2018 Volume 74 Issue 2 Pages I_137-I_146
This paper investigates the influence of a single tensile overload (OL) on fatigue life by means of finite element method. For a realistic evaluation of fatigue life, a combination of elastic-plastic material and fracture mechanics approach was applied. The interaction integral method available in WARP3D code, a multifunctional open source code, was employed to calculate stress intensity factor (SIF) based on elastic-plastic analyses. Numerical analyses performed in this study are based on experimental data taken from literature. A Single Edge Notch Tension model was applied in the numerical analyses. Two loading conditions, namely, pure constant amplitude loading (CAL) and CAL with a single tensile OL were employed. On the other hand, the geometry of the crack due to fatigue-cyclic loading was investigated. The distributions of stress/strain ahead of the crack tip, as well as the size of the induced plastic zone, were also examined. The behavior of SIF along the crack tip was discussed for loading and unloading cycles. Further, fatigue crack propagation material properties (C and m) were proposed based on elastic-plastic analyses to be used in crack propagation calculations in which their effectiveness was verified with experiments. The evaluated fatigue lives under pure CAL and CAL with a single tensile OL were validated with experiments.
