Due to the constraint of high costs and limitations of load conditions, experimental testing is not appropriate for the static study of shelter structures. Comparatively, an effective computational modeling and numerical solution demonstrates significant advantages for understanding the response of steel shelter structures. This study gives an insight into the structural integrity of the prototype shelter structure which is examined using computer simulation of the shelter structure on Abaqus/CAE 2019. The results of the computer modelling demonstrate the response of shelter structure under ten different loading conditions as per ISO 1496:2013 (E). The loading conditions are applied to various components of the shelter structure and corresponding deflection are observed.

Iron Oxide Nanoparticles (IONPs) are a multifunctional nano-material that allows for MRI imaging, intravenous-controlled drug movement, and hyperthermia. The objective of this study is to optimize and control IONP hyperthermia and cope with aggregation using Finite Element (FE) Modeling and statistical physics. The FE model is first used to demonstrate the advantages of changing IONP heat dissipation in time, which can increase energy density inside tumors while decreasing the energy delivered in healthy tissue. Here, this is defined as target-specificity. Second, this model is used to demonstrate that time-dependent IONP heat dissipation allows for control of temperature distributions inside the body. Third, the FE model is used to solve the temperature distributions resulting from capillary diffusion of IONPs. This study shows that capillary diffusion combined with direct injection results in improved homogeneity of temperature distributions. Fourth, using a square-difference scheme, non-time domain parameters including the number of IONP injections, the location of injections, IONP distribution width, and heating intensity are optimized to improve target-specificity and temperature homogeneity. Collectively, this study contributes to hyperthermia by optimizing time- and non-time- domain parameters, controlling hyperthermia, and quantifying aggregation with a new theory. / Master of Science

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No description available.

Wear and corrosion are two major threats to material integrity in multiple real-life circumstances, including oil and gas pipelines, marine and offshore infrastructures and transportations and biomedical implants. Furthermore, the synergistic effects between the two, named tribocorrosion, could cause, most of the time, severer material degradation to jeopardize materials' long-term sustainability and structural integrity. A representative case is aluminum (Al) and its alloys, which exhibit good corrosion resistance in aqueous solution due to the protection provided by the passive layer. However, these naturally formed layers are thin and delicate, leaving the materials vulnerable to simultaneous mechanical and corrosion damage, which in turn, compromise their resistance to tribocorrosion. Past research in tribocorrosion mainly relies on costly and trial-and-error experimental methods to study the materials' deformation and degradation under simultaneous wear and corrosion. In an attempt to predict tribocorrosion behavior using numerical analysis, this work developed a set of finite-element-based multiphysics models, in combination with experimental methods for parameter input and validation, focusing on different factors influencing the tribocorrosion behavior of materials. The first study developed a model with the coupling between strain and corrosion potential and investigated the effect of bulk material properties on tribocorrosion. This model was validated by existing tribocorrosion experiments of two Al-Mn alloys, to analyze the synergistic effects of mechanical and corrosion properties on the material degradation mechanisms of tribocorrosion. During consecutive passes of the counter body, significant residual stress was found to develop near the edge of the wear track, leading to highly concentrated corrosion current than elsewhere. Such non-uniform surface corrosion and stress-corrosion coupling led to variations of tribocorrosion rate over time, even though testing conditions were kept constant. Tribocorrosion rate maps were generated to predict material loss as a function of different mechanical and electrochemical properties, indicating a hard, complaint metal with high anodic Tafel slope and low exchange current density is most resistant to tribocorrosion. Secondly, the influence of microstructural design on the tribocorrosion behavior of Al-based nanostructured metallic multilayers (NMMs) was investigated computationally. Specifically, this model accounts for elastic-plastic mechanical deformation during wear and galvanic corrosion between exposed inner layers after wear. The effects of individual layer thickness (from 10 to 100 nm) and layer orientation (horizontally and vertically aligned) on the tribocorrosion behavior of Al/Cu NMMs was studied. Both factors were found to affect the subsurface stress and plastic strain distribution and localized surface corrosion kinetics, hence affecting the overall tribocorrosion rate. This model and the obtained understanding could shed light on future design and optimization strategies of NMMs against tribocorrosion. Finally, a combined experimental and computational investigation of the crystallographic effect using Al (100), (110), and (111) single crystals as model systems, to understand the effects of crystallographic orientation on the tribocorrosion kinetics by combining tribocorrosion experiments, materials characterization, and multiphysics modeling. EBSD was exploited to characterize the crystal orientation and dislocation density of the worn samples. The tribocorrosion model was built based on the results of EBSD characterization with the coupling effect of crystal orientation and corrosion. The model successfully predicted the overall tribocorrosion current of single-crystal samples, indicating the important role played by crystal orientation and dislocation density in the acceleration of corrosion. / Doctor of Philosophy / Multiple applications in batteries, aerospace, marine transportation, offshore infrastructure and biomedical implants request metal materials that are both mechanically reliable and corrosion resistant. In addition to pure mechanical wear and corrosion, the synergy of the two, which is called tribocorrosion, also poses major threat to materials' integrity and longevity. Aluminum is a widely used passive metal due to its advantage of being cheap, light-weighted and corrosion resistant, but is relatively less resistant to wear comparing to other metals. Mechanical damage could strip Al of the protection from the passive layer and also cause stress corrosion. This makes Al susceptible to tribocorrosion. Despite several previous experimental attempts to understand the mechanism of Al tribocorrosion and improve the tribocorrosion resistance of Al by alloying or structural design, there has been little quantitative model on this topic. In this dissertation, finite element (FE) multi-physics modeling was exploited to investigate the tribocorrosion phenomenon on Al systems in sea water environment. The first model was developed based on strain-electrochemistry coupling and helped study the effect of alloys' composition on the tribocorrosion resistance of the alloy. The second model studied the tribocorrosion of Al/Cu multilayers with the focus on the micro-galvanic coupling between Al and Cu layers and predicted the influence of layer thickness and orientation. The third model exploited the result of crystallographic information from EBSD characterization to study the mechanism of pure Al tribocorrosion on the crystal level. These models provide quantitative explanation to the accelerated corrosion of Al-based metals and structures, as well as guidance to future design of material with optimum wear, corrosion and tribocorrosion resistance.

