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Articles 1 - 30 of 243
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Domain Decomposition Methods For Fluid-Structure Interaction Problems Involving Elastic, Porous, Or Poroelastic Structures, Hemanta Kunwar
Domain Decomposition Methods For Fluid-Structure Interaction Problems Involving Elastic, Porous, Or Poroelastic Structures, Hemanta Kunwar
All Dissertations
We introduce two global-in-time domain decomposition methods, namely the Steklov-Poincare method and Schwarz waveform relaxation (SWR) method using Robin transmission conditions (or the Robin method), for solving fluid-structure interaction systems involving elastic, porous, or poroelastic structure. These methods allow us to formulate the coupled system as a space-time interface problem and apply iterative algorithms directly to the evolutionary problem. Each time-dependent fluid and the structure subdomain problem is solved independently, which enables the use of different time discretization schemes and time step sizes in the subsystems. This leads to an efficient way of simulating time-dependent multiphysics phenomena. For the fluid-porous …
Proof-Of-Concept For Converging Beam Small Animal Irradiator, Benjamin Insley
Proof-Of-Concept For Converging Beam Small Animal Irradiator, Benjamin Insley
Dissertations & Theses (Open Access)
The Monte Carlo particle simulator TOPAS, the multiphysics solver COMSOL., and
several analytical radiation transport methods were employed to perform an in-depth proof-ofconcept
for a high dose rate, high precision converging beam small animal irradiation platform.
In the first aim of this work, a novel carbon nanotube-based compact X-ray tube optimized for
high output and high directionality was designed and characterized. In the second aim, an
optimization algorithm was developed to customize a collimator geometry for this unique Xray
source to simultaneously maximize the irradiator’s intensity and precision. Then, a full
converging beam irradiator apparatus was fit with a multitude …
Investigating The Role Of Tesserae In Energy Absorption In Shark Cartilage, Molly Dobrow
Investigating The Role Of Tesserae In Energy Absorption In Shark Cartilage, Molly Dobrow
UNF Graduate Theses and Dissertations
Unlike mammals, shark endoskeletons are composed of cartilage, which is less stiff compared to bone. Despite this structural disadvantage, sharks have risen to become apex predators, with reported maximum posterior bite force estimates approximating 5914 N in bull sharks. Shark jaws are estimated to undergo high cycle loading within the organism’s lifecycle without evidence of failure. Fatigue resistance may relate to mineral distribution within a component of the endoskeletal system – tesserae. Tesserae are thin, roughly hexagonal tiles composed of calcium phosphate hydroxyapatite (HA) crystals and grow by accretion to eventually surround the hyaline cartilage core. Though tesserae dimensions are …
Head Impact Effects In Small Remotely Piloted Aircraft System (Srpas) Collisions: Gender Specific Risks And Vulnerable Population Protection, Md Farhan Hoque Sagar
Head Impact Effects In Small Remotely Piloted Aircraft System (Srpas) Collisions: Gender Specific Risks And Vulnerable Population Protection, Md Farhan Hoque Sagar
Electronic Thesis and Dissertation Repository
This study focuses on supporting the development of safety regulations for vulnerable populations during drone to head impacts. First, the small female head and neck model was compared to cadaveric data. Then, combined with lab’s previous work, gender-based disparities in head impact responses were highlighted, with small females experiencing higher injury risk metrics, despite lower skull von Mises stress. Beyond small females, children of various ages and their head responses during impacts were also analyzed. In addition to the previously developed quadcopter drone model, a new Mavic Pro drone model was developed, and this model was integrated with human head …
