<p>The pressure-density relationship and the pressure distribution inside the compression chamber of a newly designed New Holland BB960 large square baler were studied for the baling of alfalfa, whole green barley, barley straw, and wheat straw. An analytical model was developed for the pressure distribution inside the compression chamber of the large square baler in the x-, y-, and z-directions by assuming isotropic linear elastic properties for forage materials. In order to validate this model, a tri-axial sensor was designed and used to measure the forces inside the compression chamber when whole green barley, barley straw, and wheat straw were baled. The experimental results proved that the developed analytical model for each of the tested forage materials had a good correlation with the experimental data with a reasonable coefficient of determination (0.95) and standard error (20.0 kPa). Test data were also used to develop an empirical model for the pressure distribution inside the compression chamber of the baler for each of the tested forage materials using least square method in regression analysis. These empirical models were simple equations which were only functions of the distance from the full extension point of the plunger along the compression chamber length.</p><p>Analytical and empirical models were also developed for the pressure-density relationship of the baler for baling alfalfa and barley straw. Results showed that bale density initially decreased with distance from the plunger, and then remained almost constant up to the end of the compression chamber. The developed empirical model for both alfalfa and barley straw was a combination of a quadratic and an exponential equation. In order to validate the developed models, field tests were performed by baling alfalfa and barley straw of different moisture contents, flake sizes, and load settings. The forces on the plunger arms were recorded by a data acquisition system. The actual bale bulk density was calculated by measuring the bale dimensions and weight. Results showed that both load setting and flake size had a significant effect on the plunger force. The plunger force increased with increased load setting and flake size. Comparing analytical and empirical models for bale density as a function of the pressure on the plunger showed that the trend of variation of density with pressure in both models was similar, but the rate of change was different. The variation rate of density with pressure in the analytical model was higher than that of the empirical model. The analytical model underestimated the bale density at low plunger pressures but showed more accurate prediction at higher pressures, while the empirical model accurately predicted the bale density at both low and high pressures. Some crop properties such as coefficient of friction and modulus of elasticity were determined for the development of the pressure distribution model. Results showed that static coefficient of friction of alfalfa on a polished steel surface was a quadratic function of material moisture content, while the relationship between the coefficient of friction of barley straw on a polished steel surface and material moisture content was best expressed by a linear equation. Results of this study also proved that modulus of elasticity of alfalfa and barley straw was constant for the density range encountered in the large square baler.</p>

Unconventional oil and gas, which is of major interest in petroleum industry, often occur in reservoirs with transversely isotropic rock properties such as shales. Overlooking transverse isotropy may result in deviation in stress distribution around wellbore and inaccurate estimation of fracture initiation pressure which may jeopardize safe drilling and efficient fracturing treatment. In this work, to help understand the behavior of transversely isotropic reservoirs during drilling and fracturing, the principle of generalized plane-strain finite element formulation of anisotropic poroelastic problems is explained and a finite element model is developed from a plane-strain isotropic poroelastic model. Two numerical examples are simulated and the finite element results are compared with a closed form solution and another FE program. The validity of the developed finite element model is demonstrated. Using the validated finite element model, sensitivity analysis is carried out to evaluate the effects of transverse isotropy ratios, well azimuth, and rock bedding dip on pore pressure and stress distribution around a horizontal well. The results show that their effect cannot be neglected. The short term pore pressure distribution is sensitive to Young’ modulus ratio, while the long term pore pressure distribution is only sensitive to permeability ratio. The total stress distribution generally is not sensitive to transverse isotropy ratios. The effective stress and fracture initiation are very sensitive to Young’ modulus ratio. As the well rotates from minimum horizontal in-situ stress to maximum horizontal in-situ stress, the pore pressure and stress distributions tend to be more unevenly distributed around the wellbore, making the wellbore easier to fracture. The pore pressure and stress distributions tend to "rotate" in correspondence with the rock bedding plane. The fracture initiation potential and position will alter when rock bedding orientation varies.

