Mechanical Engineering Commons^™

Stress Generation In Ni50.3Ti29.7Hf20 Shape Memory Alloys, Utsav Shah

Theses and Dissertations--Mechanical and Aerospace Engineering

Shape memory alloys such as NiTiHf and NiTi have the ability to generate large recovery stresses when they are constrained after pre-straining and then heated above their Austenite Finish Temperature (A_f). In this work Ni_49.9Ti_50.1 (at.%), the most well-known SMA with impressive shape memory properties but limited temperature range and Ni_50.3Ti_29.7Hf₂₀, a promising high temperature shape memory alloy, were characterized to reveal their stress generation capabilities. The effects of pre-straining on stress generation were investigated via martensite reorientation method of NiTi and NiTiHf alloys by loading the samples till …

Filtered-Dynamic-Inversion Control For Unknown Minimum-Phase Systems With Unknown Relative Degree, Sumit Suryakant Kamat

Theses and Dissertations--Mechanical and Aerospace Engineering

We present filtered-dynamic-inversion (FDI) control for unknown linear time-invariant systems that are multi-input multi-output and minimum phase with unknown-but-bounded relative degree. This FDI controller requires limited model information, specifically, knowledge of an upper bound on the relative degree and knowledge of the first nonzero Markov parameter. The FDI controller is a single-parameter high-parameter-stabilizing controller that is robust to uncertainty in the relative degree. We characterize the stability of the closed-loop system. We present numerical examples, where the FDI controller is implemented in feedback with mathematical and physical systems. The numerical examples demonstrate that the FDI controller for unknown relative degree …

The Influence Of Cryogenic Machining On Surface Integrity And Functional Performance Of Titanium Alloys For Biomedical And Aerospace Applications, Ying Sun

Theses and Dissertations--Mechanical and Aerospace Engineering

The excellent properties of titanium alloys such as high strength, as well as good corrosion and fatigue resistance are desirable for the biomedical and aerospace industry. However, the same properties that make titanium alloys desirable in high-performance applications also make these space-age materials “difficult-to-machine” materials, as the titanium alloys exhibit high cutting temperatures because of their high strength and low thermal conductivity.

Cryogenic machining is a severe plastic deformation (SPD) processes which uses liquid nitrogen as the coolant to take away the heat generated during machining in a relatively short time. Cryogenic machining can significantly reduce the cutting temperatures at …

Influence Of Size Effects On Surface Generation During Finish Machining And Surface Integrity In Ti-6al-4v, Ian S. Brown

Theses and Dissertations--Mechanical and Aerospace Engineering

Finish machining is an essential manufacturing process that is used to enhance the mechanical characteristics of critical components. The deformation that occurs at the tool and workpiece interface in finish machining significantly affects a host of component properties, commonly referred to as “surface integrity” properties. Surface roughness is a machining deformation-affected characteristic that is of high relevance in contemporary manufacturing. However, over recent decades it has been made clear that the material properties of the deformed surface layers are relevant to component performance as well. Predicting the overall surface quality of a machined component is of great relevance to the …

Safety Concepts For Every Ride: A Statistical Ensemble Simulation To Mitigate Rotational Falls In Eventing Cross Country, Shannon Wood

Theses and Dissertations--Mechanical and Aerospace Engineering

Rotational falls are the leading cause of death and serious injury in the equestrian sport of eventing. Previous studies to develop safety devices used physical models representing one or at most several physical situations leading to different designs and no common understanding. In this thesis, a statistical ensemble model is developed and applied to generate and evaluate 10,000 different situations that might potentially lead to rotational falls. For accurate statistical representation of the horse and rider inertia distributions, measurements of over 400 training or competing horses and riders were recorded and incorporated. Video was recorded of 218 total competitors approaching …

Capillary Flow Of Liquid Aluminum Alloy In Wetting And Wetting/Non-Wetting Systems, Yangyang Wu

Theses and Dissertations--Mechanical and Aerospace Engineering

In this dissertation, the capillary flow of liquid aluminum alloy in both wetting and wetting/non-wetting systems is investigated.

The impact of gravity and surface topography on the capillary flow has been studied in a wetting/non-wetting assembly (an AA3003/Al₂O₃ wedge-tee configuration). The research includes (i) kinetics of liquid Al-Si-K_xAl_yF_z alloy triple line movements and dynamic macro advancing and receding contact angles and (ii) free surface profiles of the molten alloy driven by surface tension and impacted by gravity. A trade-off between the surface tension and gravity force has been found by calculating the …

Development And Application Of Novel Sound Absorbers, Weiyun Liu

Theses and Dissertations--Mechanical and Aerospace Engineering

The sound absorbers in most common use today are porous materials like fibers and foams. This work examines three alternatives to porous absorbers: microperforated panels, acoustic fabrics, and additively manufactured absorbers. The research is a combination of design, measurement and characterization of their properties, and analysis.

