Due to an increase in environmental consciousness in the construction industry there has been increasing interest in using natural building materials like rammed earth construction, straw bale construction and hempcrete construction. These materials have very small embodied energy and are carbon negative or carbon neutral. Hempcrete is a bio-composite mix made up of hemp shive, lime, cement and water. There has been extensive research undertaken on the thermal, acoustic, and mechanical properties of hempcrete. It has low density, good thermal and acoustic insulation properties, and can passively regulate humidity in a built environment. However it also has low compressive strength and modulus of elasticity. Thus hempcrete cannot be used as a direct load bearing material but can used as an infill material in timber stud walls. This thesis investigates how hempcrete can have beneficial structural effects by preventing buckling of timber (increasing the buckling load) columns when used as an infill in between columns in a timber stud wall. Eight timber walls were constructed (both half scale -1200mm high; and full scale – up to 2133mm high) with varying column dimensions. Six of the walls were infilled with hempcrete of varying density. Two walls were not infilled and were baseline tests. All walls were tested in compression. It was found that high density hempcrete (715 kg/m3) not only prevented weak axis buckling of columns but also carried some direct load. Low density hempcrete was also successful in preventing weak axis buckling of the infilled walls. In-filled walls failed in strong axis buckling at a load twice (for half scale walls with 38x89mm columns) or 4 times(full scale walls with 38x235mm columns) that of the unfilled walls. An analytical model based on buckling of a strut on an elastic foundation was proposed to predict the maximum strength hempcrete can add to a wall by preventing buckling. The timber column strength equations from CSA –O86-01 closely predicted the buckling load of the walls from the experiments. The results from the model were also put in design equations from CSA –O86-01 to predict practical failure loads if the walls failed by buckling into hempcrete. Although only a single test result was available, it was in good agreement with the model predictions. / Thesis (Master, Civil Engineering) -- Queen's University, 2012-01-30 21:18:13.842

No description available.

Corrugated paper boxes are the predominant packaging and shipping material and account for the majority of packaging refuse by weight. Wooden pallets are equally predominant in shipping, transportation and warehousing logistics. The interaction between these two components is complex and unexplored leaving industry to compensate with outdated component specific safety factors. Providing a focused exploration of the box and pallet interaction will open the door for holistic design practices that will reduce cost, weight, damage, and safety incidents. This study was separated into four chapters exploring different aspects of the corrugated box to pallet interaction. The first chapter evaluates the support surface provided by a pallet consists of deckboards spaced perpendicular to the length of the pallet. The resulting gaps between deckboards reduce the support to the box. Gaps were limited to 55% of box sidewall length for practical reasons. The effect of gaps was significant and produced a nonlinear reduction in box strength. Small boxes were more susceptible to gaps than larger boxes. Moving the gap closer to the corner increased its effect while increasing the number of gaps did not increase the effect. A modification to the McKee equation was produced that was capable of predicting the loss in strength due to gaps. The equation is novel in that is modifies a widely used equation and is the first such equation capable of handling multiple box sizes. This study also has practical implications for packaging designers who must contend with pallet gap. Chapter 2 explores the relationship between deckboard deflection and box compression strength. Testing found that reducing the stiffness of the deckboard decreases the compression strength of the box by 26.4%. The location of the box relative to the stringer also had varying effects on the box strength. A combination of deckboard stiffness and gaps produced mixed with results with gaps reducing the effect of stiffness. It was observed that lower stiffness deckboards not only deflect but also twist during compression. The torsion is suspected to have a significant influence on compression but further exploration is needed. The third chapter tests the effect of box flap length on box compression strength under various support conditions. Variables included four flap lengths, gaps between deckboards, low stiffness deckboards, column stacking and misaligned stacking. The results show that the box flaps can be reduced by 25% with no significant effect of box strength under any support condition tested. Furthermore, the box flap can be reduced by 50% with less than 10% loss in compression strength under all scenarios. These results have significant sustainability implication as 25% and 50% reduction in box flap reduce material usage by approximately 12% and 24%, respectively. In the fourth and final chapter, the theory of beam-on-elastic foundation is applied to deckboard bending and corrugated boxes. In this model the corrugated box acts and the foundation and the deckboard is the beam. Rotational stiffness, load bridging, and foundation stiffness changes required the development of novel testing solution and model development. The model was capable of predicting the distribution of force along the length sidewall but was not capable of predicting the ultimate strength of the box. The model developed in the study will be applicable in determining potential weakness in the unit load in addition to optimizing those that are over designed. These four chapters represent a considerable contribution of applicable research to a field that relied on outdated safety factors over thirty years. These safety factors often lead to costly over design in an industry where corrugated box and pallets volumes make event the smallest improvements highly beneficial. Furthermore, this research has opened the door for significant additional research that will undoubtedly provided even greater economic and sustainability benefits. / Ph. D.

No description available.

