Os GCLs (Geosynthetic Clay Liners) são materiais geossintéticos destinados a compor sistemas de controle de fluxo em obras geotécnicas e ambientais. Suas propriedades vêm sendo cada vez mais estudadas visando a avaliação de seu comportamento de curto e longo prazo. Dentre as propriedades mais importantes de um GCL, está a sua resistência ao cisalhamento interno, tendo em vista que o seu principal componente, a bentonita, possui baixa resistência quando hidratada. Este trabalho apresenta o desenvolvimento de uma nova metodologia de ensaio-índice para estimativa da resistência ao cisalhamento em GCLs - o método CTM (cisalhamento por tração modificado). A principal inovação do método proposto é o formato \"U\" da garra para fixação dos corpos-de-prova. Foram executadas duas séries de ensaios, nas quais, realizou-se uma seleção criteriosa das amostras e um plano de preparação dos corpos-de-prova, de forma a evitar que a variabilidade inerente à fabricação dos GCLs, influenciasse nos resultados obtidos. A primeira fase de testes foi realizada com o objetivo de se correlacionar os resultados do método CTM com dois outros métodos de ensaios-índice existentes: ensaio de adesão (peeling-test) e ensaio de cisalhamento por tração (shear-tensile test). Os resultados obtidos apresentaram boa correlação e o método CTM se mostrou bastante prático. A segunda série de ensaios foi realizada visando aprimorar a montagem do ensaio CTM e comparar os seus resultados com ensaios de cisalhamento direto. Novamente as metodologias se correlacionaram bem, o que justifica o desenvolvimento do método CTM. / GCLs (Geosynthetic Clay Liners) are geosynthetic products used to compose flux control barriers in geotechnical and environmental works. The mechanical properties of GCLs have to be investigated in short and long term. Among its mechanical parameters, GCL internal shear strength plays an important role in the stability of slopes of geotechnical works. The main component of a GCL, the bentonite, when hydrated, presents very low shear strength. This work presents the development of a new index test method that aims cheaply and quickly to estimate the shear strength of GCLs - the CTM method (modified shear-tensile test). The main innovation of the proposed method is the U-shape grip that imposes a state of deformation close to that observed in field works. Two series of tests were performed in which a careful selection of samples and specimens were done. This aimed to minimize variation effects, inherent to the GCL production, on the obtained results. The first series was carried out to correlate results from the CTM tests to other two index tests: peel test and shear-tensile test. The results showed a good correlation between CTM and the other test results. The second series of tests was planned to improve CTM test method in order to get even better results than peel or shear-tensile tests, apart from correlating its results to results of direct shear test. Comparisons of results show very good agreement what justifies the use of the cheaper and quicker CTM method.

The diploma thesis deals with the study of Inter-Laminar Shear Strength (ILSS) of polymer composites, based on unsaturated polyester resin with unidirectionally oriented basalt or glass fibers. The basis of the experimental part is the preparation of composite samples with different types of surface treatment of a fibers (a reinforcement) as well as the surface treatment itself. The untreated, the commercially treated fibers and the plasmatreated fibers used as reinforcement in the polymer composites were analysed by a short beam shear test and their ILSS was determined. The effect of various deposition conditions during Plasma-Enhanced Chemical Vapour Deposition (PECVD) on the value of ILSS of the composite with originally unsized glass or basalt fibers was studied. The impact of aging on the interlaminar shear strength of the composites was investigated for commercially treated glass fibers. The Scanning Electron Microscopy (SEM) is also used in the thesis together with the Energy Dispersive Spectroscopy (EDS). Based on all the results a proposal was made to correct and improve the deposition conditions and thus improve the interphase to achieve the required shear properties of polymer composites.

The project contains theoretical research of electrotechnical manufacture for lead-free reflow soldering. It contains characterization of soldering processes. Includes variations of solder paste printing, principles of part placing and also reflow soldering process. The project appoints possibilities of testing solder joints strength, mainly focused on mechanical vibrations. It describes a design and preparation of solder joint strength test methods by mechanical vibrations. It compares influence of vibrations on part types and solder alloys.

In the cold-formed steel construction, the oriented strand board is a common material for shear wall sheathing. an OSB is made by using wood chips as raw materials that undergo high temperature pressing to create a multi-larger structure material. Due to the OSB having a high strength in shear, it is an important material used in the construction field. the thesis is trying to verify published nominal shear strength in AISI-213-07 in the first part. This objective has two parts: the first part is to verify nominal shear strength (Rn) for wind and other in-plane loads for shear wall. the second part is to verify nominal shear strength (Rn) for seismic and other in-plane loads for shear wall. Secondly, the thesis verifies the design deflection equation for nominal shear strength of CFS shear walls with OSB sheathing. the test specimens were divided into eight groups which trying to verify the design deflection equation that was published in AISI-213-07 standard.

