【作者】 叶振环；

【导师】 王黎钦；

【作者基本信息】 哈尔滨工业大学 ， 机械设计及理论， 2013， 博士

【摘要】 航空发动机不断向大推重比、长寿命和高可靠性方向发展，对航空发动机高速滚动轴承的转速、载荷等指标提出了越来越苛刻的要求。长期工作在高转速和重载荷情况下的滚动轴承常呈现应力过大、温升过高等特点，发生擦伤、烧伤等失效，严重的还会带来轴承卡死抱轴等严重后果。为此，对高速滚动轴承作了大量的结构及材料方面的改进和创新，然而快速提升的苛刻工况条件已经逼近了现有材料的使用极限。同时，航空发动机在工作过程中的高转速巡航以及多工况转换的特点，使得滚动轴承的动态稳定性问题日益凸显，带来保持架断裂、转子系统失稳等严重后果，在此背景下航空发动机高速滚动轴承的全工况包络设计显得不可或缺。因此，对航空发动机高速滚动轴承进行动态性能分析，研究其高速动力学行为，是面向工况进行轴承结构优化、保证轴承工作可靠性和延长轴承寿命的必不可少的共性基础研究课题。本文围绕航空发动机轴承典型苛刻工况条件，通过建模和仿真展开轴承动态性能研究，为轴承性能优化提供依据，为轴承—转子系统可靠性和稳定性增长研究奠定基础。论文通过轴承内部零件间的运动和位置关系分析，建立了零件间的相互作用模型，建立了高速球轴承和滚子轴承的完全动力学模型。采用Newtown-Raphson算法和Runge-Kutta算法结合的方法对动力学模型求解，解决了套圈和滚动体之间高频振动对计算效率的影响，同时保证了动力学结果的精度。分析结果为分析不同工况条件下轴承的动力学行为提供了基础数据。建立的动力学模型适用于油润滑和固体润滑轴承计算，可以分析轴承装配、温差及离心作用影响，可以分析球轴承保持架的椭圆兜孔形式以及滚子轴承的母线轮廓修型影响。针对轴承装配导致的内外圈轴线不对中现象，分析了轴承内外圈偏斜对承载区载荷特性的影响：轴承内外圈偏斜不仅导致承载滚动体发生偏载现象，引起局部接触应力过大，在轴承运转过程中还会因为变刚度振动而影响承载区最大接触应力的波动。随着内外圈偏转角度的增大，轴承接触区内最大接触应力值呈现逐渐上升趋于平稳的状态，而承载区最大接触应力的波动幅度呈现先减小而后小幅增大的趋势。以改善内外圈偏斜对承载区最大接触应力的影响为目的，兼顾承载区应力波动幅度变化，给出了增加滚子数量及滚子母线对数修型的定量依据。根据建立的高速球轴承和滚子轴承动力学模型，从描述保持架稳定性的保持架质心涡动速度偏差比及反映滚动体整体打滑的保持架滑动率两方面分析了定常工况下高速滚动轴承的动态性能，分析结果可为轴承失效分析提供理论依据。结果表明：转速的增加可以提高保持架的稳定性，但导致滚动体打滑率上升。对于球轴承，控制径向载荷与轴向载荷的比值可以降低轴承滚动体的打滑率并有助于保持架稳定性的提升；对于滚子轴承，径向载荷的增加可以降低滚动体的打滑率，但同时导致保持架稳定性减弱。针对航空发动机工作中的多工况转换特点，分别就发动机启动、加速和加力三种过渡状态，分析了轴承的瞬态动力学行为。结果表明：保持架的稳定性与初始状态关系较大。轴承启动阶段，外引导保持架受滚动体推动，承受载荷较小，但在较长一段时间内处于不稳定状态；轴承加速和加载阶段，保持架受滚动体和引导套圈共同作用，速度或推力的增加会加剧保持架与套圈引导面及滚动体的碰磨。基于航空轴承高速、重载、高温的工况特点，建立了考虑配合、工作温度及高速离心载荷的轴承工作游隙计算模型，分析了轴承不同工况的工作游隙及其对轴承性能的影响。模型和分析结果为轴承配合参数设计提供指导。对建立的动力学计算模型，采用软件集成技术，通过Visual Basic和Matlab混合编程研制了滚动轴承动态性能分析软件。软件功能通过与SHABERTH软件及ADORE软件对典型算例的计算结果对比获得了模型和方法的准确性验证，表明本软件在轴承稳态动力学参数预测及轴承瞬态运动学预测两方面都具有较好的精度。基于考虑轴承微区接触载荷的疲劳寿命计算方法，建立了以疲劳寿命为目标函数，以保持架滑动率、内外圈沟曲率系数和填球角为约束条件的轴承结构参数优化模型。分析了轴承结构参数对轴承稳定性的影响。研究了轴承内外圈相对转动方式对轴承结构优化的影响。分析结果为航空发动机轴承的延寿方法提供了理论基础。针对高速轴承-转子系统的动力学耦合特点，建立了轴承-转子系统的耦合动力学分析模型，初步分析了转子对轴承动力学的影响：转子振动引起的滚动体和套圈间接触应力和相对滑动增大将对轴承疲劳寿命及温升产生不良影响，分析结果为进一步研究重载摩擦副接触微区的微观失效行为提供了基础。更多还原

