Simulation Of Prediction Of Fatigue Life For Component Of Railway Vehicle

Fatigue damage for component of railway vehicle is a complex problem which is involved in structure, material, strength, dynamics, manufacture and assembly technique, quality guarantee system and operation condition of railway vehicle, and so on. This thesis established a set of prediction method of fatigue life for component of railway vehicle in frequency domain, time domain and reliability domain, and took a bogie frame as a detailed example.Railway vehicle is mostly excited by irregularity of railway track which is input of dynamics analysis and following tasks. Spectrum density function of track is required in frequcncy domain and stochastic irregularity history of track is required in time domain. But generally, only spectrum density function of track is available. Stochastic irregularity history of track can but be measured, which is inconvenient for simulation. So spectrum density of signal in time domain is evaluated through Fourier transform in this thesis. Stochastic irregularity of railway track is obtained by Inverse Fourier transform and is interpolated by cubic spline to meet dynamics analysis in time domain, which accord with mearsured data and relate analysis in frequency domain with that in time domain.It is important for prediction of fatigue life in frequency domain to construct probability density function of stress range. Bendat, Wirsching, Dirlik and so on had brought forward different models according to spectrum band width of stress-time history. On the basis ofDirlik's model this thesis modified it and put forward a fatigue damage formula based on subsection S-N curve according to characteristic of S-N curve only fitting with high cycle fatigue. In order to obtain basic parameters of probability density function of stress range, this thesis established dynamics model of locomotive in frequency domain and got power spectrum densities of stress responses of frame from spectrum density function of track. Parameters of probability density function of stress amplitude were obtained by means of figure display and statistic method. Probability density functions of stress range were deduced from known probability density functions...