Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2009. / Includes bibliographical references (p. 293-341).

Thesis (Ph. D.)--Lehigh University, 2005. / Includes vita. Includes bibliographical references (leaves 232-245).

Thesis--Harvard. / Bibliography: p. [87]-91.

Thesis (Ph. D.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 169-182).

Thesis (doctoral)--Tempere University of Technology, 2010. / Errata slip inserted. Includes bibliographical references (p. 183-188). Also available on the World Wide Web.

Thesis (M.Eng. (Mechanical Engineering))--University of Pretoria, 1999. / Summaries in English and Afrikaans. Includes bibliographical references.

The amount of waste tyres being dumped is fast becoming a problem. These stockpiles take up valuable land and are an environmental and health problem. While incineration is the simplest way to recycle the used tyres it isn’t an efficient way to dispose of tyres. This research looks at developing a method for characterizing the New Reclamation Group (NRG) reclaim with the main focus on Hi-Res™ thermogravimetric analysis. Good quantification was possible using this technique. A trade off was established between resolution, sensitivity and time. While increasing the resolution allowed greater separation to be achieved the time for each experiment increased rapidly. Although kinetic models do exist for quantifying rubber components in vulcanized sample, they were not suitable for this study. When devulcanization causes significant molecular changes, such as with NRG reclaim, the decomposition profiles no longer match those of virgin materials. Formulations developed focused on mixing, rheometry, crosslink density and tensile properties. The NRG reclaim acted as a processing aid which lowered the maximum torque. This provides mixing safety as the temperature is decreased as a result of the lower torque. This effect was not seen with conventional reclaim. Rheometry tests indicated that the addition of the devulcanizates decreased the extent of cure. It was demonstrated that this could be linked to crosslink density. Testing of the 100%, 200%, 300% moduli correlated the crosslink density to the maximum torque. Although the addition of NRG reclaim reduced the tensile strength of the formulation, a link between crosslink density and ultimate tensile strength (UTS) couldn’t be made. The decrease in the UTS and increase in extension at break is possibly caused by an increase in low molecular weight material present in the formulations and decrease in crosslink density. This could possibly increase the mobility of polymer chains which could increases flexibility.

L'objectif de ce travail est de valoriser des déchets de pneus usagés par pyrolyse afin d'obtenir un nouveau carburant comparable avec le gazole suivant la norme EN590. L'obtention de ce carburant était réalisée via l'optimisation des conditions de pyrolyse qui sont la température, la vitesse de chauffage (puissance de la résistance électrique) et du débit d'azote. Le rôle de l'azote est limité à purger le réacteur avant le début de la pyrolyse pour 30 minutes système. Le carburant produit est comparable au gazole avec un pouvoir calorifique de 45 MJ/kg, une densité de 0,85 et une teneur en goudron 7%. / The objective of this work is to get alternative fuel comparable with the available diesel in the market following the EN590. The fuel getting was via optimization of pyrolysis conditions which are temperature, heating rate (power of electrical resistance) and inert gas flow rate. The optimum values are 465°C, 650 Watts and without inert gas flow rate. Inert gas role is limited to purge the system for 30 minutes before start the pyrolysis to get rid of oxidative gases. The obtained product is comparable with the diesel as it has GCV 45 KJ/kg, low density of 0,85 and 7% tar content.

