[pt] O volume de pneus inservíveis continua aumentando a cada ano, se tornando um tema de grande preocupação para a sociedade. Motivados por esta problemática ambiental, o presente estudo experimental propõe utilizar a borracha de pneu triturada como reforço de solos, em duas diferentes granulometrias (chips e fibras), como material alternativo para o reforço de dois tipos de solos (areia e solo argiloso). Com este fim realizaram-se ensaios mecânicos, tais como ensaios de compactação proctor standard, ensaios triaxiais do tipo consolidado e isotropicamente drenado e ensaios de adensamento unidimensional, para avaliar os efeitos da granulometria da borracha de pneu, triturada em chips e fibras (com os tamanhos médios de 4,6 mm e 2 mm, respectivamente) e do teor de borracha de pneu (5, 10 por cento e 15 por cento em relação à massa de solo seco), no comportamento mecânico de misturas de areia-borracha e de misturas solo argiloso-borracha. Os resultados mostraram que tanto os chips como as fibras de pneu de borracha contribuem no aumento dos parâmetros de resistência ao cisalhamento de ambos os solos e aumentam a energia de deformação absorvida durante o cisalhamento. Ao analisar a resposta obtida em ambos os solos, se evidencia que, tanto para a argila quanto para a areia, foi mais efetivo o reforço com 10 por cento de fibras de borracha de pneu. Todos os compósitos estudados possuem características de resistência que poderiam cumprir as exigências de determinadas obras geotécnicas (aterros sobre solos moles, reforço de taludes, solo de base de fundações superficiais), portanto o uso da borracha de pneu como reforço de solos contribuiria com o menor consumo de material natural e redução dos custos de transporte e volume de material mobilizado. / [en] The volume of discarded tires continues to increase each year, becoming a major topic of concern for society. Motivated by this environmental issue, this experimental study proposes using tire chips and tire buffings as an alternative material to improve the shear strength of two types of soil (sand and clayey soil). Because of this, standard Proctor compaction tests, consolidated-drained triaxial tests and compressibility tests were performed to assess the influence of tire rubber particle size, (with average sizes of 4.6 mm and 2 mm, respectively) and tire rubber content (5, 10 percent and 15 percent by dry weight of soil) into the mechanical behavior of sand and clayey soil. The tests results showed that both, chips and buffings contribute increasing the shear strength parameters of both the soil and increase the strain energy absorbed during the shear phase. By analyzing, the mechanical response both for clayey soil and for sand was found that the best shear strength improvement was obtained at 10 percent of tire buffings. All the composites showed resistance characteristics that would ensure the requirements for many geotechnical applications (embankments over soft soils, slope reinforcement and surface foundations), so the use of waste tires as a reinforcement material would help solve problems associated with natural resources and reducing transportation costs and earthmoving.

The research work critically analyzed the factors responsible for imprudent waste tyre management in South Africa. As an approach to determine the complexity of the problem, questionnaires were sent to one hundred and sixty (160) respondents in conjunction with interviews. Perusal of literature and interaction with industry involved in waste tyre processing to further gain knowledge of the problem and possible solutions that can be solicited to address the problem. Findings revealed that, lack of clear, focused legislation that guide the handling, disposal and processing of waste tyres remain the challenge. It is also deduced that recycling of waste tyres can provide economic benefits and opportunities. It is recommended that South Africa develop appropriate legislation that deals with handling, treatment and disposal of waste tyres, develop an incentive programme to set up initiatives as well as developing skilled and capacitated enforcement agency. / Environmental Sciences / M.A. (Environmental Management)

The research work critically analyzed the factors responsible for imprudent waste tyre management in South Africa. As an approach to determine the complexity of the problem, questionnaires were sent to one hundred and sixty (160) respondents in conjunction with interviews. Perusal of literature and interaction with industry involved in waste tyre processing to further gain knowledge of the problem and possible solutions that can be solicited to address the problem. Findings revealed that, lack of clear, focused legislation that guide the handling, disposal and processing of waste tyres remain the challenge. It is also deduced that recycling of waste tyres can provide economic benefits and opportunities. It is recommended that South Africa develop appropriate legislation that deals with handling, treatment and disposal of waste tyres, develop an incentive programme to set up initiatives as well as developing skilled and capacitated enforcement agency. / Environmental Sciences / M.A. (Environmental Management)

