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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Fatigue Testing and Data Analysis of Welded Steel Cruciform Joints

Shrestha, Alina 17 May 2013 (has links)
In this study, ABS Publication 115, “Guidance on Fatigue Assessment of Offshore Structures” is briefly reviewed. Emphasis is on the S-N curves based fatigue assessment approach of non-tubular joints, and both size and environment effects are also considered. Further, fatigue tests are performed to study the fatigue strength of load-carrying and non-load-carrying steel cruciform joints that represent typical joint types in marine structures. The experimental results are then compared against ABS fatigue assessment methods, based on nominal stress approach, which demonstrates a need for better fatigue evaluation parameter. A good fatigue parameter by definition should be consistent and should correlate the S-N data well. The equivalent structural stress parameter is introduced to investigate the fatigue behavior of welded joints using the traction based structural stress approach on finite element models of specimens, and representing the data as a single Master S-N curve.
132

Análise do desempenho na frenagem de um cavalo mecânico e semi-reboque com suspensão mecânica e sistema ABS mediante simulação em Matlab/Simulink / Analysis of the performance of tractor-semitrailer vehicles with mechanical suspension and ABS system through simulation in Matlab/Simulink

Viveros, Henry Pizarro 29 October 2010 (has links)
A presente dissertação visa analisar o desempenho na frenagem de um cavalo mecânico e semi-reboque que utiliza o sistema ABS (Antilock Braking System). Foi desenvolvido um modelo virtual de simulação utilizando a técnica dos sistemas multicorpos (Multibody System) do SimMechanics, um toolbox do Matlab/Simulink. No modelo virtual do veículo combinado foram considerados os parâmetros geométricos e mecânicos dos chassis, das suspensões, dos freios, contato pneu-pavimento e a válvula sensível à carga. São obtidas as forças normais dinâmicas no contato pneu pavimento quando o veículo está desacelerando de 20m/s até a parada completa, estas forças normais dinâmicas são entradas de uma sub-rotina em Simulink onde são calculadas as forças de frenagem, quando os freios tipo S carne são acionados. São realizadas simulações de frenagens em linha reta em pistas de média aderência (0,4) e alta aderência (0,8). As eficiências são obtidas quando o cavalo mecânico utiliza a configuração fixa de ABS tipo 6S/6M e o semi-reboque utiliza diversas configurações de ABS tipos: 2S/1M (e 4,6); 2S/2M (e 4,6); 4S/2M (e4); 4S/2M (e6); 4S/3M (e4); 4S/3M (e6); 4S/4M (e4) e 4S/4M (e6) e 6S/6M. O veículo é simulado também freando sem sistema ABS e a eficiência resultante comparada com as obtidas anteriormente. Os resultados são apresentados em figuras que mostram as forças normais dinâmicas ao pavimento, as aderências utilizadas pelos pneus e as eficiências atingidas pelas diversas configurações de ABS utilizadas no semi-reboque. Conclui-se de forma geral que configurações de ABS com mais sensores e válvulas moduladoras produzem uma eficiência maior e que a utilização de qualquer configuração de ABS como sistema complementar do sistema de freios de serviço, aumenta a eficiência de frenagem que é sempre superior ao do veículo sem sistema ABS. Esses resultados ajudam na preservação da dirigibilidade e estabilidade do veículo combinado, contribuindo assim na prevenção de acidentes de trânsito em situações de emergência. / This dissertation reports on the development of a simulation model for the analysis of the braking performance of tractor-semitrailer vehicles that use the ABS (Antilock Braking System). The model was developed using the virtual simulation technique of multibody systems with SimMechanics, a toolbox of Matlab/Simulink. In this simulation model the mechanical and geometrical parameters of the chassis, suspensions, brakes, adhesion coefficient, and load sensing valve were considered. When the vehicle is decelerating, the normal forces between the tire and road surface are obtained by the virtual model. These forces are the input of a subroutine in which the braking forces are calculated when the S Came brakes are triggered. Simulations of braking on straight line in road were made for average adhesion coefficient (0.4) and high adhesion coefficient (0.8). Efficiencies were obtained when the tractor used fixed ABS configuration of a 6S/6M type, and the semitrailer used the ABS type: 2S/lM (and 4.6); 2S/2M (and 4.6); 4S/2M (e4); 4S/2M (e6); 4S/3M (e4); 4S/3M (e6); 4S/4M (e4) and 4S/4M (e6) and 6S/6M. The results are presented in figures which show, the normal dynamic forces between tire and road, adhesions used by the tires and the efficiencies achieved by different ABS configurations installed in the semi-trailer. It is possible to conclude that in general ABS configurations with more sensors and modulating valves produce higher efficiency and the use of any configuration as a complementary system of the ABS brake system service increases the braking efficiency, which is always higher than that of a vehicle without ABS. The results help preserving the vehicle stability and maneuverability, preventing road accidents in emergency situations.
133

