A next generation nanosatellite bus is under development at the University of Toronto’s Space Flight Laboratory (SFL), and is being used for the first time in an ambitious Earth observation mission to identify and monitor atmospheric aerosol species. The spacecraft system brings together novel advanced designs that expand the capability envelope of nanosatellites, with heritage SFL technology that is presently defining the state-of-the-art in microspace applications. The work presented in this thesis pertains primarily to the development of the structural subsystem of the Nanosatellite for Earth Monitoring and Observation – Aerosol Monitor (NEMO-AM). Described extensively are the design and analysis efforts made by the author to validate and finalize the structural design in order to bring it to a manufacturing-ready stage. Subsequent work to meet the mechanical requirements of ground operations during the assembly and testing of the spacecraft is also presented.

A next generation nanosatellite bus is under development at the University of Toronto’s Space Flight Laboratory (SFL), and is being used for the first time in an ambitious Earth observation mission to identify and monitor atmospheric aerosol species. The spacecraft system brings together novel advanced designs that expand the capability envelope of nanosatellites, with heritage SFL technology that is presently defining the state-of-the-art in microspace applications. The work presented in this thesis pertains primarily to the development of the structural subsystem of the Nanosatellite for Earth Monitoring and Observation – Aerosol Monitor (NEMO-AM). Described extensively are the design and analysis efforts made by the author to validate and finalize the structural design in order to bring it to a manufacturing-ready stage. Subsequent work to meet the mechanical requirements of ground operations during the assembly and testing of the spacecraft is also presented.

This thesis discusses the mathematics of the Element Independent Corotational (EICR) Method and the more general Unified Small-Strain Corotational Formulation. The former was developed by Rankin, Brogan and Nour-Omid [106]. The latter, created by Felippa and Haugen [49], provides a theoretical frame work for the EICR and similar methods and its own enhanced methods. The EICR and similar corotational methods analyse non-linear deformation of a body by its discretization into finite elements, each with an orthogonal frame rotating (and translating) with the element. Such methods are well suited to deformations where non-linearity arises from rigid body deformation but local strains are small (1-4%) and so suited to linear analysis. This thesis focuses on such small-strain, non-linear deformations. The key concept in small-strain corotational methods is the separation of deformation into its rigid body and elastic components. The elastic component then can be analyzed linearly. Assuming rigid translation is removed first, this separation can be viewed as a polar decomposition (F = vR) of the deformation gradient (F) into a rigid rotation (R) followed by a small, approximately linear, stretch (v). This stretch usually causes shear as well as pure stretch. Using linear algebra, Chapter 3 explains the EICR Method and Unified Small-Strain Corotational Formulation initially without, and then with, the projector operator, reflecting their historical development. Projectors are orthogonal projections which simplify the isolation of elastic deformation and improve element strain invariance to rigid body deformation. Turning to Lie theory, Chapter 4 summarizes and applies relevant Lie theory to explore rigid and elastic deformation, finite element methods in general, and the EICR Method in particular. Rigid body deformation from a Lie perspective is well represented in the literature which is summarized. A less developed but emerging area in differential geometry (notably, Marsden/Hughes [82]), elastic deformation is discussed thoroughly followed by various Lie aspects of finite element analysis. Finally, the EICR Method is explored using Lie theory. Given the available research, complexity of the area, and level of this thesis, this exploration is less developed than the earlier linear algebraic discussion, but offers a useful alternative perspective on corotational methods. / Thesis (Master, Mathematics & Statistics) -- Queen's University, 2011-03-30 21:40:25.831

