Mechanical Engineering Commons^™

Optimization Constrained Cad Framework With Iso-Performing Design Generator, Kelly Eric Bowman

Theses and Dissertations

Design decisions have a large impact early in the design process. Optimization methods can help engineers improve their early decision making, however, design problems are often ill-posed for optimization at this early stage. This thesis develops engineering methods to use optimization during embodiment design, despite these difficulties. One common difficulty in designing mechanical systems is in handling the effects that design changes in one subsystem have on another. This is made more difficult in early engineering design, when design information is preliminary. Increased efforts have been made to use numerical optimization methods in early engineering design – because of the …

Freeform Fabrication Of Zirconium Diboride Parts Using Selective Laser Sintering, Ming-Chuan Leu, Erik B. Adamek, Tieshu Huang, Greg Hilmas, Fatih Dogan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Using the Selective Laser Sintering (SLS) process, both flexural test bars and 3D fuel injector components have been fabricated with zirconium diboride (ZrB₂) powder. Stearic acid was selected as the binder. Values of SLS process parameters were chosen such that the green parts could be built with sharp geometrical features and that the sintered parts could have good mechanical properties. After binder burnout and sintering, the SLS fabricated ZrB₂ test bars achieved 80% theoretical density, and the average flexural strength of the sintered samples was 195 MPa. These values demonstrate the feasibility of the SLS process for …

Direct 3d Layer Metal Deposition, Jianzhong Ruan, Lie Tang, Todd E. Sparks, Robert G. Landers, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Multi-axis slicing for solid freeform fabrication (SFF) manufacturing processes can yield non-uniform thickness layers, or 3D layers. Using the traditional parallel layer construction approach to build such a layer leads to a staircase which requires machining or other post processing to form the desired shape. This paper presents a direct 3D layer deposition approach. This approach uses an empirical model to predict the layer thickness based on experimental data. The toolpath between layers is not parallel; instead, it follows the final shape of the designed geometry and the distance between the toolpath in the adjacent layers varies at different locations. …

Layer-To-Layer Height Control For Laser Metal Deposition Processes, Lie Tang, Jianzhong Ruan, Todd E. Sparks, Robert G. Landers, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A Laser Metal Deposition (LMD) height controller design methodology is presented in this paper. The height controller utilizes the Particle Swarm Optimization (PSO) algorithm to estimate model parameters between layers using measured temperature and track height profiles. The process model parameters for the next layer are then predicted using Exponentially Weighted Moving Average (EWMA). Using the predicted model, the powder flow rate reference profile, which will produce the desired layer height reference, is then generated using Iterative Learning Control (ILC). The model parameter estimation capability is tested using a four-layer deposition. The results demonstrate the simulation based upon estimated process …

Modeling And Experimental Results Of Concentration With Support Material In Rapid Freeze Prototyping, Frances D. Bryant, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Ice structures with complex geometries and overhung areas are created by the Rapid Freeze Prototyping (RFP) process in a sufficiently cool environment by freezing water into ice as the main material in conjunction with a eutectic dextrose-water solution as the sacrificial support material. The supported areas in an ice structure are removed via an increase in temperature in a separate environment after the structure is completely fabricated. To understand to what extent these two materials mix during fabrication, two methods of modeling the concentration changes that occur near the interface of the main and support materials have been developed. The …

Microstructural Characterization Of Diode Laser Deposited Ti-6al-4v, Tian Fu, Zhiqiang Fan, Syamala R. Pulugurtha, Todd E. Sparks, Jianzhong Ruan, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laser Direct Metal Deposition (DMD) is an effective approach to manufacturing or repairing a range of metal components. The process is a layer-by-layer approach to building up a three dimensional solid object. The microstructure influences mechanical properties of the deposited parts. Thus, it is important to understand the microstructural features of diode laser deposited parts. This paper presents a microstructure analysis of a diode laser deposited Ti-6Al-4V onto a Ti-6Al-4V substrate. laser deposited parts. This paper presents a microstructure analysis of a diode laser deposited Ti-6Al-4V onto a Ti-6Al-4V substrate.

