Engineering Commons^™

Application Of Survival Analysis Techniques To Probabilistic Assessment Of Fatigue In Steel Bridges, Azam Nabizadehdarabi

Theses and Dissertations

The fatigue of engineering materials under repetitive loading is a significant issue affecting the design and durability of components and systems in a variety of engineering-related applications including civil, mechanical, aerospace, automotive, and electronics. Many factors can affect the service life of a component or system under repetitive loading, such as the type of structure, loading, connection details, stress state, peak stress or stress range, surface condition, temperature, and environmental exposure. Currently, there is no comprehensive probabilistic approach that can systematically address all the factors that contribute to fatigue on a single mathematical platform. However, advanced analysis techniques developed for …

An Application Of Clustering And Cluster Update Methods To Boiler Sensor Prediction And Case-Based-Reasoning To Boiler Repair, Timothy Edward Rooney

Theses and Dissertations

Driven by demand from both consumers and manufacturers alike, Internet of Things (IoT)

capabilities are being built into more products. Consumers want more control and access to their

devices, while manufacturers can find data gathered from IoT-capable products invaluable. In

this thesis, we use data from a growing fleet of IoT-connected boilers in the residential, lightcommercial, and medium-commercial ranges to demonstrate a framework for cluster initialization

and updating. We compare two methods of dynamically updating clusters: a sequential method

inspired by sequential K-means clustering and a cohesion-based method called DYNC. A predictive

artificial neural network system demonstrates the effectiveness of …

Application Of Solar Water Heaters For Industrial Use, Lucas T. Atkins

Theses and Dissertations

Solar water heating is a technology that is mainly used for domestic water heating in residential homes. In most applications, the idea is to make a home “off the grid” in that there is no requirement for outside infrastructure or need for energy utility to provide power to this home. This falls in line with the trend of “going green” in an effort to reduce energy use, increase efficiency, or reduce emissions and other harmful byproducts.

This technology can be adapted to reduce the energy costs of industrial manufacturing plants. By eliminating the need for certain sections of a process …

Design And Testing Of A Modular Laser System With Laser Machining And Bioprinting Capabilities, Jesus Gonzalez

Theses and Dissertations

This thesis introduces the applications of ultrafast lasers while focusing on their bioprinting capabilities. A custom system was designed to utilize a femtosecond laser for 2D and 3D applications. The characteristics of lasers allow them to be efficiently used in machining, 3D printing, research, and more. Their power and precision allow them to be used for delicate work such as bioprinting. Bioprinting is a field holding great potential to benefit society. Studies conducted over the years prove its usefulness in printing cells and biomaterials, while showing there is still much to improve upon before being able to print fully functioning …

Evaluation Of The Most Significant Factors Influencing The Production Rates Of Highway Construction Activities, Angelica M. Neira

Theses and Dissertations

The utilization of realistic production rates is key for the accurate estimation of the contract time in highway projects. Several factors have an impact on production rates and change the total duration of construction projects. To organize and complete projects in a timely, quality and financially responsible manner, projects need to be scheduled carefully. Schedulers and planners of the Texas Department of Transportation (TxDOT) have been noticing that the estimated timelines are far from the reality and want to investigate if external factors can be the cause of this discrepancy. Some of the factors considered in this study are the …

Numerical Simulations Of Comprehensive Hydrodynamic Performance Of Darpa Suboff Submarine, Kenshiro Takahashi

Theses and Dissertations

A numerical study of the DARPA SUBOFF model using computational fluid dynamics (CFD) has been presented for developing a CFD application procedure to compute the hydrodynamic performance of underwater vehicles, including submarines. Several configurations, such as bare hull, fairwater, sterns, and/or ringwing-appended hulls, were examined for the straight-ahead, steady translation and turning, and self-propelled conditions. A systematic study was conducted to ensure an adequate computational domain expansion and reasonable prism layer mesh properties for solutions independent of the parameters. The hydrodynamic forces exerted on the hull and the appendages were verified and validated in accordance with a published methodology under …

Experimental, Theoretical And Numerical Evaluation Of Wicking Models For Liquid Imbibition In Dry Porous Wicks, Mohammad Amin Faghihi Zarandi

