Fatigue Life Prediction Method for the Civil Airplane Actuator Structure Based on the First Principal Stress Correction

In this paper, a method for fatigue life prediction of the actuator structure is proposed. The size and direction of the first principal stress of the part are obtained by finite element software. Considering the size coefficient, surface processing coefficient and heat treatment coefficient, stress concentration factor is introduced. Based on the stress concentration factor, the standard S-N curve of the material manual is corrected by modifying the first principal stress. Finally, the fatigue damage of the structure under the design fatigue spectrum is estimated with the linear cumulative damage theory, thus providing a feasible way for the actuator fatigue analysis. Compared with the method of linear interpolation for fatigue life, this method is more secure and more in line with high safety and reliability requirements of civil aircraft.