Orientador: José Roberto deFrança Arruda / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-16T17:59:49Z (GMT). No. of bitstreams: 1 Santos_ThaisBarbosados_M.pdf: 1128463 bytes, checksum: c42428e12fa3b35b0b8d8ab0bb7e8538 (MD5) Previous issue date: 2010 / Resumo: O presente trabalho consiste no estudo estocástico da influência da variabilidade do pneumático no conforto vibracional dos ocupantes do veículo. Elementos de viga curva Euler-Bernoulli formam um anel que representa o pneu. Este é sujeito a uma força girante na direção radial e sua resposta é calculada através do Método do Elemento Espectral. Tal força girante é modelada como um pulso triangular fora de fase aplicada nos diferentes nós do anel. A pressão interna, os efeitos inerciais e o efeito da rigidez da parede lateral em duas direções são considerados na modelagem. A componente radial da força resultante no eixo do pneumático é analisada como critério de conforto. Ela resulta da atuação do pneu na absorção das imperfeições do solo, ou seja, é uma medida do desempenho do pneumático. Os valores obtidos através da simulação são comparados com dados experimentais fornecidos pela Pirelli Pneus Ltda. Partindo desse modelo validado, uma metodologia de aplicação da teoria estocástica para analisar a variabilidade de pneumáticos é desenvolvida e desuniformidades como emendas são inseridas no modelo como informações de caráter aleatório. O Método de Monte Carlo é utilizado como solver / Abstract: The present work consists in a stochastic study of the influence of the pneumatic variability on the vehicle passengers vibrational comfort. Euler-Bernoulli curved beam elements constitute a ring which represents a pneumatic tire. It is subjected to a rotating radial force and its response is calculated through Spectral Elements Method. The internal pressure, the inertial effects and the side-wall stiffness in two directions effect are considered in the model. The radial component of the resultant hub force is analysed as the comfort criterion. It is the tire performance result on the soil impecfections absorbation. The obtained numerical data are compared with experimental data provided by Pirelli Pneus Ltda. Starting from this validated model, a methodology for the stochastic theory application in order to represent the tire variability is developed. Imperfections like amendments are introduced in the model as informations with an aleatory character. The Monte Carlo Method is used as solver / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Orientador: Reinaldo Monteiro / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-01T04:22:16Z (GMT). No. of bitstreams: 1 Ivanauskas_NataliaMacedo_D.pdf: 14349920 bytes, checksum: 7a0f0298317ad12487219f98c5883abd (MD5) Previous issue date: 2002 / Doutorado / Doutor em Biologia Vegetal

The key goal of the following diploma thesis is to evaluate influence of the air pressure in the car tires on the driving dynamic, stability and comfort. The first part is dedicated to the theory of the driving dynamic, stability, tire parameters and tire inflation. Next practical part is focused on the drivers’ knowledge about the correct tire inflation and follows with the measurements and evaluation of the influence of the tire inflation on the driving characteristics, riding comfort and its comparison. These influences are summarized and followed up by the recommendations for the drivers and also the expert activities.

Structural engineering has progressed from design for life safety limit states to performance based engineering, in which energy dissipation systems in structural frameworks assume prime importance. A visco-hyperelastic device is a completely new type of passive energy dissipation system that not only combines the energy dissipation properties of velocity and displacement dependent devices but also provides additional stability to the structure precluding overall collapse. The device consists of a viscoelastic material placed between two steel rings. The energy dissipation in the device is due to a combination of viscoelastic dissipation from rubber and plastic dissipation due to inelastic behavior of the steel elements. The device performs well under various levels of excitation, providing an excellent means of energy dissipation. The device properties are fully controlled through modifiable parameters. An initial study was conducted on motorcycle tires to evaluate the hyperelastic behavior and energy dissipation potential of circular rubber elements, which was preceded by preliminary finite element modeling. The rubber tires provided considerable energy dissipation while displaying a nonlinear stiffening behavior. The proposed device was then developed to provide additional stiffness that was found lacking in rubber tires. Detailed finite element analyses were conducted on the proposed device using the finite element software package ABAQUS, including parametric studies to determine the effect of the various parameters of device performance. This was followed by a nonlinear dynamic response history analysis of a single-story steel frame with and without the device to study the effects of the device in controlling structural response to ground excitations. Static analyses were also done to verify the stabilizing effects of the proposed device. Results from these analyses revealed considerable energy dissipation from the device due to both viscoelastic as well as plastic energy dissipation. Detailed experimental analyses on the proposed device, finite element analyses of the device on multistory structures have been put forth as the areas of future research. It may also be worthwhile to conduct further research, as suggested, in order to evaluate the use of scrap tires which is potentially a very valuable structural engineering material. / Master of Science

