Several rubber diaphragms, of the same type used inside an hydraulic accumulator, failed a short time after they were mounted. While there is nothing special with these failures the cost, in some cases can be high. A closer look, at the damaged diaphragms reveal an interesting nonsymmetric radial deformation accompanied in some cases by cracks. Most of the analyses regarding the failures of rubber diaphragms offer explanations only from a chemical or material science point of view. We propose in this thesis a new perspective from a mechanical-structural engineering view. Therefore the main goal of the thesis is to investigate the deformation of a diaphragm and based on this analysis to propose an explanation for formation of the cracks. It is shown that the analysis of the diaphragm problem leads to a pseudo-nonconservative system and involves a buckling, a post buckling (dynamic snap-through), an eversion, and a load response analysis. The problem is approached numerically using the nite element method. The character of pseudo-nonconservativeness of the system requires, in this case, an update of the tangent stiffness matrix with a certain stiffness correction. This new correction is proposed also. The result is valid not only for this particular problem but for the entire class of problems to which the diaphragm belongs. This correction is implemented in an existing nite element program (NIKE3D) and used to analyze the diaphragm deformation. The results indicate that under the typical load condition for a diaphragm a certain deformation pattern occurs, and this can lead to the formation of cracks. This deformation matches extremely well with the actual deformed shape of a typical failed diaphragm. It is shown that the deformation pattern depends on the structural properties of the diaphragm rather than on the magnitude of the applied load. The nonsymmetry in the diaphragm deformation and the difference in the crack development is explained also. / Ph. D.

Syfte: Att med hjälp av videoanalys och programvaran Dartfish, undersöka eventuella skillnader i stödfasen på vinkeln mellan calcaneus och underlaget, hos personer med Pes planus och pes cavus, både efter en- och 45 minuters löpning på löpband.  Studiedesign: En experimentell studie. Metod: Trettiofyra personer vars fot/fötter uppmättes till pes cavus och pes planus enligt kriterierna för Medial Longitudinale Arch -angle, inkluderades i studien. Mätningarna gjordes på en stillbild med digital goniometer i programvaran Dartfish. Därefter mättes calcaneus vertikala mittlinje i förhållande till underlaget i stödfasen både efter 1 minut och 45 minuter, när försökspersonerna sprang barfota på ett löpband. Resultat: Båda fotvalvsgrupperna visade ett signifikant lägre värde, d vs ökad valgusriktning av calcaneus till underlaget, efter 45 minuter jämfört med 1 minuts löpning (p<0.05). Konklusion: Både pes cavus och pes planus tenderar att inta en calcaneusställning mer åt valgus efter 45 minuters löpning. Det behövs fortsatt forskning för att klargöra förändringen av biomekaniken efter längre tids löpning. Studiens resultat antyder att framtida studier som undersöker sambandet mellan skador och abnormala fotrörelser under belastning  även bör undersöka efter längre tids löpning.

Bakgrund: I Sverige är den generella uppfattningen att det vid val av vardagssko är rekommenderat att välja en sportsko framför en canvas tennissko. Tidigare studier har jämfört hur olika skomodeller påverkar gången, men ingen har studerat skillnader mellan sportskor och canvas tennisskor. Syfte: Undersöka hur en sko med instabil läst och platt bindsula (canvas tennissko) samt en sko med en stadig läst, en sula med bra stötdämpning och avrullning (sportsko) påverkar den mediolaterala stabiliteten olika under stödfasen. Metod: Gånganalys på fem kvinnliga deltagare. Kinetisk och kinematisk data samlades in med hjälp av ett 3D-rörelseanalyssystem. Resultat: Rörelseomfånget skiljer sig mer mellan deltagare än skomodeller. Sportskor har ett försumbart lägre rörelseomfång än canvas tennisskor. Sportskor ger mer inverterad gång än Canvas tenniskor. Steglängden och stödfasen (stance time) skiljer inte mellan de två skomodellerna. Slutsats: Fotens rörelseomfång i frontalplanet skiljer sig inte mellan canvas tennisskor och sportskor under stödfasen, men sportskon har en mer inverterad rörelse. / Background: In Sweden it is a general perception that a sports shoe is a better choice than a canvas tennis shoe for everyday use. Previous studies have investigated how different shoe models affect the gait, but none have studied the differences between sport shoes and canvas tennis shoes. Aim: Investigate how a shoe with unstable last and a flat insole (canvas tennis shoe) and a shoe with steady last, a sole with good shock absorbing and roll off (sport shoe) affect the mediolateral stability differently during stance. Methods: Gait analysis on five female participants. Kinetic and kinematic data collected with3D-modionanalysis system. Results: The range of motion differs more between participants than between shoe models. The sport shoe have a negligible lower range of motion than the canvas tennis shoe. Walking in sport shoe shows a more inverted gait than gait in canvas tennis shoe. Step length and stance time are the same in both shoe models. Conclusion: The range of motion and motion pattern of the foot in the coronal plane does not differ between canvas tennis shoes and sport shoes during stance phase, but the sport shoe has a more inverted motion.

