【作者】 李志伟；

【导师】 王黎钦；

【作者基本信息】 哈尔滨工业大学 ， 机械工程， 2023， 硕士

【摘要】 航空发动机在长时间运转过程中,润滑油也在持续不断地的循环被使用,轴承、齿轮等零部件的磨屑进入到循环的润滑油系统中,轴承密封不严以及轴承装配过程中,固体污染物进入到轴承中,会导致主轴轴承表面发生磨损,严重影响轴承的可靠性和寿命。为提高轴承材料的抗污染性能,本文基于航空发动机主轴轴承在实际运行工况下的颗粒污染情况,改进球盘式滚动接触疲劳试验机,开展在含不同浓度的SiO₂颗粒润滑油润滑下的航空轴承材料的摩擦学性能实验,基于声发射理论和技术对试验过程中的信号进行处理,研究轴承材料在颗粒污染下的磨损机制。针对现阶段航空发动机主轴轴承的极端工况,整体改进现有的球盘式滚动接触疲劳试验机。改进后试件与陪试件滚动体的最大赫兹接触压力可达到5 GPa,主轴转速可达到12000 r/min;同时搭建试验机的监控系统,实现对试验机运行状态的自动采集、分析、显示与存储,并实现试验机自动停机功能。为研究污染颗粒对航空轴承材料磨损机制的影响,提出基于声发射技术的轴承表面损伤模式识别的监测方法。通过声发射监测技术对试验过程中持续监测,提出从基于经验模态分解法的信号去噪预处理,到主成分分析、拉普拉斯评分的声发射特征选择,最终基于k-means++、CFSFDP聚类算法与小波包能量分析实现对试件损伤模式识别的球盘式试验机声发射信号分类方法。将不同浓度的SiO₂颗粒混入航空润滑油中模拟滑油污染,利用改进后的球盘式疲劳试验机,研究颗粒污染对航空轴承表面的摩擦磨损的影响机制。利用球盘式高速滚动接触疲劳试验机,开展不同浓度的SiO₂颗粒对航空轴承材料8Cr4Mo4V与G13Cr4Mo4Ni4V的摩擦学实验,发现试件表面损伤模式主要表现为划伤、压痕、切削、嵌入和材料剥落等次等级磨损,且G13Cr4Mo4Ni4V相较于8Cr4Mo4V表现出更良好的抗磨损性能。在对声发射信号分析研究中,发现在润滑油中含0.01 wt%、0.28 wt%SiO₂颗粒的试验中,磨损产生的声发射信号峰值频率幅值分布与纯净油试验有明显差异,在0.05～0.45 MHz之间存在较大峰值,而在纯净润滑油试验中,所采集到的声发射信号主要由滚动体与试件摩擦与塑性变形所产生。更多还原

【Abstract】 During the long time operation of aero engines,lubricating oil is also continuously circulated to be used.Abrasive debris from bearings,gears and other parts enter into the circulating lubricating oil system,poor sealing of bearings and solid contaminants enter into bearings during bearing assembly,which will lead to wear on the surface of main shaft bearings and seriously affect the reliability and life of bearings.In order to improve the anti-pollution performance of bearing materials,this paper improves the ball-disk rolling contact fatigue testing machine for the particle contamination of aero-engine spindle bearings under actual operating conditions,carries out the tribological performance experiments of aero-engine bearing materials under lubricating oil containing different concentrations of SiO₂particles,processes the signals during the test based on acoustic emission theory and technology,and studies the wear mechanism of bearing materials under particle contamination.The wear mechanism of bearing materials under particle contamination is investigated.The existing ball-disk type rolling contact fatigue test machine is improved for the extreme conditions of the main shaft bearings of aero-engines at this stage.After the improvement,the maximum Hertzian contact pressure between the specimen and the rolling body of the accompanying specimen can reach 5GPa,and the spindle speed can reach 12000r/min;meanwhile,the monitoring system of the testing machine is built to realize the automatic acquisition,analysis,display and storage of the operating status of the testing machine,and the automatic stopping function of the testing machine is realized.In order to study the influence of contaminated particles on the material wear mechanism of aviation bearings,a monitoring method based on acoustic emission technology is proposed for the identification of bearing surface damage patterns.Through acoustic emission monitoring technology to continuously monitor the test process,the proposed from the empirical modal decomposition method based on signal denoising pre-processing,to principal component analysis,Laplace scoring of acoustic emission feature selection,and finally based on k-means++,CFSFDP clustering algorithm and wavelet packet energy analysis to achieve damage pattern recognition of the test specimen ball and disc type testing machine acoustic emission signal classification method.Different concentrations of SiO₂ particles were mixed into aviation lubricating oil to simulate oil pollution.The influence mechanism of particle pollution on the friction and wear of aviation bearing surface was studied by using the improved ball-on-disk fatigue tester.The tribological experiments of different concentrations of SiO₂ particles on aviation bearing materials 8Cr4Mo4V and G13Cr4Mo4Ni4V were carried out by using a ball-on-disk high-speed rolling contact fatigue testing machine.It was found that the surface damage modes of the specimens were mainly characterized by scratches,indentations,cutting,embedding and material peeling.And G13Cr4Mo4Ni4V showed better wear resistance than 8Cr4Mo4V.In the analysis of acoustic emission signal,it is found that in the test of 0.01wt%and 0.28wt%SiO₂particles in lubricating oil,the peak frequency amplitude distribution of acoustic emission signal generated by wear is obviously different from that of pure oil test,and there is a large peak between 0.05 MHz and 0.45 MHz.In the pure lubricating oil test,the collected acoustic emission signal is mainly generated by the friction and plastic deformation between the rolling element and the specimen.更多还原