Parametric Analysis And Enhancement Of The Burst Capacity Model For Composite-Repaired Corroded Pipelines, Rodrigo Silva Silva-Santisteban
Parametric Analysis And Enhancement Of The Burst Capacity Model For Composite-Repaired Corroded Pipelines, Rodrigo Silva Silva-Santisteban
Electronic Thesis and Dissertation Repository
One of the main causes of pipeline failures is corrosion, which leads to a localized loss of the pipe wall thickness and hence compromises the capacity of the pipeline. Composite repair is a method to rehabilitate corroded pipelines. Design codes such as ASME PCC-2 are commonly used to design the repair thickness. As the predictive accuracy to determine the burst capacity of a composite repaired pipeline with existing models is generally poor, the main objective of the present thesis is to provide insights on the parameters that affect the burst capacity and propose improvements to the prediction of burst capacity …
Design Of Machine Tool Cross Beam Using Metal Big Area Additive Manufacturing, Tyler Poon
Design Of Machine Tool Cross Beam Using Metal Big Area Additive Manufacturing, Tyler Poon
Masters Theses
The modern world would not be what it is now without machine tools. Advances in materials and processes, such as carbon fiber and additive manufacturing (AM), enable the design space for machine tool components to expand. However, machine tool components require accurate geometry, which is not available from parts produced by metal Big Area Additive Manufacturing (mBAAM). This project outlines the process in which a traditionally manufactured machine tool component, a welded box structure on an existing machine tool, was redesigned to be made using mBAAM. The goal was to design a structure that was printable using the MedUSA system …
Friction And Heat Transfer Modeling Of The Tool And Workpiece Interface In Friction Stir Welding Of Aa 6061-T6 For Improved Simulation Accuracy, Ryan Melander
Theses and Dissertations
Friction stir welding (FSW) is a solid-state joining process that offers advantages over traditional fusion welding. The amount of heat generated during a FSW process greatly influences the final properties of the weld. The heat is generated through two main mechanisms: friction and plastic deformation, with friction being the larger contributor in a FSW process. There is a need to develop better predictive models of the heat generation and heat transfer in FSW. Almost all models seen in the literature validate temperature predictions on only one side of the tool/workpiece interface, thus ignoring possible inaccuracy that comes from incorrect partitioning …
Performance Of Helical Piles Retrofitted With A Novel Collar Vane Under Lateral And Torsional Loads, Juan Sebastian Carvajal Munoz
Performance Of Helical Piles Retrofitted With A Novel Collar Vane Under Lateral And Torsional Loads, Juan Sebastian Carvajal Munoz
Electronic Theses and Dissertations
Helical piles are lightweight deep foundations designed to support both compressive and uplift loads by mobilizing the shear strength of soil adjacent to helical plates that are welded to an extendable shaft. Helical piles are relatively inexpensive, can be installed quickly utilizing non-specialized equipment, and they are suitable for a wide range of soil conditions. However, helical piles are precluded from many applications due to their inability to support substantial lateral and torsional loads. To overcome this limitation, a novel easy-to-install Collar Vane is implemented to augment the lateral and torsional capacity of helical piles.
The Collar Vane consists of …
2d Hybrid Analytical Model Based Performance Optimization For Linear Induction Motors, Michael Thamm
2d Hybrid Analytical Model Based Performance Optimization For Linear Induction Motors, Michael Thamm
Electronic Theses and Dissertations
In this thesis the domain of double-layer, single-sided, 3-phase, integral slot winding, linear induction motor (LIM)s is analyzed. Motor meta parameters such as slots and poles are difficult to optimize since they drastically effect the configuration of the motor and require heuristic optimization implementations.