Microperforated panels are thin metallic or plastic panels with sub-millimeter size holes or perforations. Sound absorption can be tuned by adjusting the spacing between the panel and a cavity behind the panel. Several different configurations were considered where the geometry behind the panel was divided up into channels of varying length and cross-sectional area. …

Development Of Micro-Scale High Aspect Ratio Patterned Features With Electroless Nickel Plating, Lorli Smith

Theses and Dissertations--Mechanical and Aerospace Engineering

This thesis describes a novel method designed to pattern high aspect ratio metallic microscale features using a modified photolithography and electroless nickel plating process. This method utilizes modified photolithography techniques to create a polymer mold that is used to control the location of metal deposition on substrate during electroless nickel plating. In order to generate high aspect ratio mold features, a multiple spin-step process was developed to deposit thick layers of SU-8 photoresist, and inclined lithography was also used to generate tapered sidewalls that could help aid mold removal after plating. Results from electroplating experiments were evaluated using a Zygo …

Development Of Universal Solver For High Enthalpy Flows Through Ablative Materials, Umran Duzel

Theses and Dissertations--Mechanical and Aerospace Engineering

Atmospheric entry occurs at very high speeds which produces high temperature around the vehicle. Entry vehicles are thus equipped with Thermal Protection Systems which are usually made of ablative materials. This dissertation presents a new solver that models the atmospheric entry environment and the thermal protection systems. In this approach, both the external flow and the porous heat shield are solved using the same computational domain. The new solver uses the Volume Averaged Navier-Stokes Equations adapted for hypersonic non-equilibrium flow, and is thus valid for both domains. The code is verified using analytical problems, set of benchmarks and also a …

Bacterial Cell Wall Characterization Via Atomic Force And Confocal Microscopy, Joree Sandin

Theses and Dissertations--Mechanical and Aerospace Engineering

Poor oral hygiene is a severe global health issue, with about 44% of the Earth’s population suffering from untreated tooth decay, accounting for over $100 billion dollars spent on dental services per year in the United States, alone. Manual treatments, such as brushing, flossing, or swishing with antiseptic rinse are the main ways to alleviate harmful bacteria that cause these oral health problems. Streptococcus mutans (S. mutans) is a group of highly antibiotic, Gram-positive bacteria that heavily contribute to oral cavities, plaque build-up, and potential loosening or loss of dental implants if a biofilm develops. Currently, the mechanism …

Carbon Oxidation At The Atomic Level: A Computational Study On Oxidative Graphene Etching And Pitting Of Graphitic Carbon Surfaces, Simon Schmitt

Theses and Dissertations--Mechanical and Aerospace Engineering

In order to understand the oxidation of solid carbon materials by oxygen-containing gases, carbon oxidation has to be studied on the atomic level where the surface reactions occur. Graphene and graphite are etched by oxygen to form characteristic pits that are scattered across the material surface, and pitting in turn leads to microstructural changes that determine the macroscopic oxidation behavior. While this is a well-documented phenomenon, it is heretofore poorly understood due to the notorious difficulty of experiments and a lack of comprehensive computational studies. The main objective of the present work is the development of a computational framework from …

Fabrication And Characterization Of Nickel Plated Micro-Resonators For Noncommutative Orientation Control In Microrobots, Marc Manheim

Theses and Dissertations--Mechanical and Aerospace Engineering

This thesis describes a procedure for fabricating arrays of microstructures out of SU-8 photoresist and nickel, which was developed with the goal of yielding microrobots capable of 1D rotation byway of magnetically-induced beam vibration that could be used for non-commutative orientation control. Several multi-layer geometries were designed, fabricated, tested and refined. In this process, micro-adhesion of multiple SU-8 layers was also studied. A method for depositing nickel via electroless plating was also developed, tested and characterized. While no microrobots were shown to produce rotation, the final results included beams that were capable of magnetically-induced vibration when subjected to an AC …

Optimization Of Geometry Parameters Of Inkjet-Printed Silver Nanoparticle Traces On Pdms Substrates Using Response Surface Methodology, Jumana Abu-Khalaf, Loiy Al-Ghussain, Ahmad Nadi, Razan Saraireh, Abdulrahman Rabayah, Safwan Altarazi, Ala’Aldeen Al-Halhouli

Mechanical Engineering Graduate Research

Inkjet printing is an emerging technology with key advantages that make it suitable for the fabrication of stretchable circuits. Specifically, this process is cost-effective and less complex compared to conventional fabrication technologies. Inkjet printing has several process and geometry parameters that significantly affect the electromechanical properties of the printed circuits. This study aims to optimize the geometry parameters of inkjet-printed silver nanoparticle traces on plasma-treated polydimethylsiloxane (PDMS) substrates. The optimization process was conducted for two printed shapes, namely straight line and horseshoe patterns. The examined input factors for the straight line traces were: the number of inkjet-printed layers and line …

Fabrication And Evaluation Of A Novel Non-Invasive Stretchable And Wearable Respiratory Rate Sensor Based On Silver Nanoparticles Using Inkjet Printing Technology, Ala’Aldeen Al-Halhouli, Loiy Al-Ghussain, Saleem El Bouri, Haipeng Liu, Dingchang Zheng