Product Focused Freeform Fabrication Education, Frank W. Liou, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Presented in this paper is our experience of teaching freeform fabrication to students at the Missouri University of Science and Technology, and to high school students and teachers. The emphasis of the curriculum is exposing students to rapid product development technologies with the goal of creating awareness to emerging career opportunities in CAD/CAM. Starting from solid modeling, principles of freeform fabrication, to applications of rapid prototyping and manufacturing in industry sponsored product development projects, students can learn in-depth freeform fabrication technologies. Interactive course content with hands-on experience for product development is the key towards the success of the program.

Direct-To-Part Machining Waste Recycling Using Laser Metal Deposition, Todd E. Sparks, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laser metal deposition typically uses metal powders as the build material of choice. The ability to reprocess waste materials using this technology would significantly reduce the material cost and cradle-to-grave energy content of parts produced using these methods. This capability will also greatly increase the utility of laser deposition, to potential industrial uses. This paper explores the usage of machining chips as an alternate source of build material. Topics covered include material handling, material preprocessing, and comparison to powder- based deposition.

Development And Implementation Of Mathematical Modeling, Vibration And Acoustic Emission Technique To Correlate In Vivo Kinematics, Kinetics And Sound In Total Hip Arthroplasty With Different Bearing Surfaces, Diana Andreeva Glaser

Doctoral Dissertations

The evaluation of Total Hip Arthroplasty (THA) outcome is difficult and invasive methods are often applied. Fluoroscopy has been used as an in vivo diagnostic technique to determine separation which may lead to vibration propagation and audible interactions. The objective of this study was to develop a new, non-invasive technique of digitally capturing vibration and sound emissions at the hip joint interface and to correlate those with the hip kinematics derived from fluoroscopy. Additionally, an examination of the role of hip mechanics on walking performance in THA subjects of various bearings surfaces was performed.

In vivo kinematics, kinetics, corresponding vibration …

Characterization Of Dynamic Response Of Afm Cantilevers For Microscale Thermofluidic And Biophysical Sensors, Seonghwan Kim

Doctoral Dissertations

My doctoral research has focused on the characterization of dynamic response of atomic force microscope (AFM) cantilevers for thermofluidic and biophysical sensors, a novel scanning thermal microscopy technique development using a tipless microcantilever to investigate micro/nanoscale transport properties in liquid, and the characterization of the surface nanomechanical properties of biocompatible polyelectrolyte hydrogels with AFM for biomedical applications.

The temperature effects on Sader‟s viscous model for multilayered microcantilevers immersed in an aqueous medium were experimentally verified as a preliminary work. Next, temperature dependence of the near-wall oscillation of microcantilevers submerged in an aqueous medium was investigated to explore the possibility of …

From Nearfield Nanoparticle Tracking To Intracellular Vesicle Tracking, Charles H. Margraves

Doctoral Dissertations

The initial goal of this research was to measure the hindered Brownian motion of nanoparticles (100 nm to 500 nm in radii), in varying salinities of water, in order to compare the normal and tangential motion with existing theory. Using techniques developed from this work, brain cancer cells containing vesicles loaded with Nonsteroidal anti-inflammatory drug-Activated Gene-1 (NAG-1), tagged with a Green Fluorescent Protein (GFP), were examined to see what effect the glass cover slip played in hindering their motion.

Several microscopy techniques have been used in this work including Total Internal Reflection Fluorescent Microscopy (TIRFM) and Differential Interference Reflection Microscopy …

Bandwidth On Demand For Laser Communications Satellites, Alexander M. Melin

Doctoral Dissertations

Narrow beamwidth satellites such as laser communication or imaging satellites present a unique problem in control and scheduling. The narrow beamwidth limits the sources of information avail- able to the satellite. This is especially true for laser communication satellites who can only point the laser at one user at a time. For the most part, this restricts the use of laser communications satellites to fixed connections or dedicated temporary connections. However, some classes of users can benefit from the speed and security of the lasercom connection. For example, a Globalhawk unmanned aerial vehicle with time sensitive battlefield imaging would be …

A Nonlinear Finite Element Model Of Cartilage Growth, Andrew Davol, Michael S. Bingham, Robert L. Sah, Stephen M. Klisch

