【作者】 齐立群；

【导师】 张广玉；

【作者基本信息】 哈尔滨工业大学 ， 航空宇航制造工程， 2012， 博士

【摘要】 随着空间技术的发展，空间飞行器必须具有更长的使用寿命和更高的可靠性。空间机构作为飞行器中必不可少的重要组成部分，研究其接触失效的主要影响因素与抑制措施，对于提高空间飞行器的可靠性与寿命具有重要意义。由于齿轮传动系统的接触分析具有典型的代表性，本文将以其作为研究对象。在空间高真空环境下，金属接触时的粘附力及表面形貌对齿轮接触失效产生重要影响，其接触变形的过程非常复杂，涉及弹性、弹塑性及全塑性不同阶段。空间飞行器齿轮传动系统在真空环境下失效与在地面环境下失效明显不同，其热力学、接触力学及摩擦学行为具有明显的特殊性，有必要对其进行深入的研究。本文以空间某飞行器上工作的齿轮传动系统为研究对象，深入研究系统主要参数、接触表面属性和温场分布对系统接触动力学特性的影响。首先，基于Hertz接触理论建立了空间齿轮接触应力沿啮合线变化的数学模型。分析齿轮模数及齿数比对啮合接触应力的影响，得出空间齿轮接触应力分布规律。确定了影响齿轮啮合接触应力分布的主要因素，为齿轮的优化设计提供理论依据。分析了摩擦系数对空间齿轮接触应力分布的影响，得出法向力与切向力的共同作用下主剪应力的变化规律，在一定切向力作用下，应力变化幅度约为100%。采用理论分析与有限元相结合的方法，建立空间齿轮有限元接触分析模型，为热力耦合分析奠定基础。其次，基于单一粗糙峰与刚性平面接触理论，考虑真空环境中金属表面粘附力的影响，建立了粗糙表面形貌接触分析简化模型，模型有效区分了粗糙峰的弹性、弹塑性及全塑性变形。将本文的弹塑性模型与Lo等人提出的全弹性模型对比，结果表明：在较小的塑性指数时两者基本一致，随着塑性指数变大，Lo等人的全弹性模型的计算误差增大，当塑性指数超过1时，本文模型计算结果更加准确。基于本文的模型，分析了实际接触面积与名义接触面积比、切向承载能力随接触正载荷的变化关系，分析了表面硬度、表面粗糙度及无量纲塑性指数对其接触特性的影响。针对空间高真空的特点，分析了表面能对接触失效的影响，为研究空间齿轮接触失效机理奠定了基础。再次，建立了空间齿轮传动系统热网络模型。进行了真空环境下与地面大气环境下的齿轮系统温升对比实验，确定了热网络模型的边界条件。在此基础上，分析了真空环境下系统载荷、转速等运行参数对系统关键节点温度的影响，得出真空无对流散热时齿轮系统的温场分布规律。分析了齿轮转速、齿面滑动摩擦系数等参数对接触区瞬时温升的影响，得出以上参数与接触区瞬时温升变化规律。采用有限元法完成齿轮接触热力耦合分析，得出齿面瞬时温升与接触应力的变化关系。然后，针对空间齿轮寿命实验中振动测点定位困难的问题，提出了一种确定振动测点最佳位置的方法，并采用峭度指标法对理论分析得到的最佳测点进行了实验验证。研究了单一时域分析和频域分析在空间齿轮传动系统健康诊断中的局限性，指出只有在小波理论分析齿轮传动系统振动信号的基础上结合时频分析才能更准确得到空间齿轮传动系统健康状态的诊断结果。建立了空间齿轮系统健康诊断实验平台，综合运用小波变换与解调分析方法对空间齿轮传动系统运行不同阶段的振动信号进行分析，表明小波分析与解调分析相结合的方法能够有效诊断空间齿轮传动系统的健康状态，验证了该方法的有效性。最后，基于相电流细分技术，研制了适用于真空环境中工作的恒定制动转矩负载制动器。搭建了空间齿轮系统实验平台，进行了常压环境和真空环境的对比实验研究。采用扫描电镜（SEM）及原子力显微镜（AFM）观测了齿轮在真空环境下运行后啮合表面微观形貌，分析了空间齿轮齿面不同点的失效情况，分析了接触失效与应力的相互关系。进行了真空条件下和空气中常压条件下齿轮对比实验研究，分析了不同环境下齿轮主要失效形式。结果表明：真空条件下齿轮副比空气中常压条件下更易发生粘着磨损，空气中常压条件下磨损形式主要表现为疲劳磨损和磨粒磨损。研究了空间齿轮齿形及离子渗氮层厚度对齿顶失效的影响，为齿轮优化设计提供了理论依据。更多还原

