A non-intrusive direct-measuring skin friction device with a rubber RTV sheet over the surface of the floating head, gap and housing was developed for application in 3D, unsteady, transonic flight conditions. Design conditions required optimum gage performance at altitudes ranging from 15,000 to 45,000 feet, Mach numbers ranging from 0.6 to 0.99 resulting in shear values of 0.3 to 1.5 psf. under vibration conditions up to 8.0 grms over a 15 - 2,000 Hz frequency range. The gage consisted of a rubber RTV sheet-coated floating element attached to an aluminum cantilevered beam. A dual-axis, full bridge strain gage configuration was used with the application of semi-conductor strain gages to increase instrument sensitivity. The gage was studied with and without a viscous liquid (glycerin) fill in the housing. Vibration verification testing was performed at 1.0 grms in the Virginia Tech modal analysis lab to ensure adequate damping performance over a 0−3200 Hz frequency range. Tests revealed that the rubber RTV compound sheet provided adequate viscoelastic damping, with or without viscous liquid fill. Gage performance verification testing was performed on in the Virginia Tech supersonic wind tunnel at shear levels of tw = 3.9 to 5.3 psf in a Mach 2.4 flow. Skin friction values in good agreement with previous testing and analytical predictions were obtained from the tests with adequate damping in the low vibration environment of the Virginia Tech supersonic wind tunnel. The gage proved robust as it survived repeated runs including the violent start and unstart processes typical of a supersonic, blowdown wind tunnel. Flight tests were performed at NASA Dryden Flight Research Center, with the gage mounted in a plate suspended below an F-15 aircraft. This provided a mildly 3D, turbulent boundary layer on a vibrating surface. The gage was tested without liquid fill in the gage cavity, and it performed satisfactorily in this high vibration environment. The gage demonstrated adequate damping and good robustness, surviving the complete flight test intact and remained fully operational. The sensor measured skin friction values 30%-50% higher than those predicted by indirect methods and analogies generally valid for 2D, steady flows. The gage indicated trends in skin friction values for different flight conditions in good agreement with the other methods. Possible reasons for the differences in numerical values are discussed in detail, including potential uncertainties in the gage output and limitations and uncertainties in the methods used for comparison. Finally, suggestions for further development of such gages are provided for flight test applications. / Master of Science

In this study, a micromechanics-based method is developed to predict the off-axis strength of unidirectional linear elastic laminae. These composites fail by matrix cracking along a plane parallel to the fiber direction. The stresses in the matrix are calculated using a local stress analysis based on a concentric cylinder model. This model consists of a unique fiber embedded in matrix; both constituents are represented by cylinders. A finite element model is also constructed and the results of the two models compared. The stresses and strains from the concentric cylinder model are averaged over the volume of the matrix and used in a local failure function. This failure function has the form of a reduced and normalized strain energy density function where only transverse and shear terms are considered. The off-axis strength prediction method is validated using data from the literature. This failure function will be used in the near future for composites with a matrix having nonlinear properties. Experimental tensile tests on steel-cord/rubber laminae and laminates as well as on the nonlinear rubber matrix were performed. Stress-strain behavior and off-axis strength data were obtained. An approach for off-axis strength prediction for these laminae is defined based on a finite element stress analysis. The finite element analysis approach is motivated by the one used for linear composites. / 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 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.

The aim of this study is focused on the experimental investigation of dynamic wear behavior of carbon black filled rubber compounds comprising pristine styrene butadiene rubber (SBR) together with incorporated SBR ground rubber (rubber powder). We also analyzed and described quantitatively the service conditions of some dynamically loaded rubber products, which are liable to wear (e.g. conveyor belts, tires). Beside the well-known standard test method to characterize wear resistance at steady-state conditions, we used an own developed testing equipment based on gravimetric determination of mass loss of rubber test specimen to investigate the influence of rubber powder content on dynamic wear depending on varying impact energy levels. Incorporation of SBR rubber powder in SBR rubber compounds increases wear. With increasing rubber powder content the wear at steady-state conditions progressively increases. However, the level of wear at dynamic loading conditions increases only once, but stays constant subsequently even with contents of incorporated rubber powder.