Este trabalho apresenta uma metodologia para predição da distribuição de pressão sobre uma asa bi-trapezoidal genérica usando redes neurais artificiais. O toolbox de redes neurais do MatLab® foi utilizado para o treinamento e validação das redes neurais e os conjuntos de treinamentos foram obtidos por meio do software BLWF® versão 28 (Boundary Layer Wing-Fuselage) um código CFD (Computacional Fluid Dynamics) de potencial completo com correção de camada limite. Levando em consideração o nível de complexidade do problema, optou-se por dividir o estudo em três etapas de desenvolvimento. Inicialmente, uma rede neural foi treinada considerando apenas as variáveis de condição de voo e de forma em planta. Resultados promissores motivaram a criação de uma segunda rede neural, mais genérica, na qual foram adicionadas variáveis de três perfis distribuídos ao longo da asa. Porém apenas um desses perfis era variável enquanto que os demais eram parametrizados com relação à este perfil. Criou-se, por fim, uma rede neural ainda mais genérica, desta vez atentando também para as variáveis dos três perfis de modo independente. Os resultados obtidos mostram que esta metodologia pode ser usada como interessante ferramenta para obtenção de distribuição de pressão, especialmente em projetos de MDO (Multi-Disciplinary Optimization), uma vez que ela possibilita uma predição rápida, precisa e de fácil automatização de pressão em uma asa genérica. / This work shows a method for predicting pressure distribution over a generic bi-trapezoidal wing using artificial neural networks. The MatLab® Neural Network Toolbox was used for the neural network implementation and the training set was obtained using the BLWF® version 28 (Boundary Layer Wing-Fuselage), a full potential CFD (Computational Fluid Dynamics) code with boundary layer correction. The work was divided in three development phase, according with the problem complexibibility level. Initially, a neural network considering only flight conditions and plan form variables was trained. Promising results motivated the generation of a more generic neural network, considering also parameters of three airfoils distributed along the wing spanwise and chordwise. However only one airfoil was variable, the two other were parametrized in relation to the variable airfoil. At last, an even more generic neural network was generated, this time considering also the variables of the three profiles independently. The results show that this methodology can be successfully used as an interesting tool to obtain the pressure distribution, especially on the solution of MDO (Multi-Disciplinary Optimization) problems, since it allows fast prediction, automation facility and accurate measuring of the pressure distribution under a generic wing.

Pallets are the foundation of unit loads and supply chains. They provide a way to store and transport products in an efficient manner. The load capacity of pallets greatly depends on the type of packages carried by the pallet; however, current pallet design methods do not consider the effect of packages on the load carrying capacity of the pallet. This results in excessive use of materials which reduces the sustainability of unit loads, drives costs up, and creates issues for people in the supply chain. The objective of this study was to investigate the effect of a corrugated box's size and head space on pallet deflection and stress distribution on the top of the pallet as a function of pallet stiffness across multiple pallet support conditions. Data analysis identified that box size had a significant effect on the deflection of the pallet. This effect was only significant for warehouse racking across the width and length support conditions. As much as a 53% reduction in pallet deflection was observed for high stiffness pallets supporting corrugated boxes with 25.4 mm headspace when the size was increased from small to large. Meanwhile, no significant effect of box size was found for other supports. The effect of headspace was significant in some scenarios but inconsistent thus more investigation with a larger sample size is recommended. In addition, redistribution of vertical compression stresses towards the supports was observed as a function of the increasing box size. The increased concentration of compression stresses on top of the supports and the resulting lower pallet deflection could significantly increase the actual load carrying capacity of some pallet designs. / Master of Science / Pallets are the foundation of unit loads and supply chains. They provide a way to store and transport products in an efficient manner. The load capacity of pallets greatly depends on the type of packages carried by the pallet; however, current pallet design methods do not consider the effect of packages on the load carrying capacity of the pallet. This results in excessive use of materials which reduces the sustainability of unit loads, drives costs up, and creates issues for people in the supply chain. The objective of this study was to investigate the effect of a corrugated box’s size and head space on pallet deflection and stress distribution on the top of the pallet as a function of pallet stiffness across multiple pallet support conditions. The data from the study identified that box size does have an effect on the deflection of the pallet but, it was only found to be significant for the warehouse racking supports. The highest reduction in pallet deflection was 53% on the high stiffness pallets carrying corrugated boxes with 25.4 mm of headspace as the boxes increased in size. The other support conditions showed no significant effect of the box size. Headspace showed some significant effect in some conditions but was found inconsistent, therefore an investigation with a larger sample size is recommended. In addition, the redistribution of vertical compression stresses towards the supports was observed as a function of increasing box size. This increase in stress on the supports resulted in lower pallet deflection that could significantly increase the actual load carrying capacity of some pallet designs.

