Impact of journal bending on the failure of axle bearings in railroad passenger cars

2019 ◽  
Vol 234 (8) ◽  
pp. 1296-1309 ◽  
Author(s):  
Wei Chang ◽  
Hua Xu ◽  
Xi Zhang ◽  
Yu Xing ◽  
Wei Meng ◽  
...  
Keyword(s):  
Failure Mechanism ◽  
Load Distribution ◽  
Element Model ◽  
Operating Conditions ◽  
Hertzian Contact ◽  
Contact Theory ◽  
Passenger Cars ◽  
Grease Lubrication ◽  
Life Model ◽  
Hertzian Contact Theory

This research presents a systematic methodology to analyze the failure mechanism of cylindrical roller bearings of railroad passenger cars. Initially, a finite element model is developed to calculate the journal bending and internal contact load distribution, considering multi-interfacial contact parameters. Then, non-Hertzian contact theory is applied to prove the rollers’ abnormal contact behaviors, including load-distribution and displacement. Subsequently, a grease lubrication model is developed to study bearings lubrication under different operating conditions. Additionally, an exact service life model from ISO standards is used to evaluate the effect of journal bending. Finally, a system failure mechanism can be summarized and validated in the experiments, also helpful for axle box system bearings design and assembly.

Frictional Analysis of MoS2 Coated Ball Bearings: A Three-Dimensional Finite Element Analysis

1997 ◽  
Vol 119 (4) ◽  
pp. 754-763 ◽  
Author(s):  
M. R. Lovell ◽  
M. M. Khonsari ◽  
R. D. Marangoni
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Element Model ◽  
Hertzian Contact ◽  
Contact Theory ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Hertzian Contact Theory

A brief review of finite element contact and friction theory is presented for low-speed bearing operations. A three-dimensional finite element model is developed to realistically characterize the friction experienced by a coated ball bearing element. The finite elements results, which are obtained for various normal loads and ball materials, are verified using Hertzian contact theory and previous experimental tests performed by the authors. From the results, general trends for the frictional behavior of coated bearing surfaces are established and implications to the field of controls, as applied to precision positioning and tracking instruments are discussed.

Approximate Analytical Model for Hertzian Elliptical Wheel/Rail or Wheel/Crossing Contact Problems

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
F. D. Fischer ◽  
M. Wiest
Keyword(s):  
Contact Pressure ◽  
Contact Problems ◽  
Hertzian Contact ◽  
Contact Theory ◽  
Technical Accuracy ◽  
Elliptical Contact ◽  
Current Approximation ◽  
Analytical Expressions ◽  
Maximum Contact ◽  
Hertzian Contact Theory

The Hertzian contact theory is approximated according to a concept by Tanaka (2001, “A New Calculation Method of Hertz Elliptical Contact Pressure,” ASME J. Tribol., 123, pp. 887–889) yielding simple analytical expressions for the elliptical semi-axes, the maximum contact pressure, the mutual approach and the contact spring constant. Several configurations are compared using the exact Hertz theory and the current approximation. The results agree within technical accuracy.

Simulation of Traction Drive Ratio Changes

2000 ◽  
Author(s):  
Z. Zou ◽  
Y. Zhang ◽  
X. Zhang ◽  
W. Tobler
Keyword(s):  
Hertzian Contact ◽  
Contact Theory ◽  
Hydrodynamic Theory ◽  
Traction Drive ◽  
Input And Output ◽  
Piston Displacement ◽  
Simulation Results ◽  
Traction Drives ◽  
Stability And Accuracy ◽  
Hertzian Contact Theory

Abstract In the simulation model presented in this paper, the kinematic characteristics of traction drives are formulated using classical Hertzian contact theory and elasto-hydrodynamic theory. The roller swing motion is governed by an equation derived based on Newton’s Second Law and is coupled to the side slip, torque input and output, as well as ratio variations. A control strategy with feedbacks for both the roller swing and the piston displacement is applied for ratio control based on stability and responsiveness considerations. The model has been implemented systematically in Matlab/Simulink environment. The effectiveness of the ratio control system in terms of stability and accuracy is illustrated by the simulation results included in this paper.