Dimensionering av bladförband på Kamewa CPP (Controllable Pitch Propeller) / Design of blade bolt joint on Kamewa CPP

Karlsson, Lars, Köhler, Andreas January 2008 (has links)
<p><p>The thesis project is accomplished during winter and spring 2008 at Karlstad University at the faculty of technology and science. The tutor at Karlstad University is Nils Hallbäck and the examiner is Hans Johansson. Rolls-Royce at Kristinehamn in Sweden is the initiator for the project. The thesis project title is design of the blade bolt joint on Kamewa CPP. CPP stands for controllable pitch propeller. The study include two main aspects which are to analyze if the blade bolt joint which is used today can be applied on a larger propeller and if there are better solutions or other possibilities to join the blade to the hub. First the classification rules of some institutes were studied to find out which limitations there are. Bolted joint has to exceed a minimum bending strength and the bolts have to be made out of steel and their strength has to be at least 10.9. Today Rolls-Royce use ten bolts per propeller, five on each side of the blade. To analyze the strength of the blade bolt joint connection a FEM and an analytic analyze were made and the results compared with each other. Two cases were examined, one for drift and two when hitting an iceberg. The results were similar to each other for FEM and the analytic analyze. At drift all bolts were under the tensile strength of 750 MPa but when using ice loads some bolts started to deform. A new concept for the bolt connection was tested. Again the stress in the bolts stayed under the tensile strength at drift but deformed when applying ice loads. A difference between analytical and FEM analysis was that the stress difference between the bolts were minor in the FEM method. Another concept was only studied with FEM and it had a geometric locking devise combined with the same blade bolt connection as Rolls-Royce use today. At drift the locking devise didn’t support the connection much but when applying ice loads less bolts started to deform and less material in the bolts reached the tensile limit. All three concepts showed stress concentrations at the first two or three threads. The differences between the three concepts weren’t that large and to get better results other possibilities have to be considered. It is important to know how much torque has to be applied on the screw to get the right amount of pretension. Three aspects to consider are to apply the torque without getting any torsion in the screw, to lower the moment with the right coating or lubricant and to avoid the stress concentrations at the threads. Superbolts and clampnuts are two possibilities to avoid torsion in the screws. By using screw thread inserts or tension optimized threads the stress in the thread gets optimized and a coating or lubricant with a low friction coefficient will lower the torque. Three possible solutions are suggested.