Engineering Science and Materials Commons^™

The Development And Testing Of A Gyroscope-Based Neck Strengthening Rehabilitation Device, Nicole D. Devos

Electronic Thesis and Dissertation Repository

Neck pain can be debilitating, and is experienced by the majority of people at some point over the course of their life. Resistance training has been shown to have significant improvement in pain or disability for patients. There are few options available for telerehabilitation, and the use of gyroscope stabilizers is proposed for this use. A biomechanics model of a head--neck--gyroscope system was created. In order to also model the dynamics of such a system, this work proposes a blended method using the Denavit--Hartenberg (DH) convention, popular in the field of robotics, with the Lagrangian mechanics approach to analyze an …

Numerical Modeling And Simulation On Deformation And Failure Behaviors Of Polymeric Materials, Heng Feng

Electronic Thesis and Dissertation Repository

Featured by biocompatibility, high compliance and capacity in sustaining large deformation, dielectric elastomers (DEs) and hydrogels have gained extensive research popularity for their potential applications in the fields of soft robots, biomimetics, tissue engineering, drug delivery, and energy harvesting. The design of such soft and smart material-based devices and structures requires deep understanding and accurate simulation of their constitutive behaviors, which is challenged by their nonlinear material properties due to unique microstructures and multi-physics coupling. Meanwhile, in different application contexts, those structures are also susceptible to different failure modes, imposing further challenges in simulating and predicting their performance. To fulfill …

Microstructure-Informed Modeling Of Hydrogen Diffusion In Zirconium Polycrystals, Alireza Tondro

Electronic Thesis and Dissertation Repository

Zirconium alloys are widely used in the core of various types of nuclear reactors. During service, the hot water coolant reacts with zirconium and releases hydrogen atoms that ingress into the lattice of the metal alloy. With time, hydrogen concentration exceeds its terminal solid solubility limit in zirconium, and a brittle phase known as zirconium hydride forms. This phase severely deteriorates the mechanical properties of zirconium alloys, leading to safety concerns regarding the integrity of nuclear pressure tubes. This thesis uses a crystal plasticity finite element model coupled with diffusion equations to study the effects of localized deformation at the …

Near-Ir Laser Ablation Of Simulated Radiologically Contaminated Oxides On Carbon Steel Feeder Pipes, Thao Viet Do

Electronic Thesis and Dissertation Repository

As nuclear power plants age and retire from service, many countries face significant challenges concerning the safe long-term storage and disposal of large volumes of low and intermediate level radioactive wastes (L&ILW). The volumes of metallic waste are of particular concern, as when metal corrodes it produces hydrogen that could lead to pressure build-up in interim storage and disposal. In Canada, a significant fraction of the metallic wastes for Canada Deuterium Uranium (CANDU) nuclear reactors are out-of-core reactor components, such as carbon steel (CS) feeder pipes. The radioactive contamination is expected to be largely confined to the surface oxide layers …

Hydration Kinetics, Microstructure, And Mechanical Strength Development Of Cement-Based Composites Incorporating Phase Change Materials, Afshin Marani

Electronic Thesis and Dissertation Repository

The research conducted in this thesis investigates the effects of phase change materials (PCMs) on the hydration kinetics and strength development of cement-based composites using extensive experimental and numerical analyses. Purposefully, the effect of microencapsulated PCMs (MPCMs) on the strength development of cement-based mortars and concretes was evaluated using powerful machine learning models trained with the largest available experimental data. Furthermore, a novel ternary machine learning approach was proposed to optimize the mixture design of mortars and concretes based on the thermos-physical properties of the MPCMs. The results obtained from machine learning simulations suggest the assessment of the effects of …

A Dislocation-Based Crystal Plasticity Model For Hexagonal Close-Packed Polycrystals, Omid Sedaghat

Electronic Thesis and Dissertation Repository

Due to their low neutron absorption cross-section and good corrosion properties, zirconium and its alloys have been widely used as the structural material in the core of nuclear reactors. These alloys are exposed to an intensive neutron flux which may lead to dimensional instabilities and the degradation of the mechanical properties of the alloy over the service time of the reactor. The changes in deformation behavior and mechanical properties can be traced back to the formation, evolution, and interaction of the irradiation-induced microstructural defects, e.g., point defect clusters, dislocation loops, and complex dislocation line networks. However, the materials constitutive models …

A Computational Fluid Dynamics-Based Surrogate Wind Turbine Blade Aerodynamic Model For Hybrid Simulation, Eric Lalonde