One the most daunting technical challenges in the realization of biosensors is functionalizing transducing surfaces for the detection of biomolecules. Functionalization is defined as the formation of a bio-compatible interface on the transducing surfaces of bio-chemical sensors for immobilizing and subsequent sensing of biomolecules. The kinetics of functionalization reactions is a particularly important issue, since conventional functionalization protocols are associated with lengthy process times, from hours to days. The objective of this thesis is the improvement of the functionalization protocols and their kinetics for biosensing applications. This objective is realized via modeling and experimental verification of novel functionalization techniques in microfluidic environments. The improved functionalization protocols using microfluidic environments enable in-situ functionalization, which reduces the processing times and the amount of reagents consumed, compared to conventional methods. The functionalization is performed using self-assembled monolayers (SAMs) of thiols. The thiols are organic compounds with a sulphur group that assists in the chemisorption of the thiol to the surface of metals like gold. The two reactions in the functionalization process examined in this thesis are the SAM formation and the SAM/probe molecule conjugation. SAM/probe molecule conjugation is the chemical treatment of the SAM followed by the binding of the probe molecule to the SAM. In general, the probe molecule is selective in binding with a given biomolecule, called the target molecule. Within this thesis, the probe molecule is an antibody and the target molecule is an antigen. The kinetics of the reaction between the probe (antibody) and the target biomolecule (antigen) is also studied. The reaction between an antigen and its antibody is called the immunoreaction. The biosensing technique that utilizes the immunoreaction is immunoassay. A numerical model is constructed using the finite element method (FEM), and is used to study the kinetics of the functionalization reactions. The aim of the kinetic studies is to achieve both minimal process times and reagents consumption. The impact of several important parameters on the kinetics of the reactions is investigated, and the trends observed are explained using kinetic descriptive dimensionless numbers, such as the Damköhler number and the Peclet number. Careful numerical modeling of the reactions contributes to a number of findings. A considerably faster than conventional SAM formation protocol is predicted. This fast-SAM protocol is capable of reducing the process times from the conventional 24-hours to 15 minutes. The numerical simulations also predict that conventional conjugation protocols result in the overexposure of the SAM and the probe molecule to the conjugation reagents. This overexposure consequently lowers conjugation efficiencies. The immunoreaction kinetics of a 70 kilo-Dalton heat shock protein (HSP70) with its antibody in a hypothetical microchannel is also investigated through the FEM simulations. Optimal reaction conditions are determined, including the flow velocity and the surface concentration of the immobilized probes (antibodies). Based on the numerical results and a series of experimental studies, the fast-SAM protocol application is successfully confirmed. Moreover, the optimum reagent concentration for a given one- hour conjugation process time is determined. This functionalization protocol is successfully applied to immobilize the HSP70 antibody on gold surfaces. The use of the fast-SAM protocol and the predicted optimum conjugation conditions result in binding of the HSP70 antibody on gold, with the same or superior immobilization quality, compared to the conventional protocols. Upon implementation of a 70 μm.s^(-1) flow velocity, the reaction is observed to complete in around 30-35 minutes, which is close to the numerically predicted 30 minutes and 16 seconds. This immunoreaction time is considerably less than conventional 4-12 hour processes. The modified in-situ functionalization techniques achieved here are promising for substantially reducing the preparation times and improving the performance of biosensors, in general, and immunoassays, in particular.

The current trend in electronics manufacturing is to decrease the size of electronic components while attempting to increase processing power and performance. This is leading to increased interest in thinner printed wiring boards and finer line widths and wire pitches. However, mismatches in the thermomechanical properties of materials used can lead to warpage, hindering these goals. Warpage can be problematic as it leads to misalignments during package assembly, reduced tolerances, and a variety of operational failures. Current warpage prediction techniques utilize isotropic volume averaging to estimate effective material properties in layers of copper mixed with interlayer dielectric material. However, these estimates do not provide material properties with sufficient accuracy to predict warpage, as they contain no information about the orientation of the copper traces. This thesis describes the development of a new technique to predict the warpage of a particular substrate. The technique accounts for both the trace pattern planar density and planar orientation in determining effective orthotropic material properties for each layer of a multi-layer substrate. Starting with the trace pattern image, this technique first divides the trace pattern into several smaller areas for a given layer of the substrate and then uses image processing techniques to determine the copper percentage and average trace orientation in each small area. The copper percentage and average trace direction orientation are used in conjunction with the material properties of copper and the dielectric material to calculate the effective orthotropic material properties of each smaller area of the substrate. A finite-element model is then created where each layer is represented as a concatenation of several small areas with independent directional properties, and such a model is then subjected to sequential thermal excursion as seen in the actual fabrication process. The results from the models have been compared against experimental data with a great degree of accuracy. The modeling technique and the results obtained clearly demonstrate the need for the proposed subdivisional orthotropic material property calculations, as opposed to homogeneous isotropic properties typically used for each layer in computational simulations, as these more accurate directional properties are capable of predicting warpage with higher accuracy.

This research aims to understand the reliability of Sn-Ag-Cu solder interconnects used in plastic ball grid array (PBGA) packages using microstructure evolution, laser moiré interferometry and finite-element modeling. A particle coarsening based microstructure evolution of the solder joint material during thermal excursions was studied for extended periods of time lasting for several months. The microstructure evolution and particle coarsening was quantified, and acceleration factors were determined between benign field-use conditions and accelerated thermal cycling (ATC) conditions for PBGA packages with different form factors and for two different lead-free solder alloys. A new technique using laser moiré interferometry was developed to assess the deformation behavior of Sn-Ag-Cu based solder joints during thermal excursions. This technique can used to estimate the fatigue life of solder joints quickly in a matter of few days instead of months and can be extended to cover a wide range of temperature regimes. Finite-element analysis (FEA) in conjunction with experimental data from the ATC for different lead-free PBGA packages was used to develop a fatigue life model that can be used to predict solder joint fatigue life for any PBGA package. The proposed model will be able to predict the mean number of cycles required for crack initiation and crack growth rate in a solder joint.

