Mechanical Engineering Commons^™

Performance Analysis Of Cutting Graphite-Epoxy Composite Using A 90,000 Psi Abrasive Waterjet, Aiswarya Choppali

Masters Theses

"Graphite-epoxy composites are being widely used in many aerospace and structural applications because of their properties: which include lighter weight, higher strength to weight ratio and a greater flexibility in design. However, the inherent anisotropy of these composites makes it difficult to machine them using conventional methods. To overcome the major issues that develop with conventional machining such as fiber pull out, delamination, heat generation and high tooling costs, an effort is herein made to study abrasive waterjet machining of composites. An abrasive waterjet is used to cut 1" thick graphite epoxy composites based on baseline data obtained from the …

A Driving Simulator Study To Evaluate The Impact Of Portable Changeable Message Signs (Pcms) On Driver Speed Characteristics, Bharath Kolar Venkat

Masters Theses

"This research project examined the effects of sequential Portable Changeable Message Signs (PCMS) on driver behavior in work zones. PCMS are temporary traffic control (TTC) devices, part of Intelligent Transportation Systems, which supplement static signs to provide advance warning and real-time information to drivers. Text and number based messages are displayed on the PCMS for which detailed evaluation has not been carried out before. This research fills this gap using a driving simulator (DS) supplemented by objective and subjective surveys. A work zone on I-44 in rural Missouri was replicated in the DS using video recordings and GIS (Geographical Information …

Performance Evaluation Of Coaxial Horizontal Axis Hydrokinetic Turbines System, Abdulaziz M. Abutunis

Masters Theses

"Hydrokinetic energy technologies are emerging as a viable solution for renewable power generation. Unlike conventional hydropower turbines, hydrokinetic turbines are environmentally friendly; they operate at zero-head, and do not need dams to preserve the water. Unfortunately, they have a low efficiency which makes their design a challenging task. This work was focused on the hydrodynamic performance of horizontal axis hydrokinetic turbines (HAHkTs) under different turbine arrangements and flow conditions.

It was undertaken in an effort to improve the efficiency of small HAHkTs that harness a river's kinetic energy. Four sets of experiments were performed in a water tunnel to investigate …

Numerical Analysis Of Thermal Stress And Deformation In Multi-Layer Laser Metal Deposition Process, Heng Liu

Masters Theses

"Direct metal deposition (DMD) has gained increasing attention in the area of rapid manufacturing and repair. It has demonstrated the ability to produce fully dense metal parts with complex internal structures that could not be achieved by traditional manufacturing methods. However, this process involves extremely high thermal gradients and heating and cooling rates, resulting in residual stresses and distortion, which may greatly affect the product integrity. The purpose of this thesis is to study the features of thermal stress and deformation involved in the DMD process. Utilizing commercial finite element analysis (FEA) software ABAQUS, a 3-D, sequentially coupled, thermo-mechanical model …

Approximate Dynamic Programming, Local Or Global Optimal Solution?, Ali Heydari, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The problem of global optimality analysis of approximate dynamic programming-based solutions is investigated in this study. Sufficient conditions for global optimality are obtained without requiring the state penalizing terms in the cost function or the functions representing the dynamics to be convex functions. Afterwards, the theoretical results are confirmed through a qualitative analysis of an example problem. © 2014 American Automatic Control Council.

Optimal Switching Of Nonlinear Systems With Free Mode Sequence, Ali Heydari, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Approximate dynamic programming is utilized in this study to develop solutions for optimal switching problems. The order of the active subsystems and the number of switches are free, and an online solution is developed that produces optimal performance. Motivated by the development in the adaptive critic's literature, the proposed method uses a critic and as many actors as the number of subsystems in order to conduct optimal scheduling in real-time based on the instantaneous states of the system. It is observed that once the neural networks are trained offline based on the proposed algorithm, they provide solutions for a range …

