Abstract
In this paper, torsional fatigue failure of 30CrMnSiNi2A steel which exhibited non-Masing behavior was studied under different constant shear strain amplitudes, using thin-walled tubular specimens. The relationship between shear fatigue and the evolution of meso-deformation inhomogeneity and the prediction method of the torsional fatigue life curve were investigated. Shear fatigue of the material under constant amplitude was researched by numerical simulation with reference to tests, by using crystal plasticity of polycrystalline representative volume element (RVE) as the material model. Considering the non-Masing behavior of material, when determining the parameter values of the crystal plasticity model the correlation between these parameters and strain amplitude was taken into account. The meso-deformation inhomogeneity with increments in the number of cycles was characterized by using the statistical shear strain standard deviation of RVE as the basic parameter. Considering the effect of strain amplitude on fatigue damage, ratio cycle peak stress/yield stress was taken as the weight to measure the torsional fatigue damage and an improved fatigue indicator parameter (FIP) to measure the inhomogeneous deformation of the material was proposed. The torsional fatigue life curve of 30CrMnSiNi2A steel was predicted by the critical value of the FIP and then the result was confirmed.
Highlights
Shaft components, such as machine drive shafts, are subjected to torsional loading that results in fatigue failure
In order to investigate the correlation between deformation inhomogeneity evolution and fatigue life, the fatigue life of a superalloy and a pure copper under constant amplitude of tension-compression are studied by using the model of polycrystalline aggregate as the representative volume element (RVE) with crystal plasticity [23,24]
The constant amplitude torsional fatigue test of 30CrMnSiNi2A steel was carried out first and the shear cycle process was numerically simulated using the RVE constructed by Voronoi polycrystalline aggregates; subsequently the relationship between non-uniform deformation and fatigue failure under shear cycle was investigated
Summary
Shaft components, such as machine drive shafts, are subjected to torsional loading that results in fatigue failure. In order to investigate the correlation between deformation inhomogeneity evolution and fatigue life, the fatigue life of a superalloy and a pure copper under constant amplitude of tension-compression are studied by using the model of polycrystalline aggregate as the RVE with crystal plasticity [23,24]. Their investigation results show that the material deformation inhomogeneity at grain scale grows monotonically under cyclic loading. In this paper, associating test and simulation, the study was carried on for a method to predict the low-cycle torsional fatigue of a steel with obvious non-Masing behavior.
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