RELIABILITY ANALYSIS OF LOW CYCLE FATIGUE LIFE FOR A DISC

When a failure model with low cycle fatigue is identified,the failure function for reliability analysis reduced as follows:As cumulative damage of varying amplitude cycles is calculated with Miner's law,the total damage is considered to be a random value varying from 0 3 to 3,and follows logarithmic normal distribution.Furthermore,damage of low cycle loads of each amplitude is evaluated according to the formula of flow cycle fatigue life prediction proposed by R.W.Landgraf.Then,the failure function for reliability analysis is derived from the above formulas by transforming strain expression into stress expression.If a stress at certain point of a disk is influenced by a disturbance of some random variables,the stochastic finite element method is employed to find the variance of the stress distribution.When stresses in a disk are in elasto plastic condition,nonlinear SFEM is required to obtain the variance of the stresses.Finally,a numerical example for a disk with equal thickness is presented and is verified by the Monte Carlo simulation.