【作者】 刘刚；

【导师】 张卫；

【作者基本信息】 贵州大学 ， 机械制造及自动化， 2015， 硕士

【摘要】 在现代轴类零件疲劳寿命研究中,由于安装误差而引起两轴承之间不对称产生偏角的研究已经有很多且很成熟,但是由于振动以及安装误差而引起轴端的偏心对轴的疲劳寿命研究分析很少,且针对偏心及振动提出一个普遍实用的解决方法也很少。所以对轴类零件进行共振验证以及轴端偏心对疲劳寿命的影响研究具有十分重要的意义。本文通过对断轴断面形貌断裂纹理分析,得到了此轴类零件断裂主要是由于偏心、振动、断口端面在旋转的同时承受弯矩共同作用,断裂性质均为扭矩剪切应力作用下形成的过载断裂。对电机转子进行转子动力学分析,得到了转子的三阶临界转速1565.5r/min,22558r/min,22765r/min,与电机转速11076r/min对比,接近转速安全裕度分别为85.8%和50.9%,均大于危险裕度10%,研究说明了电机转子不会因为临界转速与额定转速接近而发生共振影响轴的疲劳寿命,同时通过模态仿真分析与固有频率试验分析验证了仿真与试验数据的准确性同时也说明了电机不会因为固有频率而引起共振对轴疲劳寿命产生影响。对轴伸端进行实际偏心及应力理论计算,实际极限偏心为0.125mm,轴上薄弱处应力值大小为785.44mpa,通过ANSYS有限元仿真分析软件对航空电机主轴进行模拟工况边界条件应力分析得到轴上薄弱处应力大小为752mpa,验证了计算结果与仿真分析的准确性,为主轴应力设计提供了可参考依据。查阅航空材料手册得到了30Cr Mn Si材料的疲劳寿命曲线,并求得了曲线上13个应力点对应的疲劳寿命循环次数,根据断轴处应力大小和S.N曲线拟合得到断轴处的疲劳寿命为20674个周期。针对在偏心及振动对轴类零件疲劳寿命的影响,提出了轴承在预紧力下及在轴承与衬套之间添加橡胶垫圈起到减振及偏心固定端转移的目的使轴类零件寿命得到了大大的提高,并且通过每200h记录电机前端、后端、后端侧面振动的方法对电机进行了1500h的寿命实验,且电机各部件仍能正常工作。通过理论有限元仿真让改善前后轴上薄弱处应力对比,未加橡胶圈时轴上薄弱处应力为785.44mpa,加了橡胶圈后轴上薄弱处应力大小为95.78mpa,说明在相同极限偏心0.125mm下,轴承与衬套接触面开槽加橡胶圈的方法使轴上薄弱处应力大大的减小。为今后轴类零件提高疲劳寿命的实际运用方法研究提供了可参考的理论依据。更多还原

【Abstract】 In the study of modern shaft’s fatigue and life, what caused by the asymmetry between the two bearing installation error of Angle research there has been a lot and very mature, but due to the vibration and installation error caused by the eccentric shaft end of the shaft fatigue life analysis are very few, and in view of the eccentric and vibration is a common and practical solutions are put forward also very few. So there is of great significance for shaft parts verified resonance and eccentric shaft end influence on fatigue life research. Through to analysising the broken shaft section morphology, fracture texture of this article Got the fracture is mainly due to the eccentric shaft parts, vibration, fracture face while rotating bending moment under the common function.Shear stress rupture properties are torque under the action of formation of the overload fracture. Rotor dynamics analysis was carried out on the motor rotor, the rotor of the third order critical speed is 1565.5 r/min, 22558 r/min and 22765 r/min, compared with the motor speed of 11076 r/min, close to the speed safety margin of 85.8% and 50.9% respectively, were greater than the danger margin 10%, research shows the motor rotor will not happen to resonance caused by the critical speed and rated speed close to effects shaft fatigue life, at the same time, the modal analysis and inherent frequency by modal test analysis verify the accuracy of simulation and test data also shows that the motor won’t impact on shaft fatigue life because of the inherent frequency and resonant. To actual eccentric shaft extension end and theoretical calculation, stress practical limit eccentricity is 0.125 mm, shaft weak stress value is 785.44 mpa, Through ANSYS finite element simulation analysis software of aviation motor spindle condition boundary conditions to simulate the stress analysis was weak place stress on the size of 752 mpa, the accuracy of the calculation results and simulation analysis is verified for the shaft stress design provides reference basis. Refer to manual of aviation materials received 30 Cr Mn Si material fatigue life curve, and 13 stress points on the curve corresponding to the fatigue life cycles, according to the broken shaft stress size and S.N curve fitting get broken shaft fatigue life of 20674 cycles. In eccentric and vibration influence on fatigue life of shaft parts, put forward the bearing under the pre.tightening force and add rubber gasket between bearing and bushing have vibration and the transfer of eccentric fixed end purpose gives shaft parts life greatly improved, and by every 200 hour record motor front.end and back.end, backend method of lateral vibration of motor 1500 hour life experiment was carried out, and the motor parts can still work normally. Through the theory of finite element simulation to compare the shaft’s weak place stress to before and after of the improvement,without rubber ring weak place stress on the shaft of 785.44 mpa, added a rubber ring on the rear shaft weak stress size at 95.78 mpa, shows that under the same eccentric limit of 0.125 mm, bearing and bushing interface slot with rubber ring method for weak axis stress greatly reduced. for the future practical application way to improve the shaft fatigue life research provides a theoretical basis for reference.更多还原