A Method for Predicting the Effect of Specimen Size on Fatigue Life

Abstract

The invention discloses a method for predicting an influence of the sample size on fatigue life. The method comprises the steps that by means of a function relationship between the fatigue life and stress, the fatigue life under different stress levels are converted into the fatigue life under the same stress level; statistical analysis is conducted on the fatigue life under the same stress level, and the most obedient probability distribution from is determined; the control volume of a small sample and the control volume of a big sample are calculated, and the control volume ratio of the big sample to the small sample is determined; the fatigue life N<L> of the big sample is obtained through n times of Monte Carlo simulation of the fatigue life N of the small sample under the same stress, that is, N<L>=min{N1, N2,..., Nn}; multiple fatigue life data of the big sample under the same stress are obtained; the fatigue life data of the big sample under different stress is obtained; statistical analysis is conducted on the obtained big sample fatigue life data, and a P-S-N curve is obtained. The defect that for big sample fatigue tests, the time and energy are wasted is effectively overcome.

Description

technical field [0001] The invention relates to the field of theoretical methods for fatigue life prediction, in particular to a method for predicting the influence of sample size on fatigue life. Background technique [0002] Fatigue failure analysis and life prediction are one of the key mechanical problems of engineering structural integrity. Numerous facts have shown that large-sized specimens tend to have lower fatigue life than smaller specimens under the same loading conditions. Fatigue experiments are time-consuming and laborious, especially for long-life fatigue experiments on large-scale samples. Therefore, it has very important application value to develop the prediction of fatigue life and P-S-N (failure probability-stress-life) curve of large samples through the fatigue experiment data of small samples. Contents of the invention [0003] The invention provides a method for predicting the influence of sample size on fatigue life, which is used to overcome the...

AI Technical Summary

Problems solved by technology

Fatigue experiments are time-consuming and labor-intensive, especially for long-life fatigue experiments on large-scale samples

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