A Resolução nº 258/99 do Conselho Nacional do Meio Ambiente - CONAMA, em vigor desde janeiro de 2002, obriga a destinação ambientalmente correta de pneumáticos inservíveis. Os pneus são considerados inservíveis devido ao desgaste e quando não há possibilidade de reaproveitamento para uso veicular e nem para processos de reforma. Entretanto, preservam propriedades físicas com potencial de aproveitamento na engenharia civil. Nos últimos anos surgiram várias iniciativas no Brasil, desde pesquisas acadêmicas à execução de obras, para a utilização de pneus, sobretudo em pavimentação asfáltica e aterros reforçados. Este trabalho analisa outras alternativas de aplicação de pneus inservíveis em obras geotécnicas e rodoviárias. Apresenta a caracterização dos pneus, suas propriedades físicas, parâmetros geotécnicos e geomecânicos e são realizadas análises paramétricas para cada tipo de aplicação estudada, isto é, muros de gravidade, reforço do subleito de pavimentos e aterros leves. / The Resolution nº 258/99 of the Brazilian Council for the Environment - CONAMA, in vigour since January of 2002, compels the environmentaly correct destination of scrap tires. The tires are considered used when there is no possibility of vehicle utilization or renew process. However, they preserve physical properties with potential of utilization in civil engineering. In the last years, for instance, several options were considered in Brazil, from academic researches to the execution of works, particularly in the asphalt paving industry and in reinforced embankments. This work analyzes anothers alternatives for scrap tires in geotechnical and transportation applications. It presents the characterization of tires, their physical properties and geotechnical and geomechanics parameters. It also presents parametric analyses carried out for each type of studied application, that is, gravity walls, reinforcement of road subgrades and lightweigth fill for road embankment.

Made available in DSpace on 2016-08-10T10:40:36Z (GMT). No. of bitstreams: 1 MARINA MEIRELES PEREIRA.pdf: 5021994 bytes, checksum: 7b9170817bc15d6c6c8810e83ac1330e (MD5) Previous issue date: 2016-02-15 / This research aims to apply a prediction model to a tire closed-loop supply chain to estimate the volume returned of scrap tires, through the variables that influence the amount and time that these tires are returned to destination. The methodological approach applied in this research is the modeling by applying the Transfer Function Model. It starts with the analysis that the tire closed-loop supply chain of Goiás and the Federal District is structured and there is a direct relationship between sales of tires with the amount returned. Were adopted as model input variables the amount of tires placed on the market for after-market and the size of the current fleet of these places, representing the amount of tires entered the market for new cars sold. For the output variable was considered the quantity of scrap tires collected and sent for disposal. The data for the survey were collected in the organization s databases adopted as an object of study, IBAMA, DENATRAN, ANIP and AliceWeb considering a period of 54 months. Data were analyzed by the transfer function model and the results showed that the lag time after the tires were entered on the market was around 12 months for all input variables, the return probability of the after-market are greater than the return probability of the tire fleets, and the behavior of the predicted return showed an approximate behavior of the real return with a percentage deviation of 3.4%. Therefore, this study enabled us to identify the variables that influence the return of scrap tires and scale the amount of returned volume tires and the time of this return to facilitate the planning of the tires of closed-loop supply chain. / Esta pesquisa visa aplicar um modelo de previsão a uma cadeia de suprimentos de ciclo fechado de pneus, para estimar o volume de pneus inservíveis retornados, por meio das variáveis que influenciam na quantidade e no tempo que estes pneus retornam para serem destinados. A abordagem metodológica aplicada nessa pesquisa se situa na Modelagem, aplicando o Modelo de Função de Transferência. Parte-se da análise de que a cadeia de suprimentos de ciclo fechado do Estado de Goiás e Distrito Federal está estruturada e que há uma relação direta entre as vendas de pneus com a quantidade retornada. Foram adotadas como variáveis de entrada do modelo a quantidade de pneus inseridos no mercado, pelo mercado de reposição e o tamanho da frota circulante destas localidades, representando a quantidade de pneus inseridos no mercado pelos carros novos vendidos. Para a variável de saída foi considerada a quantidade de pneus inservíveis coletados e encaminhados para destinação final. Os dados utilizados na pesquisa foram coletados em bancos de dados da organização adotada como objeto de estudo, IBAMA, DENATRAN, ANIP e AliceWeb, considerando de um período de 54 meses. Os dados foram analisados pelo modelo de função de transferência e os resultados obtidos mostraram que o tempo de defasagem da entrada de pneus no mercado foi em torno de 12 meses para todas as variáveis de entrada, que as probabilidades de retorno do mercado de reposição são maiores que as probabilidades de retorno dos pneus das frotas e que a previsão de retorno apresentou um comportamento aproximado do comportamento real do retorno com um desvio percentual de 3,4%. Portanto, este estudo possibilitou identificar as variáveis que influenciam no retorno de pneus inservíveis e a dimensionar a quantidade de volume de pneus retornados e o tempo desse retorno para viabilizar o planejamento da cadeia de suprimentos de ciclo fechado de pneus.