Photovoltaic manufacturing is material intensive with the cost of crystalline silicon wafer, used as the substrate, representing 40% to 60% of the solar cell cost. Consequently, there is a growing trend to reduce the silicon wafer thickness leading to new technical challenges related to manufacturing. Specifically, wafer breakage during handling and/or transfer is a significant issue. Therefore improved methods for breakage-free handling are needed to address this problem. An important pre-requisite for realizing such methods is the need for fundamental understanding of the effect of handling device variables on the deformation, stresses, and fracture of crystalline silicon wafers. This knowledge is lacking for wafer handling devices including the Bernoulli gripper, which is an air flow nozzle based device. A computational fluid dynamics model of the air flow generated by a Bernoulli gripper has been developed. This model predicts the air flow, pressure distribution and lifting force generated by the gripper. For thin silicon wafers, the fluid model is combined with a finite element model to analyze the effects of wafer flexibility on the equilibrium pressure distribution, lifting force and handling stresses. The effect of wafer flexibility on the air pressure distribution is found to be increasingly significant at higher air flow rates. The model yields considerable insight into the relative effects of air flow induced vacuum and the direct impingement of air on the wafer on the air pressure distribution, lifting force, and handling stress. The latter effect is found to be especially significant when the wafer deformation is large. In addition to silicon wafers, the model can also be used to determine the lifting force and handling stress produced in other flexible materials. Finally, a systematic approach for the analysis of the total stress state (handling plus residual stresses) produced in crystalline silicon wafers and its impact on wafer breakage during handling is presented. Results confirm the capability of the approach to predict wafer breakage during handling given the crack size, location and fracture toughness. This methodology is general and can be applied to other thin wafer handling devices besides the Bernoulli gripper.

L’objectif de la thèse était d’étudier l’influence de facteurs anatomiques et biomécaniques tels que la présence d’ostéophytes vertébraux, le taux de chargement et le profil sagittal rachidien (défini par l’orientation et la forme de la colonne vertébrale dans le plan sagittal) sur les traumatismes de la colonne vertébrale thoracique et lombaire. Pour ce faire, des essais expérimentaux sur spécimens cadavériques rachidiens ont été réalisés et un modèle biomécanique détaillé du rachis T1-sacrum a été raffiné, validé expérimentalement et exploité. Les résultats ont démontré que les segments ostéophytiques présentaient des fractures de moindre sévérité localisées au niveau de la vertèbre proximale, contrairement aux segments sans ostéophytes, qui présentaient des fractures sévères (souvent comminutives) au niveau de la vertèbre médiane. Ils ont également confirmé que le taux de déformation jouait un rôle-clé dans l’initiation du traumatisme et que le profil sagittal avait une influence significative sur les caractéristiques des fractures osseuses lors d’accidents impliquant un mécanisme principalement en compression. En revanche, le profil sagittal n’exercerait qu’une influence limitée sur la nature des traumatismes lors d’un accident impliquant un mécanisme de flexion-distraction. / The objective of this thesis was to study the influence of anatomical and biomechanical factors such as the presence of vertebral osteophytes, the loading rate and the sagittal profile of the spine (defined by the orientation and shape of the spine in the sagittal plane) on spinal injuries at the thoracic and lumbar levels. To fulfill this objective, experiments on human cadaveric spines were performed and a detailed biomechanical model of the spine was refined, validated against experimental data, and exploited. Results showed that the presence of large osteophytes significantly influenced the location, pattern and type of fracture, and provided to the underlying vertebra a protective mechanism against severe compression fractures (e.g. burst fractures). They also showed that the loading rate played a key-role on the onset of spinal trauma and that the sagittal profile of the spine had a significant influence on the bone fracture in accidents that involve compression mechanisms. On the other hand, the sagittal profile of the spine had a limited influence on the nature of spinal injuries in accidents that involved flexion-distraction mechanisms.