In this paper a 2D coupled thermal-stress finite element model is established and used to predict thermal phenomena at the disc-pad interface of a disc brake system. The importance of certain critical settings and parameters for the 2D FE model has been identified (such as, a limited degree of freedom for a brake pad in place of accepted practice that considers uniform contact), here a non-uniform pressure distribution resulting from friction bending moment effects due to the introduction of a pivot point. These parameters affect the distributions of both interface temperature and pressure. The simulation results show that when the interface conductance h is 10^6 W/m^2K or higher, the interface temperature distribution is no longer sensitive to friction bending moment effects. However, when h is 30000 W/m^2K or lower, the interface temperature distribution and heat partition ratio are significantly affected by the setting used for the rotational degree of freedom of the pad. The simulation results provide a useful reference for a better design of a disc brake system for different applications.

Although sitting is a large part of everyday life is the influence of the sitting positions and chair design on pressure and load distribution as well as comfort for transfemoral amputees quite unexplored. The aim of this study was therefore to examine this further. Two transfemorally amputated females (49 and 57 years old) participated in the study. Three positions were examined for each subject; sitting without foot support and sitting with the knee joints flexed 90◦ and 105◦. The pressure inside the socket was measured by two pressure sensors, placed distally and proximally on the posterior wall inside the socket. The lengthwise pressure distribution and the sidewise load distribution between the socket and the underlying material was measured by a pressure mat. In addition to this, the subjects answered a questionnaire regarding the subjective comfort for each position.  The result showed that the pressure underneath the socket were higher distally than proximally without foot support. The pressure transferred proximally as the knee became more flexed. The most even load distribution sidewise was found when the subjects sat with their knees flexed 105 degrees. Sitting with the knees flexed 90◦ was ranked as the most comfortable position. No conclusion could be made regarding the pressure inside of the socket. Additionally, according to this study the level of comfort does not have any clear relation with the sidewise load distribution or the longitudinal pressure distribution. / En stor del av livet spenderas sittandes, men den påverkan som sittposition och stoldesign har på tryckfördelning och komfort för transfemoralt amputerade är ganska outforskat. Studien ämnar därför undersöka detta. Två transfemoralt amputerade kvinnor (49 och 57 år) medverkade i studien. Tre sittpositioner undersöktes för varje testperson; sittande utan fotstöd samt sittande med knäleden i 90◦ respektive 105◦ flexion. Trycket inuti hylsan mättes med hjälp av två trycksensorer, som placerades distalt och proximalt på den bakre hylsväggen. Tryckfördelningen i längsriktningen och lastfördelningen i sidled mellan hylsan och underlaget mättes med en tryckmatta. Förutom detta svarade testpersonerna även på ett frågeformulär angående den subjektiva komforten för varje position. Resultatet visade att trycket under hylsan var högre distalt än proximalt när inget fotstöd användes. Trycket förflyttades proximalt då knät böjdes. Den mest jämna lastfördelningen mellan sidorna påträffades när knät var flekterat 105◦. Enligt frågeformuläret var den mest bekväma positionen den med 90◦ i knäleden. Ingen slutsats kunde göras angående trycket inuit hylsan. Ingen tydlig relation kunde heller inte hittas mellan den subjektiva komforten och tryck- eller lastfördelningen.

<p>A method has been developed for flexible modelling of multi-component twin-wire blade formers. Features such as suction devices, loadable blades, curved blades, and partial contact between the blades and the forming fabrics are easily incorporated. New results include a series of calculations demonstrating the non-trivial interaction between the pressure pulses when the blades are positioned successively closer together, the effects of suction on the pressure pulse generated by a blade applied to the opposing wire, and how blades of modest curvature do not necessarily stay in contact with the fabric along their full width and the implications of this on the pressure gradients in the machine direction. </p><p>The behaviour of the fibre mats as they experience the first of the blade pulses (after having been formed over a roll) is then considered in detail. Typically, the thickness of the mats decreases during the pulse, which reduces the rate of deposition of new fibres onto the webs. The amount of fibres in the sheets therefore changes marginally. Nevertheless, the resistance to drainage presented by the fibre network is seen to increase significantly due to the low permeability in highly compressed layers of the mat. As a result of the pressure gradients in the machine direction, the shear stresses in the plane of the fibre sheets can attain several hundred Pascal next to the forming fabrics.</p><p>Further, a model for sheared consolidation of flocculated suspensions is presented that extends the concept of a concentration dependent yield stress, previously employed in studies of uniaxial consolidation, to comprise flocculated phase shear strength. Rate-dependent viscous stresses are also incorporated. The theory is applied to the problem of combined compression and shearing of a strongly flocculated suspension contained between two plates, one being fixed and acting as a perfectly permeable filter, the other movable and acting as a piston by which the load is applied. Qualitatively, the evolution of the volume fraction of solids exhibits the same behaviour as during uniaxial consolidation without shear. Applying shear is however predicted to increase the rate of the drainage process, due to a reduced load bearing capacity of the flocculated phase, and correspondingly higher pore pressures. </p>