【Abstract】 To satisfy the trending of aeroengine for high thrust-weight ratio, long life andhigh reliability, high-speed rolling bearings of aeroengine is required more and morerigorous on speed and loads. Due to high contact pressure and temperature rise, kinds ofsurface failures, such as surface scratch and surface burning, even serious consequencessuch as journal sticking the on severe case, occur on rolling bearings that operates onthe high speed and heavy load conditions. Although materials and structures of spindlebearings have been gradually improved to meet requirements of aeroengine, limitationof the materials has come in the applications in critical conditions. In addition,instability of high-speed rolling bearings, which makes the cage fracture and rotorinstability happened, becomes more and more important while the aeroengine workingon different conditions. Therefore, analysis of dynamic properties and behaviors ofhigh-speed rolling bearings are basic to optimize the bearing design and key researchfor improve the reliability and life of bearings. The objects of this dissertation arehigh-speed rolling bearings of aeroengines under typical rigorous working conditions.Dynamic performances of bearings are investigated according to establishment ofdynamic model and simulation. The results provide the checking basis for bearingdesign and theoretical basis to reliability and stability growth of bearing-rotor system inaeroengine.According to the geometry and kinematic relationship of bearing elements, modelsof interaction between elements were established. Dynamic models of high speedrolling bearings were established and solved by integration method of Runge-Kutta andNewtown-Raphson which is proposed to improve the calculation efficiency and keepingprecision of dynamic results. The results could provide the basis data to analyze thebearing dynamic behavior on different conditions. The dynamic model is applied on oillubricated and solid lubricated bearing. This model can be used to analyze the influenceof assembling, temperature differential and centrifugal force. The effects of ellipticalcage pocket in ball bearing and roller profile modification in roller bearing can beinvestigated by this model.Aiming at the misalignment between inner ring and outer ring caused byassembling error, effect of tilted misalignment on loading characteristics of rollerbearings was investigated based on the dynamic model of roller bearings. The resultsshown: The deflection between inner and outer rings caused eccentric loads on rollers,generating excessive contact pressure. In addition, the fluctuation of maximum contactpressure during the running process of bearings influenced by deflection between rings.With the increase of deflection angle between inner and outer rings, the maximumcontact stress in loading zone gradually went up and then got stabilized when deflection reached to a certain angle. While during bearing running, the fluctuation range ofmaximum contact stress first gradually decreased and then modestly increased. Forimproving the loading characteristics of roller bearings under the condition of tiltmisalignment, the quantity design basis that increasing the number of roller and usinglogarithmic roller profile modification were proposed.Based on the dynamic model of rolling bearings, characteristics of rolling bearingsin steady conditions were analyzed from two aspects: deviation ratio of cage whirlspeed and cage sliding ratio. The results have significance for bearing failure analysis.The results shown: increasement of bearing velocity improves the cage stability butmakes cage sliding ratio increased meanwhile. It is available for decrease the cagesliding ratio and improves the cage stability through control the ratio of radial loads toaxial load. Increasement of radial loads on roller bearings decreases the cage slidingratio but makes cage stability become weak.According to the aeroengine features that switching between several workingconditions, transitional dynamic performance of high speed bearings in starting,accelerating and loading processes were investigated. The results shown: Initial status ofbearing has great influence on cage stability. In starting process, cage motion completeddepends on the push of rolling elements, the force on cage are less. Cage stability isworse in the beginning of bearing starting process. In the accelerating process andloading process, cage motion is influenced by rolling elements and guiding ring. Therub and impact between cage and rolling elements increased with the raising of bearingspeeds and loads.Based on the features of working condition, including high speed, heavy load andhigh temperature, of rolling bearings in aeroengines, the calculation model of bearingworking clearance, considering the assembling, temperature differential and centrifugalforce, was established. The working clearance and its effcts on bearing performancewere investigated. The model and analysis results can be used to guide the design ofbearing assembling parameters.Dynamic analysis software of rolling bearings was developed through hybridprogramming of Visual Basic and Matlab. According to the example calculation,accuracy of the dynamic model and software were validated by comparing the resultscalculated by this dissertation to the results calculated by SHABERTH and ADORE.Base on the calculation method of bearing fatigue life considering the contact loadon micro area, bearing structure optimization model, which the fatigue life as the goalfunction, the cage sliding ratio, race curvature factor and ball filling angle as theconstraint condition, was established. Effect of bearing structure on bearing stabilitywas studied. In addition, effect of rotation modes of bearings, including rotation bysingle and double rings, on bearing performance was investigated. Analysis resultsapplies theory basis for life extension of high speed rolling bearings in aeroengines.Coupling dynamic model of rolling bearing-rotor system was established to analyze the influence of rotor on dynamic behavior of bearings. The results shown:vibration of rotor makes contact loads and relative sliding of bearing between rollingelement and rings increased, and thus influence on bearing life and temperature rise.The results are basis to analyze the micro-failure behaviors of heavy-load friction pairon micro contact area.更多还原