</p></p> / <p><p>Examensarbetet har utförts på fakulteten för teknik och naturvetenskap under vintern och våren 2008 och är en kurs på 22,5 hp med kurskoden MSGC 17. Handledare på Karlstads universitet är Nils Hallbäck och examinator är Hans Johansson. Rolls-Royce i Kristinehamn är uppdragsgivaren till examensarbetet. Uppgiften är att dimensionera ett bladförband till en stor Kamewa Ulstein CP-propeller. Frågeställningen som ska besvaras är om det går att använda dagens förband och undersöka om det finns bättre alternativ eller andra lösningar på problemet. Det finns inga ritningar på den storleken av propellrar som förbandet ska göras till. Därför måste man skala upp mått från mindre propellrar. Propellerdiameter är 7,7 meter och bladet med fot väger 10 ton efter skalningen. Förbandet ska klara av DNVs (Det Norske Veritas) klassificeringskrav för böjmotstånd och förbandet dimensioneras därefter. För dagens förband behövs det mycket stora skruvar för att klara klassificeringskravet. En analytisk och en FEM-analys genomfördes för att det inte finns något material att jämföra med. Krafter som måste betraktas är centrifugalkraften, tyngdkraften, framdrivningskraften från vattnet samt en isbelastning vid kollision med ett isberg. Framdrivningskraften varierar med 20 % när propellern passerar skrovet. Resultaten från analyserna gav att dagens förband klarar belastningarna vid drift, dock att bultarna börjar deformeras vid belastning med iskraften. I den analytiska analysen antar man att alla delar (bladfot, fläns och nav) är stela och inte deformeras. Dessutom tar man inte hänsyn till böjpåkänningarna som uppstår i skruvarna. Detta tas med i FEM-analysen samt att man räknar med olinjära materialsamband. Därför uppstår det stora spänningsskillnader, upp till 210 MPa, i bultarna vid FEM-analysen vilket inte sker vid de analytiska beräkningarna. Ett antal koncept genererades och två av dessa analyserades närmare. Båda koncepten är optimerade för centrifugalkraften eftersom den utgör den största belastningen under drift om man bortser ifrån förspänningen. Koncept 1 är ett förband som består av 16 bultar per propeller med tre olika storlekar. Enligt FEM analysen fås en jämnare spänningsfördelning över skruvarna än med dagens förband, medan den analytiska metoden ger ungefär samma fördelning som vid dagens förband. Alla skruvar håller sig under sträckgränsen vid drift. Vid isbelastningen uppnås sträckgränsen i många av de mindre skruvarna och skruvarna börjar deformeras plastiskt. I detta avseende stämmer den analytiska lösningen och FEM-analysen överens. Skillnaden är att den analytiska beräkningen visar större spänningsvariation bland skruvarna dvs. att den största och minsta spänningen hos bultarna är högre än vid FEM-beräkningarna. Det andra konceptet som analyserades närmare består av en formlåsning som sitter under bladet tillsammans med samma skruvar som används vid dagens förband. Vid drift märks knappt någon skillnad. Vid isbelastningen så tar formlåsningen dock upp mer spänning och avlastar skruvarna. Färre skruvar deformeras plastiskt. Det finns möjligheter att använda sig av redan befintliga lösningar som Superbolts, clampnuts och andra verktyg. Det som är avgörande för förbandets funktion är ett korrekt åtdragningsmoment. Positivt är att samtidigt kunna förspänna skruvarna utan torsion. En lösning är att ytbehandla skruvarna med en beläggning med känd friktionskoefficient.</p><p>Tre lösningsförslag har tagits fram som ger ett bättre resultat än dagens förband.</p></p>
134