Theses and Dissertations

Nowadays commercial wicks are utilized by consumer product companies in several important commercial applications including Tiki® Brand torches, the passive lubricants of machine gears, propellant management device, and fragrance dispersion units. Spontaneous imbibition of a liquid into porous wicks, also called wicking, is modeled using the single-phase Darcy’s law after assuming a sharp flow-front marked by full saturation behind the front. An analytical expression for the height of the wicking flow-front as a function of time is tested through comprehensive experiments using different wicks and an oil as the wicking liquid. We proposed a model based on sharp liquid-front where …

An Advanced Approach For Contract Time Determination In Highway Projects, Cuauhtemoc Torres Cantu

Theses and Dissertations

In project management, finishing a project on schedule is one of the most important aspects. The Texas Department of Transportation (TxDOT) has been experiencing delays in some projects that can be accounted to an inaccurate project time estimation process. This research presents the development of a user-friendly and comprehensive computer-based contract time determination system. The enhanced system implements probabilistic scheduling techniques such as Program Evaluation and Review Technique, and Monte Carlo Simulation. Additionally, the application of a lognormal two-point PERT method is explored in this study. The new system proposes the use of a database of production rates based on …

Semantic And Qualitative Physics-Based Formal Reasoning For Functional Decomposition In Mechanical Design, Xiaoyang Mao

Theses and Dissertations

Function modeling plays an essential role in academy design studies, yet a lack of acceptance in industry. A possible reason is that the designer must have well understand of the controlled vocabularies and grammars to utilize this method. The research presented in this dissertation is to fill this gap so that designers can use function-based design method without relevant knowledge. In graph-based function models, the function verbs and flow nouns are usually chosen from predefined vocabularies. The vocabulary class definitions, combined with function modeling grammars defined at various levels of formalism, enable function-based reasoning. However, the text written in plain …

Numerical Modeling Of Phase Transition In Shock Tube Problem, Man Minh Le

Theses and Dissertations

In this work, we developed a numerical model for phase transition in shock-tube problem. This work focused on simulating shock-tube problem and the numerical framework is based on a two-phase flow model. Our simulation tool is an in-house FORTRAN multiphase compressible flow solver, RocSDT [31]. Specifically, this involves the Euler equations along with the Stiffened Gas Equation of State (EOS), an interface of liquid-gas type, and the effects of heat and mass transfer due to phase transition. This thesis described the implementation and incorporation of a phase transition model into a system of five partial differential equation model and the …

Hydrodynamic Ram Analysis Of Bonded Composite Fuel Tanks, Teddy Sedalor

Theses and Dissertations

Military aircraft are tested against a variety of ballistics threats as part of their design to assess their vulnerability. One aspect of this approach/requirement is Hydrodynamic Ram testing which accounts for projectile impact into fuel tanks. Hydrodynamic Ram (HRAM), which occurs due to overpressure created in an enclosed fluid as a result of the transfer of energy and momentum from a penetrating projectile, can be quite destructive to the enclosing structure, which makes testing expensive. Therefore the need arises for numerical methods to supplement the testing and provide more test data than can be obtained directly from the article test. …

Vehicle Interior Access Deployable Worksurface Mechanism Concept Product Design, Premchand Gunachandran

Theses and Dissertations

by

Premchand Gunachandran

The University of Wisconsin-Milwaukee, 2019

Under the Supervision of Professor Mohammad Habibur Rahman

Easy access and adjusting the vehicle interior configuration to a variety of situations and uses is the general desire for any vehicle user. To meet such desire an attempt has been made in this study to conceptualize a design to develop a new mechatronic product called re-configurable vehicle interior console mechanism to deploy a worksurface (DWS), which will provide flexible use of the vehicle’s interior of both partial and fully autonomous vehicles. This re-configurable vehicle interior console will deploy the DWS using a power …

Graphene-Fibers Hybrid Structures As Adsorbents For Heavy Metal Ions In Aqueous Solutions, Dulce C. Capitanachi

Theses and Dissertations

The project focuses on the study of graphene-fiber hybrid structures for adsorption of heavy metal ions in aqueous solutions. Polyvinyl alcohol-based graphene–fiber structures were created using centrifugal spinning and a carbonization process.