Human activities associated with the injection of fluids at depth are known to trigger earthquakes. Fluid injection increases the internal pore pressure of the host rock, which in turn reduces the effective stress and frictional resistance of faults that maintain the fractured rock system in a state of mechanical equilibrium. Under certain conditions, sufficiently high pore pressure can lower this frictional resistance below a critical threshold and initiate an earthquake – the relative motion of rock on either side of the fault plane. Many of these earthquakes are small and imperceptible without the aid of specialized instruments, but some may be large enough to pose a significant risk to life and property. Several emerging technologies that have the potential to shape the future of low-carbon energy production, including carbon capture and storage and enhanced geothermal energy production, are inextricably linked to large-scale injection of fluids into the subsurface. The risk of injection-induced earthquakes is a primary concern and potential barrier to widespread adoption of these technologies. New tools are required to help operators manage these risks and meet stakeholder expectations. Current knowledge enables operators to predict the conditions that would trigger such an earthquake, but few or no tools exist to predict the severity of the earthquakes, precluding a complete description of the risk associated with operating a large-scale injection well. This dissertation details the theoretical justification and initial validation of a methodology and software to simulate the motion of an earthquake as it occurs and quantify the severity in terms that are germane to experts in earthquake science. Specifically, this work utilizes the finite element method to solve the equations of motion dictated by the three-dimensional linear elastic constitutive equation. Novel aspects of this research include the treatment of friction at the fault interface as a constraint on the motion of the system, and the numerical methods necessary to solve this problem. This software was created exclusively with free and open source software, so that every aspect of its internal machinery may be scrutinized, replicated, and improved by future workers. / Doctor of Philosophy / Human activities associated with the injection of fluids at depth are known to trigger earthquakes. Many of these earthquakes are small and imperceptible without the aid of specialized instruments, but some may be large enough to pose a significant risk to life and property. Several emerging technologies that have the potential to shape the future of low-carbon energy production, including carbon capture and storage and enhanced geothermal energy production, are inextricably linked to large-scale injection of fluids into the subsurface. The risk of injection-induced earthquakes is a primary concern and potential barrier to widespread adoption of these technologies. New tools are required to help operators manage these risks and meet stakeholder expectations. Current knowledge enables operators to predict the conditions that would trigger such an earthquake, but few or no tools exist to predict the severity of the earthquakes, precluding a complete description of the risk associated with operating a large-scale injection well. This dissertation details the theoretical justification and initial validation of a methodology and software to simulate the motion of an earthquake as it occurs and quantify the severity in terms that are germane to experts in earthquake science. This software was created exclusively with free and open source software, so that every aspect of its internal machinery may be scrutinized, replicated, and improved by future workers.