Difference between the ideal and combined spherical joints and its effects on parallel manipulators

2019 ◽  
Vol 234 (5) ◽  
pp. 1112-1129
Author(s):  
Shuai Fan ◽  
Shouwen Fan
Keyword(s):  
Machine Tools ◽  
Parallel Manipulators ◽  
Hertzian Contact ◽  
Contact Theory ◽  
Contact Deformation ◽  
Spherical Joint ◽  
Universal Joint ◽  
Deformation Models ◽  
Hertzian Contact Theory ◽  
The Ideal

When using parallel manipulators as machine tools, the spherical joint has been widely used and replaced by a combination of a universal joint and a rotating unit, but the introduced differences and effects have not been studied in detail. In this paper, an approach to establish the mathematical models of the ideal and combined spherical joints is presented, and the differences between the two spherical joints are given from the perspective of constraints, workspace, clearance, and contact deformation. First, the non-interference workspace of a class universal joint is investigated by using a simple and clear projection method, where the constraint domain and workspace of two spherical joints are proposed. Next, the approximate clearance models of these two spherical joints are analyzed, and the corresponding contact deformation models are also given based on the Hertzian Contact theory. Finally, a 1PU + 3UPS parallel manipulator is used to verify the discrepant effects of two spherical joints on parallel manipulators. If the combined spherical joint is used, the results indicate that the improvement in the workspace is significant, but the drop in stiffness is also evident. Thus, this paper provides a theoretical basis for researchers to use combined spherical joints.

A Systematic Model for the Analysis of Contact, Side Slip and Traction of Toroidal Drives

1999 ◽  
Vol 122 (4) ◽  
pp. 523-528 ◽  
Author(s):  
Y. Zhang ◽  
X. Zhang ◽  
W. Tobler
Keyword(s):  
Traction Force ◽  
Hertzian Contact ◽  
Contact Theory ◽  
Kinematic Parameters ◽  
Traction Drive ◽  
Continuously Variable Transmissions ◽  
Toroidal Traction ◽  
Hertzian Contact Theory ◽  
Slip Force ◽  
Ratio Range

This paper presents a systematic model for the design and analysis of toroidal traction drive continuously variable transmissions (CVT). The contacts between the input disk, the roller and the output disk of the traction drive are formulated using the classical Hertzian contact theory. The traction force and side slip force occurring in CVT operation are modelled based on the elasto-hydrodynammic theory and are correlated to the traction drive geometric and kinematic parameters. The model allows for the quantitative analysis of traction drive operation under various torque inputs and over the desired ratio range. [S1050-0472(00)01004-7]

Extension of Hertzian Theory for Bodies With a Single Coating

2003 ◽  
Author(s):  
Shuangbiao Liu ◽  
Qian Wang
Keyword(s):  
Numerical Solutions ◽  
Layered Materials ◽  
Sufficient Accuracy ◽  
Hertzian Contact ◽  
Contact Theory ◽  
Numerical Analyses ◽  
Convenient Tool ◽  
Homogeneous Materials ◽  
Hertzian Contact Theory ◽  
Single Coating

The Hertzian theory is a convenient tool for analyzing counterformal bodies in mechanical contacts. However, it is limited to homogeneous materials. This paper reports the results from recent research that extends the Hertzian contact theory to layered materials. Numerical analyses are conducted to evaluate the accuracy of the formulas of the extended Hertzian theory, and the comparison with numerical solutions indicates that the formulas have sufficient accuracy.

Collision dynamics analysis of lifting the pantograph

2020 ◽  
pp. 095440972094339
Author(s):  
Yongming Yao ◽  
Ning Zhou ◽  
Dong Zou ◽  
Guiming Mei ◽  
Weihua Zhang
Keyword(s):  
Contact Force ◽  
Element Model ◽  
Vertical Displacement ◽  
Dynamic Responses ◽  
Hertzian Contact ◽  
Collision Dynamics ◽  
Collision Model ◽  
Collision Force ◽  
Multi Body ◽  
Hertzian Contact Theory

An extended pantograph-catenary (PAC) contact collision model is presented in this paper. The catenary is described by a finite element model while the pantograph is described by a multi-body model. The normal collision model is established by using the Hertzian contact theory. A 1:1 PAC collision contact test rig is built to validate the pantograph-lifting model. The dynamic responses of the PAC system during lifting the pantograph with different velocities and positions are studied. The research results show that the velocity and position of lifting the pantograph will affect the pantograph-lifting time, acceleration of collector piece, vertical displacement and contact force in the process of lifting pantograph. When the velocity of lifting the pantograph exceeds 0.5 m/s, the contact force between the pantograph and the contact wire will exceed 250 N, which is the allowed value set in the provisions of EN50367. It is essential to control the velocity of lifting the pantograph below 0.4 m/s to prevent the catenary or contact piece from being damaged due to the excessive impact force. The distribution of the droppers also affects the collision force between the PAC system.

