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Dislocation Damping and Defect Friction Damping in Magnesium: Molecular Dynamics Study
Jingyu Zhai,Xinyuan Song,Anyang Xu,Yugang Chen,Qingkai Han 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6
In this study, the molecular dynamics method was used to study the damping mechanism in Mg alloys at the atomic scale. The energy dissipated by the nucleation and motion of dislocations and by defects friction, and the effect of defects, such asvacancies, cracks, and grain boundaries, on them were studied. The study shows that different kinds of defect have differenteffects on the dislocation damping and defect friction damping. And then, the effect of strain amplitude and temperature ondamping capacity of Mg was studied. The result shows that the amplitude independent damping is caused by defect frictionand the amplitude dependent damping is mainly caused by the nucleation and motion of dislocation; the damping of Mgincreased exponentially with the temperature, and the damping peck appeared at 440 K is attributed to the appearance ofdislocations at the grain boundaries which may be caused by boundaries self-diffusion.
Characterization method of rolling bearing operation state based on feature information fusion
Ning Li,Xianghe Yun,Qingkai Han,Baogang Wen,Jingyu Zhai 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.3
Aiming at the problem of incomplete information covered by the bearing state discrimination using a single physical quantity as the data source, a characterization method based on the feature information fusion of multi-physical quantities including acceleration RMS and stiffness that are sensitive to the bearing operating state is proposed. The accelerated life test of the bearing is carried out through the bearing experiment bench, and the effect of different feature information fusion schemes to characterize the bearing state is compared, and the effectiveness of the method is verified. This paper also analyzes the different characteristics of the state evolution law between the bearing early failure caused by specific factors and the bearing reaching normal fatigue life, which provides a new method and idea for the maintenance strategy of rolling bearing such as condition-based maintenance.