Orientador: Saulo Philipe Sebastião Guerra / Banca: Kleber Pereira Lanças / Banca: Fabricio Leite / Resumo: Os pneus agrícolas e florestais interferem significativamente no desempenho e rendimento das máquinas, sendo relevante o conhecimento de suas estruturas, pois existe uma íntima ligação do equipamento com o solo, e estes são responsáveis pela sustentação, propulsão e direcionamento das máquinas. Diversas características do pneu como a pressão de inflação, área de contato e a disposição e altura das garras na banda de rodagem interferem na física do solo. O presente trabalho tem como objetivo avaliar a área de contato e os deslocamentos vertical e horizontal de dois pneus BPAF (Baixa Pressão e Alta Flutuação), um agrícola e um florestal, com as mesmas dimensões 600/55-26.5, em superfície rígida, em função da aplicação de diferentes pressões de inflação, segundo a orientação do manual técnico do fabricante, e a submissão dos mesmos a cargas suportadas. Foi utilizada uma prensa hidráulica pertencente ao NEMPA (Núcleo de Ensaio de Máquinas e Pneus Agroflorestais) da Faculdade de Ciências Agronômicas - UNESP, Câmpus de Botucatu - SP. O pneu agrícola foi submetido aos seguintes tratamentos de pressões e cargas: 48,2 kPa e 25 kN, 193 kPa e 50 kN, 234,4 kPa e 50 kN, 344,7 kPa e 50 kN. No pneu florestal foram realizados os tratamentos de pressões e cargas: 158,5 kPa e 35 kN, 241,3 kPa e 50 kN, 379,2 kPa e 50 kN e 496,4 kPa e 50 kN. Fixou-se uma folha de papel à uma superfície rígida para obtenção das áreas de contato dos pneus, e os mesmos foram prensados sobre a folha anteriormente citada. Secundariamente, foi posicionada uma fita de papel milimétrico. Foram obtidas fotos de cada área de contato e as leituras das áreas de contato foram realizadas utilizando o software ImageJ. Para obtenção dos valores dos deslocamentos horizontal e vertical utilizou-se dois sensores do tipo potenciômetros lineares. Observou-se que, com o aumento da pressão de ... / Abstract: Agriculture and forestry tires influence significantly the machines efficiency, thus it is relevant to consider their structures, because there is a directly relation between tires, that are responsible for the support, propulsion and steering of machines, and soil. There are several tires characteristics that impact soil physics, like inflation pressure, contact area, and the height of tread claws. The present study had as objective to evaluate the contact area, vertical and horizontal displacement of two BPAF (low pressure and high fluctuation) tires, one forestry and other agricultural, of same dimensions (600/55-26.5), in rigid surface, by applying different inflation pressures regarding the manufacturer's technical manual, and submitting both tires to supported loads. The experiment was accomplished using a hydraulic press in NEMPA (Agroforestry Machine and Tire Testing Center) located at Faculty of Agricultural Sciences (FCA/UNESP) in Botucatu-SP. The agricultural tire was submitted to the following pressure and loads treatments: 48,2 kPa and 25 kN, 193 kPa and 50 kN, 234,4 kPa, and 50 kN, 344,7 kPa and 50 kN. While the forestry tire was submitted to pressure and loads treatments as follow: 158,5 kPa and 35 kN, 241,3 kPa and 50 kN, 379,2 kPa, and 50 kN e 496,4 kPa and 50 kN. To get the contact area of each tire, they were pressed to a paper sheet that was fixed to a rigid surface. Then, a millimetric paper tape was placed. Pictures of each contact area were taken, and the areas were read with the software ImageJ. To obtain the values of horizontal and vertical offsets, two linear potentiometers sensors were used. It was observed that ... / Mestre

