O objetivo desse estudo é: (a) verificar o efeito do desgaste do calçado na Força de Reação do Solo (FRS) e na distribuição de pressão plantar e (b) verificar a influência do desgaste em calçados de diferentes destinações de uso. Três sujeitos participaram desse estudo, usando cada um quatro calçados de corrida, sendo dois de treinamento (T1 e T2) e dois de competição (C1 e C2). Os calçados foram submetidos ao uso correspondente a 300km. As coletas de dados foram feitas, com o calçado novo e após 100, 200 e 300km de uso, utilizando o sistema Gaitway e o sistema F-Scan. Nos calçados novos, na FRS, a Taxa de Crescimento1 (TC1) foi significativamente maior no calçado C2, do que nos calçados C1 e T2. Na distribuição de pressão plantar, pequena diferença foi observada na Área total (AT) e nos picos de pressão, entre os calçados. Na influência do desgaste nos resultados de grupo, na FRS, o TC1 apresentou valores semelhantes entre as condições Novo e 300km, portanto o choque mecânico não se alterou. Na fase ativa da FRS, oscilações pequenas foram observadas e atribuídas a possíveis variações naturais do movimento, conforme descrito por SERRÃO (1999) e WINTER (1991). Na distribuição de pressão, a AT apresentou um aumento significativo da condição Novo, para as demais condições de uso. O aumento da área foi atribuído à possível compactação do calçado, sendo que essa alteração justificaria a crença de que o calçado novo precise ser amaciado. Entre os picos de pressão analisados, apenas o Pico de Pressão do Antepé (PPA) apresentou diminuição significativa nos valores, da condição Novo para os 300km. Observou-se que após o desgaste imposto, o estresse mecânico se manteve ou se apresentou menor que nas condições iniciais. Na análise da influência do desgaste nos diferentes calçados, para TC1, as diferenças que inicialmente eram significativas tornaram-se não significativas, a partir dos 200km, entre os calçados C1, C2 e T2. Os parâmetros da fase ativa foram pouco influenciados, porém influenciados de forma distinta pelo desgaste, nos calçados analisados. Na distribuição de pressão plantar, a área de contato foi influenciada de forma distinta em cada calçado. Nos picos de pressão plantar, grandes variações foram observadas, porém não atribuíveis ao desgaste promovido no calçado. Conclui-se que o desgaste, correspondente a 300km, pouco alterou o choque mecânico e o estresse mecânico nos calçados analisados. Por meio da destinação de uso, não é possível prever a resposta de calçados de treinamento e de competição ao indivíduo, nem supor que a durabilidade do calçado de competição seja menor do que a do calçado de treinamento / The objective of this study is: (a) to verify the effect of footwear usage on the Ground Reaction Force (GRF) and on the Plantar Pressure Distribution and (b) to verify the influence of usage in footwear of different destinations of use. Three subjects had participated of this study, each one received four running shoes, two of them are designated for training regimen (T1 and T2) and two of them for competition (C1 and C2). The footwears were used for 300km. The data collections were made in four different moments, with new footwear and after 100, 200 and 300km of use, using the Gaitway system and the F-Scan system. When footwear was new, the Loading Rate1 (LR1) was significantly higher in footwear C2, than in the footwears C1 and T2. Analyzing plantar pressure distribution, small differences were observed in the Total Contact Area (TCA) and in the peak of pressure, between the footwears. In the analysis of the different usage stages, the LR1 presented similar values between the conditions New and 300km, therefore the mechanical shock did not enhanced. In the active phase of the GRF, small oscillations were observed and attributed to the possible natural variations of the movement itself, as described before by SERRÃO (1999) and WINTER (1991). In pressure distribution, the TCA showed a significant increase from the New condition, for the other conditions of use. The increase of contact area was attributed to the possible compactation of the footwear?s material, if so this would justify the belief that the new footwear needs to be softened. Considering all peak pressure variables, only Forefoot Peak Pressure (FPP) presented significant reduction in its values, from the New condition for 300km. Therefore it could be assumed that after corresponding usage of 300km, the mechanical stress remained the same or decreased compared with the earlier conditions of use. The shoes of different destinations when analyzed through the conditions, showed that the differences for LR1 that initially were significant had become not significant, from 200km, between the footwear C1, C2 and T2. In the pressure peaks plantar, great variations had been observed, however not attributable to the usage. The conclusion is that usage, correspondent 300km, has little effect on mechanical shock and on mechanical stress on the footwear analyzed in this study. By means of the use destination, it is not possible to foresee the answer of footwear to the individual, nor to assume that the durability of the footwear are worse in competition shoes than in training shoes

