Mechanical Engineering Commons^™

Photoelectrochemical And Photophysical Studies Of Carbon Nanotube And Molybdenum Disulfide Based Light Harvesting Devices, Hanyu Zhang

Open Access Dissertations

There is a critical need in utilizing solar radiation as a renewable energy source. While photovoltaic solar cells are widely used, much attention has been devoted in the past decade to developing nanotechnology for potential cost reduction and improved device efficiency and reliability. Low-dimensional materials offer unique physical properties which may be exploited for solar energy harvesting and conversion. Understanding their fundamental properties and developing relevant manufacturing strategies will thus pave the road toward high-performance, cost-effective, light-harvesting devices.

This thesis has investigated single-wall carbon nanotubes (SWCNTs) and molybdenum disulfide (MoS2) nanolayers for their light-harvesting ability in donor-acceptor systems. These materials …

Microstructure And Properties Of Spark Plasma Sintered Moalb Ceramics, Ting Lou

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Molybdenum aluminum boride (MoAlB) is a ternary transition metal boride which has promising aeronautic and nuclear applications. It inheres excellent properties of the binary transitional metal borides (e.g., MoB, ZrB₂) such as high melting temperature, high hardness, and thermal conductivity. Besides, MoAlB is superior to MoB because: (1) the Al element provides an oxidation resistance at high temperatures; (2) its nanolaminated structure consisting of M-B layers with alternating Al layers results in a unique damage tolerance property. In this research, polycrystalline MoAlB have been successfully synthesized and simultaneously sintered using spark plasma sintering (SPS) from molybdenum boride (MoB) …

Design Of A Flexible Control Platform And Miniature In Vivo Robots For Laparo-Endoscopic Single-Site Surgeries, Lou P. Cubrich

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Minimally-invasive laparoscopic procedures have proven efficacy for a wide range of surgical procedures as well as benefits such as reducing scarring, infection, recovery time, and post-operative pain. While the procedures have many advantages, there are significant shortcomings such as limited instrument motion and reduced dexterity. In recent years, robotic surgical technology has overcome some of these limitations and has become an effective tool for many types of surgeries. These robotic platforms typically have an increased workspace, greater dexterity, improved ergonomics, and finer control than traditional laparoscopic methods. This thesis presents the designs of both a four degree-of-freedom (DOF) and 5-DOF …

Dynamic Responses Of Wheel-Rail Systems With Block Dampers, Tzuyu Tseng

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The wheel-rail interaction problem has been widely studied in the past few decades. In this problem, dynamic responses at the contact areas remain the central issue since they induce damage to the rail over time. In particular, the dynamic responses at the contact areas between the wheels and rails present difficulties in understanding and mathematical modeling. Even with the computer power one has today, its mathematical modeling employs the versatile numerical analysis method, the finite element method (FEM) remains a formidable challenge due to its extremely small contact areas and in turn the extremely high stress levels. In addition, friction …

Design And Evaluation Of Pediatric Gait Rehabilitation Robots, Cale J. Stolle

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Gait therapy methodologies were studied and analyzed for their potential for pediatric patients. Using data from heel, metatarsal, and toe trajectories, a nominal gait trajectory was determined using Fourier transforms for each foot point. These average trajectories were used as a basis of evaluating each gait therapy mechanism. An existing gait therapy device (called ICARE) previously designed by researchers, including engineers at the University of Nebraska-Lincoln, was redesigned to accommodate pediatric patients. Unlike many existing designs, the pediatric ICARE did not over- or under-constrain the patient’s leg, allowing for repeated, comfortable, easily-adjusted gait motions. This design was assessed under clinical …

A Robotic Device To Assist With In-Vivo Measurement Of Human Pelvic Organ Tissue Properties, Shashank S. Kumat

Mechanical and Aerospace Engineering Theses - Archive

Measurement of the biomechanical properties of human pelvic organ tissue without undergoing minimally invasive surgery is desired for diagnostics purposes and take precautionary actions if needed. The biomechanical properties of the bladder change with age and due to diseases. Thus, identification of the viscoelastic properties of the tissue could help in detecting early stages of the disease in the bladder. A literature survey revealed that no device exists that could be used to characterize the biomechanical properties of the human bladder in-vivo. This research contributes towards the development of a diagnostic system that could be used in a medical setting …