Electronic Thesis and Dissertation Repository

Hybrid simulation (HS) is a promising technique for studying wind turbines due to the presence of scaling errors in wind tunnel testing. However, HS of wind-loaded structures is limited by the current practice of using lower-accuracy, "pre-calculated" aerodynamic loads, which uncouple the aerodynamic loading from the structural response. This thesis presents six stand-alone studies that collectively build towards a novel HS framework that employs a computational fluid dynamics (CFD) based surrogate model to generate higher-accuracy aerodynamic loads within the HS loop. An experimentally-validated residential wind turbine model equipped with an external damping system was used to illustrate the proposed framework. …

Significance Of The Vehicle Front Design And Gait Postures On Traumatic Brain Injuries Sustained By Different Pedestrian Populations During Car-To-Pedestrian Collisions (Cpcs) - A Computational Approach, Thava Kalishwara Kumar Gunasekaran

Electronic Thesis and Dissertation Repository

With the increasing prevalence of traumatic brain injuries (TBIs) in road traffic accidents (RTAs), it was identified that the shape of the vehicle's front end and pedestrian postures prior to impact significantly influence pedestrian head injuries. However, the effect of vehicle front shape parameters and gait postures on TBIs sustained in car-to-pedestrian collisions (CPCs) has yet to be quantified. This study used a computational approach to analyze the effect of vehicle shape parameters and pedestrian gait postures on pedestrian TBI risks across a diverse pedestrian population with varying body sizes. Our findings indicate that vehicle shape parameter such as BLEH …

Development Of A Wireless Telemetry Load And Displacement Sensor For Orthopaedic Applications, William Anderson

Electronic Thesis and Dissertation Repository

Due to sensor size and supporting circuitry, in vivo load and deformation measurements are currently restricted to applications within larger orthopaedic implants. The objective of this thesis is to repurpose a commercially available low-power, miniature, wireless, telemetric, tire-pressure sensor (FXTH87) to measure load and deformation for future use in biomechanical applications. The capacitive transducer membrane of the FXTH87 was modified, and a relationship was reported between applied compressive deformation and sensor signal value. The sensor package was embedded within a deformable enclosure to illustrate potential applications of the sensor for monitoring load. Finite element analysis was an effective tool to …

Joint Wind And Ice Effects On Transmission Lines In Mountainous Terrain, Daniel Davalos Arriaga

Electronic Thesis and Dissertation Repository

Atmospheric icing on mountainous terrain can produce catastrophic damages to transmission lines when incoming particles impinge and accrete on the cable surface of the system. The first challenge in wind-ice loading is determining joint statistics of wind and ice accretion on transmission lines. This study analyzes the weather characteristics for a specific site of study using 15 years of historical data to use as inputs for ice accretion modeling. The joint wind and ice hazard is characterized by simulating 500 years of icing events from the fitted probability distributions of ice accretion and wind on ice velocities. The second challenge …

Measurement And Modeling Of Micro Residual Stresses In Pure Zirconium And Zr-2.5nb Polycrystals, Abdulla Alawadi

Electronic Thesis and Dissertation Repository

In CANada Deterium Uranium (CANDU) nuclear reactors, Zr-2.5Nb alloy pressure tubes separate the hot water and cold moderator. Pressure tubes are susceptible to the diffusion of hydrogen from water and formation of a brittle phase called zirconium hydrides. The diffusion and formation of hydrides are affected by the state of stresses within the tubes. As such, it is of great significance to understand the source of the stresses that develop within the tubes. This thesis focuses on the characterization of the micro and nano scale residual stresses that develop in pure zirconium and Zr-2.5Nb polycrystals. With using three-dimensional synchrotron X-ray …

Incipient Deformation Of Small Volumes Of Fcc Metals, Mahdi Bagheripoor

Electronic Thesis and Dissertation Repository

In the area of mechanics of materials, the classic theories cannot describe the material behaviour as the volume of deformation or sample size is small enough to be compared with the size scales of the imperfections of the crystal. So, there has been a great deal of interest in investigating the plasticity of micron and nano-sized materials, in the last 20 years. As a Ph.D. research project, the deformation mechanism at small scales of fcc metals is studied based on dislocations behaviour. The effect of main parameters that haven’t been studied in detail, including, crystal orientation, pre-existing faults, grain boundaries, …

