A new finite element fatigue modeling approach for life scatter in tensile steel specimens

This paper presents the results of a finite element model developed to investigate the effects of material microstructure topology on fatigue damage evolution in dog-bone tensile specimens. The Voronoi finite element model (VFEM) developed was used to study fatigue damage evolution in AISI 4142 steel under various loading conditions. An environmental scanning electron microscope (ESEM) coupled with an Instron fatigue testing machine was used to determine the strain and fatigue life of the dog-bone 4142 steel specimens at different mean stress levels. The damage variable was obtained using the method of variation of elasticity modulus. The experimental damage versus cycle curve was then used to determine the material properties (i.e. resistance stress σR and exponent m) needed for the VFEM fatigue damage model. The VFEM model was used to corroborate the analytical and experimental fatigue results. A comparison of the results obtained from the VFEM model and ESEM indicate that they are in good agreement.