A non-dominated sorting genetic algorithm II (NSGAII) was implemented with the Platypus-Opt Python library. It serves as a robust, yet flexible integration while maximizing thrust and minimizing the mass of each motor iteration. Each iteration was accurately modelled using the hybrid analytical model (HAM), producing the necessary performance parameters for the NSGAII’s objective function. Field plotting …
Improving The Stimulation Selectivity In The Human Cochlea By Strategic Selection Of The Current Return Electrode, Ozan Cakmak
Improving The Stimulation Selectivity In The Human Cochlea By Strategic Selection Of The Current Return Electrode, Ozan Cakmak
Dissertations
The hearing quality provided by cochlear implants are poorly predicted by computer simulations. A realistic cochlear anatomy is crucial for the accuracy of predictions. In this study, the standard multipolar stimulation paradigms are revisited and Rattay’s Activating Function is evaluated in a finite element model of a realistic cochlear geometry that is based on µ-CT images and a commercial lead. The stimulation thresholds across the cochlear fibers were investigated for monopolar, bipolar, tripolar, and a novel (distant) bipolar electrode configuration using an active compartmental nerve model based on Schwartz-Eikhof-Frijns membrane dynamics. The results suggest that skipping of the stimulation point …
Predicting Surgical Outcome In Patients With Recurrent Patellar Dislocation, Dario De Caro
Predicting Surgical Outcome In Patients With Recurrent Patellar Dislocation, Dario De Caro
Boise State University Theses and Dissertations
Introduction
Lateral dislocation of the patella is a common injury in active adolescents and young adults. Patients who are ultimately managed surgically have a significantly lower risk of recurrent dislocation. However, determining the optimal surgical treatment remains a challenge, with patients sometimes undergoing multiple surgeries prior to successful stabilization. The aim of this study is to computationally evaluate patients that have undergone multiple surgeries to correct for recurrent lateral patellar dislocation and predict their clinical outcome.
Methods
Our patient cohort consisted of 16 patients with patella dislocation. Patient-specific imaging were used to create three-dimensional (3D) finite element (FE) models of …
The Effect Of Soft Tissue And Bone Morphology On The Stresses In The Foot And Ankle, Jinhyuk Kim
The Effect Of Soft Tissue And Bone Morphology On The Stresses In The Foot And Ankle, Jinhyuk Kim
Mechanical & Aerospace Engineering Theses & Dissertations
The foot and ankle interface with the ground, thus they absorb reaction forces and initiate load distribution through the body. The plantar fascia (PF) is a flexible structure that absorbs reaction forces and distributes loading across the foot. It is frequently a source of foot pain especially when people have plantar fasciitis and/or diabetes mellitus. Finite element (FE) models of the foot and ankle were created to examine the function however, the plantar fascia is frequently modeled as a 1D tension only spring, which does not represent variations caused by injury and/or disease.
As models move toward being patient specific, …
Utilization Of Finite Element Analysis Techniques For Adolescent Idiopathic Scoliosis Surgical Planning, Michael A. Polanco
Utilization Of Finite Element Analysis Techniques For Adolescent Idiopathic Scoliosis Surgical Planning, Michael A. Polanco
Mechanical & Aerospace Engineering Theses & Dissertations
Adolescent Idiopathic Scoliosis, a three-dimensional deformity of the thoracolumbar spine, affects approximately 1-3% of patients ages 10-18. Surgical correction and treatment of the spinal column is a costly and high-risk task that is consistently complicated by factors such as patient-specific spinal deformities, curve flexibility, and surgeon experience. The following dissertation utilizes finite element analysis to develop a cost-effective, building-block approach by which surgical procedures and kinematic evaluations may be investigated. All studies conducted are based off a volumetric, thoracolumbar finite element (FE) model developed from computer-aided design (CAD) anatomy whose components are kinematically validated with in-vitro data. Spinal ligament stiffness …
Cyclic Behavior Of Laterally Skewed Special Moment Frame Connections: Experimental Testing And System-Level Analyses, Mohammad Hossein Kashefizadeh
Cyclic Behavior Of Laterally Skewed Special Moment Frame Connections: Experimental Testing And System-Level Analyses, Mohammad Hossein Kashefizadeh
Graduate Theses and Dissertations
