A Novel Modeling Approach to Simulate Rolling Contact Fatigue and Three-Dimensional Spalls

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Aditya A. Walvekar ◽  
Dallin Morris ◽  
Zamzam Golmohammadi ◽  
Farshid Sadeghi ◽  
Martin Correns
Keyword(s):  
Damage Mechanics ◽  
Current Model ◽  
Rolling Contact Fatigue ◽  
Voronoi Tessellation ◽  
Three Dimensional ◽  
Contact Fatigue ◽  
Major Axis ◽  
Rolling Contact ◽  
Fe Model ◽  
Material Microstructure

In this study, a new approach has been developed to simulate three-dimensional (3D) experimental rolling contact fatigue (RCF) spalls using a two-dimensional (2D) finite element (FE) model. The model introduces a novel concept of dividing the 3D Hertzian pressure profile into 2D sections and utilizing them in a 2D continuum damage mechanics (CDM) RCF model. The distance between the two sections was determined by the size of the grains in the material microstructure. The 2D RCF model simulates characteristics of case carburized steels by incorporating hardness gradient and residual stress (RS) distribution with depth. The model also accounts for the topological randomness in the material microstructure using Voronoi tessellation. In order to define the failure criterion for the current model, sub-surface stress analysis was conducted for the Hertzian elliptical contact. It was predicted that the high shear stress region near the end of the major axis of the contact is the cause of catastrophic damage and spall formation. This prediction was validated by analyzing the spalls observed during RCF experiments using a surface profilometer. The model was implemented to predict RCF lives for 33 random material domains for different contact geometry and maximum Hertzian pressures. The model results were then compared to the RCF experiments conducted on two different test rigs, a three-ball-on-rod and a thrust bearing test apparatus (TBTA). It was found that the RCF lives obtained from the model are in good agreement with the experimental results. The results also demonstrated that the spalls generated using the analytical results resemble the spalls observed in experiments.

Effects of Grain Refinement on Rolling Contact Fatigue in Bearing Contacts

2021 ◽  
pp. 1-32
Author(s):  
Steven J Lorenz ◽  
Farshid Sadeghi ◽  
Hitesh K Trivedi ◽  
Mathew S Kirsch ◽  
Chinpei Wang
Keyword(s):  
Grain Refinement ◽  
Damage Mechanics ◽  
Rolling Contact Fatigue ◽  
Voronoi Tessellation ◽  
Contact Fatigue ◽  
Continuum Damage Mechanics ◽  
Rolling Contact ◽  
Critical Parameters ◽  
Fe Model ◽  
Grain Diameter

Abstract This paper presents a finite element (FE) model to investigate the effect of prior austenite grain refinement on rolling contact fatigue (RCF). RCF life was determined using continuum damage mechanics (CDM), which simulated material deterioration as a function of cycle. CDM calculations in this investigation considered the subsurface shear reversal to be responsible for RCF failure. To establish the CDM critical parameters torsion stress-life data from open literature of three different grain sizes for the same material was used. It was observed from the torsion S-N data that the resistance stress exhibits a linear relationship with grain diameter. As grain diameter was refined, the resistance stress increased. The damage rate exponent displayed no relation to grain diameter; hence, the average value from the three torsion S-N curves was used in this investigation. In order to assess the effect of grain refinement on RCF life, a series of unique material microstructures were constructed using the Voronoi tessellation process at eight mean grain diameters. FE simulations were devised at three contact pressures per grain size. The RCF results at the eight grain diameters indicate that fatigue performance is improved exponentially with finer grain diameter. The observed life improvements from the RCF simulations resulting from grain refinement exhibit good corroboration with existing experimental results found in open literature. A single predictive fatigue life equation was constructed from this investigation's RCF simulations to evaluate the stochastic RCF performance, given grain diameter and contact pressure, of non-conformal contacts.

