Mechanical Engineering Commons^™

Effect Of Different Graphite Materials On Electrical Conductivity And Flexural Strength Of Bipolar Plates Fabricated By Selective Laser Sintering, Nannan Guo, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Graphite is an excellent material for bipolar plates used in Proton Exchange Membrane (PEM) fuel cell due to its great chemical resistance, but the brittle nature makes it difficult to manufacture. Selective Laser Sintering (SLS) based on layer-by-layer manufacturing technology can fabricate graphite bipolar plates with complex gas flow channels. To improve the performance of bipolar plates including electrical conductivity and flexural strength, different graphite materials (natural graphite, synthetic graphite, carbon black, and carbon fiber) were investigated to fabricate test samples. These samples then went through post processing including carbonization and infiltration. The results show that bipolar plates with electrical …

Selective Laser Sintering And Freeze Extrusion Fabrication Of Scaffolds For Bone Repair Using 13-93 Bioactive Glass: A Comparison, Krishna C. R. Kolan, Nikhil P. Doiphode, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

13-93 glass is a third-generation bioactive material which accelerates the bone’s natural ability to heal by itself through bonding with surrounding tissues. It is an important requirement for synthetic scaffolds to maintain their bioactivity and mechanical strength with a porous internal architecture comparable to that of a human bone. Additive manufacturing technologies provide a better control over design and fabrication of porous structures than conventional methods. In this paper, we discuss and compare some of the common aspects in the scaffold fabrication using two such processes, viz. selective laser sintering (SLS) and freeze extrusion fabrication (FEF). Scaffolds fabricated using each …

Uncertainty Analysis In Laser Deposition Finish Machining Operations, Jomy Francis, Todd E. Sparks, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Laser Aided Manufacturing Process (LAMP) from Missouri S&T is a laser based metals rapid manufacturing process that uses machining to improve the final part's surface finish. When free-form machining, the absence of enough deposited material results in inconsistent scallop heights which result in poor surface finish or incorrect geometry in the final part. This paper investigates a probabilistic approach to various uncertainties involved in the deposition and subsequent machining of an arbitrary part. Furthermore, this paper analyses the machine errors which makes the response of Scallop Height to exceed the predefined maximum scallop height when traveling along the tool …

Investigations Of Femtosecond-Nanosecond Dual-Beam Laser Ablation Of Dielectrics, Cheng Hsiang Lin, Zheng Hua Rao, Lan Jiang, Wu Jung Tsai, Ping Han Wu, Chih Wei Chien, Shean Jen Chen, Hai Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We have conducted experimental investigations for the micromachining of dielectrics (fused silica) using an integrated femtosecond (is) and nanosecond (ns) dual-beam laser system at different time delays between the fs and ns pulses. We found that the maximum ablation enhancement occurs when the fs pulse is shot near the peak of the ns pulse envelope. Enhancements up to 13.4 times in ablation depth and 50.7 times in the amount of material removal were obtained, as compared to fs laser ablation alone. the fs pulse increases the free electron density and changes the optical properties of fused silica to have metallic …

Automated Residential Energy Monitoring: An Approach To Performance Comparisons, Christopher D. Wright, Robert B. Stone

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Techniques for residential energy usage monitoring is an emerging field that is currently drawing significant attention. This paper is a description of the current efforts to monitor and compare the performance of three solar-powered homes built at Missouri University of Science and Technology. the homes are outfitted with an array of sensors and a data logger system to measure and record electricity production, system energy use, internal home temperature and humidity, hot water production, and exterior ambient conditions the houses are experiencing. Data will be collected to measure the performance of the houses, compare to energy modeling programs, design and …

Validating Module Heuristics On Large Scale Products, Rachel Day, Robert B. Stone, Katie Grantham Lough

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Decreasing time and costs is a major objective in many businesses today. Including modularity in the early design phases can effectively decrease time spent on and costs associated with a project. the task of identifying modules within a product early in the design process (when decisions are less expensive) is made less daunting by using the techniques of functional modeling and module heuristics. This paper discusses the results of the initial efforts to verify the module heuristics on large products (products with functional models consisting of more than 30 sub-functions) since the module heuristics were originally developed on small products. …

