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Yang Tianhao,Li Shanhu,Duan Shuyong,Tao Yourui,Han Xu 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.3
Application of the intelligent on–off valve reduces heat loss. As the critical control component of the intelligent on–off valve, the health state of the brush DC motor directly impacts whether the intelligent on–off valve can perform the regular operation. Therefore, the reliability evaluation of the brush DC motor is of great significance to the whole heat supply network. In this study, the failure mechanism of the brush DC motor is analyzed, and the absolute value of steady-state current variation is taken as the performance degradation characteristic parameter. According to the performance degradation characteristic parameter, the performance degradation model based on the Wiener process is established, and the inverse power rate acceleration model is introduced into the Wiener process to derive the reliability function of the motor. Based on the actual operating conditions that the motor in the intelligent on–off valve needs to start and stop frequently, an accelerated life test based on start-stop is designed. The error analysis result shows that the error between the expected start-stop times predicted by the proposed and the actual average failure start-stop times is only 2.14%. The proposed degradation model is more accurate than the motor's traditional performance degradation model.
Influence of Li Addition on the Microstructures and Mechanical Properties of Mg–Li Alloys
Jun Zhao,Jie Fu,Bin Jiang,Aitao Tang,Haoran Sheng,Tianhao Yang,Guangsheng Huang,Dingfei Zhang,Fusheng Pan 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6
In this study, Mg-xLi (x = 0, 1, 2, 3 and 5 wt%) alloys have been extruded to examine the role of Li content on microstructuresand tensile properties. The results revealed that Li addition increased the grain size and led to the formation of the transversedirection (TD)-split texture. These were mainly attributed to the promoted DRX process and the increased activity of prismatic⟨a⟩ slip during extrusion. Tensile tests revealed that the elongation of Mg-5Li sheet reached ~ 22.4% along the ED. Moreover, it exhibited a higher elongation of ~ 27.3%, three times than pure Mg, along the TD. During tension along the ED,with increasing Li content, more prismatic ⟨a⟩ slip and preferable intergranular strain coordination ability to accommodatethe plastic strain, leading to the enhanced room-temperature ductility. In contrast, more basal ⟨a⟩ slips and extension twinswere also activated along the TD, which further contributed to the enhanced ductility. Therefore, the ductility of Mg sheetsat room temperature gradually improved with Li addition due to the combining effects of basal ⟨a⟩ slip, prismatic ⟨a⟩ slip,extension twin and preferable intergranular strain coordination ability.