Wood construction platforms are a common method for inexpensive, temporary soil stabilization under heavy machinery; however, platforms are not typically thought of as an engineered product. Review of literature has shown that only one design method is currently available and is specific to one type of platform configuration. The purpose of this thesis is to develop a design method that is simple, versatile and accurate. The proposed design method was intentionally developed so that the designer would have input in multiple areas of the design. Instrumentation allowed for increased insight into the mechanical behavior of the platforms. The objective of this research is to use measured strain, load, and deflection in conjunction with fundamental engineering mechanics principles to predict a single platform’s mechanical behavior on the ground. Results from this method compare favorably with the only other design guide available and improves the knowledge base by developing design guidance for any type of wood construction platform.

Wood and wood based composites such as hardboard have become very common materials for use in non-structural applications, which include pre-finished paneling, siding, exterior trim, furniture, and door skins. This thesis describes the results of a study of the failure of hardboard door skins. Forces applied during manufacture load the door skins in bending, and in some cases cause a split at the edge of the hardboard. A finite element model as well as a closed form solution based on mechanics of materials were developed to analyze the stresses and deformations of the door skin/stile assembly so that stresses could be predicted for various stile widths and loading conditions. The wood members that make up the frame along the perimeter of the doors, or stiles, were modeled as orthotropic and their properties were selected from available literature. The hardboard was modeled as transversely isotropic, and its properties were determined experimentally. The closed form solution developed can be used to determine the critical geometry for different combinations of hardboard thickness and adhesive joint stiffness. It predicts that as the stile width decreases, the point of maximum deflection, and greatest stresses, moves toward the outside edge of the panel. The ability to predict the critical stile width, or the stile width below which the maximum deflection and stress occurs at the outside edge of the panel, allows one to design the joint to be able to withstand specific loadings and prevent unwanted delamination of the hardboard during manufacture. / Master of Science

The main goal of this research is to develop new and innovative designs for insulated rail joints for improved life cycle and higher cost effectiveness. The research focuses on using electrically insulating materials that replace the epoxy used in current bonded insulated joints. Insulated joints (commonly known as "IJ") are widely used on railways to electrically insulate rail segments from each other, while mechanically connecting them together. The electrical insulation is necessary for accommodating track signals. The mechanical strength is needed to ensure the rail and IJs are able to withstand the vertical, longitudinal, and lateral forces that commonly occur on track. Insulating materials that can replace the epoxy used in bonded insulated joints are researched. The electrical insulation properties and mechanical strength of different materials are examined to determine the suitability of different materials for use in insulated joint. The most promising materials for use are determined to be fiber reinforced polymers and ceramics. Insulated joint designs are developed to accentuate the strengths of these two materials. The Insulating Metal Composite (IMC) insulated joint design that uses ceramics is determined to be the most promising of the new designs and is pursued through prototype fabrication. This particular joint design is analyzed structurally using both closed form analysis and FEA analysis using the software package ABAQUS. Electrical analysis using PSPICE is carried out on the joint. Prototypes of several design iterations of the insulating metal composites are built and tested. A proof of concept static bending test of the insulating metal composites used to build the IMC insulated joint is performed using a Tinius Olsen compressive tester. A rolling-wheel load test is performed on a prototype IMC component installed in rail. Finally, a prototype of a complete IMC insulated joint is fabricated and installed on the FAST test track at TTCI facility in Pueblo, Colorado for field evaluation. Electrical testing using a megohmmeter is performed on a complete prototype joint. Structural analysis shows that the components used to construct the IMC insulated joint can withstand the vertical and longitudinal loads applied to them. Electrical analysis shows that the joint can provide adequate electrical insulation and provides the required dielectric strength in the AREMA Manual for Railway Engineering. The proof of concept test shows that an IMC component can withstand 100 kips of static load without damage. The rolling-wheel load test shows that the ceramic in the IMC components can withstand a large shock load and that the rail used in the IMC insulated joints can survive repeated and shock loads. The testing of the prototype joint on the FAST track, which is ongoing at this time has shown that the new joint concept is fully capable of providing adequate electrical insulation and mechanical strength throughout the expected life of IJs. / Master of Science

Accelerated durability testing of automotive components has become a major interest as it may predict the life characteristics of the vehicle by testing fatigue failure at higher stress level within a shorter period of time. In this work, a specially designed sub-scaled experimental testing bed with the rigid and elastic supports of a simply supported beam was designed and built to compare the effects of the elastic foundation on the change of modal parameters of the tested structure which was later used to tune the FE model. Afterwards, the accelerated loading profiles of both sine sweep and random vibration were applied on the FE model to compare the deviation of the cumulative fatigue damage between the elastic and rigid supports. This work reveals a significant amount of inaccuracy in the current laboratory testing system where the dynamic properties of the tested structure are not maintained close to the real situation. / October 2016

Despite the crucial role they play in transferring loads from the superstructure to the foundation, steel column-to-footing connections have received little attention in research. Though shallow embedded connections are typically characterized as pinned, studies have shown that they exhibit significant rotational stiffness. The objective of this thesis is to quantify the rotational stiffness of such connections. A method named the continuum model is developed by which the rotational stiffness of embedded connections may be calculated. Outputs from this model are compared with experimental data on steel connections embedded in concrete. The continuum model is shown to be capable of reasonably predicting the rotational stiffness of such connections. Results from the model were consistent with those of previous experimental studies that showed that embedment lengths greater than twice the column depth fail to significantly increase stiffness. Plots of rotational stiffness vs. embedment length developed from the continuum model are provided such that rotational stiffness may be calculated for any wide flange shape at any embedment length. Simplified equations provide a simpler way for engineers to estimate the same information.