Functioncad: A Functional Modeling Application Based On The Function Design Framework, Robert L. Nagel, Kenneth L. Perry, Robert B. Stone, Daniel A. Mcadams

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents a functional modeling application, Function CAD, based on integrated functional and process modeling within the Function Design Framework. Function CAD provides for mixed, hierarchical models of environment, process and function with relationships represented via flows of material, energy and signal. This paper discusses the technical details of the Function CAD software including its two major components: (1) the library, libFCAD, for handling the internal representation of the model and (2) the GUI for user-Based model manipulation and visualization. the application of Function CAD within a computational, function- based conceptual design process is discussed along with the plugin …

Prediction Of The Transport Properties Of A Polyatomic Gas, Zhi Liang, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An Ab Initio Molecular Potential Model is Employed in This Paper to Show its Excellent Predictability for the Transport Properties of a Polyatomic Gas from Molecular Dynamics Simulations. a Quantum Mechanical Treatment of Molecular Vibrational Energies is Included in the Green and Kubo Integral Formulas for the Calculation of the Thermal Conductivity by the Metropolis Monte Carlo Method. using CO2 Gas as an Example, the Fluid Transport Properties in the Temperature Range of 300-1000 K Are Calculated Without using Any Experimental Data. the Accuracy of the Calculated Transport Properties is Significantly Improved by the Present Model, Especially for the Thermal …

Sorting Results Of Automated Concept Generators Based On Design For Manufacture And Assembly, Kerry R. Poppa, Robert B. Stone

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Early in the design process, it is desirable to produce a large number of potential solutions. Completely exploring a problem's solution space is an unreasonable expectation for an unaided designer or design team. Computational tools have emerged to help designers more fully explore possible solutions. These automated concept generators use knowledge from existing designs and the desired functionality of the new product to suggest solutions. Existing automated concept generation methods produce many candidate solutions, but often provide unmanageably large sets of solutions. Techniques are needed to organize the set of concepts into smaller groups, more easily parsed by the human …

A Natural Language To Component Term Methodology: Towards A Form Based Concept Generation Tool, Matt Robert Bohm, Robert B. Stone

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Over the last few decades design researchers have put forward theories and proposed methodologies that increase the chance that a design team will reliably arrive at the optimal solution to a given design problem. Studies, however, bear out that theories and methodologies alone will not guarantee an optimal or even good design solution. Instead, a breadth of knowledge across multiple engineering domains and the time and tools to thoroughly evaluate the design space are as important as any prescriptive design method. This work presents one of the underlying engineering technologies needed to leverage artificial intelligence approaches to thoroughly search the …

Measurement Of Refractive Index Change Of Optical Fiber Core Induced By Femtosecond Laser Scanning, Y. Han, T. Wei, Hai-Lung Tsai, Hai Xiao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We report a new method to measure the refractive index change in optical fiber core induced by femtosecond (fs) laser exposure. An in-line Fabry-Perot interferometer, serving as the measurement platform, is constructed on a commercial single-mode optical fiber by onestep femtosecond (fs) laser fabrication. A positive refractive index change is observed and measured accurately as the laser pulse energy surpasses the ablation threshold.

Observations Of Temporal Group Delays In Slow-Light Multiple Coupled Photonic Crystal Cavities, S. Kocaman, Xiaodong Yang, J. F. Mcmillan, M. B. Yu, D. L. Kwong, C. W. Wong

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We demonstrate temporal group delays in coherently coupled high- Q multicavity photonic crystals, in an all-optical analog to electromagnetically induced transparency. We report deterministic control of the group delay up to 4x the single cavity lifetime in our room-temperature chip. Supported by three-dimensional numerical simulations and theoretical analyses, our multipump beam approach enables control of the multicavity resonances and intercavity phase, in both single and double transparency peaks. The standing-wave wavelength-scale photon localization allows direct scalability for chip-scale optical pulse trapping and coupled-cavity quantum electrodynamics.