Mechanical Engineering

The long range objective of this work is to develop a cartilage growth finite element model (CGFEM), based on the theories of growing mixtures that has the capability to depict the evolution of the anisotropic and inhomogeneous mechanical properties, residual stresses, and nonhomogeneities that are attained by native adult cartilage. The CGFEM developed here simulates isotropic in vitro growth of cartilage with and without mechanical stimulation. To accomplish this analysis a commercial finite element code (ABAQUS) is combined with an external program (MATLAB) to solve an incremental equilibrium boundary value problem representing one increment of growth. This procedure is repeated …

Regulation Of Immature Cartilage Growth By Igf-I, Tgf- Β 1, Bmp-7, And Pdgf-Ab: Role Of Metabolic Balance Between Fixed Charge And Collagen Network, Anna Asanbaeva, Koichi Masuda, Eugene J-M.A. Thonar, Stephen M. Klisch, Robert L. Sah

Mechanical Engineering

Cartilage growth may involve alterations in the balance between the swelling tendency of proteoglycans and the restraining function of the collagen network. Growth factors, including IGF-I, TGF-β1, BMP-7, and PDGF-AB, regulate chondrocyte metabolism and, consequently, may regulate cartilage growth. Immature bovine articular cartilage explants from the superficial and middle zones were incubated for 13 days in basal medium or medium supplemented with serum, IGF-I, TGF-β1, BMP-7, or PDGF-AB. Variations in tissue size, accumulation of proteoglycan and collagen, and tensile properties were assessed. The inclusion of serum, IGF-I, or BMP-7 resulted in expansive tissue growth, stimulation of proteoglycan deposition but not …

The Dependence Of Measured Modulation Error Ratio On Phase Noise, Ron D. Katznelson

Ron D. Katznelson

This paper reviews the algorithms used by Vector Signal Analyzers to measure Modulation Error Ratio (MER) and derives the explicit functional dependence of measured MER on phase noise of digital transmitters. The modulation error model is introduced and the analytical expression for key estimated parameters required to obtain MER measure are derived. The essential elements of algorithms employed by MER measurement instruments to estimate amplitude scale, frequency offset, and initial phase intercept and the resulting MER are identified. The frequency response of the effective phase-noise rejection filtering action associated with a given measurement epoch is derived. It is shown that …

Sum Frequency Generation Vibrational Spectroscopy Of Pyridine Hydrogenation On Platinum Nanoparticles, Kaitlin M. Bratlie, Kyriakos Komvopoulos, Gabor A. Somorjai

Kaitlin M. Bratlie

Pyridine hydrogenation in the presence of a surface monolayer consisting of cubic Pt nanoparticles stabilized by tetradecyltrimethylammonium bromide (TTAB) was investigated by sum frequency generation (SFG) vibrational spectroscopy using total internal reflection (TIR) geometry. TIR-SFG spectra analysis revealed that a pyridinium cation (C5H5NH+) forms during pyridine hydrogenation on the Pt nanoparticle surface, and the NH group in the C5H5NH+ cation becomes more hydrogen bound with the increase of the temperature. In addition, the surface coverage of the cation decreases with the increase of the temperature. An important contribution of this study is the in situ identification of reaction intermediates adsorbed …

Uncertainty Analysis In Mcp-Based Wind Resource Assessment And Energy Production Estimation, Matthew Lackner, Anthony L. Rogers, James F. Manwell

Matthew Lackner

This paper presents a mathematical framework to properly account for uncertainty in wind resource assessment and wind energy production estimation. A meteorological tower based wind measurement campaign is considered exclusively, in which measurecorrelate- predict is used to estimate the long-term wind resource. The evaluation of a wind resource and the subsequent estimation of the annual energy production (AEP) is a highly uncertain process. Uncertainty arises at all points in the process, from measuring the wind speed to the uncertainty in a power curve. A proper assessment of uncertainty is critical for judging the feasibility and risk of a potential wind …

Furnace Blower Electricity: National And Regional Savings Potential, Florida Solar Energy Center, Victor Franco