An Approach for Modeling Material Grain Structure in Investigations of Hertzian Subsurface Stresses and Rolling Contact Fatigue

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Nick Weinzapfel ◽  
Farshid Sadeghi ◽  
Vasilios Bakolas
Keyword(s):  
Finite Element ◽  
Current Model ◽  
Rolling Contact Fatigue ◽  
Voronoi Tessellation ◽  
Contact Fatigue ◽  
Theory Of Elasticity ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Grain Structure ◽  
Finite Element Software

The continuum theory of elasticity and/or homogeneously discretized finite element models have been commonly used to investigate and analyze subsurface stresses in Hertzian contacts. These approaches, however, do not effectively capture the influence of the random microstructure topology on subsurface stress distributions in Hertzian contacts. In this paper, a finite element model for analyzing subsurface stresses in an elastic half-space subjected to a general Hertzian contact load with explicit consideration of the material microstructure topology is presented. The random internal geometry of polycrystalline microstructures is modeled using a 3D Voronoi tessellation, where each Voronoi cell represents a distinct material grain. The grains are then meshed using finite elements, and an algorithm was developed to eliminate poorly shaped elements resulting from “near degeneracy” in the Voronoi tessellations. Hertzian point and line contacts loads are applied as distributed surface loads, and the model’s response is evaluated with commercial finite element software ABAQUS. Internal stress results obtained from the current model compare well with analytical solutions from theory of elasticity. The influence of the internal microstructure topology on the subsurface stresses is demonstrated by analyzing the model’s response to an over rolling element using a critical plane approach.

A Coupled Multibody Finite Element Model for Investigating Effects of Surface Defects on Rolling Contact Fatigue

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Zamzam Golmohammadi ◽  
Farshid Sadeghi
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Surface Defects ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Internal Stresses ◽  
Fe Model ◽  
Elastic Plastic ◽  
Pile Up

A coupled multibody elastic–plastic finite element (FE) model was developed to investigate the effects of surface defects, such as dents on rolling contact fatigue (RCF). The coupled Voronoi FE model was used to determine the contact pressure acting over the surface defect, internal stresses, damage, etc. In order to determine the shape of a dent and material pile up during the over rolling process, a rigid indenter was pressed against an elastic plastic semi-infinite domain. Continuum damage mechanics (CDM) was used to account for material degradation during RCF. Using CDM, spall initiation and propagation in a line contact was modeled and investigated. A parametric study using the model was performed to examine the effects of dent sharpness, pile up ratio, and applied load on the spall formation and fatigue life. The spall patterns were found to be consistent with experimental observations from the open literature. Moreover, the results demonstrated that the dent shape and sharpness had a significant effect on pressure and thus fatigue life. Higher dent sharpness ratios significantly reduced the fatigue life.

A Statistical Damage Mechanics Model for Subsurface Initiated Spalling in Rolling Contacts

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Nihar Raje ◽  
Farshid Sadeghi ◽  
Richard G. Rateick
Keyword(s):  
Weibull Distribution ◽  
Damage Mechanics ◽  
Failure Process ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Unified Framework ◽  
Material Microstructure ◽  
Rolling Element ◽  
Microcrack Initiation ◽  
Cyclic Damage

Fatigue lives of rolling element bearings exhibit a wide scatter due to the statistical nature of the rolling contact fatigue failure process. Empirical life models that account for this dispersion do not provide insights into the physical mechanisms that lead to this scatter. One of the primary reasons for dispersion in lives is the stochastic nature of the bearing material. Here, a damage mechanics based fatigue model is introduced in conjunction with the idea of discrete material representation that takes the effect of material microstructure explicitly into account. Two sources of material randomness are considered: (1) the topological randomness due to geometric variability in the material microstructure and (2) the material property randomness due to nonuniform distribution of properties throughout the material. The effect of these variations on the subsurface stress fields in rolling element line contacts is studied. The damage model, which incorporates cyclic damage accumulation and progressive degradation of material properties with rolling contact cycling, is used to study the mechanisms of subsurface initiated spalling in bearing contacts. Crack initiation as well as propagation stages are modeled using damaged material zones in a unified framework. The spalling phenomenon is found to occur through microcrack initiation below the surface where multiple microcracks coalesce and subsequent cracks propagate to the surface. The computed crack trajectories and spall profiles are found to be consistent with experimental observations. The microcrack initiation phase is found to be only a small fraction of the total spalling life and the scatter in total life is primarily governed by the scatter in the propagation phase of the cracks through the microstructure. Spalling lives are found to follow a three-parameter Weibull distribution more closely compared to the conventionally used two-parameter Weibull distribution. The Weibull slopes obtained are within experimentally observed values for bearing steels. Spalling lives are found to follow an inverse power law relationship with respect to the contact pressure with a stress-life exponent of 9.35.