In recent years, the lifetime of an insulated railroad joint in the field has decreased due to increasing wheel loads. The goal of this research is to investigate possible changes in insulated rail joint design in order to improve the performance of the insulated joint. The finite element program ABAQUS is used to model the supported butt joint. In this model, the rail, joint bars, epoxy, and ties surrounding the joint are modeled using solid elements. The remaining ties are modeled as an elastic foundation. The rail is subjected to a tensile load, as well as a vertical wheel load that is applied to the rail using Hertz contact theory. Parametric studies are performed by varying the tie width, joint bar length, and joint bar dimensions. Two different wheel load locations are also investigated: centered about the end post, and halfway between the tie under the end post and the tie just to the left of the end post. The vertical displacement of the rail and insulated joint is one measure used to determine the effect of the parameters on the insulated joint. However, since the most common cause of failure in insulated rail joints is the debonding of the epoxy, this research also focuses on the stresses present in the epoxy when the joint is subjected to a static wheel load. The two out-of-plane shear stresses as well as the normal peel stress are used to compare the various designs of the joint. / Master of Science

[pt] Apesar do conhecimento do comportamento de estruturas sobre base elástica ser importante para a engenharia de forma geral, a motivação deste trabalho está focada na Biomecânica, nos nossos trabalhos envolvendo o grupo de pesquisa da Clínica do Dr.Ivo Pitanguy e da Santa Casa de Misericórdia. Em tese recente de Doutorado, foi realizada uma modelagem da técnica cirúrgica de expansão da pele. A expansão da pele é um processo fisiológico, definido como a capacidade que a pele tem de aumentar sua área superficial em resposta a uma deformação imposta. Durante as expansões acompanhadas pode- se observar que dependendo da região em que o expansor é implantado seu comportamento pode ser bastante distinto. Expansores que são implantados no couro cabeludo iniciam a expansão da pele assim que é introduzida a solução salina no expansor. Quando o expansor é implantado em regiões com mais gordura, como por exemplo na coxa, a expansão da pele não se inicia imediatamente tendo em vista que o expansor se deforma para dentro, pressionando a gordura (que oferece menos resistência) e não a pele. Este comportamento ocasiona abertura dos pontos na cicatriz e pode chegar a inviabilizar todo o processo de expansão naquela região. Para a simulação do processo de expansão da pele, foi feita a expansão com lençol de borracha e para a base elástica foi usado um conjunto que consistia em uma bexiga elástica preenchida com um material viscoso no seu interior. Este trabalho é pioneiro em investigar tanto numérica quanto experimentalmente o comportamento da expansão de lençóis de borracha sobre base rígida e base elástica, comparando o seu comportamento. Os resultados numéricos e experimentais da expansão do lençol de borracha tiveram uma boa concordância e a análise paramétrica da espessura do lençol de borracha comprovou a importância da obtenção mais precisa da espessura da pele pelos médicos, já que as pressões verificadas são bem diferentes para cada espessura. Foram estudadas diversas equações constitutivas, procurando a que melhor descrevesse o processo da expansão da pele. A formulação do material Neo-Hookeano obteve os melhores resultados para o lençol de borracha. Também foi feito um estudo com a formulação de energia de Delfino para estudar a expansão da pele humana. / [en] Despite the knowledge of the behavior of structures on elastic base being important for the engineering of general form, the motivation of this work is focused in the Biomechanics, in our works involving the group of research of the Clinic of the Dr.Ivo Pitanguy and the Saint Casa de Misericórdia. In recent thesis of Dsc., a modeling of the surgical technique of expansion of the skin was carried through. The expansion of the skin is a physiological process, defined as the capacity that the skin has to increase its superficial area in reply to an imposed deformation. During the expansions it could be observed that depending on the region where the expander is implanted its behavior could be sufficiently distinct. Expanders who are implanted on the head initiate the expansion of the skin immediately when the saline solution is introduced in the expander. When the expander is implanted in regions with more fat, as for example in the thigh, the expansion of the skin does not initiate immediately in view of that the expander is deformed to the inner part, pressuring the fat (that offers little resistance) and not the skin. This behavior causes opening of the points in the scar and can make impracticable the process of expansion in that region. For the simulation the process of skin expansion, it was made an expansion with rubber sheet and a set was used for the elastic base that consisted of a filled elastic bladder with a viscous material in its interior. This work is pioneer in investigating numerical and experimentally the behavior of the rubber sheet expansion on rigid base and elastic base, comparing its behavior. The numerical and experimental results of the expansion of the rubber sheet had a good agreement and the parametric analysis of the thickness of the rubber sheet proved the importance of a precise measure of the skin thickness by the doctors, since the verified pressures are different for each thickness. Diverse constituent equations had been studied, looking the one that better described the process of the expansion of the skin. The formularization of the Neo-Hook material got the best results for the rubber sheet. Also a study with the formularization of energy of Delfino was made to study the expansion of the human skin.

The objective of this study is to determine stress intensity factors (SIFs) for a crack in a radially graded FGM layer on a substrate. Functionally graded coating with an edge crack perpendicular to the interface and a homogeneous substrate are bonded together. In order to make the problem analytically tractable, geometry is modeled as an FGM strip attached to a homogeneous layer. Introducing the elastic foundation underneath the homogeneous layer, an FGM coating on a thin walled cylinder can be modeled. At first, governing equations are obtained from stress displacement and equilibrium equations. Then using an assumed form of solution in terms of Fourier Transforms for displacements and applying the boundary conditions, a singular integral equation is obtained for the mode-I problem. Solving this singular integral equation numerically, stress intensity factors are obtained as functions of crack length, strip thicknesses and inhomogeneity parameter.

