Research on Fatigue Crack Growth Model of Aircraft Structural Parts under Salt Spray

Firstly, the stress analysis of landing gear is carried out to determine the stress of landing gear struts in the retracting and retracting stages, and the mechanical model of landing gear struts is established. By using finite element method, the landing gear struts and kinematic hinges are considered as rigid bodies, and it is ignored that the influence of their deformation during extension and extension. The external load of the pole is calculated in the working process. Secondly, through the component-level performance degradation test, the same structural size as the hinge of the landing gear moving mechanism was taken as the sample, and the samples were cycled in groups according to different corrosion time. The main items of functional degradation test include three parts: wet heat test, temperature cycle test, salt spray test and tensile fatigue test. The test load is the same as the calculation and analysis results of the landing gear moving mechanism struts, and the crack propagation is recorded. Finally, BP neural network was used to analyze the data, and the relationship between crack growth and load and corrosion time at different time points was obtained, and the residual life of corrosion fatigue and its reliability calculation model were obtained. After several times of training, the required error can be achieved. The training network was used to predict that the hinge was fixed in three of the four factors, and the expression of crack propagation was determined. Then the curve fitting tool (MATLAB) was used to fit the relationship between the crack of the pole and the applied load, pendulum frequency, pendulum Angle and corrosion period, and the degradation model of 30CrMnSiA steel struts under the coupling of corrosion and fatigue failure modes was determined.