The contribution of rubber to national economic and social development is important for Indonesia. However, smallholding rubber, the dominant rubber producer, has low productivity. Various new technology programmes have been introduced by the Indonesian government with other agencies to increase the productivity of existing traditional rubber and incomes among smallholder rubber farmers in Indonesia. However, the adoption of new technology was low and the reasons for these were still unclear. This study explores how smallholder farmers in Indonesia adopt new technology. Rubber Agroforestry System (RAS) introduced mainly by International Centre for Research in Agroforestry (ICRAF) in Jambi and West Kalimantan provinces in Indonesia is used as a case study. A combination of Ethnographic Decision Tree Modeling (EDTM) proposed by Gladwin (1989a) and a logistic regression model were used as the main methodologies to determine the decision criteria of rubber farmers regarding adoption of clonal rubber. The EDTM as qualitative method helped to identify the main reasons, motivations and constraints that influenced a farmer’s decision to adopt or not adopt the new technology and also present details about the process of the farmers’ decision making. Meanwhile, logit as the quantitative method was useful to identify the significant variables involved in the decision making process. The results of this study show that the decision making process for adoption of clonal rubber is complex and influenced by various factors. The decision tree models for Jambi and West Kalimantan differed showing the importance of social context and infrastructure. The main reasons for a farmer’s decisions to adopt clonal rubber is the expectation that clonal rubber is better in growth and yield and it will increase production per ha and income. The decision to adopt is supported by evidence from demonstration plots, trust in the technology deliverers and availability of incentives. The main constraint in adoption for both areas was limitation of capital as the clonal rubber required more capital to establish. The other constraints are risk and uncertainties including pest and disease problems, the shortage of labour, lack of technical knowledge, lack of access to clonal seedlings, and observation of clonal rubber that has been of low quality or managed inadequately. The decision tree models have been tested and the results show that the models were able to predict the farmers’ decision making with good accuracy of 82% and 83%. In addition, the quantitative model shows the significant factors that determine adoption of clonal rubber in Jambi and West Kalimantan are land, incentives and income factors. The qualitative and quantitative methods contributed to increased robustness of data and give different kinds of valuable data and information to stakeholders and policy makers in Indonesia. In order to encourage rubber farmers in Jambi and West Kalimantan to adopt clonal rubber, this study suggests improving policies to ensure they are aligned with needs of the rubber farmers, improving farmers’ access to capital sources such as credit with simpler mechanisms, increasing the number and skills of extension workers, encouraging farmer to farmer learning, empowering farmers and leadership, improving infrastructure including better access to clonal seedlings and improving partnership with NGOs.

Typical rubber compounds used to manufacture industrial products such as tyres, hoses, conveyor belts, acoustics, shock pads, and engine mountings contain up to eight classes of chemical additives· including curing agents, accelerators, activators, processing aids, and antidegradants. The cure systems in these articles often consists of primary and secondary accelerators, primary and secondary activators, and elemental sulphur. Recent legislation impacting upon the working environment, safety and health has imposed a considerable burden on the manufacturers of rubber compounds to meet various obligations. The selection of raw materials and manufacturing processes that do not harm the environment is of great importance. A novel technique for preparing rubber formulations using crosslinking nanofillers such as silanised precipitated silica has been developed in this research. The silica surfaces were pre-treated with bis[3-triethoxysilylpropyl-] tetrasulphane coupling agent (TESPT).· TESPT is a sulphur containing bifunctional organosilane which chemically adheres silica to rubber and also prevents silica from interfering with the reaction mechanism of sulphur-cure systems. The tetrasulphane groups of the TESPT are rubber reactive and react in the presence of accelerator at elevated temperatures, i.e.140 -260°C, with or without elemental sulphur being present, to form crossIinks in rubbers containing chemically active double bonds for example styrene-butadiene rubber (SBR) and polybutadiene rubber (BR) .. SBR and BR rubber compounds containing 60 phr of TESPT pre-treated silica nanofiller were prepared. The silica particles were fully dispersed in the rubber, which was cured primarily by using sulphur in TESPT. The reaction between the tetrasulphane groups of TESPT and the rubbers was optimised by incorporating different accelerators and activators in the rubber. The mechanical properties of the rubber vulcanisates such as hardness, tear strength, tensile strength, elongation at break, stored' energy density at break, abrasion resistance, modulus and cyclic fatigue life were increased significantly when the treated silica filler was added. The need for the accelerator and activator was dependent on the composition of the rubber. Interestingly, the rubbers were fully cured without the use of elemental sulphur, secondary accelerator and secondary activator. As a result, a substantial reduction in the use of the curing chemicals was achieved without compromising the important properties of rubber compounds which are essential for maintaining long life and good performance of industrial rubber products in service. This approach has also helped to improve health and safety within the workplace and minimise harm to the enviromnent.Furthermore, a significant cost saving was achieved after reducing the number of curing chemicals in the rubber.

