The life of railway wheels and rails has been decreasing in recent years. This is mainly caused by more traffic and running at higher vehicle speed. A higher speed usually generates higher forces, unless compensated by improved track and vehicle designs, in the wheel-rail contact, resulting in more wear and rolling contact fatigue (RCF) damage to the wheels and rails. As recently as 15 years ago, RCF was not recognised as a serious problem. Nowadays it is a serious problem in many countries and ''artificial wear'' is being used to control the growth of cracks by preventive re-profiling and grinding of, respectively, the wheels and rails.  This can be used because a competition exists between wear and surface initiated RCF: At a high wear rate, RCF does not have the opportunity to develop further. Initiated cracks are in this case worn off and will not be able to propagate deep beneath the surface of the rail or wheel. When wheel-rail damage in terms of wear and RCF can be predicted, measures can be taken to decrease it. For example, the combination of wheel and rail profiles, or the combination of vehicle and track, can be optimised to control the damage. Not only can this lead to lower maintenance costs, but also to a safer system since high potential risks can be detected in advance. This thesis describes the development of a wheel-rail life prediction tool with regard to both wear and surface-initiated RCF. The main goal of this PhD work was to develop such a tool where vehicle-track dynamics simulations are implemented. This way, many different wheel-rail contact conditions which a wheel or a rail will encounter in reality can be taken into account. The wear prediction part of the tool had already been successfully developed by others to be used in combination with multibody simulations. The crack prediction part, however, was more difficult to be used in combination with multibody simulations since crack propagation models are time-consuming. Therefore, more concessions had to be made in the crack propagation part of the tool, since time-consuming detailed modelling of the crack, for example in Finite Elements models, was not an option. The use of simple and fast, but less accurate, crack propagation models is the first step in the development of a wheel-rail life prediction model. Another goal of this work was to verify the wheel-rail prediction tool against measurements of profile and crack development. For this purpose, the wheel profiles of trains running on the Stockholm commuter network have been measured together with the crack development on these wheels. Three train units were selected and their wheels have been measured over a period of more than a year. The maximum running distance for these wheels was 230,000 km. A chosen fatigue model was calibrated against crack and wear measurements of rails to determine two unknown parameters.  The verification of the prediction tool against the wheel measurements, however, showed that one of the calibrated parameters was not valid to predict RCF on wheels. It could be concluded that wheels experience relatively less RCF damage than rails. Once the two parameters were calibrated against the wheel measurements, the prediction tool showed promising results for predicting both wear and RCF and their trade-off. The predicted position of the damage on the tread of the wheel also agreed well with the position found in the measurements. / <p>QC 20150526</p>

Sensitivity analysis methods are investigated for the optimal design of multibody systems. In order to overcome the shortcomings inherent in existing methods, a "mixed" method is developed. The beneficial features of the finite difference and the direct differentiation methods, and equations of motion in the joint coordinates are employed in this method. As a realistic application of the sensitivity analysis, a Four-Wheel-Steering vehicle with complete suspension systems and comprehensive analytical tire model is implemented. This model keeps full nonlinearity in the governing equations of motion for accuracy, and it is simulated using an existing general-purpose multibody dynamics simulation package. However, by using the transient dynamic analysis of the nonlinear model, optimal design parameters are dependent on driving scenarios. Therefore, the transient behavior of the system is represented by a series of steady state configurations. Hence, a steady state analysis procedure which finds a steady state configuration from an arbitrary initial condition is developed. By using the steady state analysis and the sensitivity analysis, the optimal steering ratios between the angles of the front and the rear wheels are obtained over various driving conditions. A steering control strategy is developed for the vehicle simulation to follow a prescribed path. Finally, the simulation results using the optimal steering ratio are compared against the results of the conventional two-wheel steering and the steering ratio based on the linear bicycle model.

Mobility is something able-bodied people take for granted. Approximately 132,500 people in the United Kingdom have disabilities which permanently confine them to a wheelchair; 40,000 of these require a powered wheelchair. The opportunity to lead a normal life and be accepted as an equal by the able-bodied population is limited by their reduced mobility. As much freedom of movement as possible is therefore crucial for these people. Powered wheelchair users' mobility depends upon the manoeuvrability of the chair. For optimum manoeuvrability a chair must be capable of moving in any direction. Currently no omni-directional powered wheelchairs are commercially available. This thesis describes the design and deVelopment of a powered base unit for a wheelchair, controlled to instantaneously move in any direction. The novelty is principally represented by the innovative design and configuration of four omni-directional roller wheels* (LUMAN wheels) which, when individually controlled, produce the omni-directional movement of the base unit. Further novelty within the design is a set of bi-directional angled roller couplings that simultaneously disengage the wheels from the motors, via a cable linkage mechanism, and simple control system. Mathematical data models illustrate the theoretical performance of the wheel configuration, and a prototype base unit is tested to prove these hypotheses.

