scholarly journals LIFE ASSESSMENT OF RAILS BY CRITERION OF OCCURRENCE OF FATIGUE CRACKS

2021 ◽  
Vol 1 (38) ◽  
pp. 194-200
Author(s):  
V. Kosarchuk ◽  
O. Agarkov ◽  
V. Tverdomed
Keyword(s):  
Fatigue Cracks ◽  
Contact Fatigue ◽  
Life Assessment ◽  
Rolling Stock ◽  
Real Problem ◽  
Structural Element ◽  
Computational Costs ◽  
Load Carrying ◽  
Railway Wheels ◽  
Total Damage

The paper presents modern concepts of the contact fatigue crack occurrence in the railhead. Numerical simulation of the contact interaction between rails and rolling stock wheels by finite elements method are presented. During the simulation, the problem was solved in elastic and elastic-plastic formulations. We considered R65 rail profile and standard railway wheels. The conditions for the rail–wheel interaction corresponded to train movement on the straight section of the track without slipping. The modern life assessment methodology involves the calculation of the material damage increment at each point of the element as the load varies over time, and subsequent summation of this damage. Upon reaching the ultimate value of the total damage, the structural element is believed to lose its load-carrying capacity, i.e. a crack is formed in it. Despite the substantial simplification of the real problem, the computational costs for the implementation of such methods for predicting the durability will be unnecessarily high. In this regard, we propose the simplified method of the durability calculation.

scholarly journals Criteria for predicting the initiation of rolling contact fatigue damage in the railway wheels and rails

2019 ◽  
Vol 78 (3) ◽  
pp. 141-148
Author(s):  
V. I. Sakalo ◽  
A. V. Sakalo
Keyword(s):  
Fatigue Damage ◽  
Fatigue Cracks ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Basic Research ◽  
Rolling Contact ◽  
Rolling Stock ◽  
Cyclic Loads ◽  
Contact Patch ◽  
Maximal Shear Stress

The development of the methods for modeling the processes of accumulation of the rolling contact fatigue damage and wear of the wheels of the railway rolling stock and the rails is particularly relevant due to the increase in the number of damage in the recent times. The work is underway to improve the chemical composition and the technology of production of the wheel and rail steels in order to improve their mechanical properties and ability to resist the action of the cyclic loads. The methods of modeling allow predict the possibility of initiation of the fatigue cracks during operation with the sufficient accuracy in the short time. The selection of the contact fatigue criterion and the mathematical apparatus for calculating the stresses at points in the area adjacent to the contact patch to obtain the numerical values of the criterion components is the most important task in the development of modeling methods. The article focuses on the approaches based on the Dang Van criterion and the shakedown diagram for a material undergoing to the action of cyclic loads, which are widely used to assess the rolling contact fatigue of the wheels and rails. The assumptions that are used in the development of the algorithms concerning the models of the contacting bodies, the shape of the contact patch, the distribution of the contact pressures and the tangential forces are considered. The approach using the criterion — the amplitude value of the maximal shear stress is also considered. The example of modeling the process of accumulation of the rolling contact fatigue damage in the wheel of the freight car is given. The results of modeling are presented in the form of the isolines of the criterion values and the accumulated damage in the area adjacent to the contact patch. This work was supported by the Russian Foundation for Basic Research under Grant [17-01-00815A].

scholarly journals On integrated wheel and track damage prediction using vehicle–track dynamic simulations

2017 ◽  
Vol 231 (7) ◽  
pp. 775-785 ◽  
Author(s):  
Carlos Casanueva ◽  
Roger Enblom ◽  
Sebastian Stichel ◽  
Mats Berg
Keyword(s):  
Fatigue Cracks ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Rolling Stock ◽  
Substantial Part ◽  
Dynamic Simulations ◽  
Damage Prediction ◽  
Track System ◽  
Prediction Techniques