<p>During papermaking, the internal structure of the fibrenetwork constituting the paper is to a dominating extentdetermined in the forming zone of the paper machine. Thisthesis is aimed at studying the pressure distribution in bladeforming sections, which is commonly considered to be a keyquantity of the process.</p><p>Previous work has provided insight into the physics ofdifferent devices employed in blade forming. However, there hasbeen a lack of models enabling studies of the effects of theinteraction between different components on the pressuredistribution. In the thesis, a model is presented for a genericblade forming section consisting of three blades. The positionsof two of the blades are fix, and in between them is located asuction box. The third blade is applied by a prescribed forceto the opposing wire, in a position facing the suction box. Themodel admits the study of the interaction between the pulsesfrom the different blades in the blade/counterbladeconfiguration, and between the pulses and one-sidedsuction.</p><p>The wires are modelled as tensioned and perfectly flexibleEuler-Bernoulli beams of negligible mass. The suspension istreated like an inviscid fluid. Consideration is taken to theinfluence of fibre deposition on the permeability of thefabrics. By assuming the ratio between the length scales in thethickness direction and the machine direction to be small, aquasi one-dimensional model is obtained.</p><p>For maximum flexibility, the model domain is divided intomodules. Each module is solved individually using a finitedifference based discretisation. The solutions for thedifferent modules are matched with each other iteratively.</p><p>A comparison with published results for a single bladeindicates that the model can be used to obtain qualitativelycorrect predictions of the pressure distribution. New resultsinclude a series of calculations showing the non-trivialinteraction between the pressure pulses when the blades arepositioned successively closer together, the effects of suctionon the pressure pulse generated by a blade applied to theopposing wire, and how blades of modest curvature do notnecessarily stay in contact with the fabric along their fullwidth and the implication of this on the pressure gradient.</p><p><b>Descriptors:</b>fluid mechanics, blade forming, pressuredistribution, suction, interaction, permeable fabric,modules</p>

As a result of manufacturing processes, real surfaces have roughness and surface curvature. The real contact occurs only over microscopic contacts, which are typically only a few percent of the apparent contact area. Because of the surface curvature of contacting bodies, the macrocontact area is formed, the area where microcontacts are distributed randomly. The heat flow must pass through the macrocontact and then microcontacts to transfer from one body to another. This phenomenon leads to a relatively high temperature drop across the interface. Thermal contact resistance (TCR) is a complex interdisciplinary problem, which includes geometrical, mechanical, and thermal analyses. Each part includes a micro and a macro scale sub-problem. Analytical, experimental, and numerical models have been developed to predict TCR since the 1930's. Through comparison with more than 400 experimental data points, it is shown that the existing models are applicable only to the limiting cases and none of them covers the general non-conforming rough contact. The objective of this study is to develop a compact analytical model for predicting TCR for the entire range of non-conforming contacts, i. e. , from conforming rough to smooth sphere-flat in a vacuum. The contact mechanics of the joint must be known prior to solving the thermal problem. A new mechanical model is developed for spherical rough contacts. The deformation modes of the surface asperities and the bulk material of contacting bodies are assumed to be plastic and elastic, respectively. A closed set of governing relationships is derived. An algorithm and a computer code are developed to solve the relationships numerically. Applying Buckingham Pi theorem, the independent non-dimensional parameters that describe the contact problem are specified. A general pressure distribution is proposed that covers the entire spherical rough contacts, including the Hertzian smooth contact. Simple correlations are proposed for the general pressure distribution and the radius of the macrocontact area, as functions of the non-dimensional parameters. These correlations are compared with experimental data collected by others and good agreement is observed. Also a criterion is proposed to identify the flat surface, where the influence of surface curvature on the contact pressure is negligible. Thermal contact resistance is considered as the superposition of macro and micro thermal components. The flux tube geometry is chosen as the basic element in the thermal analysis of microcontacts. Simple expressions for determining TCR of non-conforming rough joints are derived which cover the entire range of TCR by using the general pressure distribution and the flux tube solution. A complete parametric study is performed; it is seen that there is a value of surface roughness that minimizes TCR. The thermal model is verified with more than 600 data points, collected by many researchers during the last 40 years, and good agreement is observed. A new approach is taken to study the thermal joint resistance. A novel model is developed for predicting the TCR of conforming rough contacts employing scale analysis methods. It is shown that the microcontacts can be modeled as heat sources on a half-space for engineering applications. The scale analysis model is extended to predict TCR over the entire range of non-conforming rough contacts by using the general pressure distribution developed in the mechanical model. It is shown that the surface curvature and contact pressure distribution have no effect on the effective micro thermal resistance. A new non-dimensional parameter is introduced as a criterion to identify the three regions of TCR, i. e. , the conforming rough, the smooth spherical, and the transition regions. An experimental program is designed and data points are collected for spherical rough contacts in a vacuum. The radius of curvature of the tested specimens are relatively large (in the order of m) and can not be seen by the naked eye. However, even at relatively large applied loads the measured joint resistance (the macro thermal component) is still large which shows the importance of surface out-of-flatness/curvature. Collected data are compared with the scale analysis model and excellent agreement is observed. The maximum relative difference between the model and the collected data is 6. 8 percent and the relative RMS difference is approximately 4 percent. Additionally, the proposed scale analysis model is compared/verified with more than 880 TCR data points collected by many researchers. These data cover a wide range of materials, surface characteristics, thermal and mechanical properties, mean joint temperature, directional heat transfer effect, and contact between dissimilar metals. The RMS difference between the model and all data is less than 13. 8 percent.