Dimensionering av bladförband på Kamewa CPP (Controllable Pitch Propeller) / Design of blade bolt joint on Kamewa CPP

Karlsson, Lars, Köhler, Andreas January 2008 (has links)
The thesis project is accomplished during winter and spring 2008 at Karlstad University at the faculty of technology and science. The tutor at Karlstad University is Nils Hallbäck and the examiner is Hans Johansson. Rolls-Royce at Kristinehamn in Sweden is the initiator for the project. The thesis project title is design of the blade bolt joint on Kamewa CPP. CPP stands for controllable pitch propeller. The study include two main aspects which are to analyze if the blade bolt joint which is used today can be applied on a larger propeller and if there are better solutions or other possibilities to join the blade to the hub. First the classification rules of some institutes were studied to find out which limitations there are. Bolted joint has to exceed a minimum bending strength and the bolts have to be made out of steel and their strength has to be at least 10.9. Today Rolls-Royce use ten bolts per propeller, five on each side of the blade. To analyze the strength of the blade bolt joint connection a FEM and an analytic analyze were made and the results compared with each other. Two cases were examined, one for drift and two when hitting an iceberg. The results were similar to each other for FEM and the analytic analyze. At drift all bolts were under the tensile strength of 750 MPa but when using ice loads some bolts started to deform. A new concept for the bolt connection was tested. Again the stress in the bolts stayed under the tensile strength at drift but deformed when applying ice loads. A difference between analytical and FEM analysis was that the stress difference between the bolts were minor in the FEM method. Another concept was only studied with FEM and it had a geometric locking devise combined with the same blade bolt connection as Rolls-Royce use today. At drift the locking devise didn’t support the connection much but when applying ice loads less bolts started to deform and less material in the bolts reached the tensile limit. All three concepts showed stress concentrations at the first two or three threads. The differences between the three concepts weren’t that large and to get better results other possibilities have to be considered. It is important to know how much torque has to be applied on the screw to get the right amount of pretension. Three aspects to consider are to apply the torque without getting any torsion in the screw, to lower the moment with the right coating or lubricant and to avoid the stress concentrations at the threads. Superbolts and clampnuts are two possibilities to avoid torsion in the screws. By using screw thread inserts or tension optimized threads the stress in the thread gets optimized and a coating or lubricant with a low friction coefficient will lower the torque. Three possible solutions are suggested. / Examensarbetet har utförts på fakulteten för teknik och naturvetenskap under vintern och våren 2008 och är en kurs på 22,5 hp med kurskoden MSGC 17. Handledare på Karlstads universitet är Nils Hallbäck och examinator är Hans Johansson. Rolls-Royce i Kristinehamn är uppdragsgivaren till examensarbetet. Uppgiften är att dimensionera ett bladförband till en stor Kamewa Ulstein CP-propeller. Frågeställningen som ska besvaras är om det går att använda dagens förband och undersöka om det finns bättre alternativ eller andra lösningar på problemet. Det finns inga ritningar på den storleken av propellrar som förbandet ska göras till. Därför måste man skala upp mått från mindre propellrar. Propellerdiameter är 7,7 meter och bladet med fot väger 10 ton efter skalningen. Förbandet ska klara av DNVs (Det Norske Veritas) klassificeringskrav för böjmotstånd och förbandet dimensioneras därefter. För dagens förband behövs det mycket stora skruvar för att klara klassificeringskravet. En analytisk och en FEM-analys genomfördes för att det inte finns något material att jämföra med. Krafter som måste betraktas är centrifugalkraften, tyngdkraften, framdrivningskraften från vattnet samt en isbelastning vid kollision med ett isberg. Framdrivningskraften varierar med 20 % när propellern passerar skrovet. Resultaten från analyserna gav att dagens förband klarar belastningarna vid drift, dock att bultarna börjar deformeras vid belastning med iskraften. I den analytiska analysen antar man att alla delar (bladfot, fläns och nav) är stela och inte deformeras. Dessutom tar man inte hänsyn till böjpåkänningarna som uppstår i skruvarna. Detta tas med i FEM-analysen samt att man räknar med olinjära materialsamband. Därför uppstår det stora spänningsskillnader, upp till 210 MPa, i bultarna vid FEM-analysen vilket inte sker vid de analytiska beräkningarna. Ett antal koncept genererades och två av dessa analyserades närmare. Båda koncepten är optimerade för centrifugalkraften eftersom den utgör den största belastningen under drift om man bortser ifrån förspänningen. Koncept 1 är ett förband som består av 16 bultar per propeller med tre olika storlekar. Enligt FEM analysen fås en jämnare spänningsfördelning över skruvarna än med dagens förband, medan den analytiska metoden ger ungefär samma fördelning som vid dagens förband. Alla skruvar håller sig under sträckgränsen vid drift. Vid isbelastningen uppnås sträckgränsen i många av de mindre skruvarna och skruvarna börjar deformeras plastiskt. I detta avseende stämmer den analytiska lösningen och FEM-analysen överens. Skillnaden är att den analytiska beräkningen visar större spänningsvariation bland skruvarna dvs. att den största och minsta spänningen hos bultarna är högre än vid FEM-beräkningarna. Det andra konceptet som analyserades närmare består av en formlåsning som sitter under bladet tillsammans med samma skruvar som används vid dagens förband. Vid drift märks knappt någon skillnad. Vid isbelastningen så tar formlåsningen dock upp mer spänning och avlastar skruvarna. Färre skruvar deformeras plastiskt. Det finns möjligheter att använda sig av redan befintliga lösningar som Superbolts, clampnuts och andra verktyg. Det som är avgörande för förbandets funktion är ett korrekt åtdragningsmoment. Positivt är att samtidigt kunna förspänna skruvarna utan torsion. En lösning är att ytbehandla skruvarna med en beläggning med känd friktionskoefficient. Tre lösningsförslag har tagits fram som ger ett bättre resultat än dagens förband.
135

