During the past years, several tools have been developed to try predicting wheel and rail wear of railway vehicles in an e-cient way. In this MSc thesis a new wear prediction tool developed by I.Persson is studied and compared with another wear prediction tool, developed by T.Jendel, which has been already validated and is in use since several years ago. The advantages that the new model gives are simpler structure, the consideration of wear as a continuous variable and that all the code is integrated in the same software. The two models have the same methodology until the part of the wear calculations and the post-processing. Wheel-rail geometry functions and time domain simulations are performed with the software GENSYS. In the simulation model the track and the vehicle are dened as well as other important properties such as vehicle speed and coe-cient of friction. Three simple tracks are used: tangent track, R=500 m curve with a cant of ht=0.15 m on the outer rail and R=1000 m curve with a cant of ht=0.1 m on the outer rail. The model is assumed to be symmetric so just outer (first and fourth axle) and inner (second and third axles) wheels are considered. During the vehicle-track interaction, the normal and tangential problems are solved. The wheel-rail contact is modelled according to Hertz's theory and Kalker's simplied theory with the help of the algorithm FASTSIM. Then wear calculations are performed according to Archard's wear law. It is applied in dierent ways, obtaining wear depth directly in Jendel's and wear volume rate in Persson's model. Jendel's model is rstly analyzed. Its specifc methodology is briefly explained and modications are performed on the code to make it work as similar as possible to Persson's model. Also parameters regarding the distance in which wear calculations are taken, the discretization of the width of the wheel and the discretization of the contact patch are analyzed. The methodology of Persson's model is also studied, most of all the performance of the post-processing which is one of the keys to the code. The parameters analyzed in this code are the ones regarding a statistical analysis performed during the post-processing and the discretization of the contact patch. Finally the comparisons between the wear depth obtained for both models are carried out. The discrepancies between the models are explained with the parameters analyzed and the dynamic behaviour of both models. Also a theoretical case is used as reference for comparison.

Rail wear can result in extensive costs for the track owner if it is not predicted and preventedin an efficient way. To limit these costs, one measure is to predict rail wear through wear simulations. The purpose with this work is to perform simulations of successive rail wear on the Swedish light rail line Tvärbanan in Stockholm, by means of the track-vehicle dynamics software GENSYS in combination with a wear calculation program developed in MATLAB. The simulation procedure is based on a methodology with a simulation set design, where the simulations to be performed are selected through a parametric study. The simulations include track-vehicle simulations, where the wheel-rail contact is modelled according to the Hertzian contact theory together with Kalker’s simplified theory (including the numerical algorithm FASTSIM). The results from the track-vehicle simulations serve as input to the wear calculations. When modelling rail wear Archard’s wear model has been used, including wear coefficients based on laboratory measurements. The measurements have been performed under dry conditions, so the wear coefficients under lubricated conditions (both natural and deliberate lubrication) are reduced by factors estimated by field observations. After the wear depth calculations the wear distribution is smoothed and the rail profile is updated. The simulation procedure continues with a new wear step as long as the desired tonnage is not attained. Four curves of Tvärbanan with different curve radii, ranging from 85 to 410 m, have beenstudied in this work. On three of the curves the high rail is deliberately lubricated, whereas no lubrication has been applied in the widest curve. The vehicle operating the light rail line is an articulated tram with two motor end bogies and one intermediate trailer bogie. The line was opened in August 1999 and extended in one direction one year later. Rail profile measurements have been carried out by SL since March 2002. The traffic tonnage at the selected sites from the opening of the line to the last measurement occasion (September2004) is at most 8.9 mega gross ton per track. The results of the rail wear prediction tool are evaluated by comparing worn-off area of the simulated rail profiles with that of the measured rail profiles. Simulated and measured resultsdo not agree too well, since the simulated rail wear is more extensive than the measured one, especially on the outer rail. However, the shapes of the simulated worn rail profiles are comparable to those of the measured rail profiles. / QC 20101123

