Structural steel design standards recognize lateral torsional buckling as a failure mode governing the capacity of long span unsupported beams with wide flange cross-sections. Standard solutions start with the closed form solution of the Vlasov thin-walled beam theory for the case of a simply supported beam under uniform moments, and modify the solution to accommodate various moment distributions through moment gradient expressions. The Vlasov theory solution is based on the assumption that cross-sectional distortional effects have a negligible effect on the predicted elastic critical moment. The present study systematically examines the validity of the Vlasov assumption related to cross-section distortion through a parametric study. A series of elastic shell finite element eigen-value buckling analyses is conducted on simply supported beams subject to uniform moments, linear moments and mid span point loads as well as cantilevers subject to top flange loading acting at the tip. Cross-sectional dimensions are selected to represent structural steel cross-section geometries used in practice. Particular attention is paid to model end connection details commonly used in practice involving moment connections with two pairs of stiffeners, simply supported ends with a pair of transverse stiffeners, simply supported ends with cleat angle details, and built in fixation at cantilever roots. The critical moments obtained from the FEA are compared to those based on conventional critical moment equations in various Standards and published solutions. The effects of web slenderness, flange slenderness, web height to flange width ratio, and span to height ratios on the critical moment ratio are systematically quantified. For some combinations of section geometries and connection details, it is shown that present solutions derived from the Vlasov theory can overestimate the lateral torsional buckling resistance for beams.

Three-dimensional (3-D) medical imaging creates notable opportunities as input toward engineering analyses, whether for basic understanding of the normal function or patho-physiology of an organ, or for the simulation of virtual surgical procedures. These analyses most often require finite element (FE) models to be constructed from patient-specific 3-D medical images. However, creation of such models can be extremely labor-intensive; in addition, image processing and mesh generation are often operator-dependent, lack robustness and may be of suboptimal quality. Focusing on the human aorta, the goal of the present work is to create a fast and robust methodology for quadrilateral surface and hexahedral volume meshing from 3-D medical images with minimal user input. By making use of the segmentation capabilities of the 3-D gradient vector flow field combined with original ray-tracing and orientation control algorithms, we will demonstrate that it is possible to incrementally grow a structured quadrilateral surface mesh of the inner wall of the aorta. The process does not only require minimal input from the user, it is also robust and very fast compared to existing methods; it effectively combines segmentation and meshing into one single effort. After successfully testing the methodology and measuring the quality of the meshes produced by it from synthetic as well as real medical image datasets, we will make use of the surface mesh of the inner aortic wall to derive hexahedral meshes of the aortic wall thickness and of the fluid domain inside the aorta. We will finally outline a tentative approach to merge several structured meshes to process the main branches of the aorta.

A pipe consisting of Inconel 600 welded to grade 106-B Carbon-Steel using Inconel 182 weld filler is used to transport heavy water in nuclear reactors. A confidential report concluded that cracking is one of the problems these pipes are currently facing. Before cracking can be fully understood the mechanical properties of the weld must be determined. This thesis analyzed the pipe at various length-scales using optical microscopy, micro-hardness testing, small and large scale tensile testing and digital image correlation (DIC). This thesis successfully achieved it goals of determining the mechanical properties and creating a model of the Inconel dissimilar metal weld. It partially met the goal of observing fracture mechanisms as it was able to observe fracture in tensile samples but was not able to successfully track crack growth.

The non-corrodible nature of FRP bars along with their high strength, light weight and ease of installation made it attractive as reinforcement especially for structures exposed to aggressive environment. In addition, the transparency of FRP bars to magnetic and electrical fields makes them an ideal alternative to traditional steel reinforcement in applications sensitive to electromagnetic fields such as magnetic resonance imaging (MRI) units. Continuous concrete beams are commonly-used elements in structures such as parking garages and overpasses, which might be exposed to extreme weather conditions and the application of de-icing salts. In such structures, using the non-corrodible FRP bars is a viable alternative to avoid steel-corrosion problems. However, the linear-elastic behaviour of FRP materials makes the ability of continuous beams to redistribute loads and moments questionable. The objective of this research project is to investigate the flexural behaviour of continuous concrete beams reinforced with FRP and their capability of moment redistribution. An experimental program was conducted at the University of Manitoba to realize the research objectives. Ten full-scale continuous concrete beams were constructed and tested to failure in the laboratory. The specimens had a rectangular cross-section of 200×300 mm and continuous over two spans of 2,800 mm each. The main investigated parameters were the amount and material of longitudinal reinforcement, the amount and material of transverse reinforcement and the spacing of used stirrups. The experimental results showed that moment redistribution in FRP-reinforced continuous concrete beams is possible if the reinforcement configuration is chosen properly, and is improved by increasing the amount of transverse reinforcement. A finite element investigation was conducted using ANSYS-software. A 3-D model was created to simulate the behaviour of continuous beams reinforced with FRP. The model was verified against the experimental results obtained from the present study. This verified model was used to investigate the effect of the concrete compressive strength, longitudinal reinforcement ratio, midspan-to-middle support reinforcement ratio and the amount of transverse reinforcement on the behaviour of FRP-reinforced beams. The analytical results of this parametric investigation along with the experimental results were used to propose an allowable limit for moment redistribution in FRP-reinforced continuous concrete beams.