The Influence Of Functional Weights On The Performance Of Least Squares Finite Element Formulation On Hybrid Meshes, Anirudh Rajagopal

Mechanical and Aerospace Engineering Theses - Archive

The Least-Squares Finite Element Method (LSFEM) is a numerical method for solving partial differential equations (PDE) approximately by minimizing the L-2 norm of the PDE residuals. Unlike the more common Galerkin approach, this method does not employ integration by parts to reduce the continuity requirements of the basis functions. Instead, the PDE is cast as a first-order system of differential equations, which allows for the solution of primary and secondary variables with the same order of accuracy. In addition, this approach always leads to a direct minimization problem and therefore not subject to the restrictive inf-sup condition and does not …

Application Of Artificial Neural Network For Evaporative Cooling In Data Centres, Feyisola Adejokun

Mechanical and Aerospace Engineering Theses - Archive

A data center is a facility that may be used to house telecommunication or storage devices. Because of the 24/7 required operation of a data center, large segments of a data center are geared towards evacuating heat generated from operating one. Data centers entail multiple operating configurations, great amount of constraints and nonlinear correlations. The need to effectively optimize a data center operation presents a daunting challenge. The data center considered in this research is a test bed modular data center (MDC). Comprising of an Information Technology (IT), DEC and IEC module. Typical MDC are dynamic and complex in nature …

Shape Optimization Of Helical Coil Tube For Maximizing Heat Transfer, Venkat Manoj Kandukuri

Mechanical and Aerospace Engineering Theses - Archive

Many researchers have observed the enhancement of heat transfer in coiled tubes compared to straight tubes with the same diameter and length. It is known fact, that in a helical coil tube the maximum axial velocity shifted towards the outer wall of the pipe and imbalance between centrifugal forces and inertial loads to a secondary motion of the fluid in the cross-section of the tube. This secondary motion is responsible for improved transport of heat energy to/from the tube walls. Previous conducted Experimental and computational parametric studies show the relationship between the increased heat transfer and parameters such as pitch, …

Self-Transport Of Liquid Drops Through A Functional Mesh For Removing Sweat Away From Skin, Manasvikumar Oza

Mechanical and Aerospace Engineering Theses - Archive

In this work, a functional mesh is developed to transport liquid drops from one side of the mesh to the other. A theoretical model is established, which has been used to obtain three design criteria. Based on these design criteria, functional meshes have been generated and tested with commercially available sponge attached to the mesh. Finally, such a mesh is demonstrated to be effective to remove sweat from human skin. As an application of this research, the concept of this functional mesh solves existing problems with a sport wear. The current sport wear is capable of absorbing sweat, but not …

Thermal Stress Analysis Of Unidirectional Composite Material By Fem Modeling, Gopal D. Gulwani

Mechanical and Aerospace Engineering Theses - Archive

Micromechanics of composite is study of complex mechanism of stress and strain transfer between fiber and matrix within a composite as well as distributions of physical fields inside heterogeneous medium. It was used successfully in predicting accurately physical properties like effective stiffness, effective linear thermal expansion of heterogeneous materials like composite. However, when it comes to strength characteristics of composite especially in transversal direction it failed to predict more accurate results. This thesis is focused on thermally induced stress analysis of unidirectional composite by finite element method. Thermal stresses which are dangerously ignored factor in mechanics of composite usually occur …

Formation Flight For Fuel Saving In Coronet Missions Of Kc-135r And F-15c/E, Christopher Allen Kniffin

Mechanical and Aerospace Engineering Theses - Archive

The fuel saving benefit of formation flight has been demonstrated through theoretical and computational analyses, simulation, wind tunnel and flight tests. When an aircraft flies in a specific region in the wake of another aircraft, it experiences upwash, which results in reduced drag and thus reduced thrust requirement. One specific USAF mission that can potentially benefit from formation flight is coronet missions. In a coronet mission, fighter aircraft are escorted and refueled, as needed, by tanker aircraft over a long range. During the flight, the receiver aircraft fly in formation with the tanker but outside of the wake of the …

Final Design Report: Grasp Data Acquisition Project Axon Vr, Michael Erberich, Jack Schultz, Tyler Yeaman

Mechanical Engineering

No abstract provided.

