Thesis (M.S.)--Naval Postgraduate School, 1977. / Includes bibliographical references (leaves 53-54).

Thesis (Ph. D.)--University of Texas at Austin, 2005. / Supervisor: Oguzhan Bayrak. Vita. Includes bibliographical references.

A influencia do plástico mole na resistência ao cisalhamento do resíduo solido urbano (RSU) vem sendo alvo constante de estudo em virtude da sua enorme relevância nesta questão. No entanto trata-se de um tema complexo, visto que, são muitas as variáveis relacionadas ao problema, tais como, a quantidade de plástico, influencia do chorume em contanto com o plástico, inclinação do plástico em relação aos esforços normais e cisalhantes, resistência à tração do plástico, questões relacionadas à mobilização de esforços resistentes pelo plástico, etc. O presente trabalho visa estudar as variáveis envolvidas em relação à contribuição do plástico mole na resistência ao cisalhamento do resíduo solido urbano. Para esta pesquisa utilizou-se dois tipos de materiais: um solo granular e composto orgânico de RSU contendo, ou não, plástico mole. A influência do chorume na contribuição de resistência devida ao plástico mole também foi analisada. Ensaios de cisalhamento direto foram realizados para todos os casos. Foi observado que há um aumento em média de 15% na resistência do solo granular na presença do plástico mole, já o composto teve um aumento de apenas 10% quando há incorporação de plástico mole ao material. Isso indica que há uma contribuição do plástico mole em relação aos esforços normais e cisalhantes na resistência ao cisalhamento do RSU, e que este estudo é importante para o melhor entendimento dos parâmetros de resistência de aterros sanitários de RSU. / The influence of soft plastic in shear strength of municipal solid waste (MSW) has been a constant target of study because of its enormous importance in this matter. However, this is a complex issue, since there are many variables related to the problem, such as the amount of plastic influence of wastewater in contact with the plastic, the plastic slope in relation to shear and normal stresses, resistance tensile plastic, issues related to the mobilization of efforts by resistant plastic, etc. The present work aims to study the variables involved regarding the contribution of the soft plastic in shear strength of municipal solid waste. For this study, we used two types of materials: a granular soil and organic compost from MSW in the presence or absence of soft plastic. The influence of wastewater on contribution of resistance due to the soft plastic was also analyzed. Direct shear test were performed for all cases. It has been observed that there is an average increase of 15% in the resistance of the granular soil in the presence of soft plastic, but the organic compost from MSW had an increase of only 10% when incorporating the soft plastic material. This indicates that there is a contribution from soft plastic with respect to shear and normal stresses on the shear strength of MSW, and this study is important for a better understanding of the strength parameters of MSW landfills.

Made available in DSpace on 2014-06-11T19:30:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-06-23Bitstream added on 2014-06-13T19:00:07Z : No. of bitstreams: 1 ricci_rp_me_bauru.pdf: 3607185 bytes, checksum: d742c0c6ab4783eb07af6258b0f9b7ad (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O processo de fabricação das pás de turbinas eólicas envolve a colagem de estruturas fabricadas em plásticos reforçados com fibra de vidro. Neste trabalho foram analisadas os três principais tipos de adesivos estruturais utilizados pelos fabricante de pás (epóxi, poliuretano e metil-metacrilato), com o objetivo de desenvolver critérios que auxiliem na seleção de adesivos e de tratamentos superficiais aplicados às estrutuaras a serem coladas. A caracterização dos adesivos envolveu dois tipos de ensaios mecânicos: o cisalhamento de juntas de sobreposição simples e a clivagem de juntas adesivas. Dois tipos de tratamento das superfícies dos aderentes foram utilizados: camada de sacrifício removível (peel-ply) e abrasão. Também foi realizada a análise dos modos de falha das juntas ensaiadas como auxílio de compatibilidade entre adesivo e substrato. Os resultados mostram que o tratamento via peel-ply foi o mais eficiente para as juntas coladas com epóxi e testadas em cisalhamento, ao apresentar um aumento de 28% na resistência em relação às superfícies sem tratamento. Imagens de microscopia eletrônica de varredura sugerem que esse tratamento gerou uma área maior de contato em relação à superfície não tratada e que causou menos danos à superfície do aderente do que o método abrasivo. Os grupos colados com adesivo metil metacrilato, independentemente do tipo de tratamento, obtiveram os maiores valores nos ensaios de clivagem, cerca de 170% superiores aos demais grupos. Para estruturas de pás corretamente projetadas para evitar cargas de peeling em suas juntas adesivas, este trabalho mostra que a melhor opção são aderentes tratados com peel-ply e colados com epóxi. Contudo, um plano de testes deve ser elaborado sempre que houver a necessidade do emprego de um novo adesivo ou método de preparação superficial / The manufacturing process of wind turbine blades involves the bonding of structures made of glass reinforced plastic. This work analyzes the theree main types of structural adhesives used by blades manufactures (epoxy, polyurethane and methyl methacrylate), with the goal of developing criteria to assist in the selection of adhesives and surface treatments applied to the structures to be bonded. The characterization of the adhesives involved two types of mechanical tests: single lap shear joints and cleavage of adhesive joints. Two types of surface treatment of the adherents were used: removable sacrifical layer (peel-ply) and abrasion. The joint failure mode analysis was also carried out as an aid to the study of compatibility between adhesive and substrate. The results show that treatment via peel-ply was the most efficient for epoxy bonded substrates tested in shear, by presenting a 28% increase in strengh compared to untreated surfaces. Images of scanning electron microscopy suggest that this treatment led to a larger area of contact relative to untreated surfaces and caused less damage to the substrate's surface than the abrasive method. The groups bonded with methyl methacrylate regardless the type of treatment, had the highest values in the cleavage test, approximately 170% higher than other groups. For propertly designed blades, that avoid peeling loads in their adhesive joints, this work shows that the best option are substrate treated with peel-ply and bonded with epoxy. However, a test plan should be prepared whenever there is the necessity of using a new adhesive or method of surface preparation