Special moment frames (SMFs) are frequently used in high seismic areas for architecturally constrained designs. SMFs provide lateral system stiffness without the use of braces that often obstruct views and architectural features. Current American Institute of Steel Construction (ASIC) provisions (AISC 341-16) provide prequalified SMF connection details; however, all prequalified details only consider orthogonal connections between the beam and column. This dissertation investigates the effect of adding skew within SMF beam-to-column connections. The study presented herein involves system-level dynamic time-history analyses of skewed SMF connections, the analytical component-level investigation into the effect of the concrete slab on behavior of the …
Electromagnetic Modeling Of A Wind Tunnel Magnetic Suspension And Balance System, Desiree Driver
Electromagnetic Modeling Of A Wind Tunnel Magnetic Suspension And Balance System, Desiree Driver
Mechanical & Aerospace Engineering Theses & Dissertations
Wind tunnels are used to study forces and moments acting on an aerodynamic body. While most results involve some interference from the mechanical supports used to hold the model, a Magnetic Suspension and Balance System (MSBS) is void of these interferences and presents an ideal test scenario. To further investigate the feasibility of dynamic stability testing at supersonic speeds using a MSBS, a preliminary design idea is currently being developed using an existing MSBS in a subsonic wind tunnel. This review focuses on the development of a mathematical model to more accurately portray the capabilities of the 6 inch Massachusetts …
Method Of Embedded Imperfections For The Direct Simulation Of Deformation Instabilities In Film-Substrate Structures, Siavash Nikravesh Kazeroni
Method Of Embedded Imperfections For The Direct Simulation Of Deformation Instabilities In Film-Substrate Structures, Siavash Nikravesh Kazeroni
Mechanical Engineering ETDs
In this dissertation, a novel finite-element methodology called “embedded imperfections” is proposed and employed for computationally simulating various types of deformation instabilities observed in film-substrate structures subjected to mechanical loading. The approach involves the incorporation of elements having distinctive material properties within the film-substrate interface. One can interpret this practice as a deliberate distribution of material defects within the numerical model. It has been shown that embedded imperfections not only can trigger the onset of instability, but also can lead to “direct” simulation of deformation instability problems in that primary and subsequent instability modes can all be captured in a …
U-Splines: Splines Over Unstructured Meshes, Steven K. Schmidt
U-Splines: Splines Over Unstructured Meshes, Steven K. Schmidt
Theses and Dissertations
U-splines are a novel approach to the construction of a spline basis for representing smooth objects in Computer-Aided Design (CAD) and Computer-Aided Engineering (CAE). A spline is a piecewise-defined function that satisfies continuity constraints between adjacent cells in a mesh. U-splines differ from existing spline constructions, such as Non-Uniform Rational B-splines (NURBS), subdivision surfaces, T-splines, and hierarchical B-splines, in that they can accommodate local variation in cell size, polynomial degree, and smoothness simultaneously over more varied mesh configurations. Mixed cell types (e.g., triangle and tetrahedron and quadrilateral and hexahedral cells in the same mesh) and T-junctions are also supported. The …
Analysis Guidelines And Functionalities Of The Catia Native Fea Solver For Composite Materials, Mohamed Edrisy
Analysis Guidelines And Functionalities Of The Catia Native Fea Solver For Composite Materials, Mohamed Edrisy
Electronic Theses and Dissertations
The emergence of commercial FEA solvers was a significant breakthrough that boosted the accuracy and complexity of engineering design. While composite materials are special materials, their mechanical properties can be custom made by considering the needs and requirements of the design problem. Given the rapidly expanding global consumption of composite materials, access to FEA solvers capable of assigning these materials is an absolute requirement.The CATIA software is a platform for designing, analyzing, and manufacturing of parts. However, there is no meaningful documentation in the public domain exploring the finite element functionalities of CATIA software for composite materials. Isotropic materials are …
Structural And Hemodynamic Analysis Of Transcatheter Aortic Valves, Dong Qiu
Structural And Hemodynamic Analysis Of Transcatheter Aortic Valves, Dong Qiu
Electronic Theses and Dissertations
The transcatheter aortic valve replacement (TAVR) procedure has become a well-established procedure for high, intermediate-risk, and low-risk patients. However, there is limited clinical data on the TAV's long-term durability, unlike SAV devices. Computational simulations can be an alternative way to evaluate the TAV devices. This dissertation aims to conduct structural and hemodynamic analyses on the TAV devices under different conditions using computational simulation approaches.