Design And Simulation Of An Abs For An Integrated Active Safety System For Road Vehicles

Sahin, Murat 01 September 2007 (has links) (PDF)
Active safety systems for road vehicles have been improved considerably in recent years along with technological advances and the increasing demand for road safety. In the development route of active safety systems which started with introduction of digital controlled ABS in the late seventies, vehicle stability control systems have been developed which today, with an integration approach, incorporate ABS and other previously developed active safety technologies. ABS, as a main part of this new structure, still maintains its importance. In this thesis, a design methodology of an antilock braking system controller for four wheeled road vehicles is presented with a detailed simulation work. In the study, it is intended to follow a flexible approach for integration with unified control structure of an integrated active safety system. The objective of the ABS controller, as in the previous designs in literature, is basically to provide retention of vehicle directional control capability and if possible shorter braking distances by controlling the wheel slip during braking. iv A hierarchical structure was adopted for the ABS controller design. A high-level controller, through vehicle longitudinal acceleration based estimation, determines reference slip values and a low-level controller attempts to track these reference slip signals by modulating braking torques. Two control alternatives were offered for the design of the low-level controller: Fuzzy Logic Control and PID Control. Performance of the ABS controller was analyzed through extensive simulations conducted in MATLAB/Simulink for different road conditions and steering maneuvers. For simulations, an 8 DOF vehicle model was constructed with nonlinear tires.
136

Technické aspekty použití 3D tisku ve výuce na ZŠ / Technical aspects of the use of 3D printing in the education at elementary school

CVRČEK, Tomáš January 2016 (has links)
This thesis in the beginning deals with the history of 3D printing and its development. For better understanding the nature of 3D printing are the significant technologies that includes. Professional part includes work with the printer MakerBot Replicator 2X. Mechanical parts of the device are analyzed together with the operating software MakerBot DesktopThe following chapter is dealing with the limits and restrictions when it is printed on said 3D printer, except that describes important aspects when working on the printer. For the creation of electronic models are suggested appropriate programs for use in elementary school. A significant milestone is forming the problems of 3D printing, which can serve as a guide for the elimination of print quality problems, malfunctioning of 3D printers and others. Interesting models are designed for teaching physics and working activities that the students facilitate understanding of the substance of the response and act as activating element within lesson. It was created a list of important sites where you can find models suitable not only for teaching in elementary schools, but also for other purposes. The last chapter deals with the economic aspect of 3D printing.
137

Análise do desempenho na frenagem de um cavalo mecânico e semi-reboque com suspensão mecânica e sistema ABS mediante simulação em Matlab/Simulink / Analysis of the performance of tractor-semitrailer vehicles with mechanical suspension and ABS system through simulation in Matlab/Simulink