O aumento da população, o crescimento das grandes cidades, da industrialização e do consumo, tem trazido preocupação com relação a sustentabilidade quanto à disponibilidade energética e quanto à destinação dos resíduos sólidos urbanos gerados. Dessa forma, é fundamental realizarem-se os estudos visando novas formas de reutilização dos resíduos gerados pelas atividades industriais. Os resíduos sólidos urbanos e os pneus inservíveis gerados trazem conseqüências ao meio ambiente e às populações quando destinados inadequadamente. A destinação final dos resíduos sólidos urbanos é complexa, sendo sempre um grande desafio para as administrações públicas. Com a Política Nacional de Resíduos Sólidos (instituída pela Lei n 12.305/2010), tem-se um marco da preservação ambiental, coma a gestão e gerenciamento de resíduos sólidos, com a ordem de prioridade: não geração, redução, reutilização, reciclagem, tratamento dos resíduos sólidos e disposição final ambientalmente adequada dos rejeitos e prevê, de forma inteligente, a atribuição aos fabricantes de responsabilidade pelo retorno de produtos descartados pelos consumidores. Uma alternativa para minimizar estes aspectos e impactos ambientais é o tratamento térmico com aproveitamento energético. Este processo contribui para mais uma solução de destinação dos resíduos, proporcionado uma redução das áreas a serem utilizadas nos aterros sanitários e contribuindo como uma fonte de geração de energia elétrica / The increase in population, the growth of big cities, industrialization and consumption, have brought with them a kind of awareness about sustainability towards availability of energy and toward the destination of generated municipal solid waste. This way, it is primordial to carry out studies aiming to find new ways to reutilize the waste generated by industrial activities. The municipal solid waste and unusable tires produced cause serious consequences to the environment and to the population when these issues are improperly addressed. The final destination of the municipal solid waste is complex and it is always a big challenge to public management. With our National Policy of solid waste (established by the law number 12.305/2010).It consists of the administration and management of solid waste with the following order of priority: non-generation, reduction, reuse, recycling, treatment of solid waste and final environmentally appropriate disposal. With this we can foresee, in an intelligent way, a responsible plan for the return of goods discarded by consumers to the original manufacturers. An alternative to minimize these aspects and the negative environmental impacts caused is the usage of the thermal treatment with the good use of energy. This process contributes to another solution to the problem of the aforementioned waste, providing a reduction of landfill spaces and contributing to a new source of electrical energy generation

A Resolução nº 258/99 do Conselho Nacional do Meio Ambiente - CONAMA, em vigor desde janeiro de 2002, obriga a destinação ambientalmente correta de pneumáticos inservíveis. Os pneus são considerados inservíveis devido ao desgaste e quando não há possibilidade de reaproveitamento para uso veicular e nem para processos de reforma. Entretanto, preservam propriedades físicas com potencial de aproveitamento na engenharia civil. Nos últimos anos surgiram várias iniciativas no Brasil, desde pesquisas acadêmicas à execução de obras, para a utilização de pneus, sobretudo em pavimentação asfáltica e aterros reforçados. Este trabalho analisa outras alternativas de aplicação de pneus inservíveis em obras geotécnicas e rodoviárias. Apresenta a caracterização dos pneus, suas propriedades físicas, parâmetros geotécnicos e geomecânicos e são realizadas análises paramétricas para cada tipo de aplicação estudada, isto é, muros de gravidade, reforço do subleito de pavimentos e aterros leves. / The Resolution nº 258/99 of the Brazilian Council for the Environment - CONAMA, in vigour since January of 2002, compels the environmentaly correct destination of scrap tires. The tires are considered used when there is no possibility of vehicle utilization or renew process. However, they preserve physical properties with potential of utilization in civil engineering. In the last years, for instance, several options were considered in Brazil, from academic researches to the execution of works, particularly in the asphalt paving industry and in reinforced embankments. This work analyzes anothers alternatives for scrap tires in geotechnical and transportation applications. It presents the characterization of tires, their physical properties and geotechnical and geomechanics parameters. It also presents parametric analyses carried out for each type of studied application, that is, gravity walls, reinforcement of road subgrades and lightweigth fill for road embankment.