Residential Energy Performance Metrics, Christopher Wright, Stuart Werner Baur, Katie Grantham, Robert B. Stone, Scott Erwin Grasman

Engineering Management and Systems Engineering Faculty Research & Creative Works

Techniques for residential energy monitoring are an emerging field that is currently drawing significant attention. This paper is a description of the current efforts to monitor and compare the performance of three solar powered homes built at Missouri University of Science and Technology. The homes are outfitted with an array of sensors and a data logger system to measure and record electricity production, system energy use, internal home temperature and humidity, hot water production, and exterior ambient conditions the houses are experiencing. Data is being collected to measure the performance of the houses, compare to energy modeling programs, design and …

Hydrogen Fuel Cell Analysis: Lessons Learned From Stationary Power Generation Final Report, Scott E. Grasman, John W. Sheffield, Fatih Dogan, Sunggyu Lee, Umit O. Koylu, Angie Rolufs

Materials Science and Engineering Faculty Research & Creative Works

This study considered opportunities for hydrogen in stationary applications in order to make recommendations related to RD&D strategies that incorporate lessons learned and best practices from relevant national and international stationary power efforts, as well as cost and environmental modeling of pathways. The study analyzed the different strategies utilized in power generation systems and identified the different challenges and opportunities for producing and using hydrogen as an energy carrier. Specific objectives included both a synopsis/critical analysis of lessons learned from previous stationary power programs and recommendations for a strategy for hydrogen infrastructure deployment. This strategy incorporates all hydrogen pathways and …

Computer Program And Method For Detecting And Predicting Valve Failure In A Reciprocating Compressor, Ming-Chuan Leu, Jagannathan Sarangapani, Raghuram Puthall Ramesh

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Embodiments of the present invention provide a method implemented by a computer program for detecting and identifying valve failure in a reciprocating compressor and further for predicting valve failure in the compressor. Embodiments of the present invention detect and predict the valve failure using wavelet analysis, logistic regression, and neural networks. A pressure signal from the valve of the reciprocating compressor presents a non-stationary waveform from which features can be extracted using wavelet packet decomposition. The extracted features, along with temperature data for the valve, are used to train a logistic regression model to classify defective and normal operation of …

Functionally Graded Materials By Laser Metal Deposition (Preprint), Syamala R. Pulugurtha, Joseph William Newkirk, Frank W. Liou, Hsin-Nan Chou

Materials Science and Engineering Faculty Research & Creative Works

Fabrication of functionally graded materials (FGMs) by laser metal deposition (LMD) has the potential to offer solutions to key engineering problems over the traditional metalworking techniques. But the issues that need to be addressed while building FGMs are intermixing in the layers and cracking due to the residual stresses. This paper is to present the study of the effect of process parameters (laser power and travel speed) on the degree of dilution between the substrate (or, previous layer) and powder material for few metallurgical systems.

Three-Dimensional Modeling Of Transport Phenomena And Their Effect On The Formation Of Ripples In Gas Metal Arc Welding, Z. H. Rao, J. Zhou, S. M. Liao, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Distinct, periodic arc-shaped ripples are observed on the surface of the weld bead in almost any welded components which have a significant effect on weld quality. This article presents the complex transport phenomena and their effect on the formation of ripples in three-dimensional moving gas metal arc welding. The transient distributions of the melt flow velocity and temperature in the weld pool, weld pool shape and dynamics, and solidified weld bead are calculated. It is found that the surface ripples are formed by the interplay between the up-and-down weld pool dynamics, caused mainly by the periodic droplet impingements, and the …

Combined H∞-Feedback Control And Iterative Learning Control Design With Application To Nanopositioning Systems, Brian E. Helfrich, Chibum Lee, Douglas A. Bristow, Jingyan Dong, Srinivasa M. Salapaka, Placid M. Ferreira, X. H. Xiao, Andrew G. Alleyne

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper examines a coordinated feedback and feedforward control design strategy for precision motion control (PMC) systems. It is assumed that the primary exogenous signals are repeated; including disturbances and references. Therefore, an iterative learning control (ILC) feedforward strategy can be used. The introduction of additional non-repeating exogenous signals, including disturbances, noise, and reset errors, necessitates the proper coordination between feedback and feedforward controllers to achieve high performance. A novel ratio of repeated versus non-repeated signal power in the frequency domain is introduced and defined as the repetitive-to-non-repetitive (RNR) ratio. This frequency specific ratio allows for a new approach to …