Henry Pizarro Viveros 29 October 2010 (has links)
A presente dissertação visa analisar o desempenho na frenagem de um cavalo mecânico e semi-reboque que utiliza o sistema ABS (Antilock Braking System). Foi desenvolvido um modelo virtual de simulação utilizando a técnica dos sistemas multicorpos (Multibody System) do SimMechanics, um toolbox do Matlab/Simulink. No modelo virtual do veículo combinado foram considerados os parâmetros geométricos e mecânicos dos chassis, das suspensões, dos freios, contato pneu-pavimento e a válvula sensível à carga. São obtidas as forças normais dinâmicas no contato pneu pavimento quando o veículo está desacelerando de 20m/s até a parada completa, estas forças normais dinâmicas são entradas de uma sub-rotina em Simulink onde são calculadas as forças de frenagem, quando os freios tipo S carne são acionados. São realizadas simulações de frenagens em linha reta em pistas de média aderência (0,4) e alta aderência (0,8). As eficiências são obtidas quando o cavalo mecânico utiliza a configuração fixa de ABS tipo 6S/6M e o semi-reboque utiliza diversas configurações de ABS tipos: 2S/1M (e 4,6); 2S/2M (e 4,6); 4S/2M (e4); 4S/2M (e6); 4S/3M (e4); 4S/3M (e6); 4S/4M (e4) e 4S/4M (e6) e 6S/6M. O veículo é simulado também freando sem sistema ABS e a eficiência resultante comparada com as obtidas anteriormente. Os resultados são apresentados em figuras que mostram as forças normais dinâmicas ao pavimento, as aderências utilizadas pelos pneus e as eficiências atingidas pelas diversas configurações de ABS utilizadas no semi-reboque. Conclui-se de forma geral que configurações de ABS com mais sensores e válvulas moduladoras produzem uma eficiência maior e que a utilização de qualquer configuração de ABS como sistema complementar do sistema de freios de serviço, aumenta a eficiência de frenagem que é sempre superior ao do veículo sem sistema ABS. Esses resultados ajudam na preservação da dirigibilidade e estabilidade do veículo combinado, contribuindo assim na prevenção de acidentes de trânsito em situações de emergência. / This dissertation reports on the development of a simulation model for the analysis of the braking performance of tractor-semitrailer vehicles that use the ABS (Antilock Braking System). The model was developed using the virtual simulation technique of multibody systems with SimMechanics, a toolbox of Matlab/Simulink. In this simulation model the mechanical and geometrical parameters of the chassis, suspensions, brakes, adhesion coefficient, and load sensing valve were considered. When the vehicle is decelerating, the normal forces between the tire and road surface are obtained by the virtual model. These forces are the input of a subroutine in which the braking forces are calculated when the S Came brakes are triggered. Simulations of braking on straight line in road were made for average adhesion coefficient (0.4) and high adhesion coefficient (0.8). Efficiencies were obtained when the tractor used fixed ABS configuration of a 6S/6M type, and the semitrailer used the ABS type: 2S/lM (and 4.6); 2S/2M (and 4.6); 4S/2M (e4); 4S/2M (e6); 4S/3M (e4); 4S/3M (e6); 4S/4M (e4) and 4S/4M (e6) and 6S/6M. The results are presented in figures which show, the normal dynamic forces between tire and road, adhesions used by the tires and the efficiencies achieved by different ABS configurations installed in the semi-trailer. It is possible to conclude that in general ABS configurations with more sensors and modulating valves produce higher efficiency and the use of any configuration as a complementary system of the ABS brake system service increases the braking efficiency, which is always higher than that of a vehicle without ABS. The results help preserving the vehicle stability and maneuverability, preventing road accidents in emergency situations.
138

