SERVICE LIFE PREDICTION METHOD OF APPARATUS UNDER NARROW-BAND RANDOM STRESS FLUCTUATION

摘要

PROBLEM TO BE SOLVED: To predict a service life of an apparatus under a narrow-band random stress fluctuation by handling a material damage process as a stochastic process, without directly handling a crack with a clear size/position. ;SOLUTION: In this service life prediction method, a probability density function of a damage accumulation quantity is found from a damage accumulation process based on a minor rule, and an apparatus service under a random stress amplitude fluctuation is predicted on the basis of the probability density function. In this service life prediction method, a damage coefficient representing damage quantity per operation is approximated with a linear expression, when the random stress amplitude fluctuation is within a narrow band, and the random stress amplitude fluctuation σ (instant aneous) is represented by the sum of a time mean value part σ(t) (mean) and a probability fluctuation part σ'(t).;COPYRIGHT: (C)2001,JPO