Characterization methods of the graphene–fiber hybrid structures (GFHS) include SEM, FTIR, TGA, and EDX. Single-step batch-type adsorption studies were performed to analyze the interaction of Cu (II) and Pb (II) ions onto GFHS surface. Different heavy metal ion concentrations were used, as well as a variation of pH values. Elemental analysis of the adsorbent’s surface after filtration experiments was studied by EDX and spectroscopy to verify the presence …

Integration Of Inboard Propulsion In Shock Mitigating Membrane Hull Technology, Korrey Rotkiske

Theses and Dissertations

Membrane Hull Technology is a strength based marine vessel design concept that seeks to utilize the in-plane properties of fiber reinforced composites to generate a lighter weight vessel with inherent shock mitigation benefits. MHT has been applied on several Naval crafts yet the design features of inboard propulsion systems have not been addressed. Inboard propulsion systems are a very common form of propulsion used in many types of marine vessels especially larger vessels. This thesis seeks to overcome the inboard engine mounting challenges of MHT which limits use of this technology in the marine industry. The fundamental design elements of …

Design Optimization For A Compliant,Continuum-Joint, Quadruped Robot, Vallan Gray Sherrod

Theses and Dissertations

Legged robots have the potential to cover terrain not accessible to wheel-based robots and vehicles. This makes them better suited to perform tasks, such as search and rescue, in real-world unstructured environments. Pneumatically-actuated, compliant robots are also more suited than their rigid counterparts to work in real-world unstructured environments with humans where unintentional contact may occur. This thesis seeks to combine the benefits of these two type of robots by implementing design methods to aid in the design choice of a 16 degree of freedom (DoF) compliant, continuum-joint quadruped. This work focuses on the design optimization, especially the definition of …

Characterization Of Local Void Content In Carbon Fiber Reinforced Plastic Parts Utilizing Observation Of In Situ Fluorescent Dye Within Epoxy, Wyatt Young Warner

Theses and Dissertations

Experimentation exploring the movement of voids within carbon fiber reinforced plastics was performed using fluorescent dye infused into the laminates observed through a transparent mold under ultraviolet light. In situ photography was used as an inspection method for void content during Resin Transfer Molding for these laminates. This in situ inspection method for determining the void content of composite laminates was compared to more common ex-situ quality inspection methods i.e. ultrasonic inspection and cross-section microscopy. Results for localized and total void count in each of these methods were directly compared to test samples and linear correlations between the three test …

Enabling Compact Devices Through Origami And Developable Mechanisms, Jacob Ryan Greenwood

Theses and Dissertations

This thesis provides resources that enable the design of novel and compact mechanical devices by providing terminology, engineering models, and design methods in the fields of developable mechanisms and origami-based engineering.The first part of this work presents engineering models to aid in the design of cylindrical developable mechanisms. These models take into account the added spatial restrictions imposed by the developable surface. Equations are provided for the kinematic analysis of cylindrical developable mechanisms. A new classification for developable mechanisms is also presented (intramobile, extramobile, and transmobile) and two graphical methods are provided for determining this classification for single-DOF planar cylindrical …

Advanced Techniques For Carbon Nanotube Templated Microfabrication, Jason Matthew Lund

Theses and Dissertations

Carbon nanotube templated microfabrication (CNT-M) is a term describing a grouping of processes where carbon nanotubes (CNTs) serve a structural role in the fabrication of a material or device. In its basic form, CNT-M is comprised of two steps: produce a template made from carbon nanotubes and infiltrate the porous template with an additional material. Vertically aligned carbon nanotube (VACNT) templates can be grown to heights ranging from microns to millimeters and lithographically patterned to a desired form. Deposition of an existing thin film material onto a CNT template will coat all template surfaces and can produce a near solid …

Study Of Wire Arc Additive Manufacturing With Aluminum Alloy 2219, Sritam Kumar Dash

Theses and Dissertations

This thesis discusses WAAM (wire arc additive manufacturing) technology using TIG (Tungsten Inert Gas) welding method with aluminum 2219 as the substrate and aluminum 2319 as the filler material. The most important characteristic of this method of manufacturing is very little wastage of material as it does not follow the conventional method of manufacturing where material is removed from a bigger block to finally achieve the desired shape. This method uses a layer by layer approach to build the part. Generally, in additive manufacturing, the production time may vary depending on the type of method used. The material deposition rate …

Enhanced Heat Transfer In Spray Cooling Through Surface Modifications: An Experimental And Computational Study, Azzam Saadi Salman