With the increasing ubiquity of networked “smart” devices that read and gather data on the physical world, the disembodied, cognitive realm of cyberspace has become “everted,” as such technologies migrate the communications networks and data collection of the Internet into the physical world. Popular open-source “maker” practices—most notably the practice of physical computing, which networks objects with digital environments using sensors and microcontrollers—increasingly push human-computer interaction (HCI) into the physical domain. Yet such practices, as political theorists and some philosophers of technology argue, bypass the very question of subjectivity, instead lauding the socioeconomic liberation of the individual afforded by open-source hardware practices. What is missing across these discourses is a technocultural framework for studying the material ways that everted technologies articulate subjects. I argue that examining the various, contradictory forms of interface that emerge from physical computing provides such a framework. To support this claim, I focus on several case studies, drawn from popular physical computing practices and communities, and analyze the particular ways that these devices articulate subjectivity. I conclude by linking my technocultural framework with various feminist theories of boundary transgression and hybridity, and end by suggesting that, in an everted landscape, the subject is politically constituted by a proximity to present time and space. / Graduate / 0585 / shaunmac@uvic.ca

With the increasing ubiquity of networked “smart” devices that read and gather data on the physical world, the disembodied, cognitive realm of cyberspace has become “everted,” as such technologies migrate the communications networks and data collection of the Internet into the physical world. Popular open-source “maker” practices—most notably the practice of physical computing, which networks objects with digital environments using sensors and microcontrollers—increasingly push human-computer interaction (HCI) into the physical domain. Yet such practices, as political theorists and some philosophers of technology argue, bypass the very question of subjectivity, instead lauding the socioeconomic liberation of the individual afforded by open-source hardware practices. What is missing across these discourses is a technocultural framework for studying the material ways that everted technologies articulate subjects. I argue that examining the various, contradictory forms of interface that emerge from physical computing provides such a framework. To support this claim, I focus on several case studies, drawn from popular physical computing practices and communities, and analyze the particular ways that these devices articulate subjectivity. I conclude by linking my technocultural framework with various feminist theories of boundary transgression and hybridity, and end by suggesting that, in an everted landscape, the subject is politically constituted by a proximity to present time and space. / Graduate / 2015-04-21 / 0585 / shaunmac@uvic.ca

