Research On Bearing Fatigue Life Of An Aviation Brushless DC Motor

Bearings are the pivotal Loaded parts of the aeronautical motors,the working environment of the aeronautical motor bearing is complicated,for example,high-temperature,high-altitude cryogenic,multi-axial random vibration,manufacturing processes,and materials all cause the fatigue failure of the aeronautical motor bearings.Therefore,It is of great theoretical value and practical significance to study the fatigue life of the aviation motor bearings.Based on the theory of cumulative damage of linear fatigue,the fatigue life of the angular contact bearing of the motor spindle is studied under the influence of temperature and multi-axis random vibration.First of all,the fatigue cumulative loss theory and fatigue life analysis methods are discussed in the article.The fitting method of the two-axis vibration stress is extended to the three-axis vibration stress.The probability density curve model of the stress amplitude of the three-axis random vibration based on the heading,vertical and lateral direction is established.Secondly,based on the analysis of the bearing mechanical loss and the electromagnetic loss of the motor,this paper uses the finite element software(ANSYS)to analyze the temperature field of the bearing.Then,thermal-structural coupled stress analysis is performed on the back-end bearing of the main shaft.After that,the multiaxial random vibration stress of the bearing is analyzed.we obtained the stress PSD and the response acceleration PSD in the dangerous parts of the bearing stress amplitude and vibration.Finally,the fatigue life is calculated by using the Dirlik model and the modified Bandat model based on the stress PSD.In the case of uniaxial vibration(heading,vertical and lateral),this software ANSYS is adopted to analyze the fatigue damage of the bearing based on the response acceleration PSD.Moreover,the fatigue life of bearing is calculated by using the Miner linear fatigue accumulation theory.The influences of the acceleration power,the temperature and the acceleration power of different frequency bands on the bearing fatigue life is studied.The feasibility and correctness of the analysis result are verified by comparing with the experimental results of fatigue life of the bearing.The results of this paper provide a basis for extending the life of the bearing and the reliability design of the airborne equipment in our country.