Defect size map for cast A357-T6 component under multiaxial fatigue loading using the Defect Stress Gradient (DSG) criterion

Experimental fatigue tests have been performed on structural components casted in A357-T6 aluminum alloy. A non-local fatigue criterion based on the stress gradient has been used in order to simulate the Wöhler diagram of the components. The criterion is accurate and shows that the stress gradient at the scale of the structure leads to good estimation of fatigue life whereas a local criterion gives results 100% below the experimental one. A critical defect size map based on a model of the whole component using the DSG (Defect Stress Gradient) criterion is provided. Simulation results have been compared with experimental results obtained on components with artificial surface defects: the DSG criterion provides good estimation of crack initiation sites.