Mechanical Engineering Graduate Research

The respiration rate (RR) is a key vital sign that links to adverse clinical outcomes and has various important uses. However, RR signals have been neglected in many clinical practices for several reasons and it is still difficult to develop low-cost RR sensors for accurate, automated, and continuous measurement. This study aims to fabricate, develop and evaluate a novel stretchable and wearable RR sensor that is low-cost and easy to use. The sensor is fabricated using the soft lithography technique of polydimethylsiloxane substrates (PDMS) for the stretchable sensor body and inkjet printing technology for creating the conductive circuit by depositing …

Optimization Of Induction Quenching Processes For Hss Roll Based On Mmpt Model, Ligang Liu, Hui Yu, Zhiqiang Yang, Chunmei Zhao, Tongguang Zhai

Chemical and Materials Engineering Faculty Publications

To improve the comprehensive performance of high speed steel (HSS) cold rolls, the induction hardening processes were analyzed by numerical simulation and experimental research. Firstly, a modified martensitic phase transformation (MMPT) model of the tested steel under stress constraints was established. Then, the MMPT model was fed into DEFORM to simulate the induction quenching processes of working rolls based on an orthogonal test design and the optimal dual frequency of the induction quenching process was obtained. The results indicate that the depth of the roll’s hardened layer increases by 32.5% and the axial residual tensile stress also becomes acceptable under …

Transient Analysis Of Diffusion-Induced Deformation In A Viscoelastic Electrode, Yaohong Suo, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

In this study, we analyze the transient diffuse-induced-deformation of an electrode consisting of the conducting polymer polypyrrole (PPY) by using the theories of linear viscoelasticity and diffusion-induced stress. We consider two constitutive relationships with dependence of viscosity on strain rate: Kelvin-Voigt model and three-parameter solid model. A numerical method is used to solve the problem of one-dimensional, transient diffusion-induced-deformation under potentiostatic operation. The numerical results reveal that the maximum displacement occurs at the free surface and the maximum stress occurs at the fixed end. The inertia term causes the stress to increase at the onset of lithiation. The stress decreases …

Using Numerical Models Of Dewatering At Coal Ash Impoundments To Understand Cost And Schedule, Peter Bell, Joel Thompson, Don Fuller

World of Coal Ash Proceedings

No abstract provided.

Investigating Ccr Units And Evaluating The Physical Properties Of Ponded Ccr, David Skeggs, Zahra Aghazadeh, Rachel Combs

World of Coal Ash Proceedings

No abstract provided.

Demonstration Of “No Migration” Alternative Performance Standard For Ccr Facilities In Arid To Semi- Arid Regions Using Unsaturated Zone Modeling, James Aiken, Katy Lindstom

World of Coal Ash Proceedings

No abstract provided.

State Vs Federal Ccr Rule Regulations: Comparisons And Impacts, Nicole Kron, Eric Nelson

World of Coal Ash Proceedings

No abstract provided.

Coal Combustion Residuals Management Using Geotextile Containers- Considerations For Various Options, Randall Wilcox, Gregg Lebster, Bryan Hamilton, Thomas Stephens

World of Coal Ash Proceedings

No abstract provided.

Continuous, Real-Time Tss Monitoring Verifies Effluent Quality And Coal Ash Management Performance While Reducing Compliance Costs, Dave Fraley, Chris Bauman, Dave Donahue

World of Coal Ash Proceedings

No abstract provided.

Effect Of Coal Fly Ash On Agricultural Crops :Second Phase Showcase Project On Use Of Fly Ash In Agriculture In And Around Thermal Power Station Areas Of National Thermal Power Corporation Ltd., India., K. Arivazhagan, M. Ravichandran, S.K. Dube, V.K. Mathur

World of Coal Ash Proceedings

No abstract provided.

Advantages Of Single Source Contracting In-Plant Ccr Services, Kevin Foody, Marcella Funderburg, Blake Whittington

World of Coal Ash Proceedings

No abstract provided.

Design And Construction Of A Ccr Landfill Adjacent To The Missouri River, Thomas Gredell, Jeffrey Fouse, Jay Ellington

World of Coal Ash Proceedings

No abstract provided.

Geochemical Tools For Groundwater Monitoring At Coal Fired Utilities, Jeff Gillow, Bruce Sass, Hari Parthasarathy

World of Coal Ash Proceedings

No abstract provided.

Bottom Ash Handling Conversions – Lessons Learned, Dustin Doerr

World of Coal Ash Proceedings

No abstract provided.

Encapsulation Of Thermoevaporation Brines Using Coal Combustion Residuals, Dale Prentice, Kirk Ellison, Gaurav Sant

World of Coal Ash Proceedings

No abstract provided.

Recycling Of Coal Ash In Agriculture: Use Of Vermicomposting Biotechnology, G.N. Chattopadhyay, Gourab Roy, Wasim Iftikar

World of Coal Ash Proceedings

No abstract provided.

Surface Water And Groundwater Mixing In Alluvial Floodplains: A Significant Issue For Understanding Contaminant Transport At Coal Ash Facilities Adjacent To Rivers, Joel Thompson, Peter Bell, John Griggs

World of Coal Ash Proceedings

No abstract provided.