Evaluation Method of Fatigue Life for M50NiL Rolling Bearing in Helicopter Transmission

摘要

In this paper, a fatigue life model of aeronautic rolling bearing made by M50NiL steel was established with Goodman formula and material P-S-N curves, based on Lundberg -- Palmgren fatigue life theory (L-P theory) and Hertz contact theory, considered the effect of thermo-mechanical coupling. The model was mostly related to the maximum Hertz contact stress and material coefficients. To solve the stress by the software of ANSYS, thermoplastic finite element method was adopted, the thermal load was calculated, and the distribution of heat stress was used for boundary conditions of stress analysis, then the regularities of loading distributions under the effect of thermo-mechanical coupling were determined. According to the data above, the fatigue life evaluation method for rolling bearing under varieties of working conditions based on loading spectrum was finally obtained, and an example which proves the method reasonable under one working condition was given, the error with the test value was 11.61%. The results show that the evaluation result calculated by this method is securer than the test result, which indicate that the method is a safe and effective evaluation method of fatigue life.