Argamassas no estado fresco são suspensões heterogêneas multifásicas com grande extensão granulométrica, tendo um comportamento relativamente complexo. Para a sua caracterização reológica já é empregado o ensaio de squeeze flow, método normalizado (ABNT NBR 15839/2010) que fornece informações importantes sobre o fluxo das argamassas em condições similares às de aplicação prática. No entanto, alguns fenômenos relevantes relacionados ao squeeze flow de suspensões não podem ser diretamente avaliados somente através da resposta padrão do ensaio (curva carga ou tensão vs. deslocamento), como o tipo de fluxo e a ocorrência de separação de fases, não havendo ainda um método consolidado para investigação destes efeitos. Neste contexto, uma técnica de mapeamento dinâmico da distribuição de pressão interfacial é apresentada como ferramenta para a complementação do método, visando permitir uma análise mais aprofundada durante o ensaio de squeeze flow em argamassas, nas configurações de área e de volume constante, que podem fornecer informações diferentes. Um método de quantificação gravimétrica da separação de fases foi empregado ainda para verificação do fenômeno. Essa metodologia inovadora requer desenvolvimento, e dessa forma são analisados, além da influência de variáveis do material, aspectos do ensaio e diferentes procedimentos de tratamento e calibração dos dados desenvolvidos para análise dos resultados. Modelos teóricos são utilizados para a comparação das distribuições de pressão experimentais com previsões para fluidos de comportamento conhecido, o que ajuda a indicar o tipo de fluxo predominante. O método desenvolvido mostrou grande potencial para a análise de fluxos complexos, sobretudo suspensões concentradas, e contribui com a ampliação do conhecimento sobre o comportamento reológico de argamassas e os fatores que o influenciam. / Mortars while in fresh state are multiphasic heterogeneous suspensions with wide granular extension, presenting a relatively complex behavior. For rheological evaluation the squeeze flow test is already employed, being a standard test (ABNT NBR 15839/2010) and providing relevant information about the flow behavior of mortars under conditions which are similar to those in practical situations. Nevertheless, important phenomena related to the squeeze flow of suspensions cannot be directly assessed by the usual results from the test (load or stress vs. displacement curves), like type of flow and the occurrence of phase separation. There is not yet a stablished method for the investigation of these effects. In this context, a dynamic pressure mapping technique is presented as a tool in addition to the method, aiming to achieve a more thorough analysis during the squeeze flow of mortars, both in constant area and constant volume configuration, which can provide different information. A phase separation quantification method was employed to validate the phenomenon. This original methodology require development, thus aspects regarding the test setup are analyzed, besides the influence of material, and different data treatment and calibration procedures developed for the analysis of test results. Theoretical models are employed for comparison between experimental pressure distribution and predictions for fluids with known behavior, which aids in the determination of flow regime predominance. The developed method has shown great potential for the analysis of complex fluids, especially concentrated suspensions, and contributes to the expansion of knowledge on the rheological behavior of mortars and the influencing factors.