Characterization And Computational Modelling For The Garnet Oxide Solid State Electrolyte Ta-Llzo, Colin A. Versnick

Electronic Thesis and Dissertation Repository

The all-solid-state-battery (ASSB) serves as a promising candidate for next generation lithium ion batteries for significant improvements in battery safety, capacity, and longevity. Of the material candidates researched to replace the conventionally used liquid electrolyte, the garnet oxide Ta-LLZO (Li_6.4La₃Zr_1.4Ta_0.6O₁₂) has received much attention thanks to its high chemical and electrochemical stability, and ionic conductivity which rivals that of liquid electrolytes. While much investigation has taken place regarding the electrochemical performance of Ta-LLZO, much less is known about the micromechanics, including microstructural characterization, stress and strain development, and material failure …

Effect Of The Nonlinear Material Viscosity On The Performance Of Dielectric Elastomer Transducers, Yuanping Li

Electronic Thesis and Dissertation Repository

As a typical type of soft electroactive materials, dielectric elastomers (DEs) are capable of producing large voltage-induced deformation, which makes them desirable materials for a variety of applications in transduction technology, including tunable oscillators, resonators, biomimetics and energy harvesters. The dynamic and energy harvesting performance of such DE-based devices is strongly affected not only by multiple failure modes such as electrical breakdown, electromechanical instability, loss-of-tension and fatigue, but also by their material viscoelasticity. Moreover, as suggested by experiments and theoretical studies, DEs possess nonlinear relaxation processes, which makes modeling of the performance of DE-based devices more challenging.

In this thesis, …

Advances In Design Methodology In Swelling Shale Rock In Southern Ontario, Thomas R.A. Lardner

Electronic Thesis and Dissertation Repository

As infrastructure requirements increase in southern Ontario, excavations within swelling rock formations will become more frequent and larger. The objective of this study is to advance design capability for structures in swelling rock through three aspects: i) developing a practical swelling model for design engineers, ii) investigate two crushable/compressible materials for the mitigation of swelling rock effects, and iii) observe and analyze the behaviour of swelling rock to current excavation techniques.

A swelling rock constitutive model has been developed. The swelling parameters include the horizontal and vertical free swell potential, threshold stress, and critical stress as well as a “pseudo-Poisson’s …

Bouncing Dynamics Of A Class Of Mem/Nem Switching Systems, Mohamed Bognash

Electronic Thesis and Dissertation Repository

The aim of the present research is to understand the bouncing dynamic behavior of NEM/MEM switches in order to improve the switch performance and reliability. It is well known that the bouncing can dramatically degrade the switch performance and life; hence, in the present study, bouncing dynamics of a cantilever-based NME/MEM switch has been studied in detail. To this end, a model of a MEM switch that incorporates electrostatic force, squeeze film air damping force as well as asperity-based contact force has been proposed for an electrostatically actuated switch. An actuation force due to piezoelectric effects is further included in …

Electrospun Collagen Fibers For Tissue Regeneration Applications, Ying Li

Electronic Thesis and Dissertation Repository

Tissue engineering aims to regenerate damaged and deceased tissue by combining cells with scaffold made from an appropriate biomaterial and providing a conducive environment to guide cell growth and the formation or regeneration of new tissue or organ. While collagen, an important material of the extracellular matrix (ECM), is a natural choice as a scaffold biomaterial, the conducive environment can only be created by having the ability to control the geometry, organization, structural and mechanical properties of the scaffold. Moreover, degradability and degradation rate control of the scaffold has to be taken into consideration too. In this work, we aim …

Effect Of Material Viscoelasticity On Frequency Tuning Of Dielectric Elastomer Membrane Resonators, Liyang Tian

Electronic Thesis and Dissertation Repository

Dielectric elastomers (DEs) capable of large voltage-induced deformation show promise for applications such as resonators and oscillators. However, the dynamic performance of such vibrational devices is not only strongly affected by the nonlinear electromechanical coupling and material hyperelasticity, but also significantly by the material viscoelasticity. The material viscoelasticity of DEs originates from the highly mobile polymer chains that constitute the polymer networks of the DE. Moreover, due to the multiple viscous polymer subnetworks, DEs possess multiple relaxation processes. Therefore, in order to predict the dynamic performance of DE-based devices, a theoretical model that accounts for the multiple relaxation processes is …

Mechanical Characterization And Shear Test Comparison For Continuous-Fiber Polymer Composites, Matthew Crossan

