Fatigue Life Estimation of ITER Conduits at 4 K
ITER superconducting magnets are designed to operate at 4 K under cyclic loading. The conduits of the magnets (e.g., central solenoid) are designed to support all the cyclic loads during operation. It is expected that fatigue fracture is the major failure mechanism for the conduits. In the present study, the fatigue life of the conduits for ITER and the model coil has been estimated by applying numerical integration of the Paris equation to a surface crack. The fatigue crack growth behavior of a 3D crack is analyzed. Discussion is given to three key factors of a 3D crack: crack type, crack aspect ratio, and the eccentricity of an embedded crack. It is found that the estimated fatigue life of the conduits for ITER or the model coil is acceptable based on the current ITER design criteria. In a thin plate, there is a linear-log relationship between the fatigue life and applied stress at given initial crack size. Either a surface or corner crack shows a shorter life than most embedded cracks. The fatigue life decreases as the crack eccentricity increases.
KeywordsFatigue Life Linear Elastic Fracture Mechanic Initial Crack Crack Depth Fatigue Crack Growth Behavior
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