The complicated process may cause the internal defects of multi-layered ceramic capacitors (MLCCs) and result in the malfunctions. This work aims to investigate the deformations of MLCCs that composed of nearly a hundred of BaTiO3 and Ni electrode films interleaved and stacked due to high pressure at elevated temperature. This study focuses on theoretical and numerical analyses. Classical laminated plate theory, linear elastic assumptions and equilibrium equations were adopted. Associated with the texts by Timoshenko and practical manufacturing process, three types of boundary conditions were considered, such as all edges simple-supported, two opposite edges simple-supported and the other two free, and four edges free. Also, two more conditions need be added, including four fixed points at corners and the elastic foundation at bottom. The numerical simulation by finite element method (FEM) incorporated with software ANSYS was used to obtain the displacement field of MLCCs due to high pressure at elevated temperature. The MLCCs were divided into nine regions with suitably different boundary conditions. Compared with the numerical results the analytical solutions of nine regions were found satisfactorily acceptable, i.e., the errors were about 0.1% - 6.2% for the boundary conditions of four edges free and four corners fixed. The errors about 0.13% - 6.15% were also acceptable for the boundary conditions of two opposite edges simple-supported and the others free. However, the analytical solutions did not agree with the numerical results for the case of all the boundary conditions simple-supported. Finally the proposed theoretical methodology provides an analytical method alternatively, instead of FEM and ANSYS, to analyze a nearly hundred layered MLCCs.

<p>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.</p><p>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.</p><p>Paper<b> A </b>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.</p><p>In papers<b> B </b>and <b>C</b> 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.</p><p>Paper <b>D</b> 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.</p>

No description available.

A clássica teoria de Euler-Bernoulli para vibrações transversais de vigas elásticas é sabido não ser adequada para vibrações de altas freqüências, como é o caso de vibração de vigas curtas. Esta teoria assume que a deflexão deve-se somente ao momento fletor, uma vez que os efeitos da inércia de rotação e da força cortante são negligenciados. Lord Rayleigh complementou a teoria clássica demonstrando a contribuição da inércia de rotação e Timoshenko estendeu a teoria ao incluir os efeitos da força cortante. A equação resultante é conhecida como sendo a que caracteriza a chamada teoria de viga de Timoshenko. Usando-se a matriz de rigidez dinâmica, as freqüências naturais e a resposta dinâmica de estruturas de barras são determinadas e comparadas de acordo com resultados de quatro modelos de vibração. São estudados o problema de vibração flexional de vigas, pórticos e grelhas, bem como o problema de fundação elástica segundo o modelo de Winkler e também a versão mais avançada que é o modelo de Pasternak. / Classical Euler-Bernoulli theory for transverse vibrations of elastic beams is known to be inadequate to consider high frequency modes which occur for short beams, for example. This theory is derived under the assumption that the deflection is only due to bending. The effects of rotary inertia and shear deformation are ignored. Lord Rayleigh improved the classical theory by considering the effect of rotary inertia. Timoshenko extended the theory to include the effects of shear deformation. The resulting equation is known as Timoshenko beam theory. The natural frequencies and dynamic reponse of framed structures are determined by using the dynamic stiffness matrix and compered according to these theories. The flexional vibration problems of beams, plane frames and grids are analysed, as well problems of elastic foundation according the well known Winkler model and also the more general Pasternak model.

A clássica teoria de Euler-Bernoulli para vibrações transversais de vigas elásticas é sabido não ser adequada para vibrações de altas freqüências, como é o caso de vibração de vigas curtas. Esta teoria assume que a deflexão deve-se somente ao momento fletor, uma vez que os efeitos da inércia de rotação e da força cortante são negligenciados. Lord Rayleigh complementou a teoria clássica demonstrando a contribuição da inércia de rotação e Timoshenko estendeu a teoria ao incluir os efeitos da força cortante. A equação resultante é conhecida como sendo a que caracteriza a chamada teoria de viga de Timoshenko. Usando-se a matriz de rigidez dinâmica, as freqüências naturais e a resposta dinâmica de estruturas de barras são determinadas e comparadas de acordo com resultados de quatro modelos de vibração. São estudados o problema de vibração flexional de vigas, pórticos e grelhas, bem como o problema de fundação elástica segundo o modelo de Winkler e também a versão mais avançada que é o modelo de Pasternak. / Classical Euler-Bernoulli theory for transverse vibrations of elastic beams is known to be inadequate to consider high frequency modes which occur for short beams, for example. This theory is derived under the assumption that the deflection is only due to bending. The effects of rotary inertia and shear deformation are ignored. Lord Rayleigh improved the classical theory by considering the effect of rotary inertia. Timoshenko extended the theory to include the effects of shear deformation. The resulting equation is known as Timoshenko beam theory. The natural frequencies and dynamic reponse of framed structures are determined by using the dynamic stiffness matrix and compered according to these theories. The flexional vibration problems of beams, plane frames and grids are analysed, as well problems of elastic foundation according the well known Winkler model and also the more general Pasternak model.