The renewal costs for wheels and rails are a substantial part of the costs for rolling stock operators and infrastructure managers all over the world. The causes for reprofiling or grinding are, in most cases, related to the following: (1) wheel or rail profiles with unacceptable wear, (2) appearance of rolling contact fatigue cracks in the surface, and (3) wheel flats caused by locking wheels during braking. The first two causes are related to the dynamic behavior of the vehicle–track system, and can be predicted using multibody simulations. However, there are several limitations that restrain the usefulness of these prediction techniques, such as simulation time constraints, necessary simplifications, and lack of experimental data that lead to educated assumptions. In this paper, we take the end-user perspective in order to show whether the latest developments in wheel–rail damage prediction can be integrated in a simplified framework, and subsequently used by the different stakeholders for an improved management of the different assets involved in the operation of rail vehicles.

Analysis of wear debris in rolling contact fatigue cracks of pearlitic railway wheels

Wear ◽  
2014 ◽  
Vol 314 (1-2) ◽  
pp. 51-56 ◽  
Author(s):  
K. Cvetkovski ◽  
J. Ahlström ◽  
M. Norell ◽  
C. Persson
Keyword(s):  
Wear Debris ◽  
Fatigue Cracks ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Railway Wheels

Tribology of rail bogie

2018 ◽  
Vol 77 (4) ◽  
pp. 230-240
Author(s):  
D. P. Markov
Keyword(s):  
Contact Fatigue ◽  
Basic Element ◽  
Difficult Problem ◽  
Railway Track ◽  
Rolling Stock ◽  
Kinematic Parameters ◽  
Approximate Estimation ◽  
Railway Bogie ◽  
Classical Calculation

Railway bogie is the basic element that determines the force, kinematic, power and other parameters of the rolling stock, and its movement in the railway track has not been studied enough. Classical calculation of the kinematic and dynamic parameters of the bogie's motion with the determination of the position of its center of rotation, the instantaneous axes of rotation of wheelsets, the magnitudes and directions of all forces present a difficult problem even in quasi-static theory. The paper shows a simplified method that allows one to explain, within the limits of one article, the main kinematic and force parameters of the bogie movement (installation angles, clearance between the wheel flanges and side surfaces of the rails), wear and contact damage to the wheels and rails. Tribology of the railway bogie is an important part of transport tribology, the foundation of the theory of wheel-rail tribosystem, without which it is impossible to understand the mechanisms of catastrophic wear, derailments, contact fatigue, cohesion of wheels and rails. In the article basic questions are considered, without which it is impossible to analyze the movement of the bogie: physical foundations of wheel movement along the rail, types of relative motion of contacting bodies, tribological characteristics linking the force and kinematic parameters of the bogie. Kinematics and dynamics of a two-wheeled bogie-rail bicycle are analyzed instead of a single wheel and a wheelset, which makes it clearer and easier to explain how and what forces act on the bogie and how they affect on its position in the rail track. To calculate the motion parameters of a four-wheeled bogie, it is represented as two two-wheeled, moving each on its own rail. Connections between them are replaced by moments with respect to the point of contact between the flange of the guide wheel and the rail. This approach made it possible to give an approximate estimation of the main kinematic and force parameters of the motion of an ideal bogie (without axes skewing) in curves, to understand how the corners of the bogie installation and the gaps between the flanges of the wheels and rails vary when moving with different speeds, how wear and contact injuries arise and to give recommendations for their assessment and elimination.

scholarly journals Mapping of scatter in fatigue life assessment of welded structures—a round-robin study

2021 ◽  
Author(s):  
Gustav Hultgren ◽  
Mansoor Khurshid ◽  
Peter Haglund ◽  
Zuheir Barsoum
Keyword(s):  
Fatigue Life ◽  
Round Robin ◽  
Life Assessment ◽  
Fatigue Life Assessment ◽  
Fatigue Life Estimation ◽  
Box Structures ◽  
Load Carrying ◽  
Local Stresses ◽  
Sources Of Variation ◽  
Global And Local