Running is known to provide important health benefits. However, the incidence of injury among runners is high, particularly among novice runners, which discourages long term participation in the sport. The knee is the most commonly injured joint in novice runners. In general, aberrant frontal and transverse plane kinematics are associated with the development of knee injuries in runners. It was unknown whether the high rate of knee injury in novice runners was due to abnormal kinematics. Further, it was unclear whether these risk factors for injury could be improved. This dissertation includes four studies investigating kinematics in novice runners, how they change with training and evaluation of a running assessment. The first study compared frontal and transverse plane kinematics of female novice and experienced runners. Novice runners displayed more knee kinematics associated with injury than experienced runners, which may contribute to their higher risk of injury. The second study investigated the effects of two different training programs on kinematics of novice runners: one program consisted of 8 weeks of walking followed by 8 weeks of running, the other consisted of 8 weeks of strength/plyometric training followed by 8 weeks of running. Results demonstrated that training produced small changes in kinematics, however all types of training produced a mix of beneficial and detrimental effects. Participants who completed the study displayed better knee kinematics 8 than those who dropped out, which may have influenced their ability to complete the program. The third study sought to investigate changes in coordination of the hip and ankle joints, and their contributions to knee joint angles thought to contribute to injury. Results demonstrated that both the hip and the ankle may influence changes in knee kinematics, however the relative motion of the hip and the ankle appears to remain stable with training. In the final study, we investigated the reliability and validity of the Running Readiness Scale (RRS), as a low cost assessment of kinematics related to injury in runners. The RRS demonstrated good inter and intra rater reliability. Further, the RRS appeared to effectively discriminate between runners according to knee abduction, but not knee internal rotation.

Functionally graded structures have material properties that continuously vary in one or more directions. Examples include human teeth, seashells, bamboo stems and human organs, where the varying volume fraction of fibers and their orientations optimize functionality. Deformations of such structures typically involve bending, stretching, and shearing. An everyday example of shearing deformation is the twisting of wet fabrics to extract water. In this study, we analytically examine the large deformations of functionally graded Mooney-Rivlin circular cylinders, focusing on how radial grading of material moduli can be beneficially utilized. We investigate the finite deformations caused by pressures applied to the bounding surfaces and axial loads or twisting moments on the end faces. We also simulate residual stresses in a hollow cylinder either by inverting it inside out or by closing a longitudinal wedge opening parallel to the cylinder axis through axisymmetric deformation before other loads are applied. It is observed that the maximum shear stress in an initially stress-free Mooney-Rivlin cylinder can occur at an interior point. In the absence of axial forces on the end faces, the cylinder elongates when twisted, with the degree of elongation depending on the grading of the material moduli. These findings should aid numerical analysts in verifying their algorithms for simulating large deformations of rubber-like materials modeled by the Mooney-Rivlin relation. / Master of Science / Functionally graded materials (FGMs) are composites whose properties vary in one or more directions to exploit the functionality of the individual components. An example would be a sheet of material that is fully metallic on one side and fully ceramic on the other, with properties changing gradually through the thickness. The Mooney-Rivlin model is used to capture the stress-strain response of rubber-like materials. Therefore, functionally graded Mooney-Rivlin cylinders are rubber-like composite cylinders whose properties change throughout their thickness. Functionally graded cylinders have a wide array of applications, including in pressure vessels, vibration damping systems and tires. Therefore, having a thorough understanding of the stresses induced in these cylinders when subjected to loads is essential for safe and reliable designs. This research aims to investigate the effects of material inhomogeneity on the stresses induced in functionally graded cylinders subjected to torsion, radial expansion, eversion, and various combinations of these. Furthermore, realizing that stresses induced during the fabrication process cannot be easily quantified, we study a problem in which these induced stresses can be determined and analyze their effect on subsequent deformations of the cylinder when subjected to torsion and radial expansion. To achieve this aim, we use a member of Ericksen's third family of universal deformations, which mathematically describes torsion, inflation, and eversion, along with the Mooney-Rivlin model to determine the stress state resulting from deformation. The results show that for cylinders of the same geometry in the stress-free undeformed state subjected to identical surface tractions, material inhomogeneities greatly influence the stresses in the cylinder. It was also found that the magnitude of the normal and shear stresses, axial stretch, and the geometry of the cylinder after deformation depend on the type of deformation and functional grading. Additionally, the results indicate that the normal stresses induced in an initially stressed cylinder are much greater than those in a cylinder that is initially stress-free when subjected to the same boundary conditions.

