| With the continuous development of the world economy,the research and development and production of aircraft in China has entered the golden opportunity for development.As an important connection part of aircraft piping system,the research on the strength and fatigue characteristics of flexible connectors has attracted widespread attention.In this paper,the coil part of the fuel duct flex is taken as the research object,starting from the aspects of static strength and dynamic characteristics,determining the location of the danger point and studying its vibration characteristics,and predicting fatigue life,the main research content is as follows:Firstly,the flexible connector and its accompanying test pieces and tooling are modeled and assembled according to the actual vibration durability test installation requirements,and the static strength analysis of the sleeve thickness and collar part that has attracted more attention in engineering practice is analyzed from the two directions of theoretical calculation and finite element simulation.The verification conclusion shows that the safety margin of the two weak structures is greater than 0,which meets the static strength requirements.Secondly,the dynamic characteristics of the tooling components are analyzed in the finite element environment,and the natural frequencies and mode shapes of the first six orders of the tooling components and flexible connectors are output in the modal analysis module,and the results show that the natural frequencies of the components overlap with the basic vibration frequency of aviation pipeline equipment,and there is a risk of resonance,and the resonance frequency is 810 Hz.Using the vibration of the aviation piston engine as the excitation,the harmonic response analysis of the tooling components was carried out,and it was determined that the stress of the conduit components was large when the random vibration spectrum in the Y direction was input,and the danger point was the chamfer of the root of the collar.Next,the random vibration test parameters are checked,the vibration test platform is selected,and the actual PSD image is obtained through the vibration test.Based on Ncode20.0,the minimum fatigue life value of the danger point is N=2E+07 times,and the position appears in the groove at the bottom of the collar,and the one-dimensional stress spectrum with the same mean is output by using mathematical analysis software such as MATLAB.The life prediction method and principle are expounded,the fuzzy linear Miner rule is introduced based on the shortcomings of the linear Miner rule,the feasibility of the model calculation and the accuracy of the prediction results are verified by example,and the accuracy is higher when the fixed half-liter normal distribution function and the half-liter stepped function are used as membership functions when the loading order of plastic materials is finally determined from low to high.Finally,according to the stress spectrum,the linear Miner rule and the fuzzy linear Miner law are applied to the vibration fatigue life of the danger point,and the reliability and accuracy of the calculation results of several methods are comprehensively compared,and the fatigue life of the flexible connector is finally predicted to be2.26E+06 times and 31.389 years,and the predicted life value is within the specified life range,and the fatigue damage occurs at the chamfer of the root of the collar. |
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