AbstractA round-robin study has been carried out within a national project in Sweden with the addition of an international participant, where several industrial partners and universities are participating. The project aims to identify variation and sources of variation in welding production, map scatter in fatigue life estimation, and define and develop concepts to reduce these, in all steps of product development. The participating organisations were asked to carry out fatigue life assessment of welded box structures, which is a component in load-carrying structures. The estimations of fatigue life have also been compared with fatigue test results. Detailed drawings, loads and material data were also given to the participants. The participants were supposed to use assessment methods based on global and local stresses using the design codes or recommendations they currently use in-house. Differences were identified between both methods and participants using the same codes/recommendations. Applicability and conditions from the cases in the codes were also identified to be differently evaluated between the participants. It could be concluded that for the applied cases the nominal stress method often overestimated the fatigue life and had a high scatter in the estimations by different participants. The effective notch method is conservative in comparison to the life of tested components with little scatter between the results derived by the participants.

scholarly journals Multiaxial fatigue study on steel transversal attachments under constant amplitude proportional and non-proportional loadings

2018 ◽  
Vol 165 ◽  
pp. 16007
Author(s):  
Martin Garcia ◽  
Claudio A. Pereira Baptista ◽  
Alain Nussbaumer
Keyword(s):  
Fatigue Life ◽  
High Strength ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Life Assessment ◽  
Experimental Program ◽  
Proportional Loading ◽  
Load Carrying ◽  
Stress States ◽  
Experimental Values

In this study, the multiaxial fatigue strength of full-scale transversal attachment is assessed and compared to original experimental results and others found in the literature. Mild strength S235JR steel is used and an exploratory investigation on the use of high strength S690QL steel and the effect of non-proportional loading is presented. The study focuses on non-load carrying fillet welds as commonly used in bridge design and more generally between main girders and struts. The experimental program includes 33 uniaxial and multiaxial fatigue tests and was partially carried out on a new multiaxial setup that allows proportional and non-proportional tests in a typical welded detail. The fatigue life is then compared with estimations obtained from local approaches with the help of 3D finite element models. The multiaxial fatigue life assessment with some of the well-known local approaches is shown to be suited to the analysis under multiaxial stress states. The accuracy of each models and approaches is compared to the experimental values considering all the previously cited parameters.

Thermal Effects in Contact Fatigue Under Oscillatory Normal Load

1965 ◽  
Vol 87 (1) ◽  
pp. 177-184 ◽  
Author(s):  
R. A. Burton ◽  
J. C. Tyler ◽  
P. M. Ku
Keyword(s):  
Energy Dissipation ◽  
Dynamic Load ◽  
Normal Load ◽  
Fatigue Cracks ◽  
Thermal Transformation ◽  
Contact Fatigue ◽  
Contact Temperature ◽  
Flat Specimen ◽  
Exponential Relationship ◽  
Specimen Temperature

Experiments are reported wherein contact fatigue was brought about by the application of an oscillatory normal load between a ball and a flat specimen. Plots of the flat-specimen temperature versus time showed that a rapid temperature rise occurred in the initial stage of crack formation, and thus provided an early indication of fatigue. Thermal resistances were measured for the apparatus components as well as the specimen contact. Using these, it was possible to apply the measured flat-specimen temperature to obtain estimates of the contact temperature as well as the energy dissipation rate prior to the incidence of fatigue cracks. It was shown that the contact temperature did not rise sufficiently to produce annealing in the test specimens. Thus, toroidal rings of hardened and softened material in the stressed zone could not be attributed to thermal transformation of the bearing steel. It was also shown that energy dissipation due to cyclic loading varied in approximate exponential relationship with dynamic load, and decreased upon increase of static load when dynamic load was maintained constant.

scholarly journals Influence of the steel grades on rolling contact fatigue of railway wheels

2011 ◽  
Vol 10 ◽  
pp. 2627-2632 ◽  
Author(s):  
A. Langueh ◽  
J-F. Brunel ◽  
E. Charkaluk ◽  
P. Dufrénoy ◽  
F. Demilly
Keyword(s):  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Steel Grades ◽  
Railway Wheels
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