Life Prediction of Notched Specimens Using Multiaxial Surface and Subsurface Strain Analyses

Multiaxial fatigue life prediction analyses are applied to notched specimens subjected to high strain constant amplitude loading. The specimens are made from isotropic and anisotropic batches of the structural steel EN15R. Two sets of experimental data are used for the analyses; data from the biaxial fatigue of thin walled specimens and data from the uniaxial fatigue of hourglass specimens. The maximum strain parameter and two multiaxial fatigue approaches, the Brown-Miller and the Lohr-Ellison theories, are used to predict the fatigue life. A simple subsurface strain model is developed to overcome the geometry difference between the thin walled biaxial specimens and the solid bar notched specimens. Fairly good life prediction is obtained with the multiaxial fatigue parameters and the subsurface model using elastic-plastic finite element simulations.