Descreve-se os principais tipos de desgaste atuantes em rodas ferroviárias tais como desgaste abrasivo e desgaste por deslizamento. No desgaste por deslizamento os principais mecanismos são deformação plástica, fadiga de contato, fadiga termomecânica, oxidação e escorregamento. Avalia-se o efeito de variáveis como dureza, microestrutura, composição química da liga e escorregamento no desgaste e em seus mecanismos. Compara-se os tipos e mecanismos de desgaste verificados em rodas ferroviárias utilizadas em trens para transporte de minérios, com os obtidos em laboratório através de ensaio de desgaste disco-contra-disco de materiais de roda e trilho. No ensaio, o desgaste foi medido por pesagem dos corpos-de-prova verificando após distâncias predeterminadas a perda de massa. Avaliou-se a influência da carga, dureza, composição química e escorregamento no desgaste. Verificou-se que o desgaste aumenta com a carga e diminui com o aumento da dureza. Aços de rodas com adição de Cromo e Vanádio apresentam um melhor desempenho em desgaste se comparados com aços AAR M 107/208 Classe B ou C. Análise microscópica dos corpos-de-prova após ensaio, mostrou que tal como nas rodas em serviço, os tipos de desgaste atuantes foram desgaste abrasivo e por deslizamento com mecanismos diversos como deformação plástica, delaminação e oxidação. Mecanismo semelhante a delaminação é a formação de escamas ou shelling em rodas. Verificou-se também a formação de camada branca na superfície desgastada, característico de transformação martensítica em aço. Mecanismo similar a este é o de formação de \"spalling\" em rodas. Apresenta-se uma metodologia para desenvolvimento de materiais de rodas, compreendendo ensaios de desgaste em laboratório, produção de rodas e acompanhamento de desempenho em campo, onde se confirma o melhor desempenho de materiais AAR M 107/208 classe C com adição de Cromo e Vanádio se comparado com aços convencionais conforme ) conforme normas AAR M 107/208. / The main types of railroad wheels wear, such as abrasive wear and sliding wear are describe. The main mechanisms of sliding wear are the plastic deformation, the contact fatigue, termomechanical fatigue, oxidation and ship wear. The variables such as hardness, microstructure, chemical composition of alloy and effects of the sliding on wear mechanisms are evaluated. The wear types and mechanisms detected on wheels and rail materials from the real railroad cars tracks, from mining company, are compared with those observed at laboratory testing on disc-against-disc wear testing. The wear rate was measured by mass loss after predefined testing distances. The influence of the load, the hardness and the sliding on the wear rate were also evaluated. It was observed that the wear of the Wheel materials increases with the load increasing and decreases with the material hardness increasing. A better performance was observed for steels AAR M 107/208 class C with Chromium and Vanadium additions when compared to AAR M 107/2088 grade B or C steels. The microscopic examination of the test specimens, as well as on the wheels removed from service, showed occurrence of the abrasive wear and sliding wear with various mechanisms such as plastic deformation, delamination and oxidation wear. A similar mechanism to the delamination is the shelling on wheels. It was observed the formation of White layer on worn surface typical to the martensitic transformation of steel. A similar mechanism is the spalling of wheels material, It is also proposed a methodology for Wheel materials development, including laboratory wear tests, the manufacturing of wheels and the use and attendance of the wheels in service. AAR M 208 grade C steels with Chromium and Vanadium additions presented a better performance when compared the standard AAR M 107/208 steels.

There is a need to improve the JU Solar Team's new solar cell powered electric car's driving capabilities for the Bridgestone World Solar Challenge 2019. Partly to improve the car's safety and the ability to meet the competition requirements, but also to minimize effects that contribute to increased rolling resistance. The work is carried out at Jönköping Institute of Technology with support from ÅF Automotive in Trollhättan. The work aims to parameterize driving characteristics with engineering requirements, evaluate how the rolling resistance can be minimized, how negative driving characteristics can be minimized and a weight comparison with wheel suspension from 2017. This is the basis for the construction of the 2019 wheel suspension adapted for new body designed and manufactured in parallel with this work. The study includes performed measurements of the side force impact on steering angle change and camber change, calculation of load case, concept generation and evaluation, computer-aided strength evaluations. The results of the survey show great weaknesses in the 2017 solar car. In the case of an applied side force in the front wheel, a large wheel angle change occurs. This is largely due to under-dimensioned steering arms and the geometric design of the points. The influence of the side force on the steering angle has theoretically been reduced by at least 44% verified in CAD environment. In addition to this improvement, the entire wheel suspension system's attachments and sub-components are stiffer, which should contribute to an even greater improvement. The study also shows that the steering angle was insufficient to meet the competition requirements, which could be improved by 21.2% greater steering angle on the wheels. The spring and damper's operating ratio in comparison with the wheel has also been evaluated and has been able to be increased from 31% to 51.5%. This leads to reduced forces on the link arms and body by 20.5% during the same external load case. The study is limited to evaluating the hard points of the wheel suspension as well as the strength and design of the link arms, steering arm, suspension and damping attachment.