O objetivo básico deste trabalho era verificar e quantificar o efeito coanda quando aplicado a um ambiente de atmosfera estagnada na qual a velocidade do escoamento livre é igual a zero. Um aparelho constituído da combinação de um motor e uma hélice combinados com um revestimento externo originalmente utilizado como um componente básico em um túnel de vento experimental. Uma seção de contração de madeira foi projetada e construída para ser unida logo à frente do conjunto hélice/motor, formando um jato retangular. Um aerofólio de seção constante foi testado, formando um jato retangular. Um aerofólio de seção constante foi testado, fixado imediatamente à frente do escoamento do bocal de saída, utilizando uma envergadura igual à largura do jato do bocal de saída. Foram feitas medições do perfil do limite do jato sobre uma distância que excede aquelas incluindo (ambas) as medidas da corda (conhecida do aerofólio). O perfil de velocidade do escoamento induzido sobre a superfície superior de um aerofólio de seção NASA GA(w)-1 foi tomado para um aerofólio limpo e com uma faixa com rugosidade num ponto próximo ao bordo de ataque. O aerofólio foi testado com e sem a faixa de rugosidade, com pontos de tomada de pressão estática ao longo de sua corda fornecendo assim sua distribuição de pressão. O aerofólio foi testado para ângulos de ataque entre zero a quarenta e cinco graus referentes à ilha do escoamento do jato. Os resultados foram registrados e analisados conseqüentemente. / The basic objective of this work was to verify and quantify the Coanda Effect when applied to a stagnent atmosphere in which the free stream velocity was zero. An apparatus consisting of a motor and fan combination combined with external fairings originally used in an experimental wind tunnel was used as the basic component. A wooden contraction section was designed and built to be joined immediately downstream of the fan/motor combination, providing a rectangular jet. A constant section airfoil was tested, suspended immediately downstream of the outlet mouth using a span length equal to that of the mouth of the jet. Measurements were made of the jet limit profile over a distance that exceeded that including the aerofoil chord. The velocity profile induced by the jet flow over the upper surface of a NASA GA(W)-1 section aerofoil was measured for the clean one and with a roughness strip in place near the leading edge. The aerofoil was tested with chordwise static pressure points along the centerline giving the respective pressure distribution, also with and without a roughness strip added. There were different tests for angles of attack with reference to the jet centerline between zero and forty five degrees. The results were registered and analysed accordingly.

O objetivo básico deste trabalho era verificar e quantificar o efeito coanda quando aplicado a um ambiente de atmosfera estagnada na qual a velocidade do escoamento livre é igual a zero. Um aparelho constituído da combinação de um motor e uma hélice combinados com um revestimento externo originalmente utilizado como um componente básico em um túnel de vento experimental. Uma seção de contração de madeira foi projetada e construída para ser unida logo à frente do conjunto hélice/motor, formando um jato retangular. Um aerofólio de seção constante foi testado, formando um jato retangular. Um aerofólio de seção constante foi testado, fixado imediatamente à frente do escoamento do bocal de saída, utilizando uma envergadura igual à largura do jato do bocal de saída. Foram feitas medições do perfil do limite do jato sobre uma distância que excede aquelas incluindo (ambas) as medidas da corda (conhecida do aerofólio). O perfil de velocidade do escoamento induzido sobre a superfície superior de um aerofólio de seção NASA GA(w)-1 foi tomado para um aerofólio limpo e com uma faixa com rugosidade num ponto próximo ao bordo de ataque. O aerofólio foi testado com e sem a faixa de rugosidade, com pontos de tomada de pressão estática ao longo de sua corda fornecendo assim sua distribuição de pressão. O aerofólio foi testado para ângulos de ataque entre zero a quarenta e cinco graus referentes à ilha do escoamento do jato. Os resultados foram registrados e analisados conseqüentemente. / The basic objective of this work was to verify and quantify the Coanda Effect when applied to a stagnent atmosphere in which the free stream velocity was zero. An apparatus consisting of a motor and fan combination combined with external fairings originally used in an experimental wind tunnel was used as the basic component. A wooden contraction section was designed and built to be joined immediately downstream of the fan/motor combination, providing a rectangular jet. A constant section airfoil was tested, suspended immediately downstream of the outlet mouth using a span length equal to that of the mouth of the jet. Measurements were made of the jet limit profile over a distance that exceeded that including the aerofoil chord. The velocity profile induced by the jet flow over the upper surface of a NASA GA(W)-1 section aerofoil was measured for the clean one and with a roughness strip in place near the leading edge. The aerofoil was tested with chordwise static pressure points along the centerline giving the respective pressure distribution, also with and without a roughness strip added. There were different tests for angles of attack with reference to the jet centerline between zero and forty five degrees. The results were registered and analysed accordingly.