FSEC Energy Research Center®

Currently, total electricity consumption of furnaces is unregulated, tested at laboratory conditions using the DOE test procedure, and is reported in the GAMA directory as varying from 76 kWh/year to 1,953 kWh/year. Furnace blowers account for about 80% of the total furnace electricity consumption and are primarily used to distribute warm air throughout the home during furnace operation as well as distribute cold air during air conditioning operation. Yet the furnace test procedure does not provide a means to calculate the electricity consumption during cooling operation or standby, which account for a large fraction of the total electricity consumption. Furthermore, …

How Energy Efficient Are Modern Dishwashers?, Florida Solar Energy Center, David Hoak

FSEC Energy Research Center®

We present measurements of three recent vintage dishwashers of very different efficiencies showing that while they are substantially more efficient than older dishwashers, those tested will still use electric resistance elements for supplemental heat, even when supplied by solar water heating systems producing very hot water. We did find the DOE test results provide a reasonable guide to comparative performance, but suggest improvements that will make them more representative. We also identify a variety of influences on efficiency and performance to reduce dishwasher energy use.

Nightcool: A Nocturnal Radiation Cooling Concept, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

An experimental evaluation has been conducted on a night sky cooling system designed to substantially reduce space cooling needs in homes in North American climates. The system uses a sealed attic covered by a highly conductive metal roof (a roof integrated radiator) which is selectively linked by air flow to the main zone with the attic zone to provide cooling - largely during nighttime hours. Available house mass is used to store sensible cooling. Currently, the system's capability for solar dehumidification with minimal electricity input is demonstrated.

Very Low Energy Homes In The United States: Perspectives On Performance From Measured Data, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

We present measured annual performance data from a dozen recent-vintage very low energy homes in North America. Many of the designs combine greater energy efficiency with solar electric photovoltaic power in an attempt to create Zero Energy Homes (ZEH). We also provide measured data from the first home constructed to the German Passivhaus standard in the United States. Several projects either exceeded or come very close to true net zero energy when evaluated over a year.

The data indicate that very low energy use buildings can very readily be achieved in North America. Annual energy use half that or less …

Computer Model To Predict Drillstring Lateral Vibration Modes And Frequencies Using The Finite-Element-Method And Modal Analysis, David Bukowitz, Rafael Bravo, Joaquin Moran

Publications and Scholarship

A computer program based on the finite element method was developed to predict the lateral vibra- tion modes and frequencies in the Bottom Hole Assembly (BHA) of a drillstring. This model is applicable in both a planning and a real time mode of operation to avoid resonance problems. The analysis used in this model proceeds in two stages. The first stage solves the two-dimensional nonlinear static deformation of the drillstring; this gives the deformed shape of the BHA and the side forces at points where the BHA touches the wellbore wall. In this way, the length of the BHA that …

Issues On Stability Of Adp Feedback Controllers For Dynamical Systems, S. N. Balakrishnan, Jie Ding, F. L. Lewis

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper traces the development of neural-network (NN)-based feedback controllers that are derived from the principle of adaptive/approximate dynamic programming (ADP) and discusses their closed-loop stability. Different versions of NN structures in the literature, which embed mathematical mappings related to solutions of the ADP-formulated problems called “adaptive critics” or “action-critic” networks, are discussed. Distinction between the two classes of ADP applications is pointed out. Furthermore, papers in “model-free” development and model-based neurocontrollers are reviewed in terms of their contributions to stability issues. Recent literature suggests that work in ADP-based feedback controllers with assured stability is growing in diverse forms.

The Role Of Silicon Content On Environmental Degradations Of T91 Steels, Ajit K. Roy, D. Maitra, Pankaj Kumar

Mechanical Engineering Faculty Research

T91 grade steels showed a gradual enhancement in tensile ductility at ambient temperature due to an increase in Si content from 0.5 to 2.0 weight percent (wt.%). However, the ultimate tensile strength was reduced only above 1.5 wt.% Si. The corrosion potential became more active in an acidic solution with increasing temperature. The cracking susceptibility in a similar environment under a slow-strain-rate (SSR) condition was enhanced at higher temperatures showing reduced ductility, time to failure, and true failure stress. Cathodic potentials applied to the test specimens in SSR testing caused an enhanced cracking tendency at 30 and 60°C, suggesting hydrogen …

Tensile Deformation Of A Nickel-Base Alloy At Elevated Temperatures, Ajit K. Roy, Anand Venkatesh, Vikram Marthandam