Final Design Report: Allergen Mixing Assistant (Ama) Micro-Refrigeration Redesigning, Mitchell Parks, Minwoo (Michael) Suh

Mechanical Engineering

Abstract

Allergen Mixing Assistant (AMA) by Xtract Solutions is a device designed to more “effectively refrigerate, organize, and mix allergenic extracts”. Although Xtract Solutions intended the product to be fully automated, the company has decided against its automation and declared its current design as a minimum viable product whose components are too expensive, difficult to source and complex. Therefore, Cal Poly AMA design team - Mitchell Parks and Minwoo Suh - has decided to replace these expensive components with much more economical alternatives as shown below:

Stirling cooler

→

Thermoelectric (Peltier) cooler

Custom Arduino

Controller Card

→

TEC Thermostat *** …

Biofuel Gasification For Residential Heating, Bryan Duke, Courtney Mcintosh, Jeron Hogan

Mechanical Engineering

No abstract provided.

Design And Validation Of An Electro-Hydraulic Pressure-Control Valve And Closed-Loop Controller, Jerry Boza

Dissertations

Electro-hydraulic pressure-control valves are used in many applications, such as manufacturing equipment, agricultural machinery, and aircrafts to name a few. They are often used to actuate hydraulic clutches, such as those found in power shift transmissions. A traditional pressure-control valve with open-loop control algorithm is typically used in clutch applications. This scheme often results in inconsistent or undesirable system behavior due to the nature of open-loop control as well as the nonlinear system dynamics and uncertainties.

In this research two new electro-hydraulic pressure-control valves were designed in order to decouple the valve and control port (hydraulic) dynamics. This was achieved …

The Effect Of Process Parameters And Surface Condition On Bond Strength Between Additively Manufactured Components And Polymer Substrates, Bharat Bhushan Chivukula

Graduate Theses and Dissertations

Additive patching is a process in which printers with multiple axes deposit molten material onto a pre-defined surface to form a bond. Studying the effect of surface roughness and process parameters selected for printing auxiliary part on the bond helps in improving the strength of the final component. Particularly, the influence of surface roughness, as established by adhesion theory, has not been evaluated in the framework of additive manufacturing (AM). A full factorial design of experiments with five replications was conducted on two levels and three factors, viz., layer thickness, surface roughness, and raster angle to examine the underlying effects …

Materials, Mechanics, And Patterning Techniques For Elastomer-Based Stretchable Conductors, X. Yu, B. Mahajan, W. Shou, Heng Pan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Design For Manufacturability And Assembly Of An Assistive Technician Creeper, Including Single Drive Control Of A Multi-Degree Of Freedom Kinematic Mechanism, Larry T. Wilde Jr.

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In 2011, a team of engineering students at Utah State University designed and built an assistive technician creeper to assist persons with lower-extremity physical disabilities to work in low-clearance areas. In order to put this technology on the market, a complete product redesign was needed to address safety and functionality concerns. This thesis outlines the specific design needs, presents the detailed design approach, and summarizes the final creeper solution. The mechanisms of the initial prototype were modified to independently incline or recline the upper body, and raise or lower the seat surface with a single motor. This will be especially …

Feasibility Of Friction Stir Processing (Fsp) As A Method Of Healing Cracks In Irradiated 304l Stainless Steels, Cameron Cornelius Gunter

Theses and Dissertations

The current US fleet of nuclear reactors has been in service for three decades. Over this period, existing welds in stainless steel (SS) shrouds have sustained stress corrosion cracking (SCC) and are in need of repair. Additionally, helium has formed interstitially as a byproduct of proton bombardment. Current repair technology, such as TIG welding, puts extreme amounts of heat into the material and allows for interstitial helium atoms to aggregate and form bubbles/voids at grain boundaries. This significantly weakens the material, proving to be a very counterproductive and ineffective repair technique. Much study has been done on friction stir processing …

Autonomous Goal-Based Mapping And Navigation Using A Ground Robot, Jeffrey L. Ferrin

Theses and Dissertations

Ground robotic vehicles are used in many different applications. Many of these uses include tele-operation of the robot. This allows the robot to be deployed in locations that are too difficult or are unsafe for human access. The ability of a ground robot to autonomously navigate to a desired location without a-priori map information and without using GPS would allow robotic vehicles to be used in many of these situations and would free the operator to focus on other more important tasks. The purpose of this research is to develop algorithms that enable a ground robot to autonomously navigate to …

