A crossing nose is a component of railway infrastructure subject to very severe loading conditions. Depending on the severity of these loads, the occurrence of structural fatigue, severe plastic deformation, or rolling fatigue may occur. Under fatigue conditions with high plastic deformation, cyclic plasticity approaches, together with local plasticity models, become more viable for mechanical design. In this work, the fatigue behavior in strain-controlled conditions of 51CrV4 steel, applicable to the crossing nose component, was evaluated. In this investigation, both strain-life and energy-life approaches were considered for fatigue prediction analysis. The results were considered through obtaining a Ramberg-Osgood cyclic elasto-plastic curve. Since this component is subject to cyclic loading, even if spaced in time, the isotropic and kinematic cyclic hardening behavior of the Chaboche model was subsequently analyzed, considering a comparative approach between experimental data and the FEM. As a result, the material properties and finite element model parameters presented in this work can contribute to the enrichment of the literature on strain-life fatigue and cyclic plasticity, and they could be applied in mechanical designs with 51CrV4 steel components or used in other future analyses.
This paper presents a research about the monotonic and failure behaviours of bolted joints made of thin plates of S350GD and S355MC steels grades applied for rack structures. A full factorial matrix of static monotonic tests was performed considering two joints configurations, two material thicknesses, three surface coatings and two preload levels. Slip tests were also performed according to the EN 1090-2 standard to evaluate joint slip factors for the three material surface conditions. Numerical simulations of static tests were also performed using J2 plasticity and compared with experimental data. From experimental results, it is verified that increasing thickness and preload results an increasing of failure loads and sliding loads, respectively. Slip tests revealed the lowest slip factors for the painted specimens, followed by uncoated specimens and the higher slip factor was verified for zinc-coated specimens. Regarding failure modes, it verified that the S355MC specimens with single connection fractured by shear, while the S350GD specimens fractured from splitting and shear. In addition, for specimens with multiple connections for both materials, the failure occurred in net cross-section. The FE results reproduced conveniently the ultimate loads as well as the failure modes, including the clamping and friction effects.
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