La sécurité du piéton est un problème de santé publique, qui doit être traité tant par les acteurs de la recherche que par l'industrie automobile pour apporter des solutions technologiques innovantes. Dans les accidents impliquant des piétons, le premier contact est généralement localisé sur les membres inférieurs exhibant de fréquentes et nombreuses lésions pouvant être très sévères. Compte tenu des caractéristiques biomécaniques du membre inférieur, comment améliorer les critères de blessures existants pour contribuer au développement d'une voiture moins agressive pour les piétons ? La présente étude vise donc à promouvoir des améliorations significatives de critères de blessure des membres inférieurs pour la sécurité des piétons combinant des essais expérimentaux et des simulations numériques. Un modèle par éléments finis des membres inférieurs (modèle LLMS) a été utilisé et amélioré pour étudier les réponses mécaniques des membres inférieurs dans des conditions de chargement realists. Une attention particulière a été accordée sur la capacité du modèle à prédire séparément les blessures des os longs et celles de l'articulation du genou pour développer deux critères de blessures distincts. Pour le tibia, la nature de sa structure et les conditions de chargement qui lui sont appliquées nous ont conduit à proposer une courbe quadratique de moment en flexion qui tient compte de différents points d'impact. Pour le genou, le critère de blessure a été établi à partir d'une fonction combinant cisaillement latéral et flexion latérale. Ce critère permet de hiérarchiser la nature et la sévérité des lésions en fonction du mécanisme de blessure prépondérant. / Pedestrian safety is a worldwide concern, which needs to be investigated by both vehicle manufacturers and researchers to approach innovative solutions. In car-Pedestrian accidents, lower limbs have been demonstrated to be the most frequently injured body region of the pedestrian. Given the biomechanical features of lower limbs, how the existing injury criteria could be improved to aid the development of a pedestrian friendly car? The current study aims to promote significant improvements in the injury criteria of lower limbs for pedestrian safety combining experimental tests and numerical simulations. A finite element lower limb model (LLMS model) was used and improved to investigate the mechanical responses of lower limbs in the loading conditions reflecting the car-Pedestrian impact. A particular attention was paid on the model ability of predicting separately the injuries of long bones and knee joints to develop the corresponding injury criteria. With regard to the tibia structure and its loading condition in pedestrian accidents, we proposed a quadratic curve of bending moments to tibia locations as its injury tolerance. Given dominant injury mechanisms of the ligaments, the knee injury criterion was established as a function of combined joint kinematics including lateral bending and lateral shearing. Moreover, these criteria are relevant with the previous and current experimental test results. Finally, the efficiency of the proposed criteria was evaluated by a parametric study of the realistic car-Pedestrian impact conditions.

La myélopathie cervicale est une maladie chronique dégénérative de la moelle épinière dont la fréquence augmente avec l’âge. Elle est caractérisée par une compression mécanique menant à un endommagement de la structure médullaire et peut être source de handicaps sévères dégradant la qualité de vie. Néanmoins, la prise en charge clinique reste délicate.C’est pourquoi les travaux conduits dans le cadre de cette thèse se sont focalisés sur la compréhension des phénomènes biomécaniques à l’origine de cet endommagement (via des méthodes de simulation par éléments finis) et les conséquences microstructurelles pouvant être observées par IRM multi-paramétrique. Plus précisément, le but était d’établir un lien entre la cause mécanique et les conséquences structurelles menant aux déficits cliniques afin de mieux comprendre et prédire l’évolution de ces pathologies.Pour atteindre cela, une caractérisation de la morphologie et microstructure de la moelle épinière saine a été conduite par IRM, procurant à la fois une source de données normatives pour évaluer les atteintes chez patients mais aussi des données d’entrée pour raffiner les modèles numériques utilisés. D’un point de vue biomécanique, les phénomènes mécaniques observés lors d’une compression médullaire telle que pouvant être rencontrée dans une myélopathie cervicale ont été étudiés. Bien qu’à confirmer, les résultats obtenus au cours de ces travaux sont encourageants et posent une première pierre vers l’établissement de nouvelles méthodes permettant de mieux comprendre l’origine des déficits observés chez des patients souffrant de lésions médullaires en étudiant le lien entre mécanique, microstructure et fonction. / Cervical myelopathy is a chronic degenerative spinal cord pathology whose incidence increases with age. It is characterized by a mechanical compression leading to structural spinal cord damage. It can be at the origin of severe handicap hampering the quality of life. However, the clinical management remains challenging.This is why the work conducted in this thesis was focused on the comprehension of the biomechanics of the spinal cord damage (through numerical simulation finite element methods) and microstructural consequences that can be observed with multi-parametric MR imaging. More specifically, the final goal was to link the mechanical cause to the structural consequences at the origin of the clinical deficits in order to better understand and predict the pathology’s evolution.To reach that end, a characterization of the morphology and microstructure of the spinal cord was achieved using MRI, procuring on one side a normative database useful to study the alterations encountered in patients, and on another side to refine the numerical models employed. From a biomechanical perspective, the mechanisms of spinal cord compression as encountered in cervical myelopathy were studied using finite element analysis. The results obtained, which should be confirmed, are encouraging and represent a first stone towards the establishment of new methods in order to help in the clinical management of patients with spinal cord lesions by linking the mechanics, microstructure and function of the spinal cord.