Wheel Spalling Literature Review

2008 ◽  
Author(s):  
Scott M. Cummings ◽  
Cameron P. Lonsdale
Keyword(s):  
Literature Review ◽  
Analytical Model ◽  
Analytical Models ◽  
Prevention Research ◽  
Multiple Sources ◽  
Slide Test ◽  
Defect Prevention ◽  
Train Speed ◽  
Adhesion Level ◽  
Research Consortium

As a means of determining the conditions under which a patch of martensite (and eventually a spall) is formed on a wheel tread, the Wheel Defect Prevention Research Consortium (WDPRC) has conducted a review of wheel slide test reports and analytical models for the prediction of contact patch temperature due to wheel slide. The relative merits of the analytical models are discussed and applied to the known/assumed conditions, i.e., speed, axle load, and wheel/rail coefficients of friction (COF) for each of the wheel slide tests. The accuracy of the analytical models is evaluated with respect to test data under a variety of conditions from multiple sources. After selecting the most appropriate analytical model, wheel slide temperature predictions are given for empty cars at a variety of speeds and wheel/rail COF levels. It is concluded that the potential exists to create martensite on sliding wheels with almost any realistic combination of axle load, wheel slide duration, train speed, and wheel/rail adhesion level. Additionally, sources of wheel spalling are discussed with a focus on misapplied hand brakes and malfunctioning air brake systems. Multiple authors noted the presence of tread damage on one wheel of a wheelset with no damage at the corresponding circumferential location of the mate wheel. The accompanying theories to explain this seemingly counterintuitive finding are restated in this literature review. At the end of the paper, the actions of the WDPRC to reduce wheel spalling are briefly outlined.

Brake Shoe Force Variation

2009 ◽  
Author(s):  
Scott Cummings
Keyword(s):  
Elevated Temperatures ◽  
Prevention Research ◽  
Brake Shoe ◽  
Potential Source ◽  
Temperature Detector ◽  
Defect Prevention ◽  
Force Variation ◽  
Freight Car ◽  
Research Consortium ◽  
System Designs

The Wheel Defect Prevention Research Consortium (WDPRC) has conducted a review and analysis of existing literature and existing data related to brake shoe force (BSF) variation in freight car brake rigging. This work was conducted to explore the sources of BSF variation, define the expected amount of BSF variation, and describe some of the existing brake system designs that may help reduce the amount of BSF variation. Wheel temperature is related to BSF due to the use of the wheel tread as a brake drum. Variation in BSF within a given railcar is one potential source of elevated wheel temperatures and thermal mechanical shelling (TMS) damage to the wheels. At elevated temperatures, wheels become less resistant to fatigue damage due to changes in the material mechanical properties and relief of beneficial residual stresses. Data recorded by a wayside wheel temperature detector shows that eliminating wheel temperature differences within individual cars could reduce the number of wheels reaching temperatures of concern for TMS by a factor of eight.

Service Wheel Temperatures and Car Condition in Relation to Thermal Mechanical Shelling

2008 ◽  
Author(s):  
Scott M. Cummings
Keyword(s):  
Real Time ◽  
Large Temperature ◽  
Prevention Research ◽  
Replacement Rate ◽  
Temperature Detector ◽  
Defect Prevention ◽  
Research Consortium ◽  
Possible Cause

