12. Reliability Assessment by Simulation of Fatigue Crack Growth : Data Acquisition and Analysis Method

概要

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A method is proposed for estimation of the probability distribution of fatigue crack growth life and reliability assessment of structures by simulating material resistance to fatigue crack growth along a crack path. The data for the simulation can be obtained from a few fatigue tests, The material resistance is treated as a spatial non-Gaussian (eventually Weibull, in this report) random process. Therefore, a non-Gaussian random fields simulation method proposed by Shinozuka, et al. is applied with statistical data obtained experimentally. The statistical analysis of the material resistance is performed with the data obtained by stress intensity factor controlled tests. The main results obtained are: (1) This method is useful to estimate the probability distribution of fatigue crack growth life; (2) the material resistance seems to follow a 3-parameter Weibull distribution; (3) this method is useful for simulation of rather long fatigue crack; (4) using this method, the probability distribution of fatigue crack growth life can be estimated from very few fatigue tests; (5) the smallest life can be determined; and (6) stress intensity factor controlled test is preferable for the statistical analysis.
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