Electronic Thesis and Dissertation Repository

As fiber-reinforced composites continue to be used in a wide-range of high performance structures, more detailed understanding and accurate prediction of stress-strain behaviour is necessary to improving designs and reducing costs. This thesis compares the experimental behaviour of a continuous fiber polymer composite of carbon fiber and epoxy resin using Digital Image Correlation to analytical and theoretical predictions. Furthermore, an in-depth analysis of shear testing methods reveals the advantages and limitations of different testing standards. Finally, the limitations of the Iosipescu Shear test (ASTM 5379) fixture to break high-strain-to-failure composites in comparison to the V-notched Rail Shear Fixture (ASTM 7078) …

Bubble-Induced Inverse Gas-Liquid-Solid Fluidized Bed, Xiliang Sun

Electronic Thesis and Dissertation Repository

Gas-liquid-solid fluidized beds have been widely applied in wastewater treatment, however, the current method of wastewater process has several limitations. Hence, an improved method is in demand. A 3.5 height and 0.1534m inner diameter column was used to study the hydrodynamic characteristics of a bubble-induced three-phase inverse fluidized bed. Air, water and three types of low-density particles were employed as gas, liquid and solid phases.

The hydrodynamic properties in the bubble-induced three-phase fluidized bed were investigated to provide the basic information for the industrial process, such as flow regime, bed expansion ratio and phase holdups. A flow regime map containing …

Process-Structure-Property Relationships For High Pressure Die-Cast Magnesium Alloys, Pouya Sharifi

Electronic Thesis and Dissertation Repository

The primary goal of this study was to conduct experiments and simulation modeling to determine the relevant filling and solidification process parameters that influence microstructural features of the high-pressure die-cast magnesium alloy AM60. This work continues from the previous research that has been carried out by Dr. Jeff Wood’s research group over the last sixteen years.

Metallographic and spherical microindentation were used to analyze the influence of microstructural features on the flow stress for both skin (finer grain sizes) and core (larger grain sizes) of high pressure die castings (HPDC), as well as different regions of gravity cast stepped-plate. It …

Study On The Mechanical Behavior Of Directly Compounded Long Glass Fiber Reinforced Polyamide 6 Composites, Yuchao Liu

Electronic Thesis and Dissertation Repository

With great lightweight potential, high performance-to-cost ratio and mass productivity, direct-compounded long fiber thermoplastics (D-LFT) have drawn great attention from the automotive industry. With better mechanical properties and higher service temperature, polyamide 6 (PA6) was used to replace polypropylene (PP) which is almost the exclusively used matrix for the D-LFT process currently. The investigation was performed on this new material with a focus on the effect of fiber content, processing parameters, temperature and tailored reinforcement on mechanical behavior. The results show that the mechanical properties of this new material are sensitive to the variation of fiber content and service temperature …

Numerical Studies For Improving Fracture Toughness Resistance Curve Testing Using Single-Edge (Notched) Tension Specimens, Yifan Huang

Electronic Thesis and Dissertation Repository

The fracture toughness resistance curve, i.e. the J-integral resistance curve (J-R curve) or the crack tip opening displacement resistance (CTOD-R) curves, is widely used in the integrity assessment and strain-based design of energy pipelines with respect to planar defects (i.e. cracks). This thesis deals with issues related to the experimental determination of the J(CTOD)-R curves using the newly-developed single-edge (notched) tension (SE(T)) specimens. In the first study, the plastic geometry factor, i.e. the η_pl factor, used to evaluate J in a J-R curve test based on …

Kinetics Of Length Scale Dependent Deformation Of Gold Microspheres And Micropillars, A Z M Ariful Islam

Electronic Thesis and Dissertation Repository

In this thesis length and time scale dependence of the operative plastic deformation mechanisms in Au is studied. Uniaxial compression tests were performed at various loading rates on FIB-milled Au micropillars and single-crystalline Au microspheres of diameter ranging from 0.8 to 6.0 µm to investigate the incipient and bulk plasticity events. Constant-load ambient-temperature creep tests were performed on the micropillars to study the time-dependent plasticity at very slow strain rates. Uniaxial compression tests were also performed on coated Au microspheres to study the effect of extrinsic constraint on the deformation mechanisms.