The Wheel Defect Prevention Research Consortium (WDPRC) examined data from a wayside wheel temperature detector (WTD) located near the bottom of a grade in order to explore the root causes of hot wheels and thermal mechanical shelling. Not surprisingly, the data showed that most hot wheels, defined in this paper as a wayside WTD reading of 260°C (500°F) or greater, are found in trains descending the grade (descending trains), although they can be found in trains ascending the grade (ascending trains) as well. The majority of cars with hot wheels in ascending trains have the brakes applied at all wheel locations in the car, with unreleased or partially released hand brakes as a possible cause. While relatively few descending trains (15 out of 393) had many cars with hot wheels, these trains accounted for more than 20 percent of the descending cars with hot wheels, indicating that operational improvements could substantially reduce the quantity of hot wheels. Seventy-six percent of the descending cars with hot wheels had only a single wheel at or above 260°C (500°F). While the wheels in these cars are generally at higher temperatures than the wheels of other cars in the train, there were large temperature differences between individual wheel locations. Evidence of repeated hot wheel behavior was found in about 37 percent of the group of descending cars with hot wheels and about 20 percent of individual hot wheel locations. Two different car inspections were conducted based on the WTD data. First, a “near-real-time” inspection was conducted in which cars were quickly checked for obvious problems without removing them from the train. Next, an intensive inspection/test/teardown was conducted on bad actor cars, which showed repeated hot wheel behavior. Good actor cars, which repeatedly did not show hot wheels, were also present at the inspection/test/teardown for comparison. The cause of the hot wheels was not evident for the majority of cars at both inspections, however, bad actor cars were found to have twice the historical wheelset replacement rate of good actor cars.

Brake Shoe Coefficient of Friction Variation

2009 ◽  
Author(s):  
Scott Cummings ◽  
Tom McCabe ◽  
Glenn Guelde ◽  
Dan Gosselin
Keyword(s):  
Coefficient Of Friction ◽  
Prevention Research ◽  
Brake Shoe ◽  
Test Matrix ◽  
Potential Source ◽  
Defect Prevention ◽  
Research Consortium

A series of dynamometer tests were conducted by the Wheel Defect Prevention Research Consortium (WDPRC) to quantify the amount of expected variation in brake shoe coefficient of friction (COF) and resulting wheel temperature throughout the life of an individual brake shoe. Variations in brake shoe COF within an individual railcar are one potential source of elevated wheel temperatures and thermal mechanical shelling (TMS) damage to the wheels. High friction composition and tread conditioning brake shoes were installed in the “as manufactured” condition with no wear-in or machining at the beginning of the test matrix which consisted of seventeen stop tests and twelve grade tests. For each brake shoe tested, the average COF and maximum wheel temperature were recorded during eleven identical light grade tests interspersed throughout the test matrix.

scholarly journals Novel Structure and Thermal Design and Analysis for CubeSats in Formation Flying

Aerospace ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 150
Author(s):  
Yeon-Kyu Park ◽  
Geuk-Nam Kim ◽  
Sang-Young Park
Keyword(s):  
Analytical Model ◽  
Formation Flying ◽  
Thermal Environment ◽  
Thermal Analyses ◽  
Thermal Design ◽  
Analytical Models ◽  
Test Results ◽  
Solar Panels ◽  
Novel Structure ◽  
Micro Propulsion

The CANYVAL-C (CubeSat Astronomy by NASA and Yonsei using a virtual telescope alignment for coronagraph) is a space science demonstration mission that involves taking several images of the solar corona with two CubeSats—1U CubeSat (Timon) and 2U CubeSat (Pumbaa)—in formation flying. In this study, we developed and evaluated structural and thermal designs of the CubeSats Timon and Pumbaa through finite element analyses, considering the nonlinearity effects of the nylon wire of the deployable solar panels installed in Pumbaa. On-orbit thermal analyses were performed with an accurate analytical model for a visible camera on Timon and a micro propulsion system on Pumbaa, which has a narrow operating temperature range. Finally, the analytical models were correlated for enhancing the reliability of the numerical analysis. The test results indicated that the CubeSats are structurally safe with respect to the launch environment and can activate each component under the space thermal environment. The natural frequency of the nylon wire for the deployable solar panels was found to increase significantly as the wire was tightened strongly. The conditions of the thermal vacuum and cycling testing were implemented in the thermal analytical model, which reduced the differences between the analysis and testing.