Studying the Effect of Tangential Forces on Rolling Contact Fatigue in Rails Considering Microstructure

2019 ◽  
Author(s):  
Mohamad Ghodrati ◽  
Mehdi Ahmadian ◽  
Reza Mirzaeifar
Keyword(s):  
Rolling Contact Fatigue ◽  
Three Dimensional ◽  
Contact Fatigue ◽  
Material Model ◽  
Element Model ◽  
Rolling Contact ◽  
Traction Forces ◽  
Steel Microstructure ◽  
Initiation And Propagation ◽  
Tangential Forces

In this paper, the micro-mechanical mechanisms behind the initiation and propagation of rolling contact fatigue (RCF) damages caused by the large traction forces are investigated. This study provides a three-dimensional (3D) model for studying the rolling contact fatigue in rails. Since rolling contact fatigue is highly dependent on the rail’s steel microstructure behavior, a proper 3D approach to capture the microstructure- and orientation-dependent mechanical behavior is required. A precise material model known as crystal plasticity is used for this purpose. Additionally, a cohesive zone approach is implemented to capture the crack initiation and propagation at the grain boundaries. Using the 3D finite element model which is developed for this study, we evaluate the effect of various parameters such as traction forces along the rail, and also the normal forces on the RCF response. The results reveal that the RCF cracks initiate slightly below the rail surface. These cracks start propagating toward the rail surface when the contact force is applied in repeated load cycles. The results also indicate that the depth at which RCF initiates depends on the ratio between the longitudinal traction forces and the normal loads. With larger traction forces, the cracks initiate closer, or at the rail surface, whereas larger normal loads promote the cracks initiation beneath the surface.

Material Response to Rolling Contact Loading

1985 ◽  
Vol 107 (3) ◽  
pp. 359-364 ◽  
Author(s):  
A. P. Voskamp
Keyword(s):  
Rolling Contact Fatigue ◽  
Three Dimensional ◽  
Contact Fatigue ◽  
Load Cycle ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Microplastic Deformation ◽  
Contact Loading ◽  
Material Response ◽  
Deep Groove

The material response to rolling contact loading has been analyzed using quantitative X-ray diffraction methods. This has led to the discovery of preferred crystalline orientation in very narrow subsurface regions of endurance-tested 6309 deep groove ball bearing inner rings. The high hydrostatic pressure field, derived from the load-induced three-dimensional stress field in each Hertzian contact load cycle, allows substantial microplastic deformation to be accommodated in the subsurface layers. This microplastic deformation is accompanied by transformation of retained austenite, decay of martensite and the development of texture and residual stresses, one of which is a subsurface tensile stress in a direction normal to the surface. Both the preferred orientation and the tensile residual stress allow for crack propagation parallel to the rolling contact surface. Based on these findings, an outline of a qualitative model for rolling contact fatigue is presented.

scholarly journals TOWARDS MACHINE VISION BASED RAILWAY ASSETS PREDICTIVE MAINTENANCE

2020 ◽  
Vol 19 (2) ◽  
pp. 125
Author(s):  
Ivan Ćirić ◽  
Milan Banić ◽  
Miloš Simonović ◽  
Aleksandar Miltenović ◽  
Dušan Stamenković ◽  
...  
Keyword(s):  
Machine Vision ◽  
High Speed ◽  
Rolling Contact Fatigue ◽  
Three Dimensional ◽  
Contact Fatigue ◽  
Operational Reliability ◽  
Rolling Contact ◽  
Camera System ◽  
Novel Technologies ◽  
Three Dimensional Coordinate

The main goal of this paper is to present novel technologies that can contribute to safety, competitiveness, efficiency and operational reliability of Railway infrastructure through the development of innovative solutions for measuring and monitoring of railway assets based on machine vision. Measuring the transversal position of the wheels on the rail, as well as identification of the defects of the wheel and the rail (such as deformation of rail head edge, lateral wear, worn wheels, cracks in wheel and rail, rolling contact fatigue, corrugation and other irregularities) can increase reliability and lower maintenance costs. Currently, there is a need on the market for the innovative solution, namely the on-board high-speed stereo camera system augmented with a system that projects custom pattern (fringe scanner system) for measuring the transversal position of the wheels on the rail, robust to environmental conditions and waste along the track that can provide reliable measurements of transversal position of the wheels up to 200 km/h. New trends in Precise Industrial 3D Metrology are showing that stereo vision is an absolute must have in modern specialized optical precision measuring systems for the three-dimensional coordinate measurement.

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