Fretting Fatigue Life Prediction Analysis Of Dovetail Structure

Fretting fatigue has been a long-term source of damage to aircraft turbine engine components during use.This particular type of damage will greatly shorten the life of engine components.At the same time,fretting fatigue cracks induced and propagated under high frequency vibration loads may cause unpredictable engine component failure.This type of damage may occur in many mechanical systems,such as bolts,riveted joints,keyway couplings,and bearings.However,helium-connected structures,which are critical components in steam turbines and engines,have a particularly severe effect on the damage caused by fretting fatigue.So the research on the fretting fatigue of dovetail structure has important engineering application value.Taking the fretting failure of aircraft engine dovetail joints as the starting point in the actual project,this project systematically studied the fretting fatigue phenomenon of the dovetail structure in the engine.This article analyzed the experimental data and phenomena obtained in the research group.A certain conclusion was reached,and the stress distribution in dovetail fatigue was analyzed using finite element method.At the same time,the position,direction and life of the crack initiation were predicted.In addition,the fretting fatigue crack propagation behavior of dovetail was simulated using the extended finite element method(XFEM).The main contents are as follows:(1)On the basis of the research on the fretting fatigue test of the dovetail structure in the research group,the study found that the fatigue life of the dovetail structure caused by fretting fatigue is reduced by about 70%,which seriously affects the service life of the components.Through the observation of the fretting fatigue crack of dovetail structure,it was found that the crack initiated at the contact end,the initiation angle was about 45�,and then propagated to a certain length and then spread along the direction perpendicular to the contact surface.(2)The finite element method based on ABAQUS was used to analyze the fretting fatigue behavior of dovetail structure.It was found that the stress concentration phenomenon occurred at the contact end.This location has a strong stress gradient effect in the depth direction,and this is where the crack initiation occurs..The multi-axial fatigue interface model of SWT and FS is used to predict the position,direction and life of crack initiation.The theory of critical distance(TCD)is introduced to further improve the prediction model of fretting fatigue crack initiation life.The new prediction method can better predict Fretting fatigue crack initiation life.(3)Based on the extended finite element method(XFEM),the fretting fatigue crack propagation behavior was simulated,and the XFEM and traditional finite element method were compared to simulate the crack propagation results because they only need to divide the grid once during the simulation.Obtained more accurate results,verifying the reliability and use value of XFEM in engineering applications.