Biodiesel and hydrotreated vegetable oil (HVO) are currently viewed by the transportation sector as the most viable alternative fuels to replace petroleum-based fuels. The use of biodiesel has, however, been limited by the deteriorative effect of biodiesel on rubber parts in automobile fuel systems. This work therefore aimed at investigating the degradation of acrylonitrile butadiene rubber (NBR) and fluoroelastomers (FKM) on exposure to biodiesel and HVO at different temperatures and oxygen concentrations in an automated ageing equipment and a high-pressure autoclave. The oxidation of biodiesel at 80 °C was promoted by an increase in the oxygen partial pressure, resulting in the formation of larger amounts of hydroperoxides and acids in the fuel. The fatty acid methyl esters of the biodiesel oxidized less at 150 °C on autoclave aging, because the termination reactions between alkyl and alkylperoxyl radicals dominated over the initiation reactions. HVO consists of saturated hydrocarbons, and remained intact during the exposure. The NBR absorbed a large amount of biodiesel due to fuel-driven internal cavitation in the rubber, and the uptake increased with increasing oxygen partial pressure due to the increase in concentration of oxidation products of the biodiesel. The absence of a tan δ peak (dynamical mechanical measurements) of the bound rubber and the appearance of carbon black particles devoid of rubber suggested that the cavitation was caused by the detachment of bound rubber from particle surfaces. A significant decrease in the strain-at-break and in the Payne-effect amplitude of NBR exposed to biodiesel was explained as being due to the damage caused by biodiesel to the rubber-carbon-black network. During the high-temperature autoclave ageing, the NBR swelled less in biodiesel, and showed a small decrease in the strain-at-break due to the cleavage of rubber chains. The degradation of NBR in the absence of carbon black was due only to biodiesel-promoted oxidative crosslinking. The zinc cations released by the dissolution of zinc oxide particles in biodiesel promoted reduction reactions in the acrylonitrile part of the NBR. Heat-treated star-shaped ZnO particles dissolved more slowly in biodiesel than the commercial ZnO nanoparticles due to the elimination of inter-particle porosity by heat treatment. The fuel sorption was hindered in HVO-exposed NBR by the steric constraints of the bulky HVO molecules. The extensibility of NBR decreased only slightly after exposure to HVO, due to the migration of plasticizer from the rubber. The bisphenol-cured FKM co- and terpolymer swelled more than the peroxide-cured GFLT-type FKM in biodiesel due to the chain cleavage caused by the attack of biodiesel on the double bonds formed during the bisphenol curing. The FKM rubbers absorbed biodiesel faster, and to a greater extent, with increasing oxygen concentration. It is suggested that the extensive biodiesel uptake and the decrease in the strain-at-break and Young’s modulus of the FKM terpolymer was due to dehydrofluorination of the rubber by the coordination complexes of biodiesel and magnesium oxide and calcium hydroxide particles. An increase in the CH2-concentration of the extracted FKM rubbers suggested that biodiesel was grafted onto the FKM at the unsaturated sites resulting from dehydrofluorination. / <p>QC 20170227</p>

Piracicaba-SP é situada no extremo Sul da área preferencial para plantio de seringueira no Brasil, com pouca informação disponível sobre o desempenho de clones sob suas condições ambientais. O desempenho de crescimento e produtividade de dez clones de seringueira (Hevea spp.) foi avaliado. Os clones estudados foram CATI 21, IAC 15, IAN 873, GT 1, PB 235, PB 252, PR 107, PR 261, RRIM 526 e RRIM 600. O ensaio foi instalado no campo experimental do Departamento de Produção Vegetal da ESALQ/USP, em Piracicaba-SP, Brasil, sob delineamento de blocos inteiramente casualizados com cinco repetições. Foi avaliado o número e porcentagem de plantas em sangria e a produtividade anual. A sangria iniciou-se com a idade de 6,5 anos das árvores, no sistema de explotação de ½ S d/7 9m/y ET 3.3% 9/y. IAN 873 e PB 252 foram os maiores produtores, suplantando a produção do RRIM 600, que apresentou produtividade similar a do CATI 21 e do IAC 15. PR 107 e GT1 apresentaram produtividade intermediária, logo abaixo daqueles, mas com boas características secundárias como de produtividade e crescimento tardios e crescentes. PB 235, de forma inesperada, foi pouco produtivo. RRIM 526 teve produtividade imediatamente abaixo do PB 235 e sem qualquer característica secundária atrativa para recomendá-lo. PR 261 apresentou a produtividade