Made available in DSpace on 2015-12-10T14:22:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-08-17. Added 1 bitstream(s) on 2015-12-10T14:28:51Z : No. of bitstreams: 1 000853177.pdf: 1073099 bytes, checksum: 53eb636a12a46cefc685c1b53a30cca3 (MD5) / Os pneus agrícolas e florestais interferem significativamente no desempenho e rendimento das máquinas, sendo relevante o conhecimento de suas estruturas, pois existe uma íntima ligação do equipamento com o solo, e estes são responsáveis pela sustentação, propulsão e direcionamento das máquinas. Diversas características do pneu como a pressão de inflação, área de contato e a disposição e altura das garras na banda de rodagem interferem na física do solo. O presente trabalho tem como objetivo avaliar a área de contato e os deslocamentos vertical e horizontal de dois pneus BPAF (Baixa Pressão e Alta Flutuação), um agrícola e um florestal, com as mesmas dimensões 600/55-26.5, em superfície rígida, em função da aplicação de diferentes pressões de inflação, segundo a orientação do manual técnico do fabricante, e a submissão dos mesmos a cargas suportadas. Foi utilizada uma prensa hidráulica pertencente ao NEMPA (Núcleo de Ensaio de Máquinas e Pneus Agroflorestais) da Faculdade de Ciências Agronômicas - UNESP, Câmpus de Botucatu - SP. O pneu agrícola foi submetido aos seguintes tratamentos de pressões e cargas: 48,2 kPa e 25 kN, 193 kPa e 50 kN, 234,4 kPa e 50 kN, 344,7 kPa e 50 kN. No pneu florestal foram realizados os tratamentos de pressões e cargas: 158,5 kPa e 35 kN, 241,3 kPa e 50 kN, 379,2 kPa e 50 kN e 496,4 kPa e 50 kN. Fixou-se uma folha de papel à uma superfície rígida para obtenção das áreas de contato dos pneus, e os mesmos foram prensados sobre a folha anteriormente citada. Secundariamente, foi posicionada uma fita de papel milimétrico. Foram obtidas fotos de cada área de contato e as leituras das áreas de contato foram realizadas utilizando o software ImageJ. Para obtenção dos valores dos deslocamentos horizontal e vertical utilizou-se dois sensores do tipo potenciômetros lineares. Observou-se que, com o aumento da pressão de ... / Agriculture and forestry tires influence significantly the machines efficiency, thus it is relevant to consider their structures, because there is a directly relation between tires, that are responsible for the support, propulsion and steering of machines, and soil. There are several tires characteristics that impact soil physics, like inflation pressure, contact area, and the height of tread claws. The present study had as objective to evaluate the contact area, vertical and horizontal displacement of two BPAF (low pressure and high fluctuation) tires, one forestry and other agricultural, of same dimensions (600/55-26.5), in rigid surface, by applying different inflation pressures regarding the manufacturer's technical manual, and submitting both tires to supported loads. The experiment was accomplished using a hydraulic press in NEMPA (Agroforestry Machine and Tire Testing Center) located at Faculty of Agricultural Sciences (FCA/UNESP) in Botucatu-SP. The agricultural tire was submitted to the following pressure and loads treatments: 48,2 kPa and 25 kN, 193 kPa and 50 kN, 234,4 kPa, and 50 kN, 344,7 kPa and 50 kN. While the forestry tire was submitted to pressure and loads treatments as follow: 158,5 kPa and 35 kN, 241,3 kPa and 50 kN, 379,2 kPa, and 50 kN e 496,4 kPa and 50 kN. To get the contact area of each tire, they were pressed to a paper sheet that was fixed to a rigid surface. Then, a millimetric paper tape was placed. Pictures of each contact area were taken, and the areas were read with the software ImageJ. To obtain the values of horizontal and vertical offsets, two linear potentiometers sensors were used. It was observed that ...

Vehicle suspension optimisation is a complex and difficult task, as there are a variety of factors influencing the dynamic performance of a vehicle. During suspension development, the optimisation of a selected few of these factors is often to the detriment of others, as they are all inter-related. In addition, expertise in vehicle setup and suspension tuning is scarce, and is limited to experienced racing teams and large automotive manufacturers with extensive research and development capabilities. The motivation for this research was therefore to provide objective and user-friendly methodologies for vehicle suspension optimisation, in order to support student projects like Formula Student, while having relevance to the needs of the South African automotive industry and racing community. With the onset of digital data acquisition, it has become feasible to take real-time measurements of tyre temperatures, to provide information on how a tyre is performing at a specific point on the track. Measuring the tyre surface temperature can provide a useful indication on whether the tyre is loaded equally or not, and what suspension adjustments should be made to improve tyre load distribution.

In this dissertation, a group of vehicle dynamics simulation tools is developed with two primary goals: to accurately represent vehicle behavior and to provide insight that improves the understanding of vehicle performance. Three tools are developed that focus on tire modeling, vehicle modeling and lap time simulation. Tire modeling is based on Nondimensional Tire Theory, which is extended to provide a flexible model structure that allows arbitrary inputs to be included. For example, rim width is incorporated as a continuous variable in addition to vertical load, inclination angle and inflation pressure. Model order is determined statistically and only significant effects are included. The fitting process is shown to provide satisfactory fits while fit parameters clearly demonstrate characteristic behavior of the tire. To represent the behavior of a complete vehicle, a Nondimensional Tire Model is used, along with a three degree of freedom vehicle model, to create Milliken Moment Diagrams (MMD) at different speeds, longitudinal accelerations, and under various yaw rate conditions. In addition to the normal utility of MMDs for understanding vehicle performance, they are used to develop Limit Acceleration Surfaces that represent the longitudinal, lateral and yaw acceleration limits of the vehicle. Quasi-transient lap time simulation is developed that simulates the performance of a vehicle on a predetermined path based on the Limit Acceleration Surfaces described above. The method improves on the quasi-static simulation method by representing yaw dynamics and indicating the vehicle's stability and controllability over the lap. These improvements are accomplished while maintaining the simplicity and computational efficiency of the two degree of freedom method. / Graduation date: 2013