The effects of geometric offsets on the dynamic responses of a Scott—Russell amplifying mechanism with flexible hinges

2009 ◽  
Vol 223 (10) ◽  
pp. 2413-2423 ◽  
Author(s):  
C-M Chen ◽  
R-F Fung
Keyword(s):  
Numerical Simulations ◽  
Analytical Model ◽  
Dynamic Responses ◽  
Analytical Models ◽  
Dynamic Equations ◽  
Magnification Factor ◽  
Flexure Hinges ◽  
Magnification Factors ◽  
Straight Line ◽  
Deviation Factor

The dynamic equations of a micro-positioning Scott—Russell (SR) mechanism associated with two flexible hinges and an offset are developed to calculate output responses. Both rigid and flexible hinges are considered to explore the results. The main features in the kinematics of the SR mechanism are its displacement amplification and straight-line motion, which are widely needed in practical industries. The manufacturing inaccuracy of the SR mechanism definitely causes geometric offsets of flexure hinges, and affects displacement amplification and straight-line output motion. Analytical models based on kinematics and Hamilton's principle are derived to explore the variation of linearity ratio, magnification factor, and deviation factor due to various offsets and link lengths. From numerical simulations for the SR mechanism with various offsets of flexible hinges in the conditions of different link lengths, it is found that offsets of flexure hinges obviously affect the amplifying factor and linearity ratio, and appear to dominate the changes of magnification factors. Moreover, an analytical model is also used to predict magnification factors due to various offsets. Finally, some conclusions concerning the effects of offset on the performance of the SR mechanism are drawn.

Modeling of residual stresses by correlating surface topography in machining of AISI 52100 steel

2021 ◽  
pp. 1-26
Author(s):  
Chao Liu ◽  
Yan He ◽  
Yufeng Li ◽  
Yulin Wang ◽  
Shilong Wang ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Cutting Force ◽  
Surface Topography ◽  
Analytical Model ◽  
Analytical Models ◽  
Workpiece Surface ◽  
Dynamic Cutting Force ◽  
Intermittent Cutting ◽  
Effect Of Surface

Abstract The residual stresses could affect the ability of components to bear loading conditions and also the performance. The researchers considered workpiece surface as a plane and ignored the effect of surface topography induced by the intermittent cutting process when modeling residual stresses. The aim of this research develops an analytical model to predict workpiece residual stresses during intermittent machining by correlating the effect of surface topography. The relative motions of tool and workpiece are analyzed for modeling thermal-mechanical and surface topography. The influence of dynamic cutting force and thermal on different positions of surface topography is also considered in analytical model. Then the residual stresses model with the surface topography effect can be developed in intermittent cutting. The analytical models of dynamic cutting force, surface topography and residual stresses are verified by the experiments. The variation trend of evaluated values of the residual stress of workpiece is basically consistent with that of measured values. The compressive residual stress of workpiece surface in highest point of the surface topography are higher than that in the lowest point.

scholarly journals Approximate Analytical Models of Shock-Wave Structure at Steady Mach Reflection

Fluids ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 305
Author(s):  
Mikhail V. Chernyshov ◽  
Karina E. Savelova ◽  
Anna S. Kapralova
Keyword(s):  
Experimental Data ◽  
Shock Wave ◽  
Comparative Analysis ◽  
Analytical Model ◽  
Mach Reflection ◽  
Supersonic Jet ◽  
Wave Structure ◽  
Analytical Models ◽  
Analytical Prediction ◽  
Shock Wave Structure

In this study, we obtain the comparative analysis of methods of quick approximate analytical prediction of Mach shock height in planar steady supersonic flows (for example, in supersonic jet flow and in narrowing channel between two wedges), that are developed since the 1980s and being actively modernized now. A new analytical model based on flow averaging downstream curved Mach shock is proposed, which seems more accurate than preceding models, comparing with numerical and experimental data.

