Molecular dynamics study of fatigue behavior of nickel single-crystal under cyclic shear deformation and hyper-gravity condition
YD Xiao and XJ Deng and YW Ma and BW Huang and WY Hu, MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING, 30, 055006 (2022).
Dynamic mechanical properties play an essential role in governing the intrinsic fatigue behavior of superalloys. In this work, 001(010), 110(-110), and 101(010) pre-existing center cracks model of nickel single crystals under increasing cyclic shear deformations were studied by molecular dynamics simulations. More importantly, we introduced three hyper-gravity forces, i.e. 3 x 10(12) g, 4 x 10(12) g, and 5 x 10(12) g, during the fatigue deformation to simulate the high-speed rotation of the blade. The stress intensity factor for the first dislocation nucleation indicates that the critical stress is strongly dependent on the hyper-gravity intensities and temperatures. The fatigue life decreased rapidly with the elevated hyper-gravity strength. Moreover, the 001(010) crack propagation shows a brittle-to-ductile transition at temperatures below 300 K and is suppressed at high temperatures. The crack length in the relation to hyper-gravity intensities is discussed and shows anisotropy along the direction of hyper-gravity. No crack propagation is observed in 110(-110) and 101(010) central crack models.
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