Mechanical Engineering Faculty Research

The results of tensile testing involving Waspaloy indicate that the failure strain was gradually reduced at temperatures ranging between ambient and 300 °C. Further, serrations were observed in the engineering stress versus strain diagrams in the temperature range of 300-600 °C. The reduced failure strain and the formation of serrations in these temperature regimes could be the result of dynamic strain aging of this alloy. The extent of work hardening due to plastic deformation was reduced at temperatures above 300 °C. A combination of ductile and intergranular brittle failures was seen at temperatures above 600 °C. γ′ was detected at …

Reinforcement Learning Based Dual-Control Methodology For Complex Nonlinear Discrete-Time Systems With Application To Spark Engine Egr Operation, Peter Shih, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier

Electrical and Computer Engineering Faculty Research & Creative Works

A novel reinforcement-learning-based dual-control methodology adaptive neural network (NN) controller is developed to deliver a desired tracking performance for a class of complex feedback nonlinear discrete-time systems, which consists of a second-order nonlinear discrete-time system in nonstrict feedback form and an affine nonlinear discrete-time system, in the presence of bounded and unknown disturbances. For example, the exhaust gas recirculation (EGR) operation of a spark ignition (SI) engine is modeled by using such a complex nonlinear discrete-time system. A dual-controller approach is undertaken where primary adaptive critic NN controller is designed for the nonstrict feedback nonlinear discrete-time system whereas the secondary …

Ductile-Regime Machining Of Silicon Carbide And Quartz, Deepak Ravindra

Masters Theses

Silicon carbide (SiC) and quartz are one of the advanced engineered ceramic materials designed to operate in extreme environments. One of the main reasons for the choice of these materials is due to its excellent electrical, mechanical and optical properties that benefit the semiconductor, MEMS and optoelectronic industry respectively. Manufacturing these materials is extremely challenging due to its high hardness, brittle characteristics and poor machinability. Severe fracture can result when trying to machine SiC and quartz due to its low fracture toughness. However, from past and current research efforts, it has been proven that ductile regime machining of brittle materials …

Investigating Isolated Neuromuscular Control Contributions To Non-Contact Anterior Cruciate Ligament Injury Risk Via Computer Simulation Methods, Scott G. Mclean, Xuemei Huang, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

Background

Despite the ongoing evolution of anterior cruciate ligament injury prevention methods, injury rates and the associated sex-disparity remain. Strategies capable of successfully countering key control parameters existent within the injury mechanism thus remain elusive. Forward dynamics model simulations afford an expedited means to study realistic injury causing scenarios, while controlling all facets of the movement control strategy. Utilizing these methods, the current study examined the potential for perturbations in key initial contact neuromuscular parameters to injure the anterior cruciate ligament during the stance phase of sidestep cutting maneuvers.

Methods

Controlled experiments were performed on optimized and validated subject-specific forward …

Development Of A Slide-Rolling Contact Fatigue Tester, Gregory T. Dvorak

Theses and Dissertations

Contact fatigue failure is a common problem experienced in many applications such as bearings, gears and railway tracks. In recent years, research companies have developed finishing processes which aim to improve a component's contact fatigue life. One such process has been patented by REM Chemicals in Texas. Preliminary contact fatigue tests have shown that this superfinishing process could potentially improve a component’s contact fatigue life by 300%. Before this technology can move from the laboratory to an industrial platform, more tests are needed to verify the claim. To the best of the author’s knowledge, no standard process or test machine …

Aerobatic Maneuvering Of Miniature Air Vehicles Using Attitude Trajectories, James K. Hall, Timothy W. Mclain

Faculty Publications

We develop aerobatic maneuvering for miniature air vehicles (MAVs) using time-parameterized attitude trajectory generation and an associated attitude tracking control law. We develop two methodologies, polynomial or trigonometric, for creating smooth functions that specify pitch and roll angle trajectories. For both approaches, the functions are constrained by the maneuver boundary conditions for aircraft position and velocity. We develop a feedback control law to regulate aircraft orientation throughout the maneuvers. The performance of our trajectory generation algorithm and our attitude tracking control law is demonstrated through simulated and actual flight tests of aerobatic maneuvers.