[pt] O estudo de estacas semi-enterradas tem grande importância na construção civil devido principalmente à sua ampla aplicação em diversas áreas da engenharia. O presente trabalho tem como objetivo obter uma solução exata para as freqüências naturais e modos de vibração dessas estacas e, com base nestes resultados, analisar o comportamento do sistema não-linear. A análise das vibrações lineares parte da obtenção de um funcional de energia e dedução das equações diferenciais parciais de movimento para o trecho enterrado e desenterrado e a determinação das diversas famílias de soluções para cada equação de movimento em função dos parâmetros adimensionais característicos do problema. Essa solução exata possibilita mostrar a influência dos parâmetros de carregamento, de rigidez da fundação, da altura da fundação e das condições de apoio nas freqüências naturais e modos de vibração. A não- linearidade do problema é originária da geometria da estrutura e a sua consideração implica na obtenção de equações diferenciais não-lineares. A resolução destas equações é feita de forma aproximada, empregando-se o método de Ritz para discretizar a coluna no espaço e os métodos de Galerkin-Urabe e do Balanço Harmônico para resolver as equações de movimento resultantes do processo de discretização. Com base nestes resultados, analisa-se a influência dos parâmetros físicos e geométricos do sistema coluna-fundação nas vibrações livres e forçadas da estaca. / [en] The study of partially embedded piles is an important topic in civil engineering due to its use in several engineering fields. The aim of the present work is to derive an exact solution for the natural frequencies and vibration modes of these piles and, based on these results, to analyze the nonlinear behavior of the column-foundation system. In order to study the free vibration problem, the energy functional of the system is obtained, allowing the derivation of the partial differential equations of motion for the buried and unburied parts of the pile. The possible solutions of these equations are then obtained as a function of a set of non-dimensional parameters characteristic of the problem. The consideration of the geometric nonlinearity of the beam leads to a set of nonlinear differential equations. The solution of these equations is obtained by employing the Ritz method to discretize the column in space and the methods of Galerkin- Urabe and Harmonic Balance to derive an approximate solution for the resulting equations of motion. Based on these results, the influence of the geometrical and physical parameters of the column-foundation system on the free and forced non-linear vibrations of the pile is analyzed.

The general trend toward increased use of computer models and simulations during product development has led to a need for accurate and reliable product models. The function of many products relies on contact interfaces between interacting components. To simulate the behavior of such products, accurate models of both components and interfaces are required. Depending on the purpose of the simulation, interface models of different degrees of complexity are needed. In simulation of very large systems with many interfaces, it might be computationally expensive to integrate detailed models of each individual interface. Condensed models, or abstractions, that describe the interface properties with a minimum of degrees of freedom are therefore required. This thesis deals with mechanical interfaces with an emphasis on friction. In the four appended papers friction models are discussed in terms of condensed models, as well as in terms of more detailed contact models. The aim is to study how friction can be modeled in behavioral simulation of products and to discuss the convenience and relevance of using different types of friction models as building blocks of a system model in behavioral simulations. Paper A presents a review of existing condensed friction models for sliding contacts under different running conditions and discusses the models from both simulation and tribological points of view. In papers B and C a simplified contact model, called the elastic foundation model, is used to model friction in a boundary-lubricated rolling and sliding contact. The model is integrated in a dynamic rigid body model of a mechanical system, the system behavior is simulated, and the result is compared with experimental results. Paper D discusses the application of the elastic foundation model to rough surface contact problems and investigates how the error in the elastic foundation results depends on surface roughness. / QC 20101129

<p> Various analytical methods for studying the behaviour of shallow conical shells on Euler-Winkler elastic foundation are presented. </p> <p> To account for the nature of concrete and the geometric properties of the shallow conical shell, Poisson's ratio and certain radial and circumferential deformations of the middle surface are neglected in deriving the basic differential equation. Analytical methods employed in the solution of this shell problem are the GECKELER and asymptotic types of approximations. </p> <p> The presentations of various methods of analysis are made for a representative case of dimensions and loadings of the conical shell to make them as applicable as possible to the cases of thin conical shell commonly encountered in industry. </p> <p> The shell structure studied is a tank in the form of a rotationally symmetrical cylindrical shell supported by a shallow conical shell foundation. The construction joint between the conical shell and the cylindrical shell is either monolithic or hinged. </p> <p> The analytical results of this water tank supported on Euler-Winkler elastic foundation are compared with the corresponding findings of W. Flügge, who assumed a uniform soil bearing pressure acting on the conical shell structure. </p> The method of analysis which possesses obvious advantages over the other methods studied is selected to examine the effect of different elastic stiffness coefficients of the soil. The validity of simplifying the soil bearing pressure to a uniform distribution by most designers can consequently be studied by comparing it to the bearing pressures of an ideal elastic soil which is postulated to react to its deformation like a bed of independent elastic springs. </p> / Thesis / Master of Engineering (ME)