Quality is a multi-dimensional concept and can be viewed from different perspectives (Fiore &Kimle, 1997:5). From the professional women’s (consumer) perspective career wear quality can be measured on both tangible (functional or sensory) and non-tangible (emotional, cognitive and importance of the self and others) levels. From the retailer’s perspective quality is measured mostly based on intrinsic product features (durability), thus relating to one component of career wear quality of professional women. The discrepancy between the two may result in consumer dissatisfaction and impacts negatively on return sales to the retailer. Quality evaluation occurs at two stages during the consumer decision making process. Firstly, quality is evaluated in-store, during the decision-making stage, and secondly during product use. The quality indicators that professional women use during these stages may not be the same. In this study an exploration was thus done on the tangible and non-tangible quality indicators that professional women use to evaluate career wear quality both during the purchase decision-making stage and during product use. Each of these was measured according to its importance to the respondents during the decision-making stage and during product use and subsequently compared, since the importance of quality indicators may differ between the two stages. The systems theory approach was used to compile the conceptual framework for this study. The systems perspective acknowledges the sequence, relationship and interdependency of the individual indicators that are used to evaluate clothing products. These indicators are considered as so-called inputs and are transformed in terms of outputs, which are interpreted in terms of customer satisfaction or dissatisfaction. The respondents were full-time employed professional women in the legal, financial, engineering and medical industries, as these women require the suitable qualification and registration with the appropriate professional body. This group has spending power and their third largest household expenditure is clothing products. A snowball technique was used to recruit participants/respondents for both the qualitative phase, during which a focus group was held, and for the quantitative data collection (questionnaire) phase. The qualitative technique (focus group) was used to gain insight into the exact quality indicators and specific terminology the target population uses when evaluating career wear quality during the purchase decision making stage and during product use. The questionnaire was compiled against the theoretical background and the information gained from the focus group. Through the use of t-tests and the Pearson’s correlation coefficient it was found that respondents used similar quality indicators to evaluate career wear quality both during the decision-making stage and during product use. Tangible quality indicators were seen as significantly more important than non-tangible quality indicators to respondents during both stages of quality evaluation. Appropriate and adequate information regarding tangible quality indicators must thus be made available by retailers to professional women at the point of purchase. This may ensure consumer satisfaction during product use and facilitate return sales for the retailer. / Dissertation (MConsumer Science)--University of Pretoria, 2010. / Consumer Science / unrestricted

Various methods exist for measuring and analyzing dental wear patterns in mam-mals, and these patterns have been extensively studied in ungulates. Mesowear has proven useful as a method to compare large numbers of individuals, particularly fossil individuals, observe trends through time or between groups, and estimate paleoenvi-ronmental conditions. Levels of attrition (tooth-on-tooth wear) and abrasion (tooth-on-food wear) can be readily compared by observing the shape of the cusp and relative crown height of the tooth. This study uses a modified method of mesowear analysis, examining actual cusp angles of the population of Tapirus polkensis from the Gray Fossil Site, a densely canopied, hickory and oak dominated forest located in Gray, Tennes-see. Crown height and cusp angle were measured for 38 specimens arranged into eruption series from young juveniles to old adults. Results found a strong correlation between eruption series and cusp angle with a steady increase in mean angle as the individuals increase in age. A strong correlation between cusp angle and crown height was also found. Overall, the population showed relatively low wear rates, as would be expected of a forest-dwelling browser. As a mesowear analysis across all age groups for a population has not been conducted before, this study could be useful for measuring relative wear rates at different life stages and could be applied across other com-munities.

Titanium alloys support a wide range of practical applications due to their excellent mechanical properties. These include high strength-to-weight ratio, high mechanical strength at elevated temperatures and remarkable oxidation resistance. Machinability investigations so far have been intentionally focused on Ti-6Al-4V, which is commonly used in the aerospace research and development. However, a new classes of titanium alloys are also being developed for these applications. Ti-5Al-5Mo-5V-3C, also known as Ti5553, is included in this new category of titanium grade alloys. It corresponds to a near beta titanium alloy and generally it is employed on the production of high strength parts. Its high tensile strength combined with low weight (compared to Ti64) makes Ti5553 a suitable choice for landing gear parts and advanced structural components. However, due to the previously mentioned mechanical properties of Ti5553, machining processes can be difficult. During the cutting tests, the cutting zone experiences high cutting temperatures, and combined with a low rate of heat transfer, it generates stress and premature tool failure. By using several distinct experimental approaches, this work presents a comparison between different machining conditions (combinations of tools and coolants) to diagnose wear processes and identify better cutting parameters. The main objective of this research is to establish an understanding of how these parameters affect tribological aspects when machining Ti5553. The results of machining studies demonstrate different wear behaviour for CBN and PCD tools under various cutting environments (different coolant modes). These operating conditions can considerably affect the cutting forces leading to an increased tool life and improved surface integrity by decreasing, the residual stress and roughness, as well as work of hardening the workpiece during machining operations. / Thesis / Master of Applied Science (MASc)

No description available.

