strain controlled loading at a temperature of 650 degrees C is investigated by numerical simulations on the micro-level, focusing on the inhomogeneous evolution of plastic deformation in a polycrystalline aggregate. A methodology (Zhang et al., 2011, 2013) to predict the low-cycle fatigue life by micro-level simulations along with statistical analysis is applied following the steps: (1) A statistically representative volume element (RVE) consisting of a number of crystal grains is constructed by Voronoi tessellation. Stresses and plastic strains are calculated by a crystal plasticity model including nonlinear kinematic hardening. (2) The RVE is subjected to repeated symmetric tensile-compressive loading. (3) The inhomogeneous stress and strain fields are statistically analyzed during the load cycles. (4) Failure by LCF is strain controlled and occurs if either of the quantities, standard deviation of longitudinal strain in tensile direction, maximum or statistical average of first principal strains in the RVE at the tension peak of cyclic loading reaches a respective critical value. (5) Using the present methodology, a family of failure curves for fatigue lives under different strain amplitudes can be predicted by varying the critical values. Finally, appropriate critical values can be identified by a respective cyclic experiment with only one strain amplitude. (C) 2015 Elsevier Ltd. All rights reserved.
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