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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 1982, Vol. 3 ›› Issue (1): 37-44.

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A LOCAL STRAIN FATIGUE ANALYSIS METHOD AND COMPUTER PROGRAM

Wu Yisheng   

  1. Institute of Mechanics, Chinese Academy of Sciences
  • Received:1980-08-01 Revised:1900-01-01 Online:1982-03-25 Published:1982-03-25

Abstract: A local strain fatigue analysis method is presented for evaluation of fatigue life. First, the three parameter elements of load increment, strain increment and stress increment are constructed by using the cyclic stress-strain curve of the material and the cyclic load notched strain curve of notched specimens. Then, the local stress-strain analysis of notched specimens under complex load is made by means of these elements and "availability coefficient matrix"given by R. M. Wetzel. The damage of each cycle is determined on the basis of local strain amplitude and correction for the effect of mean stress. Last, the damage can be cumulated according to Miner's linear cumulative damage theory and the life can be evaluated.The features of this method consist in adoption of three parameter elements of load increment, stress increment and strain increment; one-step transformation from loadtime histories to local stress and strain-time histories, then the computation procedure is simplified.The example of the Cumulative Fatigue Damage Division of the SAE Fatigue Design and Evaluation Committee has been computed with our program. The crack formation lives of the notched specimens for two materials under vehicle transmission load have been evaluated and the results are quite consistent with W. R. Brose's results and experiments. This demonstrates that the presented method and program are simple, reliable and rapid. This program can work more than 50 peaks per second and may be available for engineering evaluation of the crack formation life.