Methods of reusing/recycling the more than 250 million automobile and truck tires which are worn out each year were investigated. The existing methods of reusing tires account for about 30 percent of the volume of scrap tires generated each year. These methods are, Retreading, Reclaiming (by reducing to ground up rubber and fiber), and Tire Splitting (stamp items out of sidewall and tread areas). Several possibilities for reusing/recycling the unused 70 percent were discovered. These methods are as follows: Destructive Distillation -- a method of recovering chemicals from tires by pyrolitic action. It is anticipated that eventually as much as 60 percent of all scrap tires may be reused by this method. Expanded Reclaimed Usage -- The use of crumb rubber as an asphalt additive will improve life and durability of highway paving as much as 300 percent. Artificial Reefs -- The tires are compressed and banded then dumped in the ocean to expand old or create new reefs. Carbon Black -- A method whereby the tire is carburized and the resulting carbon black used in new tire formulation. An investigation of the possibility of using one or more of the above methods for the East Central Florida area indicates that artificial reefs should provide the most useful, least cost method for disposal of scrap tires.

The major objective of this study was to determine the relations between certain electrical parameters (resistance, capacitance) and mechanical parameters (stress, strain) for carbon black loaded rubber. Resistance and capacitance were measured under constant strain and constant stress conditions in an effort to determine these relations for rubber filled with 30 to 70 parts carbon black per hundred parts rubber. Seven materials for making electrical contact were investigated. Silver paint was found to result in low contact resistance, to be reliable, and fairly inexpensive. Electrical parameters (resistance, capacitance) and mechanical parameters (stress, strain) were found to exhibit similar trends as functions of carbon black content. This is in agreement with previous theories of the conduction network and electron percolation. Resistance and stress relaxation equations were quantitatively determined. These follow a power law time dependence, with relaxation rates depending mainly on carbon black content and temperature. / M.S.

The growth of the automobile Industry in the past 50 years is radical. The development of chassis control systems have grown drastically due to the demand for safer, faster and more comfortable vehicles. For example, the invention of Anti-lock Braking System (ABS) has resulted in saving more than a million lives since its adaptation while also allowing the vehicles to commute faster. As we move into the autonomous vehicles era, demand for additional information about tire-road interaction to improve the performance of the onboard chassis control systems, is high. This is due to the fact that the interaction between the tire and the road surface determines the stability boundary limits of the vehicles. In this research, a real-time system to classify the road surface into five major categories was developed. The five surfaces include Dry Asphalt, Wet Asphalt, Snow, and Ice and dry Concrete. tri-axial accelerometers were placed on the inner liner of the tires. An advanced signal processing technique was utilized along with a machine learning model to classify the road surfaces. The instrumented Volkswagen Jetta with intelligent tires was retrofitted with new instrumentation for collecting data and evaluating the performance of the developed real-time system. A comprehensive study on road surface classification was performed in order to determine the features of the classification algorithm. Performance of the real-time system is discussed in details and compared with offline results. / Master of Science / The automobile industry has been improving road transportation safety over the past 50 years. While we enter the autonomous vehicles era, the safety of the vehicle is of primary concern. In order to get the autonomous vehicles to production, we will have to improve the on board vehicle control systems to adapt to all surfaces. Gaining more accurate information about the tire and road interaction will help in improving the control systems. Tires have always been considered a passive element of the vehicle. However, more recently, the idea of “tire as a sensor” has surfaced and has become one of the major research thrusts in tire as well as vehicle companies. The intelligent tire research at the Center for Tire Research (CenTiRe) begun in 2010 and has been going strong. In this work, we have developed a classification algorithm to classify the road surfaces in real-time based on acceleration measured inside the tire. The information regarding the road surface would be highly beneficial for the developing new control strategies, automate service vehicles and aid surface prediction in autonomous vehicles.

The main goal of this study is to improve the understanding of the interaction between a pneumatic tire and deformable terrain. A design of experiments has been implemented, that gives insight into the effect of individual tire and soil parameters, specifically wheel slip, normal load, inflation pres-sure, and soil compaction, as well as into the effect of combinations of such parameters on the tire and soil behavior. The results of such test data is exceedingly relevant, providing significant infor-mation to tire design for tire manufacturers, to users for operating conditions selection, as well as providing modeling parameters for tire models. Moreover, experimental investigation of tire-soil interaction provides validation data for tire models operating under similar conditions. In support of the validation of a soft soil tire model currently being developed at Virginia Tech under the auspices of the Automotive Research Center, experimental work has been performed on a low-speed, indoor single-wheel tester built to investigate studies in terramechanics. The terramechanics rig provides a well-controlled environment to assure repeatable testing conditions and void vehicle component ef-fects. The test tire for the rig is instrumented with a wireless sensory system that measures tire de-flection at the contact patch; combining this system with other instruments of the rig allows accurate estimations of wheel sinkage. A methodical soil preparation procedure has rendered great data to analyze several relations, such as the drawbar pull and the sinkage dependency on slip. The data col-lected indicated that, when looking at the effect of individual parameters, by increasing the soil com-paction, the normal load, and by decreasing the inflation pressure will result in a higher normalized drawbar pull. A higher normal load under all conditions consistently lowered the max tire sinkage depth. The sinkage has increased dramatically with the slip ratio, growing threefold larger at high slip (70-90%) when compared to lower slip (0-5%) ratios. / Master of Science

