On Strain Equivalent Method for thin Bulge-like Specimen and Low Cycle Fatigue Life Estimation Model of Zr-4 Alloy

A series of strain fatigue tests on small slice specimens with 1.3 mm thickness of Zr-4 alloy were conducted.Fatigue damage equivalent method based on the local damage equivalent assumptions between a thin Bugle-Like specimen and a straight specimen was presented.Based on the elastic-plastic finite element analysis,the equivalent conversion model of the Zr-4 alloy thin specimen from transversal strain to uniaxial strain was established.The model considers the geometrical effect and Poisson effect.With the results of the test,Manson-Coffin(M-C) model for Zr-4 alloy strain fatigue life prediction was presented.Research shows that,thin bulge-like specimen based on the equivalent conversion model can be effectively applied to low cycle fatigue tests of the thin sheet metals and their life estimation.GB recommended strain conversion formula which is applied to fatigue life prediction of thin bulge-like specimens of Zr-4 alloy would bring great security.