No description available.

Grinding is a complex material removal process with a large number of parameters influencing each other. In the process, the grinding wheel surface contacts the workpiece at high speed and under high pressure. The complexity of the process lies in the multiple microscopic interaction modes in the wheel-workpiece contact zone, including cutting, plowing, sliding, chip/workpiece friction, chip/bond friction, and bond/workpiece friction. Any subtle changes of the microscopic modes could result in a dramatic variation in the process. To capture the minute microscopic changes in the process and acquire better understanding of the mechanism, a physics-based model is necessary to quantify the microscopic interactions, through which the process output can be correlated with the input parameters. In the dissertation, the grinding process is regarded as an integration of all microscopic interactions, and a methodology is established for the physics based modeling. To determine the engagement condition for all micro-modes quantitatively, a virtual grinding wheel model is developed based on wheel fabrication procedure analysis and a kinematics simulation is conducted according to the operational parameters of the grinding process. A Finite Element Analysis (FEA) is carried out to study the single grain cutting under different conditions to characterize and quantify the grain-workpiece interface. Given the engagement condition on each individual grain with the workpiece from the physics-based simulation, the force, chip generation, and material plastic flow can be determined through the simulation results. Therefore, the microscopic output on each discrete point in the wheel-workpiece contact zone can be derived, and the grinding process technical output is the integrated product of all microscopic interaction output. From the perspective of process prediction and optimization, the simulation can provide the output value including the tangential force and surface texture. In terms of the microscopic analysis for mechanism study, the simulation is able to estimate the number of cutting and plowing grains, cutting and plowing force, probability of loading occurrence, which can be used as evidence for process diagnosis and improvement. A series of experiments are carried out to verify the simulation results. The simulation results are consistent with the experimental results in terms of the tangential force and surface roughness Ra for dry grinding of hardened D2 steel. The methodology enables the description of the 'inside story' in grinding processes from a microscopic point of view, which also helps explain and predict the time dependent behavior in grinding. Furthermore, the process model can be used for grinding force (or power) estimation for multiple-stage grinding cycles which includes rough, semi-finish, finish, and spark out. Therefore, the grinding process design can be carried out proactively while eliminating 'trial and error'. In addition, the grinding wheel model itself can be used to guide the recipe development and optimization of grinding wheels. While the single grain micro-cutting model can be used to study the mechanism of single grit cutting under various complex conditions, it can also be used to derive the optimal parameters for specific grains or process conditions.

This thesis analyzes the interior of the solar car, used by the JU Solar Team, to improve the user experience in terms of user interaction and ergonomics. Following the Design Thinking methodology, it starts with a research phase to understand how the user interacts with the car and the elements required for this interaction during the race. It also studies the dimension of the actual interior and the anthropometric factors, some changes are proposed for a more efficient use of the space. The next phase explores new buttons and configurations for the steering wheel. The use of prototypes and sketches leads the development of the ideas, which are further developed and defined, including the graphical design and the dimensions of the interior. In the findings, the redesign of the steering wheel and interior is shown in several renders with an explanation of the final design decisions, which can be summarized in: A new shape for the steering wheel where most of the buttons have been added with new shapes and colors. The emergency buttons and light indicators have been allocated on a central control panel. The user has access to the buttons without releasing the steering wheel and the dimension of the canapé has been reduced thanks to a more efficient use of the space. As a part of the thesis a full scale model of the steering wheels and a 1:10 scale model of the interior is provided. This thesis solves some of the problems in the actual design of the solar car and explore some of the important factors in user interaction. A human-centered design approach to a project usually driven by the performance of the car and not the user experience. / Denna avhandling omfattar utveckling av interiör för solbilar med inriktning mot att förbättra för användaren. Arbetet avser att appliceras på Ju Solar teams solbil som ska delta för Högskolan i Jönköping i World Solar Challenge 2017. Forskningen i projektet fokuserar på att förstå hur användaren interagerar och samspelar med bilen och de faktiska problem som föraren har att hantera under tävlingen. Studien omfattar också antropometriska mått där förslag på ändringar gjorts för att optimera utrymmet. Utvärdering av idéer har gjorts med hjälp av skisser och prototyper, som inkluderar den grafiska designen Designbesluten kan sammanfattas med följande: • De viktiga knapparna är alla samlade i ratten. • Användning av form och färg samt position för att enkelt kunna skilja mellan knappar och dess funktioner. • Ny form för ratten med en extra grepp-zon i den övre delen. Ny utformning av knappar, former och konfiguration för ratten. • En central manöverpanel med ljusindikatorer för föraren. • Nya dimensioner av interiören för att minska förarhuvens storlek och därmed minska luftmotståndet. Som en del av avhandlingen finns en fullskalemodell av ratten och en modell i skala 1:10 av interiören tillhandahålls. Solbilar utvecklas vanligen med prestanda som prioritet men denna avhandling utforskar de problemområden som finns i anslutning till solbilens förarmiljö med människan i centrum.