The tire-terrain interaction is complex and tremendously important; it impacts the performance and safety of the vehicle and its occupants. Icy roads further enhance these complexities and adversely affect the handling of the vehicle. The analysis of the tire-ice contact focusing on individual aspects of tire construction and operation is imperative for tire industry's future. This study investigates the effects of the tread rubber compound on the drawbar pull performance of tires in contact with an ice layer near its melting point. A set of sixteen tires of eight different rubber compounds were considered. The tires were identical in design and tread patterns but have different tread rubber compounds. To study the effect of the tread rubber compound, all operational parameters were kept constant during the testing conducted on the Terramechanics Rig at the Terramechanics, Multibody, and Vehicle Systems laboratory. The tests led to conclusive evidence of the effect of the tread rubber compound on the drawbar performance (found to be most prominent in the linear region of the drawbar-slip curve) and on the resistive forces of free-rolling tires. Modeling of the tire-ice contact for estimation of temperature rise and water film height was performed using ATIIM 2.0. The performance of this in-house model was compared against three classical tire-ice friction models. A parametrization of the Magic Formula tire model was performed using experimental data and a Genetic Algorithm. The dependence of individual factors of the Magic Formula on the ambient temperature, tire age, and tread rubber compounds was investigated. / Master of Science / The interaction between the tire and icy road conditions in the context of the safety of the occupants of the vehicle is a demanding test of the skills of the driver. The expected maneuvers of a vehicle in response to the actions of the driver become heavily unpredictable depending on a variety of factors like the thickness of the ice, its temperature, ambient temperature, the conditions of the vehicle and the tire, etc. To overcome the issues that could arise, the development of winter tires got a boost, especially with siping and rubber compounding technology. This research focuses on the effects on the tire performance on ice due to the variation in the tread rubber compounds. The experimental accomplishment of the same was performed using the Terramechanics rig at the Terramechanics, Multibody, and Vehicle Systems (TMVS) laboratory. It was found that the effect of the rubber compound is most pronounced in the region where most vehicles operate under normal circumstances. An attempt was made to simulate the temperature rise in the contact patch and the water film that exists due to the localized melting of ice caused by frictional heating. Three classical friction models were used to compare the predictions against ATIIM 2.0, an in-house developed model. Using an optimization technique namely the Genetic Algorithm, efforts were made to understand the effects of the tread rubber compound, the ambient temperature, and the aging of the tire on the parameters of the Magic Formula model, an empirical model describing the performance of the tire.

In conjunction with Atlantic Pacific Engineering and the Henry County Public Service Authority, Virginia Tech’s Environmental Engineering program measured the emissions from an experimental scrap tire incinerator/wastewater treatment plant sludge dryer. This report recounts the techniques used and the results obtained during this testing. The Virginia Department of Environmental Quality supplied a list of pollutants of permitting interest which included a variety of criteria pollutants, toxics, and metals. Sampling for all the listed compounds required adherence to EPA Methods 5, 201A, 29, 0010, 0011, 0030, 6, 7D, 26A, and 18. Emissions testing transpired during the incinerator’s 72-hour test burn: 0800 October 30th to 0800 November 2nd, 1995. Due to time constraints, only part of one nonpotable water sampling series was completed rather than the proposed duplicate testing using both drying agents: nonpotable water and sludge. High particulate (57 lb/hr) and metal (21.4 lb/hr total) emissions indicate a fairly significant amount of air pollution control equipment will be necessary for a commercial plant. Both nitrogen oxides and sulfur dioxide had low emission rates: 1.73 lb/hr and 0.64 lb/hr, respectively, due to the nonpotable water spray acting as a fairly efficient scrubber removing a great deal of nitrogen oxides, sulfur dioxide, and some metals. Because of sample analysis preparation problems, no organics results were obtained. Commercial development of this incinerator will have to include a sizable quantity of air pollution control equipment: a $5 million plant will need approximately $1 million worth of control equipment. / Master of Science