During uniaxial compression, both the Au micropillars and microspheres …

Doped Tio2 Nanowires For Applications In Dye Sensitized Solar Cells And Sacrifical Hydrogen Production, Qasem Alsharari

Electronic Thesis and Dissertation Repository

This thesis explores the synthesis of metal oxide 1-D nanowires using a sol-gel method in supercritical carbon dioxide (sc-CO₂), as an environmental friendly enabling solvent. Porous nanowires were synthesized and their performance was tested in dye sensitized solar cell and sacrifical hydrogen production. Titanium isopropoxide (TIP) was used as a precursor for titania synthesis while copper, bismuth and indium were examined as dopants, respectively. The sol-gel reactions were catalyzed by acetic acid in CO₂ at a temperature of 60 °C and pressure of 5000 psi. It was observed that acetic acid/monomer ratio > 4 produced nanowires while a …

Electromechanical Coupling Behavior Of Dielectric Elastomer Transducers, Jianyou Zhou

Electronic Thesis and Dissertation Repository

Dielectric elastomer transducers with large deformation, high energy output, light weight and low cost have been drawing great interest from both the research and industry communities, and shown potential for versatile applications in biomimetics, dynamics, robotics and energy harvesting. However, in addition to multiple failure modes such as electrical breakdown, electromechanical instability, loss-of-tension and fatigue, the performance of dielectric elastomer transducers are also strongly influenced by the hyperelastic and viscoelastic properties of the material. Also, the interplay among these material properties and the failure modes is rather difficult to predict. Therefore, in order to provide guidelines for the optimal design …

The Effect Of Backing Material On Carbon Fibre Severing For High-Volume Production Of Composites, Ryan W. Alexander

Electronic Thesis and Dissertation Repository

The replacement of steel with lightweight carbon fibre reinforced polymer (CFRP) represents one of the alternatives seriously considered by carmakers in preparation for the emission regulations of the future. While CFRPs have been used for a few decades across several industries, the recent price fall of carbon fibres have also made CFRPs attractive for high-volume automotive applications. Some challenges to address before the full-scale deployment of composites in the automotive industry are related to the efficient severing of carbon fibres. To address this, the present study investigated the effects of backing on the performance of carbon fibre severing through the …

The Effect Of Fixation Plate Length On Spinal Instability Following Anterior Cervical Plate Fixation For The Repair Of In Vitro Flexion-Distraction Injuries, Abdulaziz J. Al-Kuwari

Electronic Thesis and Dissertation Repository

Abstract:

The Effect of Fixation Plate Length on Spinal Instability Following Anterior Cervical Plate Fixation for the Repair of in Vitro Flexion-Distraction Injuries

Introduction: Anterior cervical decompression and fusion with a plate (ACDFP) is a commonly performed treatment following a traumatic injury to the subaxial cervical spine. The purpose of the presented work was to determine the biomechanical effect of plate length on cervical spine kinematic stability following ACDFP stabilization for a simulated traumatic injury.

Methods: Eleven fresh-frozen cadaveric C5-C6 and C6-C7 motion segments were examined in this study. To assess kinematics, flexibility testing was performed on each specimen …

Size-Dependent Electroelastic Properties Of Piezoelectric Nanoplates, Zhengrong Zhang

Electronic Thesis and Dissertation Repository

With the development of nanotechnology, piezoelectric nanostructures have attracted a surge of interests in research communities for the potential applications as transistors, sensors, actuators, resonators and energy harvesters in nanoelectromechanical systems (NEMS) due to their high electromechanical coupling and unique features at the nano-scale. Piezoelectric nanomaterials have been characterized to possess size-dependent electromechanical coupling properties from both experimental and theoretical perspectives. Therefore it is of great importance to investigate the physical mechanisms of these distinct nano-scale structure features in order to fulfill the design and application of those piezoelectricity-based nanodevices.

Due to large surface to volume ratio and manifest strain …

Micromechanics Modeling Of The Electrical Conductivity Of Carbon Nanotude (Cnt)- Polymer Nanocomposites, Chuang Feng

Electronic Thesis and Dissertation Repository

The addition of carbon nanotubes (CNTs) in polymers to form conductive composites has been attracting great interest from research and industry communities due to their potential applications. Experiments and simulations have demonstrated that the addition of a very small amount of CNTs into polymers can significantly improve the electrical conductivity of the composites. Such significant improvement in the electrical conductivity is attributed to two conductivity mechanisms: nanoscale electron hopping and microscale conductive networks. Understanding and prediction of the overall electrical conductivity of the composites with the incorporation of the conductivity mechanisms that underpin the macroscopic electrical properties are essential for …