Biofidelity of finite element head model (FEHM) includes geometric and material aspects. A FEHM with inhomogeneous material properties was proposed to improve material biofidelity. The proposed FEHM was validated against experimental data and good agreements were observed. The capability of the proposed model in simulating large tissue deformation was also demonstrated. Influences of inhomogeneous material properties on the mechanical responses of head were investigated by comparing with homogeneous material model. The inhomogeneous material properties induce large peak strains in head constituents, which are probably the cause of various brain injuries. Helmets are effective in preventing head injuries. Parametric studies were conducted to investigate how changes in helmet shell stiffness, foam density and pad thickness influence the performance of a helmet in protecting the brain. Results showed that strain energy absorbed by foam component, contact stress on the interfaces and intracranial responses are significantly affected by foam density and pad thickness.

This thesis studies the application of a multi-objective niched Pareto genetic algorithm on the design optimization of an electric field mill sensor. The original sensor requires resonant operation. The objective of the algorithm presented is to optimize the geometry eliminating the need for resonant operation which can be difficult to maintain in the presence of an unpredictable changing environment. The algorithm evaluates each design using finite element simulations. A population of sensor designs is evolved towards an optimal Pareto frontier of solutions. Several candidate solutions are selected that offer superior displacement, frequency, and stress concentrations. These designs were modified for fabrication using the PolyMUMPs abrication process but failed to operate due to the process. In order to fabricate the sensors in-house with a silicon-on-glass process, an anodic bonding apparatus has been designed, built, and tested.

Forging operations are widely used for manufacturing processes. Forging process is done hot, warm or cold. All three temperature ranges have advantages and disadvantages. The aim of this study is to combine the advantages of hot and cold forging in a flange forming process with cylindirical workpieces in a single step. The process idea is the partial heating of the workpiece at locations where large deformations occur and to keep the parts of the workpiece cold at regions where high precision forming is required. Firstly, the process idea has been investigated virtually by the finite element method supplying the theoretical verification of the feasibility of the novel process. By this analysis also the process limits have been estimated. All analysis are based on an elastoplastic large strain material law with thermomechanical coupling. The experimental part of the study served to realize the new process idea and to verify the process window. In the experimental study two different materials, three different part geometries and different initial conditions such as temperature field, lubrication etc. have been investigated. The specifimens are heated by induction.

This thesis focuses on the investigation of behavior of thick and moderately thick laminates under transverse and horizontal loading for different boundary conditions and configurations. An efficient finite element solution is proposed for analyzing composite laminates. Based on a combination of composite theory and 3-D Elasticity Theory, a 3-D finite element program is developed in MATLAB for calculating the stresses, strains and deformations of composite laminates under transverse and/or horizontal loading for different boundary conditions. The applicability of the formulation to analysis of laminated rubber bearings is also examined in this study. Since it is very important to calculate the correct stress state when developing models for composite behavior, the 3-D Elasticity Theory is used in this research. Numerical results are presented for various problems with different lamination schemes, loading and boundary conditions. In order to verify the analysis and the numerical calculations, numerical solutions obtained in this study are compared with available closed form solutions in the literature, experiment results and a commercial finite element program, namely ANSYS. The results obtained using the present finite element is found to be in acceptable and good agreement with the closed form solutions in the literature for thick and moderately thick rectangular and square plates.

Bolts and rivets are produced by cold forging technique. A great majority of metal forming companies prefer to use their dexterity rather than science and technology. The main aim of this thesis is to establish an environment for developing technology in bolt production by reducing trial and error. In this thesis finite element method is utilized to model bolt forming for correcting tooling designs, removing production defects and estimating forging forces. Material characterization, precise determination of boundary conditions and verification of numerical results are also investigated. It is shown how efficient the finite element method is for technology development in metal forming industry. Furthermore, two anomalies in extrusion process are presented: The hump and the force hill in extrusion force-displacement curve. Reasons of these two anomalies are studied using finite element simulations and verified by experiments. Thesis also explains reduction methods of three-dimensional problems to axisymmetric models and compares the results.

This thesis is for the investigation of the design and analysis processes of filament wound composite tubes under combined loading. The problem is studied by using a computational tool based on the Finite Element Method (FEM). Filament wound tubes are modeled as multi layered orthotropic tubes. Several analyses are performed on layered orthotropic tubes by using FEM. Results of the FEM are examined in order to investigate characteristics of filament wound tubes under different combined loading conditions. Winding angle, level of orthotropy and various ratios of the loading conditions were the main concerns of the study. The results of the FEM analysis are discussed for each loading condition. Both pure loading and combined loading analysis results were consistent with the ones mentioned in literature, such as optimum winding angles, optimum loading ratios and optimum level of orthotropy. Modeling parameters, assumptions and source of errors are also discussed. Finally, the required data is obtained for the design of filament wound composite tubes under combined loading.