Theses and Dissertations

Today, dissipating high heat flux safely is one of the greatest challenges for thermal engineers in thermal management systems, and it becomes a critical barrier to technological developments for many engineering applications. Due to technological advances and aggressive micro-miniaturization of electronic components, the surface area of most devices has shrunk while the computational power increased exponentially. Therefore, the amount of heat dissipated from surfaces has increased significantly. Numerous cooling techniques have been introduced to replace the traditional air cooling systems and to maintain the efficiency and reliability of electronic components. Microelectronics work efficiently and safely at surface temperatures of < 100 ℃ and 125 ℃ for general and defense applications, respectively. One of the proposed alternative schemes is spray cooling, which is considered one of the most advanced cooling methods. It is used for high and ultra-high heat flux dissipation, as it can dissipate 150-200 W/cm2 while maintaining the surface temperature within this range. Also, spray cooling removes a large amount of energy at a lower liquid flow rate compared to other cooling techniques, such as jet impingement and microchannel heat sink. The thermal performance of spray cooling systems can be enhanced either actively or passively. Active enhancement is a very efficient technique; however, it adds more pumping power. The present work focuses on three main objectives: evaluating and analyzing spray cooling performance, developing a three-dimensional numerical multi-phase model for heat transfer process in spray cooling and enhancing the thermal performance of spray cooling passively.

First, …

Computational Wave Field Modeling In Anisotropic Media, Sajan Shrestha

Theses and Dissertations

In this thesis, a meshless semi-analytical computational method is presented to compute the ultrasonic wave field in generalized anisotropic material while understanding the physics of wave propagation in detail. To understand the wave-damage interaction in an anisotropic material, it is neither feasible nor cost-effective to perform multiple experiments in the laboratory. Hence, recently the computational nondestructive evaluation (CNDE) received much attention to performing the NDE experiments in a virtual environment. In this thesis, a fundamental framework is constructed to perform the CNDE experiment of a thick composite specimen in a Pulse-Echo (PE) and through-transmission mode. To achieve the target, the …

Using A Nondispersive Wave Propagation For Measuring Dynamic Fracture Initiation Toughness Of Materials: Experimental And Numerical Based Study, Ali Fahad Fahem

Theses and Dissertations

Fracture mechanics has been a subject of great interest in the engineering community for decades. During this period, fracture parameters such as Stress Intensity Factor (SIF), J-integral, and Crack-Tip Opening Displacement (CTOD) have been developed and used to characterize the fracture properties of most engineering materials under quasi-static loading condition. Usually, these properties are obtained experimentally by using standard methods such as ASTM E399, E1820 or E1920 to evaluate the stress intensity factor ������ ������������, elastic-plastic toughness ������ ������������ and crack tip opening displacement (CTOD) respectively. Conversely, most critical engineering applications are subjected to a sudden or high strain rate …

Developing Origami-Based Approaches To Realize Novel Architectures And Behaviors For Deployable Space Arrays, Nathan Alan Pehrson

Theses and Dissertations

Origami-based approaches for the folding of thick materials for specific application to large deployable space arrays is explored in this work. The folding approaches presented utilize strain energy, spatial kinematics, membranes, compliant mechanisms, and or in combination together to fold finite-thickness materials viewed through the lens of origami-based engineering. Novel architectures and behaviors of mechanisms are developed to achieve packaging efficiency, deployment, and self-stiffening. A method for the folding of monolithic thick-sheet materials is developed by incorporating compliant mechanisms into the material itself to strategically add degrees of freedom. The design and characterization of the compliant mechanisms with consideration to …

Quantification Of Material Degradation For Material State Awareness Of Composite Materials., Vahid Tavaf

Theses and Dissertations

The objectives of this research are to develop a comprehensive method to quantify the material degradation of composite materials in the presence of distributed damages and predict the failure in the defected composites using the updated effective material properties. Defects can grow in composites at the macro scale caused by the microscale voids, matrix cracks, fiber breakages starting from manufacturing processes to the high and low cycle fatigue loads, high temperature, and high humidity during operation. Hence, to predict a more realistic failure model, it is necessary to consider the repercussions of degraded materials. The proposed research work is divided …

The Impact Of Patient-Specific Vascular Structure On Localized Cooling In The Human Heart, Nathan Paul Spangenberg

