机械类专业硕士论文代写:在温度变化基础上关

发布时间:2019-09-23 17:35

  机械类专业硕士论文代写:在温度变化基础上关于润滑脂对接触疲劳寿命影响的探讨与研究
  
        目录:
  摘要 4-5
  Abstract 5
  第1章绪论 8-16
  1.1课题背景 8
  1.2研究的目的和意义 8-9
  1.3国内外研究现状 9-15
  1.3.1滚动接触疲劳的研究 9-12
  1.3.2润滑脂的研究 12-14
  1.3.3温度对润滑脂的影响的研究 14-15
  1.4课题研究的主要内容 15-16
  第2章疲劳试验机的改进及疲劳试验设计 16-25
  2.1试验机及试验材料 16-18
  2.1.1试验机 16-17
  2.1.2试验材料 17-18
  2.2试验台的改进和试件的设计 18-20
  2.2.1试验台的改进 18-19
  2.2.2试件的设计 19-20
  2.3接触应力的确定 20-21
  2.4润滑脂的选择及使用 21-24
  2.4.1润滑脂的选择 21-22
  2.4.2填脂量的确定 22-24
  2.5本章小结 24-25
  第3章滚动接触疲劳试件温度场分布 25-41
  3.1摩擦力矩的分析和计算 25-30
  3.1.1摩擦力矩的分析 25-26
  3.1.2摩擦力矩的计算 26-30
  3.2边界条件的计算 30-32
  3.2.1对流换热系数 30-32
  3.3温度场分布及分析 32-40
  3.3.1模型的假设简化 32-33
  3.3.2温度场仿真与试验结果的比较 33-40
  3.4本章小结 40-41
  第4章滚动接触疲劳试验结果及分析 41-56
  4.1脂润滑条件下疲劳寿命试验结果分析 41-47
  4.1.1试验结果 41-43
  4.1.2威布尔分布曲线 43-44
  4.1.3试验数据分析 44-47
  4.2温度变化对脂润滑性能的影响机理 47-52
  4.2.1润滑脂蒸发性的影响及试验分析 47-49
  4.2.2润滑脂粘温特性试验及分析 49-51
  4.2.3温度对润滑脂强度极限的影响 51-52
  4.3其他因素对接触疲劳寿命的影响 52-54
  4.4脂润滑接触疲劳寿命的机理分析 54-55
  4.5本章小结 55-56
  结论 56-58
  参考文献 58-61
  攻读学位期间发表的学术论文 61-63
  致谢 63

【摘要】 轴承在我国航空、航天、机械、国防等工业领域应用广泛,它的寿命将直接影响主机的工作状态。轴承的主要失效形式是滚动接触疲劳,研究和改善润滑剂的润滑性能是提高轴承滚动接触疲劳寿命和工作可靠性的重要途径。随着现代工业的发展,轴承在工作中经常处于温度变化的环境中,因此当温度变化时,润滑脂润滑性能对接触疲劳寿命的研究具有重要的理论意义和实用价值。本文选用3#通用锂基脂作为试验用脂,并对原有滚动接触疲劳试验台进行了改进,分别在五个不同的环境温度下测量得出滚动接触区的温度。同时计算得到了接触区产生的摩擦生热率及试验的边界条件,利用ANSYS软件进行温度场分析,通过仿真得到接触区温度。两者对比得到了润滑脂在工作中实际所处的温度。利用威布尔斜率k,额定寿命L10和中值寿命L50作为评价指标,研究了不同温度对滚动接触疲劳寿命的影响,得出接触疲劳寿命随温度的升高而降低。在试验设定温度范围内,温度的变化只会对润滑条件产生影响,因此接触疲劳寿命的变化反映了润滑脂热特性的变化。试验结果表明,温度上升基础油的蒸发量增加,并且在高温时蒸发严重;粘度会有大幅下降,造成分油量增加,油膜承载力下降;润滑脂的强度极限也随之降低,导致润滑脂的分油量增加,附着力下降;这些因素综合作用的结果,最终导致润滑脂润滑性能的降低,与接触疲劳寿命试验结果相吻合。

机械类专业硕士论文代写【Abstract】 Bearing is widely applied in aviation, astronautics, machinery and national defense. The performance of machinery equipment is directly affected by bearing’s life. Rolling contact fatigue is one of the main inactivation types of bearing. Research and improvement of lubricating property of grease are important ways to increase the bearing service life and reliability. With the development of modern industry , bearing always works at variable temperature environment. So, it both have theoretical significance and practical value to research the variation of contact fatigue life which is caused by lubricating property of grease at different temperatures.In this paper 3# general purpose lithium lubricating grease is selected as experimental grease., and the temperature of contact zone is measured respectively under different ambient temperature with improved experimental bench. And then the heat generation rate caused by friction and boundary condition are figured out. Simulation results of contact zone’s temperature have also been calculated in ANSYS software. Comparing the measurement results with simulation results, operating temperature of lubricating grease is got.Using Weibull slope k, rated life L10, and median life L50 as evaluating indicator, results of contact fatigue experiment indicate that contact fatigue life decreases with the increment of temperature. Within the bounds of experimental temperature, contact fatigue life reflects grease’s lubricating property directly. Research results show that evaporated quantity of base oil increases with temperature rise, and lose more base oil at high temperature. At the same time, viscosity will decrease drastically that causes much sum of grease bleeding and declining bearing capacity of oil films. Besides, strength limit of lubricating grease decreases with the increase of temperature as well, which gives an edge to amount of grease bleeding and weakens adhesive ability of lubricating grease. The integrated effects of these factors deteriorate the lubricating property of lubricating grease. It is identical with the result of contact fatigue experiment.

【关键词】 滚动接触疲劳; 温度场; 润滑脂; 摩擦力矩;

【Key words】 rolling contact fatigue; temperature field; lubricating grease; friction moment;

 

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