mais baixa entre todos os clones. IAN 873, PB 252, RRIM 600, pelo bom desempenho no campo experimental e em diversas outras situações, são elegíveis para recomendação aos produtores para plantio comercial em grande escala, na região de Piracicaba. CATI 21 e IAC 15, pelo bom desempenho no campo experimental são elegíveis para recomendação aos produtores para plantio comercial em escala experimental, na região de Piracicaba. PR 261 não deve ser recomendado para plantio na região de Piracicaba. / Piracicaba-SP is on the extreme southern region suitable for rubber planting in Brazil, with little information on the performance of clones under its environmental conditions. The performance of growth and yield of ten rubber tree clones (Hevea spp.) were evaluated. The studied clones were CATI 21, IAC 15, IAN 873, GT 1, PB 235, PB, 252, PR 107, PR 261, RRIM 526 and RRIM 600. The trial was established in the experimental field of de Crop Production Department of the ESALQ/USP, at Piracicaba-SP, Brazil, under complete randomized block design with five replications. It was assessed the number and percentage of trees under tapping and yearly rubber yield. Tapping started at the trees age of 6,5 years, with the ½ S d/7 9m/y ET 3.3% 9/y exploitation system. IAN 873 and PB 252 were the highest producers, out-yielding RRIM 600, which presented similar yield then CATI 21 and IAC 15. PR 107 and GT1 had intermediate yield, immediately below the formers, but with good secondary characteristics as late and increasing growth and yield. PB 235, unexpectedly, was a low yielder. RRIM 526 was immediately below PB 235 without any attractive characteristic to recommend it. PR 261 presented the lowest yield. IAN 873, PB 252, RRIM 600, because their good performance in the experiment and their widely-tested good performance elsewhere, should be recommended for commercial planting in large scale. CATI 21 and IAC 15, because their good performance in the experiment, should be recommended for commercial planting in small scale. PR 261 should not be recommended for commercial planting in Piracicaba.

O Acre testemunhou dois momentos históricos fundamentais para a sua colonização, ambos relacionados à extração da borracha, sendo o segundo patrocinado pelos Estados Unidos da América que, na Segunda Guerra Mundial, através dos Acordos de Washington, encontrou, no Brasil, a fonte do látex, matéria prima necessária para a produção bélica, uma vez que a Malásia, fornecedora, até então, não mais o fazia por imposição do governo japonês, que tomou seus campos de produção. Esse processo migratório campanhista levou aos seringais amazônicos, no início da década de 40 do século passado, mais de 75 mil jovens, que trocaram a seca do sertão nordestino pela úmida e tropical Floresta Amazônica, enfrentando dificuldades de adaptação dramáticas, atestadas pela morte de cerca de 25 mil Soldados da Borracha, ao final da guerra. O objetivo foi o de resgatar as memórias e histórias sobre o cuidado da saúde desses brasileiros que foram submetidos a vulnerabilidades e traumas culturais, sociais, familiares e de saúde, em prol de acordo que rendeu ao governo brasileiro pouco mais que o Banco da Amazônia e a Usina de Aço de Volta Redonda (RJ). O estudo foi quali-quantitativo, através de entrevistas, gravadas e transcritas, de trabalhadores procedentes do Nordeste que atuaram nos seringais da Amazônia, e que migraram para a capital do Acre, Rio Branco, entre as décadas de 40 e 60. Para análise das entrevistas foi utilizada a técnica do Discurso do Sujeito Coletivo,por meio do programa QualiQuantiSoft®. Os relatos mostraram situações de desamparo e descreveram a luta pela sobrevivência diante das adversidades desses homens e mulheres que, se hoje estão disponíveis para relatar esses fatos, provavelmente ainda o fazem por terem se transformado, em algum momento logo após a chegada, em amazônidas / The state of Acre has testified two fundamental historical moments in its colonization, both related to rubber extraction, the second being sponsored by the United States of America that, in World War II, through The Washington Agreement, found, in Brazil, a latex source, raw material needed in the war industries, as Malaysia, the supplier until then, no longer could offer it because Japans government took the production fields. This migratory process campaign led to the amazon seringais (rubber camps), in the early 40s of the last century, more than 75 thousand young men, who had chose the wet and humid tropical Amazon rainforest instead of their home, the dry and poor brazilian Northeastern region, facing dramatics adaptation difficulties, proved by the death of approximately 