Objetivo: Evaluar la resistencia adhesiva a dentina de sistemas adhesivos universales Ambar™ Universal (FGM), Tetric® N-Bond Universal (Ivoclar), Scotchbond™ Universal (3M ESPE) con y sin cinta celuloide como inhibidor de la capa de oxígeno. Materiales y Métodos: 90 dientes bovinos fueron seleccionadas y cortados. Se expuso la dentina con una lija grano 320 y las coronas fueron fijadas en bases acrílicas. Se distribuyeron en tres grupos(n=30): G1-Ambar™Universal; G2-Tetric®N-Bond Universal; G3-Scotchbond™ Universal. Los procedimientos adhesivos fueron aplicados según cada fabricante y se empleó la técnica de inhibición de la capa de oxígeno con cinta celuloide según cada grupo. El procedimiento restaurador fue realizado con microcilindros (2mm.x4mm) de resina Filtek™Z350XT-A2. Las muestras fueron almacenadas en una estufa por 24 horas. Se evaluó la resistencia adhesiva en una máquina de ensayo universal mediante test de cizallamiento (0,5 mm/min,500N), el tipo de fractura fue evaluada con un microscopio digital Dino-Lite (x50). La estadística descriptiva se realizó mediante media, desviación estándar; y la inferencial se realizó mediante pruebas de Kruskall-Wallis y U de Mann Whitney. Resultados: No se observaron diferencias significativas al comparar la resistencia adhesiva de los adhesivos Tetric® N-Bond Universal (4.14±1.73)(4.62±3.79), Scotchbond™ Universal (6.48±2.26)(10.64±4.68) a excepción de Ambar™ Universal (11.34±6.47)(10.74±4.45). Asimismo, se compararon estos adhesivos según la técnica con inhibición(p=0.001) y sin inhibición(p=0.002). Conclusiones: Ambar™ Universal presentó mayor resistencia adhesiva en la técnica con inhibición que los otros adhesivos empleados. Sin embargo, no hubo diferencia entre los valores de resistencia con y sin técnica de inhibición. / Objective: To evaluate dentine bond strength of universal adhesive systems Ambar™ Universal (FGM), Tetric® N-Bond Universal (Ivoclar), Scotchbond™ Universal (3M ESPE) with or without celluloid strip as an oxygen-inhibited layer. Materials and methods: 90 bovine teeth were selected and cleaned. Dentine was exposed with #320-grit silicon carbide paper and the crowns placed on acrylic bases. They were distributed in three groups (n=30): G1-Ambar™ Universal; G2-Tetric® N-Bond Universal; G3-Scotchbond™ Universal. The adhesives procedures were made according to the manufacturer's instructions and the oxygen-inhibited layer technique using celluloid strip was applied according to each group. The restorative process was made using cylinders (2mmx4mm) with composite resin Filtek™Z350XT-A2. The samples were stored in an incubator for 24 hours. Each group was subjected to the shear bond strength test (0.5mm/min,500N) and the type of fracture was evaluated using a digital microscope Dino-Lite (x50). The data were estimated through descriptive statistics (mean, standard deviation) and the inferential was analysed by Kruskall-Wallis and U Mann Whitney test. Results: No significant differences were observed when comparing bond strength of three adhesives Tetric® N-Bond Universal (4.14 ± 1.73)(4.62 ± 3.79), Scotchbond™ Universal (6.48 ± 2.26)(10.64 ± 4.68) except Ambar™ Universal (11.34 ± 6.47)(10.74 ± 4.45). Likewise, adhesives were compared with oxygen-inhibited layer (p=0.001) and without (p=0.002). Conclusions: Ambar™ Universal showed the highest bond strength with oxygen-inhibited technique instead of the others used adhesives However, no differences were observed between the strength values with oxygen-inhibited layer or without it. / Tesis

Joints are the main features encountered in rock and sliding of rock blocks on joints is classified as the principal source of instability in underground excavations. In this regard, joints’ peak shear strength is the controlling parameter. However, given the difficulty in estimating it, shear tests are often performed. These are often quite expensive and also time consuming and, therefore, it would be valuable if shear tests could be artificially performed using numerical models. The objective of this study is to prove the possibility to perform virtual numerical shear tests in a PCF2D environment that resemble the laboratory ones. A numerical model of a granite rock joint has been created by means of a calibration process. Both the intact rock microparameters and the smooth joint scale have been calibrated against macroparameters derived from shear tests performed in laboratory. A new parameter, the length ratio, is introduced which takes into account the effective length of the smooth joint compared to the theoretical one. The normal and shear stiffnesses, the cohesion and the tensile force ought to be scaled against the length ratio. Four simple regular joint profiles have been tested in the PFC2D environment. The analysis shows good results both from a qualitative and from a quantitative point of view. The difference in peak shear strength with respect to the one computed with Patton´s formula is in the order of 1% which indicates a good accuracy of the model. In addition, four profiles of one real rough mated joint have been tested. From the scanned surface data, a two-dimensional profile has been extracted with four different resolutions. In this case, however, interlocking of particles along the smooth joint occurs, giving rise to an unrealistic distribution of normal and shear forces. A possible explanation to the problem is discussed based on recent developments in the study of numerical shear tests with PFC2D.

<p>QCR 20161026</p>

The deep mining and civil engineering industry need to perform rock stability analyses during excavation projects. The stability is mainly controlled by the shear strength of the rock fractures, which are the weakest point of the rock mass. In turn, the shear strength is governed by the mechanical properties of the fractures. It is both time and cost demanding to determine the properties of the rock fractures in laboratory. Also, the interpretation of the results requires a deep understanding of the normal and shear behaviour of rock fractures. This study aims to investigate if it is possible to determine the peak shear strength of rock fractures by merely estimating fracture parameters during field mapping and core logging. SKB supplied test results on drilled bore cores from site investigations in Forsmark and Laxemar for deep nuclear waste deposits. SKB generated data of high quality and in large quantity, which made it very valuable for the purpose of the study. The study begins with a literature review and an interaction matrix, clarifying the relationships between mechanical properties and affecting parameters of rock fractures. The predicted relationships of the parameters are then tested in an analysis based on the compiled data from SKB. The results show that the peak friction angle, the residual friction angle and the dilation angle are possible to approximate for open granite fractures in deep mining projects. Further on, the study proposes that the joint matching coefficient is included in the field mapping and core logging since it has a strong influence on the mechanical behaviour of the fracture, notably the normal and shear stiffness. Finally, the study questions estimations of JRC on small samples.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 275-277. / by Maureen Anne Kestler. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 133-135. / by William Eugene Hadge. / M.S.