Fatigue crack initiation life prediction of railroad wheels

Abstract.A rolling contact fatigue (RCF) differs from the classic fatigue in a stress-state. Nowadays, a prediction of the RCF is still not on the sufficient level. A lot of researchers tried to apply different multiaxial fatigue criteria (MFC) to the RCF, respectively they modified some or even proposed new one. Our paper focuses on assessment of bearing life estimation based on mentioned methods with experimental validation in laboratory. Comparison and summarization of different methods used in MFC life estimation is presented, with inclusion of fatigue material properties, hardness and probability. Mainly bearing steels are used for evaluation and region of high-cycle and giga-cycle fatigue.

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“…The Liu and Mahadevan criterion [20,21] provides a good match of life results with an experiment even for bearing steel. [11] provides a proof.…”

Section: Liu and Mahadevanmentioning

confidence: 91%

“…These data provided input for the criteria. The final results of the number of cycles up to failure was recalculated to a number of rotations using equation (21). Here, angle was equal to /2, thus, the number of rotations were always equal to number of cycles divided by half of number of balls.…”

Section: Numerical Analysismentioning

confidence: 99%

Case study of multiaxial criteria for rolling contact fatigue of bearing steels

2018

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“…A significant number of investigators have attempted to determine the physical mechanisms involved in rolling contact fatigue of bearings and proposed models to predict their fatigue lives [18,19,21,[144][145][146].…”

Section: Rolling Contact Fatiguementioning

confidence: 99%

Multiscale modeling and simulation of rolling contact fatigue

Gharehbagh

Ali

2018

International Journal of Fatigue

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iii ABSTRACT In this thesis, a hierarchical multiscale method was developed to predict rolling contact fatigue lives of mechanical systems. In the proposed multiscale method, the molecular modeling and simulation of lubricant was conducted to investigate the friction between rolling contact surfaces. The calculated friction coefficient was passed to the continuum model of rolling contact components to predict fatigue lives.Molecular dynamics modeling and simulation of thin film lubrication and lubricated contact surfaces were carried out to investigate mechanisms of hydrodynamic lubrication at nano-scale first. Although various lubricant alkane chains were considered in the molecular model, the chain length of eight united molecules were mainly employed in this thesis. In addition, the effects of temperature and nano-particles (debris) on the friction forces were discussed. It was found that the existing of nano-particles (debris) could increase the friction force between contact surfaces with hydrodynamic lubrication.In the continuum model of the developed multiscale method, finite element analysis was employed to predict rolling contact fatigue life of rolling contact components, including bearing and gear-tooth. Specifically, the fatigue crack initiation of bearing was studied, and then the fatigue crack initiation and propagation in gear-tooth. In addition, the enhancement of gear-tooth fatigue life by using composite patches was discussed as well. It should be noted that the friction coefficient used in the continuum model was calculated in the molecular model. It is one-way message passing in iv the developed multiscale method.Another continuum method was studied and developed in this thesis to provide alternate methods for the continuum model in the proposed multiscale framework.Peridynamics method has advantages in modeling and simulation of discontinuities, including cracks, over the conventional finite element methods. The applications of Peridynamics in predicting fatigue crack initiation and propagation lives were discussed in this thesis. v PUBLIC ABSTRACTThis research aims to develop a hierarchical multiscale method to predict rolling contact fatigue lives of mechanical systems. In the proposed multiscale method, the molecular modeling and simulation of lubricant was conducted to investigate the friction between rolling contact surfaces. The calculated friction coefficient was passed to the continuum model of rolling contact components to predict fatigue lives.Molecular dynamics modeling and simulation of thin film lubrication and lubricated contact surfaces were carried out to investigate mechanisms of hydrodynamic lubrication at nano-scale first. In addition, the effects of temperature and nano-particles (debris) on the friction forces were discussed. It was found that the existing of nanoparticles (debris) could increase the friction force between contact surfaces with hydrodynamic lubrication.In the continuum model of the developed multiscale method, finite element analysis was employed to pred...

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“…A study in (Liu et al, 2006) introduced a sub-modelling technique into fatigue life prediction on wheels to overcome this problem. While the feasibility of sub-modelling technique on W/R rolling contact analysis has not yet been verified.…”

Section: Section Of Railway Engineering Faculty Of Civil Engineeringmentioning

confidence: 99%

“…For example, in predicting fatigue life of rails and wheels (Desimone et al, 2006, Ekberg et al, 2002, simple engineering formulas are commonly utilized together with Multibody system(MBS) analysis. However, due to the assumption of rigid components and elastic material behaviour in MBS simulation, a continuum approach, Finite element method(FEM) cooperating with advanced fatigue life models (Liu et al, 2006, Ringsberg et al, 2000, Sraml et al, 2003 is often employed to do crack initiation/propagation analysis because of its striking versatility. In FEM analysis, material behaviour can be described by sophisticated elasto-plastic models.…”

Section: Introductionmentioning

confidence: 99%