This paper presents a biotribological study on cartilage wear and friction, using a system of cartilage-on-stainless steel. This study is a part of the ongoing biotribology research by Dr. Furey at the Virginia Polytechnic Institute and State University. Two loads (65 N and 20 N) and three lubricants (saline reference, reference + hyaluronic acid, and bovine synovial fluid) were tested and evaluated using several analysis techniques. These techniques included wear analysis by hydroxyproline measurement, scanning electron microscopy (SEM), histologic sectioning and staining, numerical analysis of friction and specimen displacement data, and Fourier transform infrared (FTIR) analysis. Biochemical wear analysis showed that, under high load, the saline reference generated the most wear, hyaluronic acid produced less wear, and bovine synovial fluid produced the least. Wear was sensitive to load with all three lubricants, but was not significantly affected by the lubricant under low load. SEM photographs and histologic sections showed evidence of plowing and surface delamination, as well as another wear mechanism that produced wear markings perpendicular to the direction of sliding. Opaque films remained on the polished stainless steel disks after saline and hyaluronic acid tests, but not after synovial fluid tests. FTIR analysis of these films, as well as fresh and worn cartilage, showed that the cartilage experienced chemical changes during sliding. / Master of Science

With the constant scaling of semiconductor devices, reliability of these devices is a huge concern. One of the biggest reliability issues is a phenomenon known as electromigration (EM) [1] [2]. Electromigration is the transport of material caused by the gradual movement of the ions in a conductor due to the momentum transfer between conducting electrons and diffusing metal atoms [27]. The damage induced by electromigration appears as the formation of voids and hillocks, resulting in electrical discontinuity. Based on previous Electromigration research [15], I have created a tool chain that identifies where electromigration is likely to occur in large-scale integrated circuits. Using this tool chain, it is possible to identify the mean-time to failure (MTTF) of several common and high priority circuits such as complex adders and memories. Furthermore, this tool chain allows designers to isolate weak-points in these circuits to improve the overall MTTF of the circuit. The result is that with a few simple changes, circuits can be redesigned to increase the MTTF, at minimal cost to the system.

In manufacturing, monitoring machine health is an important step when implementing Industry 4.0 and ensures effective machining operations and minimal downtime. Monitoring the health of cutting tools during a machining process helps contain the faults associated with gradual tool wear, because they can be tracked and responded to as wear worsens. Left unchecked, tool failures can lead to more severe problems, such as dimensional and surface issues with machined workpieces and lower overall productivity during the machining process. This research explores the use of a machine vision setup used internally by the McMaster Manufacturing Research Institute (MMRI) in their three lathe machines. This machine vision setup provides a direct indication of the tool's maximum flank wear (VBmax), which, according to ISO 3685:1993(E), is set to be 300 µm. Also investigated was the use of image processing and analysis methods to determine the flank wear without removing the tool from the machine. This new, in-machine vision setup is intended to replace the use of an external optical microscope, which requires extended downtime between cutting passes. As a result of this replacement, the experimentation downtime was decreased by around 98.6%, leading to the experiment time to decrease from 5 weeks or more to just a couple of days. In addition, the difference in measurement between a commonly used optical microscope and in-machine vision setup was found to be ±3µm. / Thesis / Master of Science (MSc)

A new methodology was developed to observe and measure tool wear during the die compaction process. The newly developed method is a non-destructive test using silicon rubber to transcript die surface profiles. Tool wear was observed and measured by recording surface roughness and diameter of the cylindrical die replicas on a surface profiler including weight loss in the die. To validate this procedure, an aluminum alloy powder without lubricant was compacted to examine the effect on die wear. The die materials were machined from several wrought and composite materials. A further dimension to the program was the variance of compaction pressures and lubricants.