Asphalt pavement rutting is one of the most commonly observed pavement distresses and is a major safety concern to transportation agencies. Millions of dollars are reportedly spent annually to repair rutted asphalt pavements. Research into improvements of hot-mix asphalt materials, mix designs and methods of pavement evaluation and design, including laboratory and field testing, can provide extended pavement life and significant cost savings in pavement maintenance and rehabilitation. This research describes a method of predicting the behaviour of various asphalt mixes and linking these behaviours to an accelerated performance testing tool and pavement in-situ performance. The elastic, plastic, viscoelastic and viscoplastic components of asphalt mix deformation are also examined for their relevance to asphalt rutting prediction. The finite element method (FEM) allows for analysis of nonlinear viscoplastic behaviour of asphalt mixes. This research determines the critical characteristics of asphalt mixes which control rutting potential and investigates the methods of laboratory testing which can be used to determine these characteristics. The Hamburg Wheel Rut Tester (HWRT) is used in this research for asphalt laboratory accelerated rutting resistance testing and for calibration of material parameters developed in triaxial repeated load creep and creep recovery testing. The rutting resistance criteria used in the HWRT are developed for various traffic loading levels. The results and mix ranking associated with the laboratory testing are compared with the results and mix ranking associated with FEM modeling and new mechanistic-empirical method of pavement design analyses. A good relationship is observed between laboratory measured and analytically predicted performance of asphalt mixes. The result of this research is a practical framework for developing material parameters in laboratory testing which can be used in FEM modeling of accelerated performance testing and pavement in-situ performance.

Elevated intracranial pressure (ICP) in closed head injury may lead to a vegetative state and even death. Current methods available for measuring ICP may cause infection, haemorrhage or not reliable. A patient-specific correlation between ICP and an external vibration response was used for ICP evaluation, which based on finite element (FE) modeling. In FE modeling, a two dimensional FE model of human head was built in ANSYS. Geometry information was obtained from a magnetic resonance image of the human head, while the material properties were acquired from literatures. Vibration responses, e.g., displacement, velocity, acceleration and equivalent strain, were obtained for applied ICPs in FE analyses. Correlations between ICP and vibration responses were established. Effects of impact magnitude and impact duration were studied. Response sensitivity was defined to find a vibration response that is sensitive to ICP change. A procedure based on response sensitivity was proposed for ICP evaluation.

Elevated intracranial pressure (ICP) in closed head injury may lead to a vegetative state and even death. Current methods available for measuring ICP may cause infection, haemorrhage or not reliable. A patient-specific correlation between ICP and an external vibration response was used for ICP evaluation, which based on finite element (FE) modeling. In FE modeling, a two dimensional FE model of human head was built in ANSYS. Geometry information was obtained from a magnetic resonance image of the human head, while the material properties were acquired from literatures. Vibration responses, e.g., displacement, velocity, acceleration and equivalent strain, were obtained for applied ICPs in FE analyses. Correlations between ICP and vibration responses were established. Effects of impact magnitude and impact duration were studied. Response sensitivity was defined to find a vibration response that is sensitive to ICP change. A procedure based on response sensitivity was proposed for ICP evaluation.

Moisture damage is one of the major causes of deterioration of pavements. An example is the damage caused by flooding. While the effects of pore water pressure in pavement have been studied using finite element modeling, few of the models consider a realistic moving tire and the viscoelastic behavior of the asphalt layer. Consequently, a three-dimensional finite element simulation based on Biot consolidation theory and Schapery's non-linear viscoelasticity model, was developed to accurately simulate and analyze the detrimental effects of saturated layers in asphalt pavements. In addition, a parametric study is conducted to analyze the response of pavements with varying surface and base thickness, base and subgrade permeability, and vehicle speeds under different level of saturation. The results indicate that the effects of pore water pressure be considered in the design of pavements in flood-prone areas and in the proposal of flood management plans. Ultimately, the implementation of a "flood resilient" asphalt pavement could be effective in reducing the cost of road restoration and repair in flood-prone areas. / Master of Science / Moisture damage is one of the major causes of deterioration of pavements. An example is the damage caused by flooding. While the effects of pore water pressure in pavement have been studied using finite element modeling, few of the models have accurately modeled the behavior of the asphalt concrete and have not considered the realistic loading conditions. Consequently, a three-dimensional finite element simulation was developed to accurately simulate and analyze the detrimental effects of saturated layers in asphalt pavements. In addition, a parametric study is conducted to analyze the response of pavements with varying surface and base thickness, base and subgrade permeability, and vehicle speeds under different level of saturation. The results indicate that the effects of pore water pressure be considered in the design of pavements in flood-prone areas and in the proposal of flood management plans. Ultimately, the implementation of a "flood resilient" asphalt pavement could be effective in reducing the cost of road restoration and repair in flood-prone areas.