| Summary: | 碩士 === 中華大學 === 機械與航太工程研究所 === 91 === The crack initiation life of cylindrical specimens with circumferential groove under out-of-phase multiaxial cyclic loading was studied. It is found that the crack initiation life under out-of-phase loading is longer than that under in-phase loading for the evidence of addition hardening effect. To find the local stress/strain history at the stress concentrations, finite element method was used to estimate the local behavior under the cyclic multiaxial loading. Four critical plane approaches; Brown-Miller model, Lohr-Ellison model, Fatemi-Socie model, and Smith-Watson-Topper model, were used to predict the crack initiation life with the assistance of the smooth specimen data. The critical planes for specific models were found by a numerical program in the strain space. Furthermore, the fracture surfaces were also examined in the study.
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