Effects Of Shielding Gas Compositions On Arc Plasma And Metal Transfer In Gas Metal Arc Welding, Z. H. Rao, S. M. Liao, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This article presents the effects of shielding gas compositions on the transient transport phenomena, including the distributions of temperature, flow velocity, current density, and electromagnetic force in the arc and the metal, and arc pressure in gas metal arc welding of mild steel at a constant current input. The shielding gas considered includes pure argon, 75% Ar, 50% Ar, and 25% Ar with the balance of helium. It is found that the shielding gas composition has significant influences on the arc characteristics; droplet formation, detachment, transfer, and impingement onto the workpiece; and weld pool dynamics and weld bead profile. As …

Measurement Sensitivity In Tapping-Mode Atomic Force Microscopy Using A Bi-Harmonic Drive Signal, Santosh R. Kodandarama, Douglas A. Bristow

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In tapping mode atomic force microscopy, surface features are measured indirectly via the amplitude of the tapping cantilever. a change in surface profile is detectable only if it results in an amplitude change that is significant enough to be measured by the optics. Previous works have focused on improving sensitivity through the system's Q-factor, either by changing physical cantilever properties or using feedback control, but those approaches undesirably slow down the dynamic response. in this work we take a novel approach to sensitivity amplification by reshaping the tapping trajectory. by shaping the trajectory so that the probe spends a greater …

Guidance And Control For Chase Uav Via Sliding Mode Approach, Takeshi Yamasaki, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This study focuses on integrated guidance and control for a chasing UAV against a maneuvering target. a sliding mode approach is selected to develop the integrated guidance and control using a full model of nonlinear, rigid body, 6 Degree-Of-Freedom equations of motion including nonlinear aerodynamics for the target-following capability and maneuverability enhancement against uncertain target maneuvers. Intermediate control variables for the integrated guidance and control system are carefully selected and approximated time derivatives of a sliding surface are applied such that a sliding surface structure is simple and sufficient to propagate the actuator input to the sliding surface in order …

Direct Detection Of No Produced By High-Temperature Surface-Catalyzed Atom Recombination, Dušan A. Pejaković, Jochen Marschall, Lian Duan, Maria P. Martin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The surface-catalytic recombination of oxygen and nitrogen atoms to form nitric oxide was confirmed by the direct detection of product NO molecules, using single-photon laser-induced fluorescence spectroscopy. Experiments were performed from room temperature to 1200 K in a quartz diffusion-tube sidearm reactor enclosed in a high temperature tube furnace. Atomic nitrogen was generated using a microwave discharge, and atomic oxygen was produced via the rapid gas-phase titration reaction N + NO → O + N2. The use of isotopically labeled titration gases 15N16O and 15N18O allowed for the unambiguous identification of nitric oxide produced by the O + N surface …

Direct Numerical Simulation Of Hypersonic Turbulent Boundary Layers With Varying Freestream Mach Number, L. (Lian) Duan, I. Beekman, M. P. Mart́In

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, the effects of freestream Mach number on the statistics and large-scale structures in compressible turbulent boundary layers are investigated using direct numerical simulations (DNS). DNS of turbulent boundary layers with nominal freestream Mach number ranging from 3 to 8 are performed. The validity of Morkovin's scaling, strong Reynolds analogy, and Walz's equation are assessed. We find that many of the scaling relations used to express compressible boundary layer statistics in terms of incompressible boundary layers still hold for the range of freestream Mach number considered. Compressibility effects are enhanced with increasing freestream Mach number but remain insignificant, …

Solid Oxide Fuel Cell Electrode Characterization And Improvement For Fuel Flexibility And Supplemental Power Production, Isaiah D. Kellogg

Doctoral Dissertations

"Solid oxide fuel cells (SOFC) were fabricated and the electrodes tested for their individual catalytic effectiveness in various fuels by exposing each electrode to mixed gas while the opposite electrode was exposed to its respective pure gas. Mixed hydrogen and oxygen gas was successfully utilized as fuel in a single chamber SOFC (SC-SOFC). The conditions at which the porous nickel-yttria-stabilized zirconia (Ni-YSZ) cermet anode performed well did not significantly overlap the conditions at which the La₀.₈Sr₀.₂Fe₀.₈Co₀.₂ oxide (LSCF) cathode performed well, but there was significant catalytic activity at both electrodes which increased the open circuit voltage (OCV) beyond that predicted …