25 thousand Rubber Soldiers by the end of the war. The objective was to restore the memories and histories about the health care of those Brazilians who were submitted to all cultural, social and family vulnerabilities as much as health trauma experiences, this all to participate in the Brazilian-North American agreement which promoted to the Brazilian government a little more than the Bank of Amazonia and the Volta Redonda Steel Mill (RJ). This was both a qualitative and quantitative study, made through interviews, recorded and transcribed, with the Rubber Soldiers (RBs) who had worked in the Amazon seringais and later, between the 40s and 60s, went to live in the capital of Acre, Rio Branco. The interviews analysis was done by the Collective Subject Discourse Analysis through the QualiQuantiSoft® software. Reports collected from the RBs showed helplessness scenario and described the struggle for survival facing adversities of living in the middle of the jungle. The RBs probably are still here to tell it because they have transformed themselves, at some point soon after their arrival, in amazon natives

O conhecimento das diferentes fases do ciclo básico de vida da espécie vegetal constitui uma ferramenta eficaz de manejo e que uma vez identificados possibilita alcançar boas produtividades e melhor qualidade ao produto comercial. O objetivo deste trabalho foi avaliar o desempenho produtivo e as características químicas da borracha de quatro clones de seringueira, sob diferentes sistemas de sangria, estádios fenológicos e condições edafoclimáticas. O experimento foi instalado na área experimental do Departamento de Produção Vegetal da Escola Superior de Agricultura Luiz de Queiroz, da ESALQ/USP, no município de Piracicaba, SP (2242`30``S, 4738`00``W) e na Agência Paulista de Tecnologia dos Agronegócios (APTA) - Pólo Regional do Desenvolvimento Tecnológico de Agronegócios do Noroeste Paulista, no município de Votuporanga, SP (20°20S, 49°50W). O delineamento experimental adotado foi o de blocos casualizados em esquema parcela subdividida com três ou quatro réplicas. Os tratamentos principais (clones GT 1, PB 235, IAN 873 e RRIM 600) foram alocados nas parcelas e os tratamentos secundários (sistemas de sangria: ½S d/2; ½S d/4 ET 2,5%; ½S d/7 ET 2,5%) constituíram as subparcelas. As variáveis analisadas foram: produção de borracha seca, teores de cinzas e de macronutrientes e micronutrientes da borracha natural. As amostras de borracha natural foram obtidas nos estádios fenológicos: refolhamento; folhas maduras e senescência de folhas. Concluiu-se que a produção e as características da borracha são influenciadas pelas condições edafoclimáticas, pelos sistemas de sangria dependendo do estádio fenológico. A produção e os teores de nutrientes são mais influenciados pela prática de sangria do que pelo material genético, no estádio de senescência e em condições restritivas para a planta. / The knowledge of the different phases of the basic life cycle of plant species is an effective tool of management and that once identified possible to obtain good yields and better quality to the commercial product. The objective of this work was to evaluate the yield performance and chemical characteristics of the rubber of four rubber tree clones under different tapping systems, phenological stages and edaphoclimatic conditions. The experiment was carried in experimental area of the Departamento de Produção Vegetal da Escola Superior de Agricultura Luiz de Queiroz, da ESALQ/USP, Brazil (2242`30``S, 4738`00``W) and in Agência Paulista de Tecnologia dos Agronegócios (APTA) - Pólo Regional do Desenvolvimento Tecnológico de Agronegócios do Noroeste Paulista, in Votuporanga city São Paulo State, Brazil (20 ° 20\'S, 49 ° 50\'W). The experimental design was in randomized block design with split plot and three or four replicates. The main treatments (GT 1, PB 235, IAN 873 and RRIM 600 clones) were allocated in the plots and secondary treatments (tapping systems: ½S d/2; ½S d/4 ET 2.5%; ½ S d/7 ET 2.5%) constituted the subplots. The analyzed variables were: dry rubber yield, ash content, macronutrients and micronutrients of the natural rubber. Samples of natural rubber were obtained in the phenological stages: leaves development, mature leaves and leaves senescence. It was concluded that the yield and chemical characteristics of the rubber are influenced by the edaphoclimatic conditions, by the tapping systems and depending of the phenological stages. The yield and nutrients content of natural rubber is more influenced by the tapping practice than the genetic material in the leaves senescence stage and under restrictive conditions for the plant.