Research On Fatigue Reliability And Functional Reliability With Interrelated Multiple Failure Modes Of Landing Gear Steering Mechanism

The landing gear system determines aircraft's safety performance during the takeoff and landing process.Complexity of operating environment and frequent ground handling has raised very high requirements for fatigue performance and functional reliability of the nose wheel steering mechanism.Therefore,the nose wheel steering mechanism of "Xinzhou" 700 aircraft is chosen as the research object in this paper,and the research on fatigue reliability and functional reliability with interrelated multiple failure modes of mechanism are also carried out.For fatigue reliability analys is,instantaneous accumulated damage and fatigue damage strength are both regarded as random variables in this paper,and a fatigue cumulative damage probability model based on dynamic fatigue damage interference theory is proposed.Through the dynamic finite element simulation of the steering mechanism and the nominal stress method,this paper analyzes the fatigue life and reliability of key components of the steering mechanism.The results show that the fatigue life and reliability of the steering mechanism meet the design requirements.In this paper,a series model of mechanism reliability analys is with interrelated multiple failure modes is proposed,and the neural network response surface method and analysis flow for solving this model are also given.In view of the failure of starting mechanism,failure of speed and positioning accuracy of the nose wheel steering mechanism,this paper analyzes the functional reliability and parameter sensitivity of the steering mechanism under different temperatures considering that the failure modes are completely independent and relevant.And the accuracy and applicability of the reliability analys is method considering the correlation of failure modes are verified by comparing with the reliability results of the mechanism based on the experimental data.Finally,the high-and-low temperature durability test system of landing gear was designed.And the durability of the mechanism components was verified through 300,000 turning function tests.The variation regularity and range of the steering system parameters were also analyzed.Furthermore,the recommended values of landing gear's system parameters in the external field are provided.At the same time,the functional reliability of steering mechanism and the influence of temperature on reliability were analyzed by using the failure data of the function test.