Initially, the impact of the bicuspid aortic valve on the TAV devices was evaluated. The result indicated that the CoreValve-like supra-annular self-expandable device was likely to have increased stress and strain on the leaflet when it …
Pymoocfd - A Multi-Objective Optimization Framework For Cfd, George Martin Cunningham Love
Pymoocfd - A Multi-Objective Optimization Framework For Cfd, George Martin Cunningham Love
Graduate College Dissertations and Theses
Modern computational resource have solidified the use of computer modeling as an integral part of the engineering design process. This is particularly impressive when it comes to high-dimensional models such as computational fluid dynamics (CFD) models. CFD models are now capable of producing results with a level of confidence that would previously have required physical experimentation. Simultaneously, the development of machine learning techniques and algorithms has increased exponentially in recent years. This acceleration is also due to the widespread availability of modern computational resources. Thus far, the cross-over between these fields has been mostly focused on computer models with low …
Self-Oscillating Induction Heater, Patrick Rice
Self-Oscillating Induction Heater, Patrick Rice
Dissertations, Master's Theses and Master's Reports
This report develops a control system to keep an induction heater in resonance. When a metallic workpiece is inserted in the air core of the workcoil, the resonant frequency changes. Different workpiece materials affect the resonant frequency and power. This presents a problem since changing the resonant frequency of the circuit while keeping the frequency constant reduces the maximum power of the circuit. Finite element analysis is used to find the circuit parameters of the workcoil and workpiece interaction. A non-linear controller which oscillates based on the resonant frequency of an LC tank is created. Nyquist and describing function analysis …
Spline-Based Contact: Algorithms And Applications, Pulama Bhattacharya
Spline-Based Contact: Algorithms And Applications, Pulama Bhattacharya
Theses and Dissertations
Contact is one of the most challenging nonlinearities to solve in solid mechanics. In traditional linear finite element analysis, the contact surface is only C^0 continuous, as a result, the normal to the contact surface is not continuous. The normal contact force is directed along the normal in the direction of the contact surface, and therefore, the contact force is discontinuous. This issue is tackled in linear finite element analysis using various surface smoothing techniques, however, a better solution is to use isogeometric analysis where the solution space is spanned by smooth spline basis functions. Unfortunately, spline-based isogeometric contact analysis …
Mechanical Interfacial Locking And Multiscale Modeling Of Reinforced Thermoplastic Composites For Structural Applications, Anmol Kothari
Mechanical Interfacial Locking And Multiscale Modeling Of Reinforced Thermoplastic Composites For Structural Applications, Anmol Kothari
All Dissertations
The ever-growing pressure of reducing the adverse impact of transportation systems on environment has pushed industries towards fuel-efficient and sustainable solutions. While several approaches have been used to improve fuel efficiency, the light-weighting of structural components has proven broadly effective. In this regard, reinforced thermoplastic composites (RTPC), owing to their high recyclability, higher impact strength and fast cycle times, have become competitive candidates at an industrial scale. However, to implement RTPC toward large scale structural applications several challenges pertaining to material design and manufacturing effects need to be addressed. To this end, a computational study is carried out to address …
Optimized Tip Cooling Using Am Process, Alberto H. Gamez, Lourdes Sarmiento Martinez, Andrew Van Bogelen
Optimized Tip Cooling Using Am Process, Alberto H. Gamez, Lourdes Sarmiento Martinez, Andrew Van Bogelen
Mechanical Engineering
This Final Design Review (FDR) reports on the senior design project undertaken by our team of mechanical engineering seniors at California Polytechnic State University, San Luis Obispo. This project seeks to use the additive manufacturing process to improve the existing design of a Taurus 60 gas turbine injector tip. The current injector tip is owned by Solar Turbines, a designer and manufacturer of gas turbines for electric generation, propulsion, as well as natural resource transportation. The challenge at hand is to design a new injector tip that will be reliable for at least 60,000 hours and provide ease of replacement, …
Guidelines For Designing The Overhead Transmission Tower Foundations Adjacent To Cohesionless Slopes, Meshel Q. Alkahtani
Guidelines For Designing The Overhead Transmission Tower Foundations Adjacent To Cohesionless Slopes, Meshel Q. Alkahtani
Electronic Thesis and Dissertation Repository