Leveraging data science to enhance suicide prevention research: a literature review

2021 ◽  
pp. injuryprev-2021-044322
Author(s):  
Avital Rachelle Wulz ◽  
Royal Law ◽  
Jing Wang ◽  
Amy Funk Wolkin
Keyword(s):  
Risk Factors ◽  
Literature Review ◽  
Injury Prevention ◽  
Suicide Prevention ◽  
Data Science ◽  
Population Level ◽  
Individual Risk ◽  
Prevention Research ◽  
Science Method ◽  
Individual Level

ObjectiveThe purpose of this research is to identify how data science is applied in suicide prevention literature, describe the current landscape of this literature and highlight areas where data science may be useful for future injury prevention research.DesignWe conducted a literature review of injury prevention and data science in April 2020 and January 2021 in three databases.MethodsFor the included 99 articles, we extracted the following: (1) author(s) and year; (2) title; (3) study approach (4) reason for applying data science method; (5) data science method type; (6) study description; (7) data source and (8) focus on a disproportionately affected population.ResultsResults showed the literature on data science and suicide more than doubled from 2019 to 2020, with articles with individual-level approaches more prevalent than population-level approaches. Most population-level articles applied data science methods to describe (n=10) outcomes, while most individual-level articles identified risk factors (n=27). Machine learning was the most common data science method applied in the studies (n=48). A wide array of data sources was used for suicide research, with most articles (n=45) using social media and web-based behaviour data. Eleven studies demonstrated the value of applying data science to suicide prevention literature for disproportionately affected groups.ConclusionData science techniques proved to be effective tools in describing suicidal thoughts or behaviour, identifying individual risk factors and predicting outcomes. Future research should focus on identifying how data science can be applied in other injury-related topics.

Updating of Non-Conservative Systems Using Inverse Methods

1997 ◽  
Author(s):  
Ladislav Starek ◽  
Milos Musil ◽  
Daniel J. Inman
Keyword(s):  
Analytical Model ◽  
Degrees Of Freedom ◽  
Ad Hoc ◽  
Natural Frequencies ◽  
Eigenvalue Problems ◽  
Model Updating ◽  
Analytical Models ◽  
Mode Shapes ◽  
Element Analysis ◽  
Modal Data

Abstract Several incompatibilities exist between analytical models and experimentally obtained data for many systems. In particular finite element analysis (FEA) modeling often produces analytical modal data that does not agree with measured modal data from experimental modal analysis (EMA). These two methods account for the majority of activity in vibration modeling used in industry. The existence of these discrepancies has spanned the discipline of model updating as summarized in the review articles by Inman (1990), Imregun (1991), and Friswell (1995). In this situation the analytical model is characterized by a large number of degrees of freedom (and hence modes), ad hoc damping mechanisms and real eigenvectors (mode shapes). The FEM model produces a mass, damping and stiffness matrix which is numerically solved for modal data consisting of natural frequencies, mode shapes and damping ratios. Common practice is to compare this analytically generated modal data with natural frequencies, mode shapes and damping ratios obtained from EMA. The EMA data is characterized by a small number of modes, incomplete and complex mode shapes and non proportional damping. It is very common in practice for this experimentally obtained modal data to be in minor disagreement with the analytically derived modal data. The point of view taken is that the analytical model is in error and must be refined or corrected based on experimented data. The approach proposed here is to use the results of inverse eigenvalue problems to develop methods for model updating for damped systems. The inverse problem has been addressed by Lancaster and Maroulas (1987), Starek and Inman (1992,1993,1994,1997) and is summarized for undamped systems in the text by Gladwell (1986). There are many sophisticated model updating methods available. The purpose of this paper is to introduce using inverse eigenvalues calculated as a possible approach to solving the model updating problem. The approach is new and as such many of the practical and important issues of noise, incomplete data, etc. are not yet resolved. Hence, the method introduced here is only useful for low order lumped parameter models of the type used for machines rather than structures. In particular, it will be assumed that the entries and geometry of the lumped components is also known.

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