M.Ing. / In this study a comparison is made between the punching shear capacities of square slabs reinforced with 3CR 12 corrosion resisting stainless steel and high tensile strength carbon steel. A square column 11 0 mm x 11 0 mm is used to simulate the point load on the slab. Three different slab depths were chosen for the experimental procedure. The South African concrete design specification SABS 0 I 00, the Eurocode concrete design specification and Menetrey's design model are used to determine the theoretical punching shear capacities of the slabs. It is concluded in this study that the procedures described in the concrete design codes and by Menetrey to determine the punching shear stress of concrete slabs reinforced with high strength carbon steel reinforcing bar compare well with the experimental results when 3CR I 2 corrosion resisting steel is used as reinforcing bar in concrete. The experimental results do not compare well with the theoretical results when the new Eurocode is used.

D.Ing. / The quantification of the surface roughness in order to determine the shear behaviour of rock joints has been performed using many approaches, amongst which the most important are the joint roughness coefficient, statistical methods and the fractal approach. None of these approaches explicitly considers the contribution of grain size to the creation of surface roughness. An investigation has been undertaken to determine whether the grain size may be related to the surface roughness characteristics and also to assess its impact on the shear behaviour of rock joints. The influence of grain size on the shear behaviour of rock joints has been experimentally and numerically studied using a profile measurement approach followed by shear tests in the laboratory. Fresh rock joints in model material made of aggregates of no rite in resin and two natural rock types, namely norite and sandstone, were used for the investigation. A numerical analysis of the study has been performed using the Particle Flow Code PFC20 • Investigation of the model material has resulted in the conceptualisation of grain size parameters. Of the proposed grain size parameters, the average particle size index As has been successfully used to define the particle size distribution of a rock joint for both physical and numerical tests. From the profile measurements, four roughness parameters, n~mely the average inclination angle I, the root mean square of the first derivative Z2, the modified root mean square of the first derivative Z2' and the fractal dimension D, have been computed and a regression analysis conducted. Physical and numerical results have demonstrated that grain size distribution, expressed in terms of average particle size index As shows a good correlation respectively with the root mean square ofthe first derivative Z2, and its modified version Z2'. The root mean square of the first derivative Z2, and the modified root mean square of the first derivative Z2' increase with the average particle size index As. However, no correlation has been found between the grain size parameter and the fractal dimension D or the average inclination angle I. It has also been found that the joint roughness coefficient JRC and the peak friction angle ~P correlate very well with the average particle size index As. The greater the average particle grain size the higher the joint roughness coefficient JRC and the peak friction angle ~p· The type of correlation between JRC and ~P with As depends on the rock type. Exponential shear strength model has been derived where the average particle size index As is related to the peak friction angle via the residual friction angle ~r·

No description available.

No description available.

An investigation of shear response for various composite material systems is presented. The uniformity of the strain fields is studied experimentally and numerically for different specimen configurations. Conventional strain gage measurements and the moiré interferometry technique are employed to obtain information of actual deformation of the specimen. Based on the contour maps of displacement obtained from moiré tests, the localized hybrid method is used to quantify the magnitude and scale of the nonuniform deformation in the real strain fields. The finite element analysis is also performed for predicting the global nonuniformity of the strain fields. It is shown that the significant nonuniformity in shear deformation observed in experimental results can not be predicted by the existing analytical and numerical models. It is considered that the nonuniformity is primarily at a local level, which is associated with the material inhomogeneity. The implication of the local non-uniform deformation fields on the material property evaluation and failure prediction are discussed. The nonlinearity of shear response is investigated experimentally by performing strain gage and moiré tests. Curve fitting techniques proved to be a convenient and effective tool for characterizing the nonlinear shear response of composites. It is suggested that not only the initial shear modulus but also other coefficients of the fitting function be used for the evaluation of nonlinear shear behavior of a composite. The experimental results show that the nonlinearity has no significant effect on the shear strain distribution, verifying the validity of correction factors in the nonlinear range. Shear stress at a selected shear strain level is suggested as an engineering definition for shear strength of composites. The shear response of some novel composites is also investigated, the test results of which are presented. / Ph. D.

The well-known Timoshenko beam equations (which include transverse shear deformation and rotary inertia effects) are extended for a wide-flanged structure to include the additional shear lag deformation of the flanges; thus, cross-sections of the beam are allowed to distort instead of remaining plane sections. The effect of relative flange bending (bending of the flanges relative to the web) is also included and the integro-differential equations appropriate to the problem are derived. The frequency equation is given in closed form (neglecting the relative flange bending) and solutions for various values of the nondimensional parameters are given. A reduction of the elementary frequency by as much as 40 percent in the first mode is shown. / Master of Science