Maskless Additive Manufacturing Of Micro Structures By Laser Sintering Of Nanoparticles, Vivekram Ramanathan

Masters Theses

"The focus of this study was to investigate an alternate microfabrication process of sintering nanoparticles using a patterned laser light to generate two dimensional (2D) and three dimensional (3D) geometries. With trends of producing electronic and medical devices using cheaper and faster technologies, a new procedure was developed to deposit and bond miniature patterns of silver nanoparticles onto silicon substrates.

The process consists of spraying silver nanoparticles onto the substrate while a patterned or modulated laser beam is focused onto the sprayed nanoparticles. These nanoparticles exposed under the modulated laser light undergo partial melting or sintering and adhere to the …

Decentralized Coordinated Ilc System Design And Transient Growth Control Using Iteration-Varying Filter, Qing Liu

Masters Theses

"In automation control area, with the increasing demand in task complexity and high control precision, coordination between systems is required. There are mainly two types of coordinated systems, decentralized and centralized. This thesis is focused on a large array of coordinated systems, and the decentralized structure is preferred. To achieve high control precision in a coordinated system, many existing approaches may work, and in the system performing the repeating process, Iterative Learning Control (ILC) is a useful approach. Therefore, in this thesis, a decentralized coordinated ILC system is proposed and analyzed. The proposed control system is especially useful in coordinating …

Integration And Characterization Of An Electrical Storage System For A Hydrogen Fuel Cell Plug-In Hybrid Electric Vehicle, Edward Alexei Anculle Arauco

Masters Theses

"Hydrogen fuel cell hybrid vehicles are an advance technology that promises to solve the energy crisis in transportation and green houses emissions. Even more, Plug-in or extended range vehicles can add diversity in energy sources. Extended range vehicles have the capability to extract energy from the grid and hence reduce the cost of operation of the vehicle. EcoCAR: the NeXt Challenge is a Noth [sic] American competition with seventeen schools participating across North America. Missouri S&T is developing a Fuel Cell Plug-in Hybrid electric vehicle which has a large lithium-ion battery able to store 16 kWh. The fuel cell powertrain …

Validation Of Driving Simulator And Driver Perception Of Vehicle Mounted Attenuator Markings In Work Zones, Durga Raj Mathur

Masters Theses

"This research work sought to validate the driving simulator at Missouri University of Science and Technology and to evaluate the vehicle mounted attenuator (VMA) markings for various times of day. For comprehensive validation of the driving simulator, a framework is proposed which is demonstrated using a fixed-base driving simulator. Objective and subjective evaluations were conducted, and validation of the driving simulator was performed at specific locations and along the highway. Field data were collected for a partial lane closure using a global positioning system (GPS) along the work zone and supplemented with video recordings of traffic data at specific locations …

Synthesis And Characterization Of Microspheres For Controlled Release, Gurpartap Singh Sandhu

Masters Theses

"Synthetic hydroxyapatite (HAp, (Ca₁₀(PO₄)₆(OH)₂) has always been of interest in medical applications because of its similarities to inorganic bone matrix. It has been used in biomedical applications for bone repair and substitution due to its biocompatibility. However, there are some differences in the stoichiometry, composition, and mechanical properties of human bone as compared to pure HAP. HAp particles have been successfully used as drug delivery carriers which deliver the drug to the affected part of the body and the remaining apatite gets degraded by the physiological processes in the body. In the present work, emphasis was on developing mechanically stronger …

Quantification Of Product Color Preference In A Utility Function, Hannah L. Turner

Masters Theses

"Currently, many marketing and engineering tools exist to help a designer optimize quantitative attributes of a product, such as height, weight, volume, or cost. However, these methods cannot effectively take into consideration aesthetic attributes of a product, or any other attributes for which there is no understood functional relationship between the attribute's potential values and the consumer's preference. This research has begun the work of developing this necessary functional relationship for the aesthetic attribute of color and has created a methodology for further research. To do this, colors were represented by their red, green, and blue light components, and preference …