多因素耦合下剥落损伤随机分布特性对轴承疲劳寿命的影响

Effect of random distribution of spalling damage on bearing fatigue life under multi-factor coupling

以控制力矩陀螺的角接触球轴承为研究对象,考虑环境温度、摩擦热、对流换热、轴向力和转速等复杂多应力耦合作用及剥落损伤特征,推导其传热模型、接触应力仿真模型和疲劳寿命仿真模型。对比轴承有疲劳剥落损伤和无疲劳剥落损伤2种情况,分别给出典型工况下的温度、应力和疲劳寿命结果,讨论轴向力和转速对温度和应力的影响,总结疲劳损伤的特征尺寸随机分布对应力和疲劳寿命的影响。结果表明:在同样的条件下,剥落损伤引起的应力集中效应很明显,并且会引起区域温度升高;分别改变转速和轴向力,转速对温度和应力影响更明显;随着轴向力和转速增加,损伤轴承的最高温度和最大应力的大小和增长率均大于无损伤轴承;应力和疲劳寿命对剥落区域的直径更敏感,最大应力随直径增大呈先增大后减小的抛物线形关系,并随着深度增加而减小;虽然当剥落区域取最小直径且最大深度、最小深度且最大直径这2种情况下轴承疲劳寿命大于0,但是在剥落区域直径和深度的大部分取值范围内轴承疲劳寿命均为0。

Taking angular contact ball bearing of control moment gyroscope as object,the heat transfer model,contact stress simulation model and fatigue life simulation model are given by considering the complex multi-stress coupling effects and spalling damage characteristics such as ambient temperature,friction heat,convective heat transfer,axial force and rotation speed.On the comparison between two kinds of bearings with and without fatigue spalling damage,the temperature result,the stress result,and the fatigue life result under typical working condition are obtained.The effects of axial force and rotation rate on temperature and stress are discussed,and the influence of the random size distribution of fatigue damage characteristics on the distribution characteristics of stress and fatigue life is analyzed.The results show that:under the same conditions,the stress concentration effect caused by spalling damage is obvious,and it can lead to the regional temperature increase;when the speed and the axial force are changed separately,the effect of rotation speed on temperature and stress is more obvious;with the increase of axial force and rotation speed,the value and growth rate of maximum temperature and maximum stress of damaged bearings are larger than that of non-damaged bearings;the stress and fatigue life are more sensitive to the diameter of spalling area than the depth,and the maximum stress increases first and then decreases with diameter increase,and the maximum stress decreases with the increase of depth;though the fatigue life of the bearing is more than 0 when the minimum diameter and the maximum depth coincides,or the minimum depth and the maximum diameter coincides,but at the most values of the diameter and depth of the spalling area,the fatigue life of the bearing is 0.