Foundations supporting electrical transmission line towers are subjected to oblique loading due to tower own weight along with wind loading. Due to land limitation and linear alignment of transmission lines, many power transmission towers are situated in sand near sloping grounds and proper evaluation of their foundation performance is essential for the safety and reliability of the critical power transmission lines. There is currently no guidance available on the behaviour of transmission towers foundations constructed near slopes. Thus, the primary objectives of this study are to evaluate the response of transmission tower foundations in cohesionless sloping grounds and investigate the …
Thermal Deformation In High Pressure Die Casting Shot Sleeves, Ross Crowley
Thermal Deformation In High Pressure Die Casting Shot Sleeves, Ross Crowley
Dissertations (1934 -)
Replacement of shot sleeves represents a significant cost in cold chamber high pressure die casting (HPDC) processes. It is well known that the service life of a shot sleeve is closely related to its thermomechanical deformation behavior, so an improved understanding of this behavior is needed to guide the design of shot sleeves for increased service life. Prior research efforts have analyzed shot sleeve deformation but were based on 2D representations and did not consider transient effects from the molten metal’s flow behavior. This objective of this study was to analyze thermo-mechanical deformation during the injection sequence by using a …
Finite Element Analysis Of Complex Vectorbloc Beam-Column Connections, Labiba Kalam
Finite Element Analysis Of Complex Vectorbloc Beam-Column Connections, Labiba Kalam
Electronic Theses and Dissertations
Steel modular construction provides an efficient alternative to traditional construction practices. A key component to modular construction is the connection between the individual modules, which hold the building together against applied loads such as gravity, snow, and wind. The VectorBloc connector is an innovative cast steel connector that is used in the connections between steel modules made from hollow structural steel (HSS) members. The current VectorBloc connector, called VB4, is limited in its uplift capacity and thus faces challenges when applied to structures facing high uplift forces. Thus, a new design of the VectorBloc connector, called VB6, with a focus …
Finite Element Analysis Of Complex Vectorbloc Beam-Column Connections, Labiba Kalem
Finite Element Analysis Of Complex Vectorbloc Beam-Column Connections, Labiba Kalem
Electronic Theses and Dissertations
Steel modular construction provides an efficient alternative to traditional construction practices. A key component to modular construction is the connection between the individual modules, which hold the building together against applied loads such as gravity, snow, and wind. The VectorBloc connector is an innovative cast steel connector that is used in the connections between steel modules made from hollow structural steel (HSS) members. The current VectorBloc connector, called VB4, is limited in its uplift capacity and thus faces challenges when applied to structures facing high uplift forces. Thus, a new design of the VectorBloc connector, called VB6, with a focus …
Evaluation Of Additively Manufactured Lattices Under High Strain Rate Impact, Derek G. Spear
Evaluation Of Additively Manufactured Lattices Under High Strain Rate Impact, Derek G. Spear
Theses and Dissertations
Several additively manufactured lattice designs and configurations were evaluated under compression loads under various strain rates from quasi-static to highly dynamic. These experiments examined how the mechanical behavior of the lattice changed based on the lattice design properties and the applied strain rates. The modulus of elasticity, yield strength, plateau stress, and toughness were observed to decrease with an increase in strain rate, revealing that the lattice designs exhibit a negative strain rate sensitivity. A new lattice flow stress model was developed to account for the mechanical response of the lattice and was incorporated into a computational model for simulation. …
Thermal Experimentation Of Pa6 And Pa66 Thermoplastic Through Transmission Laser Welding, Sarajane Hill
Thermal Experimentation Of Pa6 And Pa66 Thermoplastic Through Transmission Laser Welding, Sarajane Hill
Theses and Dissertations
Thermoplastic welding utilizes a fiber laser to join samples that are clamped together. Laser energy is transferred through the natural sample to the interface with the opaque sample where heat energy creates a weld through conduction and radiation heat transfer modes. The overall goal of this research is to understand the effect of heat source loading on PA6 and PA66 thermoplastic materials from laser through transmission welding that is used to join natural and opaque materials. The welding process is studied through a combination of finite element simulation, experimentation, and design of experiment modeling. The results of temperature profile and …