The primary goal of this work is to design and implement a clutch and brake system on the single tire Terramechanics rig of Advanced Vehicle Dynamics Laboratory (AVDL) at Virginia Tech. This test rig was designed and built to study the performance of tires in off-road conditions on surfaces such as soil, sand, and ice. Understanding the braking performance of tires is crucial, especially for terrains like ice, which has a low coefficient of friction. Also, rolling resistance is one of the important aspects affecting the tractive performance of a vehicle and its fuel consumption. Investigating these experimentally will help improve tire models performance. The current configuration of the test rig does not have braking and free rolling capabilities. This study involves modifications on the rig to enable free rolling testing when the clutch is disengaged and to allow braking when the clutch is engaged and the brake applied. The first part of this work involves the design and fabrication of a clutch system that would not require major changes in the setup of the test rig; this includes selecting the appropriate clutch that would meet the torque requirement, the size that would fit in the space available, and the capability to be remotely operated. The test rig's carriage has to be modified in order to fit a pneumatic clutch, its adapter, a new transmission shaft, and the mounting frame for the clutch system. The components of the actuation system consisting of pneumatic lines, the pressure regulator, valves, etc., have to be installed. Easy operation of the clutch from a remote location is enabled through the installation of a solenoid valve. The second part of this work is to design, fabricate, and install a braking system. The main task is to design a customized braking system that satisfies the various physical and functional constraints of the current configuration of the Terramechanics rig. Some other tasks are the design and fabrication of a customized rotor, selection of a suitable caliper, and design and fabrication of a customized mounting bracket for the caliper. A hydraulic actuation system is selected since it is suitable for this configuration and enables remote operation of the brakes. Finally, the rig is upgraded with the assembly of these two systems onto it. / Master of Science / The main goal of this project is to increase the testing capabilities of the single tire Terramechanics rig of Advanced Vehicle Dynamics Laboratory (AVDL) at Virginia Tech. The first task is to enable the rig to have the tire in free rolling condition. This will allow to study rolling resistance of the tire on various off-road conditions such as soil, sand, etc. The free rolling capability will also allow evaluation of the rolling radius of a tire. A customized clutch system was designed to achieve this free rolling requirement. The second task of this project was to implement braking capabilities to the rig. Apart from the traction performance of tires on off-road conditions such as ice, the other parameter is its performance during braking as it is an important factor leading to safety on roads. A customized disc brake system is designed to add braking capabilities to the rig. This free rolling and braking systems has to implemented taking into account the various physical and functional constraints of the rig. The work involves the design and fabrication of various customized components followed by the assembly of these components along with their actuation systems.

Pneumatic tires have been an essential part of the automobile since the early 20th century. Providing load carrying, braking, accelerating and turning capability as well as a certain degree isolation from the road, they fail to function without the presence of air pressure inside them. Run-flat tire systems allow the vehicle to continue running with reduced driving speeds for a certain specified range in case of loss of air pressure due to puncture or damage. In this work, the design of self-supporting and insert supported run-flat systems was approached using CAE. Two tire FE models of sizes 175/70 R14 and 175/60 R18 were used in this study. All structural and thermal simulations were done using ABAQUS and ENDURICA software was used for fatigue life simulation. Distance travelled before failure was used as the primary parameter for design evaluation along with secondary parameters of contact patch area and contact pressure, tire temperature profiles and rolling resistance. Ride comfort and handling characteristics are important performance parameters for a tire. Thus, a limited study to quantify the effect of run-flat system on the ride and handling properties was also conducted. The target design values for maximum load were fixed according to ETRTO standards while the maximum operating speed and the desired mileage in deflated condition was fixed at 45 mph and 50 miles, respectively. The initial part of the design process for the auxiliary supported design involved using a rigid cylindrical structure of varying height and thickness as a rim-mounted run-flat insert to get estimate of life of tire structure for different levels of deformation. The results were then used as input for designing a deformable rim mounted insert using reinforced rubber material. For the self-supported design, the sidewall of the tire was modified to increase its section thickness from an average value of 5 mm in the original design to 10 mm and 15 mm by addition of rubber material. For each thickness value, three designs based on the location in the tire structure where the material addition began relative to the belt edges of the tire were created. The designs were compared in terms of their fatigue life and contact patch area. For both types of run-flat designs, a candidate design, which satisfied the performance criteria, was found using the simulation results for the tire and run-flat system. It was concluded that a simulation-based approach can be used to design innovative run-flat systems for pneumatic tires. / Master of Science / Pneumatic tires have been an essential part of the automobile since the early 20th century. Providing load carrying, braking, accelerating and turning capability as well as a certain degree isolation from the road, they fail to function without the presence of air pressure inside them. Run-flat tire systems allow the vehicle to continue running with reduced driving speeds for a certain specified range in case of loss of air pressure due to puncture or damage. In this work, the design of self-supporting and insert supported run-flat systems was approached using computer aided design and simulation methods. Two tire models of 14-inch and 18-inch wheel sizes were used in this study and distance travelled before failure when running in deflated condition was used as the primary parameter for design evaluation. Ride comfort and handling characteristics are important performance parameters for a tire. Thus, a limited study to quantify the effect of run-flat system on the ride and handling properties was also conducted. The maximum operating speed and the desired mileage in deflated condition was fixed as design targets at 45 mph and 50 miles, respectively. For both types of run-flat designs, a candidate design, which satisfied the performance criteria, was found using the simulation results for the tire and run-flat system. It was concluded that a simulation-based approach can be used to design innovative run-flat systems for pneumatic tires.