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. 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. 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. / QC 20101022

No description available.

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.

Squeeze Film Dampers (SFDs) are employed in high-speed Turbomachinery, particularly aircraft jet engines, to provide external damping. Despite numerous successful applications, it is widely acknowledged that the theoretical models used for SFD design are either overly simplified or incapable of taking into account all the features such as cavitation, air entrainment etc., affecting the performance of a SFD. On the other hand, experimental investigation of flow field and dynamic performance of SFDs can be expensive and time consuming. The current work simulates the flow field inside the dynamically deforming annular gap of a SFD using the commercial computational fluid dynamics (CFD) code Fluent and compares the results to the experimental data of San Andrés and Delgado. The dynamic mesh capability of Fluent and a User Defined Function (UDF) was used to replicate the deforming gap and motion of the rotor respectively. Two dimensional simulations were first performed with different combinations of rotor whirl speed, operating pressures and with and without incorporating the cavitation model. The fluid used in the simulations was ISO VG 2 Mobil Velocite no. 3. After the successful use of the cavitation model in the 2D case, a 3D model with the same dimensions as the experimental setup was built and meshed. The simulations were run for a whirl speed of 50 Hz and an orbit amplitude of 74 μm with no through flow and an inlet pressure of 31kPa (gauge). The resulting pressures at the mid-span of the SFD land were obtained. They closely agreed with those obtained experimentally by San Andrés and Delgado.

No description available.

It has been desirable for years to develop non-intrusive/non-invasiveprocedures to determine the pressures and stresses at various levels andinterfaces in the railroad track structure in order to optimize track designs andimprove subsequent track performance. Recent research has developedsatisfactory procedures for measuring pressures in the track structure at theballast/subballast/subgrade levels using earth pressure cells. The researchreported in this thesis documents the development of a technique for measuringthe pressures in the track, at the rail/tie plate/tie interfaces, using a very thinpressure sensitive Tekscan sensor. The Tekscan Measurement System uses asensor composed of a matrix-based array of force sensitive cells, similar to ministrain gauges, to obtain accurate pressure distributions between two surfaces inthe track. This thesis specifically describes: 1) the optimum procedure to installthe sensors into the track, 2) the recommended practices to effectively collectdata with the software, and 3) the accepted techniques for analyzing the results.Both laboratory calibration and in-track testing have been conducted and theresults are presented. The findings attest to the usefulness and practicality of theprocedure for accurately measuring pressures in railroad tracks. The proceduremay also be applicable for a wide variety of specific track related measurementssuch as validating curve geometric criteria, assessing crossing diamond impactpressures, and evaluating the advantages/disadvantages of various types of tieplates, fastenings and tie compositions.

The overall objectives of this thesis are to determine if Indirect and Direct Design methods currently used for reinforced concrete pipe are able to accurately predict the capacity of the pipe, to identify discrepancies between the two methods, and to provide potential modifications to the methods to reduce inconsistencies. As part of this investigation, two 0.6 m pipes (nominal strength classes 100-D and a 140-D) and two 1.2 m pipes (a 65-D with Wall B and a 65-D with Wall C) were tested under single wheel pair loading at burial depths of 1.2, 0.6 and 0.3 m. The test pipes did not crack at the applied service load of 110 kN and did not pass the crack width limit until between 2.5 and 4 times the service load. A 0.6 m 100-D pipe was also tested under simulated deep burial and it was found that the calculated test D-Load is 1.9 times greater than the designated D-Load of the test pipe. It was found that both methods were conservative and that the Direct Design method should be modified to more closely align with the Indirect Design. An investigation of the Direct Design parameters found that by considering thick ring theory and the Modified Compression Field Theory with two layers of reinforcement, the required amount of steel from Direct Design could be made to align very closely with the Indirect Design. An additional test was completed to further assess the Direct Design method on a 0.6 m 140-D pipe to measure the pressure around the circumference of the pipe and compare this measured pressure to the commonly used pressure distribution for Direct Design. The results show that at the minimum cover (0.3 m) the test pressure is higher than predicted at the crown, lower than predicted at the invert, and nearly zero at the shoulder, springline, and haunch, which is inconsistent with most of the predicted results at these locations. / Thesis (Master, Civil Engineering) -- Queen's University, 2014-06-20 16:29:39.037