【Abstract】 With the development of space technology, the spacecraft requires longer servicelife and higher reliability. The space mechanism is an essential and major component ofspace vehicle. It is significant to study the key factors and suppression measures ofcontact failure for improving the reliability and service life of spacecrafts. Consideringthe contact analysis of gear transmission system being a typical representative, the gearswere treated as the research object in this paper. In the space high vacuum environment,adhesion and surface morphology of metal contact will bring important impact on thegears contact failure. The contact deformation is very complex and involves elastic,elasto-plastic and plastic deformation. Failure of the space vehicle gear in the vacuumenvironment is obviously different with that in a terrestrial environment. Thethermodynamics, contact mechanics and tribology behavior has a distinct specificity.Therefore, it is necessary to conduct further research. In this paper, as an example, thegear parameters, the surface properties, the temperature distribution and contactcharacteristics of a gear transmission system in spacecraft were explored.Firstly, a mathematical model of contact stress variation of gear along meshing linewas built, based on the Hertz contact theory. By analyzing the impacts of gear moduleand gear ratio to meshing contact stress; distribution regularities of space gear contactstress were obtained. The influence of frictional coefficient on contact stress of gearmeshing was analyzed. The main shear variation under the common function of normalforce and tangential force was obtained. The results showed that the stress changed byabout100%when the tangential force increased to a certain value. By the means of thetheoretical analysis and finite element method, the model of space gear meshing finiteelement was built, and lay the foundation for thermo-mechanical coupled analysisSecondly, based on the single rough peak and rigid plane contact theory, acylindrical rough surface contact model was established by considering the metalsurface adhesion in the vacuum environment. This model can effectively distinguish theelastic, elasto-plastic and full plastic deformation. By comparing the elasto-plasticitymodel with Lo’s full plastic model, the results showed that the difference is very smallat a small plastic index. With the increasing of plasticity index, Lo’s full plastic modelcalculation error increase, and the calculation results of the present model is moreaccurate when the plasticity index is larger than1. Based on this elasto-plasticity model, the ratio between the actual contact area and the nominal contact area and the tangentialcarrying capacity changes with the contact positive load were analyzed. The cylindricalsurface hardness, surface roughness and the impacts of dimensionless plastic index onits contact character also were studied. Aiming at the characteristics of space highvacuum, the influence of surface energy on the contact failure of gear meshing wasanalyzed. The above studies provide a foundation for the further research on the spacesmall gear contact failure mechanism.Thirdly, a thermal network of space gear driven system model was set up.Experiments of the ordinary pressure and the vacuum environment were performed, theboundary condition of the thermal network model was determined. The impacts ofoperating parameters such as the load and the rotate speed on temperatures of key nodesin the vacuum environment were analyzed. The temperature distribution regulars ofthe gear system when vacuum no convection heat dissipation were obtained. Theimpacts of load torque, rotate speed and sliding friction index on the transienttemperature rise in the gear mesh contact area were analyzed. The flash temperaturedistribution laws of the gear system were obtained. Using a built finite element contactanalysis model, thermo-mechanical coupled analysis was carried out. The relationshipbetween the instantaneous temperature and the contact stress on the tooth meshing wasobtained.Then, aiming at the difficulties of vibration spot locating in the space gear servicelife experiment, a method of locating optimize vibration spot was set up and theoptimized vibration spot obtained by this method was verified by the kurtosis indexmethod. The limitation of single time domain analysis and frequency domain analysiswere carried out in the space gear driven system fault diagnosis. The results show thatthe frequency analysis can obtain more precise diagnosis results of the health statuswhen the single time domain analysis combined with the frequency domain analysis andthe wavelet theory analyze the gear driven system vibration signal. The health diagnosisexperiment platform of the space gear system was built. In this system, the vibrationsignal in various phases of the space gear driven system was analyzed, using acombination of wavelet transform and demodulation analysis method. The result showsthat the combination of wavelet analysis and demodulation analysis can effectivelydiagnose the health status of space active components.Finally, based on the current subdivision technology and using magnetic resistancetype stepping motor, a constant braking torque load brake used in the vacuum environment was developed. An experimental platform for the space gear system wasbuilt. The experiment comparing the ordinary pressure with the vacuum environmentwas performed. Using SEM and AFM, microstructure figures of gear meshing surfaceunder the vacuum environment were observed. The contact failure of different locationin the gear tooth surface and the mutual relations of contact failure and stress wereanalyzed. In order to study the friction wear mechanism of the gear in a space craft,comparing experiments of gear in the vacuum and the ordinary pressure environmentwere carried out. The main failure mode in different environments was also studied. Theresults show that the attached wear is more likely to occur under the vacuum conditionthan under the ordinary pressure condition, and the main wear under the ordinarycondition are the fatigue wear and the abrasive wear. In order to analyze the addendumfailure of the space gear, the ion nitriding layer thickness was studied. It provides atheoretical basis for the gear optimize design.更多还原