Design And Development Of An Improved Anti-Lock Braking System For Two-Wheelers

Mohan, S 08 1900 (has links) (PDF)
In today’s fast moving world, automobiles are facing challenges in terms of having to survive road accidents, increasing traffic, bad road-conditions and high/express ways. Brake systems play a vital role in controlling the vehicle speed while avoiding road accidents. The conventional brake systems consist of basically an actuator, transmission and frictional parts. This system is difficult for manipulated control by the driver during emergency and panic braking situations. In particular road and environmental conditions, it requires certain skill to have safe and effective brake control, which is always not possible from all drivers. Wheel locking is a predominant phenomenon during panic braking and this will cause vehicle skidding resulting in injuries and road accidents. In the case of a two-wheeler, being a single-track vehicle, skidding is one of the major causes for fatal road accidents due to loss in lateral balance. As the road safety regulations are becoming more stringent, the anti-lock brake systems (ABS) will replace the conventional brake systems in all road vehicles to avoid accidents and to improve vehicle safety. Early ABS systems, developed in the last 100-years, use intermittent and cyclic brake pressure control by sensing the wheel speed or wheel-slip as one of the major control inputs. Regulating the brake pressure with a preset threshold value is another method. These ABS systems have used electronics, or hydraulics or pure mechanical control. However, such ABS are not widely used in two-wheelers and other low cost vehicles till now, because of several limitations identified as follows: High cost, power supply needed for its operation in the case of intermittent and cyclic brake control, susceptibility to failure in the electronics system, interference from RF signals (from cell-phones for example), uneasiness to drivers from pedal pulsations with pedal noise, heavier weight, increased vehicle vibrations and failure modes of wheels due to torsional vibrations. The present research work is carried out to develop a new mechanical ABS concept, which will address most of the above problems. During braking, the change in rider-input force will change wheel reactions. This change is made proportional to the change in rider input force only upto wheel locking. Such a principle is used to develop the new mechanical ABS. The new concept regulates the output force from the ABS, by sensing the dynamic wheel reactions with increase in rider-response. The ABS output force is regulated by one of the following ways: (a) Slipping-down the lever-ratio or (b) preventing the excessive brake input force. Based on the parameters like less number of parts, least weight, simplicity, reliability, efficiency, durability, time-response, etc., the second method (of preventing the excessive brake input force) has been chosen. Further a new concept of ABS interconnecting system is proposed for usage between the front and rear wheels of the vehicle. This interconnecting system will ensure that the two mechanical ABS systems function at any kind of braking-balance between the front and rear applications. An analytical vehicle model has been developed with several input parameters like mass, geometry, inertia, aerodynamic properties, frictions of road and bearing-supports, road gradients, etc. From this analytical model, the dynamic wheel reactions and limiting adhesion of each tyre for various braking conditions are determined and the results are used to design the mechanical ABS. The same analytical model is used to predict the brake performance like stopping distance, vehicle deceleration and the vehicle speed variation for ideal braking conditions. The new ABS is modelled in Pro-E using the inputs from the analytical model. To evaluate the concept, a functional proto-type is built and fitted on a motorcycle. The ABS is evaluated for its functionality and performance at different road (level surface, up-gradients and down gradients) and environmental conditions (dry and wet road conditions). Using the VBOX II, proximate sensors and load-cells fitted on the vehicle, the vehicle stopping distance, wheel slip and pedal force are measured. The results show that wheel locking does not occur under panic driving conditions, which is the primary objective. In addition, the results show a good agreement with the predicted stopping distance and vehicle deceleration from the analytical model. As there is good scope for this new mechanical ABS for use in two-wheelers and other low cost vehicles, further research is needed to make this system work in curvilinear motion & banked surfaces.
139

Analýza vzniku blokovacích stop v závislosti na zpomalení vozidla / Braking marks creation analysis in dependence of vehicle deceleration

Svoboda, Lukáš January 2021 (has links)
The work is divided into two parts – theoretical and practical. The first, theoretical part is focused on introduction with the problematics, describing the concept of translation motion and brake physics, defining terms adhesion and friction, skid, driving resistances, calculation formulas etc. After the mechanics chapter follows the chapter about tire and its composition and properties, and a brake system chapter, describing Anti-lock brake system (ABS) and some other important brake-support systems. Second part of this thesis is focused on practical side, which contains acceleration measuring and skid marks creation, followed by evaluation of measured data in form of calculations and graphs.
140

Zkoušky vybraných vlastností materiálů pro 3D tisk / Testing of selected material properties for 3D printing

Čáslavský, František January 2019 (has links)
This thesis deals with 3D printing, materials used for 3D printing, testing of the materials and learning their real parameters. Goal of the thesis is comparing selected materials, executing series of mechanical test and selecting suitable material for printing high-quality plastic parts for use in automobiles, especially for reproduction of parts that are no longer made for oldtimers and for use in motorsport.

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