Resource dependencies have increased substantially at colleges and universities over the years due to economic declines, recessionary periods, and decreased funding from state allocations. The purpose of this study was to advance an understanding of private support for higher education as a source of supplementary funding. As the environment continues to become more competitive for outside resources, institutions of higher education can benefit from more substantive and objective research on private voluntary support to better meet their growing needs for additional resources. Effective financial management requires a greater understanding of the expected size of financial contributions to assist with strategic planning and managing expenditure demands. This is especially true during periods of broad economic downturn when many institutions' revenue sources simultaneously suffer economic shocks through reduced endowment earnings; reductions in state appropriations; and external pressures by students, parents, and other stakeholders to keep tuition rates low. The same economic pressures that affect institutional revenue sources also affect the receipt of charitable contributions. Thus, the relationship between charitable donations and the economy is central to understanding whether these contributions help to stabilize the volatility of institutional revenues. This study examined private giving data reported to the Council for Aid to Education's annual Voluntary Support of Education survey from 1987 to 2012. Only gifts contributed by alumni, foundations, corporations, other individuals, and parents to public and private baccalaureate, master's, and doctoral institutions were considered. Giving data were adjusted through the Consumer Price Index, standardized by enrollment, and correlated with three economic indicators: Average Duration of Unemployment, Employees on Nonagricultural Payrolls, and the Standard & Poor's 500 Stock Price Index. The statistical analysis selected to examine each of the four research questions was multiple linear regression used to discover to what relationships exist between economic indicators and private giving to higher education by institutional type, institutional classification, and giving source. This study revealed that differences in private giving exist when correlated to economic indicators. Based on these results, it appears that charitable funding directed to support higher education institutions are based to some extent on resource providers' ability to expend support at particular times in the economic environment. As observed throughout all four research questions, the Average Duration of Unemployment indicator had a larger impact on charitable giving to higher education than did the Standard & Poor's 500 Stock Price Index indicator. The results of the Fisher's r to z transformations indicated that the regression model for alumni giving to public higher education institutions was determined to be the statistically strongest prediction model, followed by the regression model for foundation giving to public institutions. While fundraising continues to be only one source of additional funding, it cannot be ignored that the generosity of private donors since the earliest days of this country has helped to create, support and sustain the vital functions of colleges and universities. While the pursuit of private support may have been left primarily to the private institutions over the years, more recent developments in state and government funding patterns to higher education make the constant search for additional support sources a reality for today's public higher education institutions as well. Academic leadership must be cognizant that fiscal flexibility in times of economic prosperity as well as in times of economic downturns can be supplemented by the philanthropic intent of those interested in not only an institution's presence or prestige but also by its impact on students, families, communities, customers, and the economy. Institutions of higher education and their institutional advancement programs can greatly benefit from research studies that provide additional substantive and objective research.

<p>This report contains the first step towards a complete, fully autonomous, robust bucket fill regulator for a wheel loader working with gravel materials.</p><p>The bucket fill procedure is the most critical part of the work cycle of a wheel loader. It is a task that has a long learning curve and also is weary, even for experienced drivers. The automation of it could therefore have a big impact on the cost effectiveness for wheel loaders and for the comfort of the drivers.</p><p>In this report, a suggestion for the complete solution of an automatic bucket fill regulator is presented. A regulator prototype is also constructed with a Volvo L120F as the base. The scope for the prototype is limited to one type of gravel material and quite optimal conditions for the wheel loader, but the complete solution is kept in mind throughout the synthesis. The constructed regulator is prepared for expansion, but the implementation and field testing is limited to the scope.</p>