Evolvability And Excess Capability As A Response To Uncertain And Future Requirements, Jeffrey Douglas Allen

Theses and Dissertations

Product and system designers face many challenges in the modern world. Designing products that will be subject to emerging or uncertain requirements can be one of the most significant of these challenges. A major risk associated with emerging or uncertain requirements is premature obsolescence. Large-scale, complex engineered systems, such as, aircraft, spacecraft, large seagoing vessels, communication and power systems are especially susceptible to this issue. However, this challenge is not limited to only large-scale complex systems. Even relatively simple products can suffer from premature obsolescence and even failure to be initially accepted, due to inadequately understood or changing requirements. One …

Extending Time Until Failure During Leaking In Inflatable, Pneumatically Actuated Soft Robots, Joshua Parker Wilson

Theses and Dissertations

Soft robots and particularly inflatable robots are of interest because they are lightweight, compact, robust to impact, and can interact with humans and their environment relatively safely compared to rigid and heavy traditional robots. Improved safety is due to their low mass that results in low-energy collisions and their compliant, soft construction. Inflatable robots (which are a type of soft robot) are also robust to impact and have a high torque to weight ratio. As a result inflatable robots may be used for many applications such as space exploration, search and rescue, and human-robot interaction. One of the potential problems …

3-Axis Automated Probe Traverse For Aerodynamic Testing, Tananant Boonya-Ananta, Ricky Wai, Zander Oostman, Teyvon Brooks

Mechanical Engineering

Our primary objective is to design, build, and test an automated traverse to hold measurement probes in Cal Poly’s low speed wind tunnel. The device should cause minimal flow disturbance. It’s movements must be able to cover eighty percent of the three-dimensional test section. The device should have a mounting point for interchangeable probes. The assembly is to be integrated with the current frame structure on the wind tunnel test section, and should allow very minimal deflection of the measurement probe. The user should be able to control the motion of the traverse via a computer interface which supports automatic …

Revolutionized Additive Manufacturing, Matthew Walker, Winthrop Townsend, Luca Fuller

Mechanical Engineering

No abstract provided.

Haul Truck Tires Recycling, Omkar Bhave

Chemical Engineering Undergraduate Honors Theses

The disposal of large Off-the-Road (OTR) tires is an increasingly important concern. These tires can weigh up to 8,450 pounds with an overall diameter and width of approximately 140.7 inches and 45.1 inches respectively. OTR tires are used for mining vehicles such as haul trucks, wheel loaders, backhoes, graders, and trenchers.[1] These new tires cost between $38,000 and $50,000 each, depending on multiple factors including oil prices and the cyclical nature of the industry. Haul trucks contain six tires per vehicle, and mines replace these tires around every 9-12 months.[2] Statistics regarding discarded OTR tires are not provided by the …

Me-Em Enewsbrief, December 2016, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical and Aerospace Engineering eNewsBrief

No abstract provided.

Fiber Glass Mat Splice Automation, Max Weinstein, Charles Scott Forbes, Max Kilpatrick

Mechanical Engineering

Currently, GAF has two operators manually splice together each roll of fiberglass mat. To save money and resources, GAF wants to automate this splicing process. Our team is responsible for stage 3 of 5 in this automation process. We are responsible for ensuring that the system is able to move autonomously to the necessary positions required for splicing together the rolls of fiberglass mat. We have determined the best solution for accomplishing this movement is to use linear slide actuators. This document will describe the process by which we arrived at our solution, the details of our solution, and a …

Compression Molded Composite Component, Greg Hermansen, Larsson Johnson, Joanne Medrano, Kyle Hammell

Mechanical Engineering

The following final design report outlines the design and fabrication of a carbon fiber compression molded sunglasses case. It intends to guide the development of a future lab activity for a composites undergraduate course at Cal Poly – San Luis Obispo. The activity aims to support an educational investigation in "out-of-autoclave" composites manufacturing methods, such as compression molding, which offer some key benefits over autoclave molding. The methodology behind the creation of a conceptual design, an initial prototype, and a final product is laid out in detail below.

Cal Poly Microgrid - Solar Panel Mounts, Dylan Mayer, Christian Odegard, Gregory Pellegrino, Connor Mckay

Mechanical Engineering

No abstract provided.