Theses and Dissertations

Acute Myocardial Infarction (AMI) is the leading cause of worldwide death and disability, and approximately 720,000 Americans will experience an AMI in 2018. Studies have shown that rapid hypothermia therapy (<35°C) before reperfusion in patients with AMI can reduce infarct size by 37%. Localized therapeutic hypothermia has proven the potential to cool heart tissue rapidly following AMI, 3°C in 5 minutes. Using Materialise Mimics digital imaging software and the finite volume method we analyzed temperature distributions in six patient-specific left main coronary artery (LMCA) models. A mock circulatory loop was used to determine the exiting temperatures of a standard 7 Fr catheter to feed into our model with flow rates ranging from 29.2 ml/min to 68.85 ml/min. Our work showed that therapeutic hypothermia (TH) temperatures were evident at the outlets of three out of all six heart models, which varied in each left anterior descending (LAD) and left circumflex (LCX) artery depending on flowrate. Results of this study indicate that biovariability in patient-specific vascular structures significantly impacts therapeutic hypothermia (TH) treatment methods. These results indicate that further research is needed to examine more accurate physiological effects, such as pulsatile flow and vessel wall thickness. Future models will be used to provide insight to guide more efficient TH device designs and operation parameters to optimize patient outcomes following AMI.

Initial Development Of A Prototype Sensor Testbed For Fetal Monitoring, Christian Beauvais

Theses and Dissertations

The objective of this research is to design and manufacture a device that exhibits some of the bio-physiological signals relevant to fetal health monitoring. Currently, limited options exist for testing the performance of monitoring devices such as the tocodynamometer (TOCO) and electrocardiograph (ECG) that measure the bio-physiological signals of a woman and her fetus. Sensor designers need ways of generating and acquiring signals that do not carry the ethical burden of human testing. The development of such a device, as considered in this work, may involve using muscle wire or an inflatable tube as prospective foundations for simulating uterine contraction. …

Parametric Study Of Selective Laser Alloying Of Elemental Titanium And Boron Powders Using An Automated Deposition Mechanism, Julian V. Gonzalez

Theses and Dissertations

An automatic powder deposition and leveling mechanism was designed and constructed to assist in surface roughness experiments for titanium-boron samples. Previously developed energy models and x-ray diffraction analysis was used to confirm the creation of titanium diboride samples. To study TiB2 at different energy values, a 52 (2 factors, 5 levels) factorial design was used and carried out under an argon atmosphere, through the AM250 laser melting system. Two experimental runs were carried out and a total of 50 samples were assigned a surface roughness measurement through the Dektak XT profilometer. Graphically and with statistical analysis, the data was determined …

A Study Of Human Balance And Coordination Using A Head Mounted Display, Daniel Gracia De Luna

Theses and Dissertations

Virtual Reality (VR) is growing with new technologies and applications. The new technologies help the user to feel more immersed in virtual environments, but interaction and immersion is an area that has not been well studied. Immersion is the feeling and reaction of users while they are in a virtual environment. This investigation is focused on the study of the human balance and coordination when human subjects are inside a virtual environment. Over 60 subjects are studied under an experiment, where their trajectory is captured and analyzed to identify possible differences or similitudes between male and female subjects.

Electrostatically Actuated Double Wall Carbon Nanotubes To Include Intertube Van Der Waals Forces, Ezequiel Juarez Ocanas

Theses and Dissertations

This work deals with the amplitude-frequency and amplitude-voltage responses of parametric and primary resonances of electrostatically actuated double-walled carbon nanotubes (DWCNTs). Nonlinear forces acting on the DWCNT are intertube van der Waals and electrostatic forces. Soft AC excitation and small viscous damping are assumed. In coaxial vibration, the outer and inner carbon nanotubes move together (in-phase), maintaining their geometric concentricity; while in noncoaxial vibration, the CNTs move in opposite direction (out-of-phase). Modal coordinate transformation is formulated. The Harmonic Balance Method (HBM) is used to find the free response solutions of the DWCNT. The Reduced Order Model (ROM) method is also …

Assessment Of Some Of The Common Practices Used In Scheduling Highway Projects, Jennifer Reyes

Theses and Dissertations

There are several factors documented in the literature that can affect the accuracy of estimated project durations in highway construction, such as weather, location, and soil conditions. Recently, the Texas Department of Transportation (TxDOT) raised a concern regarding some of the practices used when estimating the contract time for projects. This research presents an assessment of the effect that two practices identified have on the estimated project duration. These two practices include: 1) the estimated lead/lag times in project schedules and 2) scheduling with only critical or controlling activities. The effect of these practices is measured, primarily, by using four …