Reinvestigation into railway wheel-track interaction and suspension damage

2020 ◽  
pp. 095440972093202
Author(s):  
Renfan Luo ◽  
David Vincent
Keyword(s):  
High Speed ◽  
Sensitivity Study ◽  
Hertzian Contact ◽  
Contact Theory ◽  
Fe Model ◽  
Fe Modelling ◽  
Wheel Flat ◽  
The Impact ◽  
Hertzian Contact Theory ◽  
Wheel Track

Without considering either velocity or acceleration effects, the current conventional method presented in literature applies the vertical deflection of a wheel centre caused by a flat defect to the Hertzian contact theory. This method has been numerically and theoretically proved to be inappropriate and can incorrectly predict a higher wheel-rail impact force for a low speed than a high speed. Therefore, under a hypothesis of no wheel bouncing and sliding, two new methods, the velocity-based and the acceleration-based have been proposed. The former method takes the wheel centre deflection change in each computational increment from the Hertzian contact theory while the latter applies the wheel centre acceleration caused by the flat in revolutions to the wheel as a force in dynamic simulation, which interprets the speed effects on impacts precisely. A sensitivity study proves that the velocity-based method is unreliable as opposed to the acceleration-based method. A beam/rigid FE model has also been developed to inspect the wheel-track interaction by performing dynamic analysis in the time domain. It has been found out that the impact responses predicted by the FE analysis and the velocity method are similar and the FE results heavily depend on the compute increment, which implies the FE modelling in ABAQUS may be unreliable for this issue with current applied increments. Finally, the results calculated using the acceleration method have been employed to study the suspension/damper torsional stress caused by a wheel flat. This indicates that a wheel flat may lead to potential fatigue damage if without proper maintenance management.

Force and Moment Characteristics of a Rhombi Tessellated Non-Pneumatic Tire

2016 ◽  
Vol 44 (2) ◽  
pp. 130-148 ◽  
Author(s):  
Anand Suresh Kumar ◽  
Ramarathnam Krishna Kumar
Keyword(s):  
Load Distribution ◽  
Three Dimensional ◽  
Element Model ◽  
Operating Conditions ◽  
Lateral Stiffness ◽  
Contact Pressure Distribution ◽  
Static Behavior ◽  
Pneumatic Tire ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

ABSTRACT There has been a recent spate of activities in the design of non-pneumatic tires (NPTs). The validation of a NPT's design is incomplete unless its performance is compared with an equivalent pneumatic tire. Apart from its static behavior, an evaluation of the tire's performance can be done by observing its force and moment (F&M) characteristics. In the present work, an NPT has been designed with an aperiodic rhombi tessellated spoke acting as the load bearing member, where the “unit cell” design is based on the vertical, circumferential, and lateral stiffness offered by the structure. A three-dimensional finite element model has been used to capture the mechanics of load distribution in the spoke, contact patch, and variation of contact pressure distribution when the tire is subjected to different operating conditions. SIMULIA/Abaqus has been used to conduct static loading, acceleration/braking, and cornering analyses. The F&M characteristics have been extracted from these simulations and compared with those of a 165/70R14 passenger car tire. The variation in the vertical and circumferential stiffness based on the spoke geometry has also been highlighted. The use of conventional pneumatic tire's belts to alter the NPT's lateral stiffness, despite the tire behaving like a “bottom loader,” adds uniqueness to the design. The NPT's capability to match the pneumatic tire's performance and the variability observed in the tire's F&M characteristics reiterate the freedom available in NPT design, thus providing the opportunity to have similar tires with varying performance characteristics.

Impact of Flexible Bent Beam Using Component Mode Techniques

1999 ◽  
Author(s):  
Cristian I. Diaconescu ◽  
Dan B. Marghitu
Keyword(s):  
Power Series ◽  
Elastic Beam ◽  
Point Of View ◽  
Component Mode Synthesis ◽  
Hertzian Contact ◽  
Contact Theory ◽  
Rigid Surface ◽  
Plastic Indentation ◽  
The Impact ◽  
Hertzian Contact Theory

Abstract The Component Mode Synthesis technique is applied to the impact of a flexible curved bar. The mode functions are selected such that the method can be made computationally as simple as possible, without compromising accuracy. From this point of view, a simple power series is selected. Both transversal and axial elastic deflection are considered. To describe the impact between the elastic beam and the rigid surface the classical Hertzian contact theory and elastio-plastic indentation theory are used.

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