The influence of strain state on the nucleation and early growth of fatigue cracks was investigated. Thin walled tubular specimens of Inconel 718 were subjected to combinations of axial and torsional loading in the low cycle fatigue regime. The changes in crack growth rates as a function of crack size were examined at effective strain amplitudes of 0.01 and 0.005. The crack growth rates under pure torsion, combined loading and axial loading were found to be similar for the same crack size. Crack growth rates were interpreted based on an elastoplastic fracture mechanics characterization. A strain intensity range parameter was defined based on the shear and normal strain calculated on the crack plane. For mixed mode loading conditions, similar crack growth rates were observed at a given range of strain intensity.
|Original language||English (US)|
|Title of host publication||Unknown Host Publication Title|
|Publisher||Am. Soc. Test. & Mater|
|ISBN (Print)||0803109253, 9780803109254|
|State||Published - Jan 1 1988|
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