Made available in DSpace on 2016-12-06T17:07:16Z (GMT). No. of bitstreams: 1 Joao Otacilio.pdf: 1115427 bytes, checksum: b2c572e56990d8fc350a9e27e16cffbe (MD5) Previous issue date: 2008-04-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The aim of this study was to examine the influence of the rearfoot eversion motion on the biomechanical variables of the walking related with the plantar pressure distribution and the center of pressure (COP). Twenty-one male subjects (mean age 27 years ± 8 years, height 1.78m ± 0.6m and body mass 76kg ± 10kg) have participated of the study. Subjects were separate into two groups considering the Maximum Rearfoot Eversion Angle: Normal Group (n-11) - which had an angle < 8° and Overpronation Group (n=10) - which had an angle &#8805; 8°. The experimental data acquisition consisted in the evaluation of the barefoot gait in a straight line on a EVA walkway (flat stuff), and a controlled speed of 5 km / h ± 5%. The variables examined were: Maximum Rearfoot Eversion Angle, Media Plantar Pressure, Plantar Pressure Peak, Contact Area, Relative Load, Mean Velocity of the COP and Medial and Lateral displacement of the COP. The kinematic data has been acquired by the Spica Technology Corporation video system with two video cameras synchronized with a sampling rate of 955 Hz. For the kinetic data acquisition was used the Novel Emed-XR system with a sampling rate of 100 Hz. The Shapiro-Wilk test has been applied for the statistical analysis to verify the normality of the data and the statistical test One-Way ANOVA was used to compare the kinetic variables intra-group in different regions of the foot. The Student t-test was used to compare these inter-groups variables and the Pearson statistical test to check possible correlation between the Maximum Rearfoot Eversion Angle and kinetic variables. The level of significance adopted was 0.05. Analyzing the variables Media Plantar Pressure, Plantar Pressure Peak and Relative Load between different regions of the foot intra-groups, had been observed that both groups has shown a similar pattern of distribution of plantar pressure, but differentiating themselves only by the intensities of these variables. Plantar Pressure Peak and Contact Area variables have been compared among themselves in different regions of the foot inter-groups and, it was observed that the Normal Group showed higher mean values significant statistically, especially on the region of the heel and mid-foot. There was no significant statistically difference on the regions examined when the variables Media Plantar Pressure, Relative Load, Mean Velocity of the COP and Medial and Lateral displacement of the COP were compared between Normal Group and Overpronation Group. Analyzing possible correlations between the Maximum Rearfoot Eversion Angle and kinetic variables can be observed that the variables Media Plantar Pressure, Plantar Pressure Peak, Contact Area and Relative Load have shown positive significant statistically correlations with the Maximum Rearfoot Eversion Angle mainly in the mid-foot. However, there were no correlations on the variables of Mean Velocity of the COP and Medial and Lateral Displacement of the COP. These results suggest that the increase in the rearfoot eversion angle (overpronation) affects considerably some biomechanical variables such as the distribution of plantar pressure during the gait. This study demonstrates the importance of the analysis of the distribution of pressure on the clinical and preventive situation, since it has a great potential to predict abnormal movements during the locomotion. / Esta pesquisa teve como objetivo analisar a influência do movimento de eversão do calcanhar sobre as variáveis biomecânicas da marcha relativas à distribuição de pressão plantar (DPP) e o centro de pressão (COP). Participaram do estudo 21 sujeitos do sexo masculino (média de idade 27 anos ± 8 anos, estatura de 178cm ± 6cm e massa corporal de 76kg ± 10kg). Os sujeitos foram divididos em dois grupos, considerando o Ângulo Máximo de Eversão do Calcanhar: Grupo Normal (n=11) - sujeitos que apresentavam Ângulo Máximo de Eversão do Calcanhar < 8° e Grupo Overpronado (n=10) - sujeitos que apresentavam Ângulo Máximo de Eversão do Calcanhar &#8805; 8°. A coleta de dados consistiu - se em avaliar o andar de forma descalça em linha reta sobre uma passarela de EVA sem qualquer inclinação em relação à linha do horizonte e com uma velocidade controlada de 5km/h ± 5%. As variáveis analisadas foram: Ângulo Máximo de Eversão do Calcanhar, Pressão Plantar Média, Pico de Pressão Plantar, Área de contato, Carga Relativa, Velocidade Média do COP e Deslocamento Medial e Lateral do COP. Para a aquisição dos dados cinemáticos foi utilizado o sistema Spica Technology Corporation com duas câmeras de vídeo sincronizadas, com taxa de amostragem de 955Hz. Para a aquisição dos dados cinéticos utilizou-se o sistema Novel Emed- XR com taxa de amostragem de 100Hz. Na análise estatística foi aplicado o teste de Shapiro-Wilk para verificar a normalidade dos dados. Para comparar as variáveis cinéticas intra-grupo nas diferentes regiões do pé, foi utilizado o teste ANOVA One-Way. Já comparando estas variáveis inter-grupos, foi utilizado o teste t de Student para amostras independentes. Para verificar possíveis correlações entre o Ângulo Máximo de Eversão do Calcanhar e as variáveis cinéticas analisadas, utilizou-se o teste de Pearson. O nível de significância adotado foi de 0,05. Ao comparar as variáveis Pressão Plantar Média , Pico de Pressão Plantar e Carga Relativa entre as diferentes regiões do pé intra-grupo, pode-se observar que ambos os grupos apresentaram um padrão de distribuição de pressão plantar semelhante, diferenciando-se apenas pelas intensidades dessas variáveis. Já ao comparar as variáveis Pico de Pressão Plantar e Área de Contato nas diferentes regiões do pé intergrupos, observou-se que o Grupo Normal apresentou maiores valores médios, estatisticamente significativos, principalmente na região do calcanhar e do médio pé. Em relação às variáveis Pressão Plantar Média , Carga Relativa , Velocidade Média do COP e Deslocamento Medial e Lateral do COP não foram encontradas diferenças estatisticamente significativas ao comparar o Grupo Normal e o Grupo Overpronado em nenhuma das regiões analisadas. Ao analisar possíveis correlações entre o Ângulo Máximo de Eversão do Calcanhar e as variáveis cinéticas, pode-se observar que as variáveis Pressão Plantar Média , Pico de Pressão Plantar , Área de Contato e Carga Relativa apresentaram correlações positivas estatisticamente significativas com o Ângulo Máximo de Eversão do Calcanhar , principalmente na região do médio pé. Já as variáveis Velocidade Média do COP e Deslocamento Medial e Lateral do COP não apresentaram correlações estatisticamente significativas. Assim, é possível concluir que o aumento do ângulo de eversão do calcanhar (overpronação) afetou consideravelmente algumas variáveis biomecânicas da distribuição de pressão plantar durante a marcha. Isso demonstra a importância da análise da distribuição de pressão plantar no quadro clínico e preventivo, pois a mesma possui um grande potencial para predizer movimentos anormais durante a locomoção.

Gyroscopes have been used in previous studies to measure the peak angular velocity of the shoe or foot in the frontal plane (evVel). However, it is not clear whether different test conditions (footwear hardness or locomotion speed) can influence the accuracy of evVel. The purpose of the present study was to compare the accuracy of gyroscopes and electrogoniometers when measuring evVel and the time until evVel (t_evVel) in 12 different conditions using a single axis gyroscope attached to the heel cap. Twenty-four recreational runners were instructed to walk and run on a 15-m indoor track at four locomotion speeds (1.5, 2.5, and 3.5 m/s, and individual running speed) and in three footwear conditions (low to high hardness). The gyroscope data and electrogoniometer data were sampled at a rate of 1000 Hz. Comparisons between both measurement devices showed small mean differences up to 49.8 ± 46.9 deg/s for evVel and up to 5.3 ± 3.5 ms for t_evVel. Furthermore, strong relationships between gyroscope and electrogoniometer data were found for evVel as well as for t_evVel for all conditions. It can be concluded that gyroscopes can be used to accurately determine evVel and t_evVel under a variety of conditions.

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