<p>Strukturiranje elastomernih kompozita dodavanjem različitih vrsta nanopunila je dovelo do značajnog pobolj&scaron;anja njihovih primenskih svojstava, a samim tim i do povećanja njihove potencijalne primene kao pogodnih materijala za specijalne namene. U ovom radu, dobijene su dve grupe elastomernih hibridnih materijala za specijalne namene (na osnovu stirenbutadienskog elastomera i na osnovu termoplastičnih poliuretana).<br />U prvom delu istraživanja, veliki doprinos u razvoju industrije gume je postignut strukturiranju stirenbutadienskih nanokompozita primenom nanočestica punila silicijum(IV)oksida različitih morfolo&scaron;kih svojstava, dobijenih hidrotermičkom i termičkom obradom, primenom tri eksperimentalno modelovana punila silicijum(IV)oksida (dobijena taloženjem iz Na-vodenog stakla sa sumpornom kiselinom), kao i hibridnog punila (kombinacije čestica aktivne čađi i SiO₂ optimalnih svojstava). Izvr&scaron;ena je analiza uticaja strukture, povr&scaron;ine i povr&scaron;inske aktivnosti nanopunila na ojačanje elastomera, kao i provera koncepata, modela i teorija ojačanja na neumreženim i umreženim sistemima stirenbutadienskih elastomera ojačanih modifikovanim punilima SiO₂. Primenom mnogobrojnih metoda karakterizacije, sveobuhvatno je ispitan uticaj nanopunila na karakteristike me&scaron;anja, reolo&scaron;ka svojstva pripremljenih hibridnih nanokompozita, sposobnost umrežavanja u neumreženom materijalu, kao i na toplotna, dinamičko-mehanička i mehanička svojstva umreženih nanokompozita, radi projektovanja i optimizovanja sastava SBR hibridnih materijala za razvoj modelnog protektora sa optimalnim svojstvima za ekolo&scaron;ke ili &quot;zelene pneumatike&quot;. Drugi deo istraživanja je bio posvećen dobijanju segmentiranih poliuretanskih elastomernih nanokompozita primenom alifatičnih polikarbonatnih diola i nanočestica bentonita, koji nalaze primenu u medicini, građevinarstvu, u industriji name&scaron;taja i sportske opreme. Primenom mnogobrojnih metoda za karakterizaciju, ispitan je složen mehanizam uticaja tvrdih segmenata, termodinamičke nekompatibilnosti i prisustva nanočestica punila bentonita na strukturu i morfologiju, kao i na toplotna i dinamičko-mehanička svojstva pripremljenih poliuretanskih termoplastičnih elastomera. Dobijeni podaci o obrazovanju vodoničnih veza, termičkoj stabilnosti i termičkoj dekompoziciji, kao i o temperaturama prelaska u staklasto stanje i oblasti raskidanja čvorova fizičkih veza, predstavljaju značajan doprinos napretku strukturiranja poliuretanskih elastomera i nanokompozita na osnovu alifatičnih polikarbonatnih diola, i omogućavaju primenu ovih materijala za specijalne namene.</p> / <p>The structuring of elastomeric composites by addition of different nanofillers has led to a significant improvement of their end-use properties, and therefore, to their potential application as suitable materials for special applications. In this work, two types of elastomeric hybrid materials for special purposes were obtained (based on styrene-bustadiene elastomer or on segmented thermoplastic polyurethanes).<br />In the first part of the study, a major contribution to the development of the rubber industry was achieved by structuring styrene-butadiene nanocomposites, applying silica nanoparticles of various morphological properties: prepared by hydrothermal or thermal treatment, three experimentally prepared SiO2 fillers (obtained by precipitation from sodium silicate with sulfuric acid), as well as a hybrid filler (combination of carbon black and SiO2 fillers with optimal properties). The analysis of the influence of the nanoparticles structure, surface and surface activity on the reinforcment of SBR elastomers, as well as the verification of concepts, models and reinforcement theories on non-cross-linked and cross-linked systems of styrene-butadiene nanocomposites was performed. Using the numerous characterization methods, the influence of nanofillers on the mixing characteristics, the rheological properties of the prepared hybrid nanocomposites, as well as the thermal, dynamic-mechanical and mechanical properties of cross-linked SBR nanocomposites was studied, in order to design and optimize the composition of SBR hybrid materials for development of environmental friendly or &quot;green&quot; tyre protector model.<br />The second part of the research was devoted to the preparation of segmented polyurethane elastomeric nanocomposites using aliphatic polycarbonate diols and bentonite nanoparticles, that have found the significant application in the medicine, construction, the furniture and sports equipment industry. Applying numerous characterization methods, a complex mechanism of the influence of the hard segments, thermodynamic incompatibility and the presence of bentonite filler on the structure and morphology, as well as on the thermal and dynamic-mechanical properties of the synthesized thermoplastic elastomers was studied. The obtained data on the hydrogen bonds formation, thermal stability and thermal decomposition, as well as the glass transition temperature and physical crosslink disruption temparature range, makes a significant contribution to the progress in structuring of polycarbonate-based polyurethane elastomers and their hybrid materials, and improves their potential applications for the special purposes.</p>

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

M. Tech. : Mathematical Technology. / Attempts will be made to extend the elementary quarter-mass models (for instance Gillepse, 1992, [5]; Kiecke & Nielsen, 2000, [6] and Singiresu, 2004, [7]) of a motor vehicle suspension system to include the radial vibrations of a rubber tyre in the model. Tangential vibrations of the tyre surface were investigated by Bekker (2009, [8]) and the possible incorporation of such vibrations into a suspension model invites the possibility of future study.