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Mechanics in Engineering ›› 2004, Vol. 26 ›› Issue (5): 0-0.doi: 10.6052/1000-0879-2003-263

• Mechanics in engigeering •    

A SIMPLE AND PRACTICAL METHOD FOR ESTIMATION OF

  

  • Received:2003-06-19 Revised:1900-01-01 Online:2004-10-10 Published:2004-10-10

Abstract: This paper presents an equivalent load method for estimation of fatigue crack initiation life under spectrum loading. A weight factor and a coefficient of correction are added to the formula of root mean square of variable-amplitude-loading, respectively, to reflect influence of different loading range and mean stress upon variable-amplitude-fatigue life, and then the corresponding constant-amplitude-loading instead of the variable-amplitude-loading is used to estimate fatigue crack initiation life under spectrum loading. The method is easy to use as it only depends on constant-amplitude $S$-$N$ curve and uniaxial mechanical property of the material and it does not contain any undetermined parameters. The results of fifteen sets of random fatigue test data under three spectrum types for two materials are compared with three parallel methods. Miner rule, modified Miner rule and Root-Mean-Square method, and the average life-prediction accuracy of the method is improved, respectively, by 99.1, 24.6 and 50.0 per cent.

Key words: fatigue, life prediction, spectrum