Comparison Of Magnetic Probe Calibration At Nano And Millitesla Magnitudes, Ryan A. Pahl, Joshua L. Rovey, David Pommerenke

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Magnetic field probes are invaluable diagnostics for pulsed inductive plasma devices where field magnitudes on the order of tenths of tesla or larger are common. Typical methods of providing a broadband calibration of Ḃ probes involve either a Helmholtz coil driven by a function generator or a network analyzer. Both calibration methods typically produce field magnitudes of tens of microtesla or less, at least three and as many as six orders of magnitude lower than their intended use. This calibration factor is then assumed constant regardless of magnetic field magnitude and the effects of experimental setup are ignored. This work …

Parametric Studies Of The Thermal And Momentum Accommodation Of Monoatomic And Diatomic Gases On Solid Surfaces, Zhi Liang, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Thermal Accommodation Coefficient (TAC) and the Momentum Accommodation Coefficient (MAC) Are the Two Fundamental Parameters Quantifying the Solid-Gas Energy and Momentum Exchange Efficiencies. We Use Molecular Dynamics (MD) Simulations to Study the Effect of Individual Interfacial Parameters Including, (I) Solid-Gas Interaction Strength, (Ii) Gas-Solid Atomic Mass Ratio, (Iii) Solid Elastic Stiffness, and (Iv) Temperature, on TAC and MAC at Solid Surfaces in Contact with Monoatomic and Diatomic Gases. in Addition to Offering a Fundamental Understanding on How These Individual Parameters Affect the Nature of Gas-Solid Collisions, We Provide an Extensive Database for the TAC and MAC. We Also Study …

Probabilistic Engineering Analysis And Design Under Time-Dependent Uncertainty, Zhen Hu

Doctoral Dissertations

"Time-dependent uncertainties, such as time-variant stochastic loadings and random deterioration of material properties, are inherent in engineering applications. Not considering these uncertainties in the design process may result in catastrophic failures after the designed products are put into operation. Although significant progress has been made in probabilistic engineering design, quantifying and mitigating the effects of time-dependent uncertainty is still challenging. This dissertation aims to help build high reliability into products under time-dependent uncertainty by addressing two research issues. The first one is to efficiently and accurately predict the time-dependent reliability while the second one is to effectively design the time-dependent …

Modeling And Simulation Of Continuous Fiber-Reinforced Ceramic Composites, Venkata Bheemreddy

Doctoral Dissertations

"Finite element modeling framework based on cohesive damage modeling, constitutive material behavior using user-material subroutines, and extended finite element method (XFEM), are developed for studying the failure behavior of continuous fiber-reinforced ceramic matrix composites (CFCCs) by the example of a silicon carbide matrix reinforced with silicon carbide fiber (SiC/SiCf) composite. This work deals with developing comprehensive numerical models for three problems: (1) fiber/matrix interface debonding and fiber pull-out, (2) mechanical behavior of a CFCC using a representative volume element (RVE) approach, and (3) microstructure image-based modeling of a CFCC using object oriented finite element analysis (OOF). Load versus displacement behavior …

Modeling And Simulation Of Hydrokinetic Composite Turbine System, Haifeng Li

Doctoral Dissertations

"The utilization of kinetic energy from the river is promising as an attractive alternative to other available renewable energy resources. Hydrokinetic turbine systems are advantageous over traditional dam based hydropower systems due to "zero-head" and mobility. The objective of this study is to design and analyze hydrokinetic composite turbine system in operation. Fatigue study and structural optimization of composite turbine blades were conducted. System level performance of the composite hydrokinetic turbine was evaluated. A fully-coupled blade element momentum-finite element method algorithm has been developed to compute the stress response of the turbine blade subjected to hydrodynamic and buoyancy loadings during …

Performance Evaluation Of Polyurethane Composites Using Vacuum Infusion Process, Mohaned M. Mohamed

Doctoral Dissertations

"Glass fiber-reinforced polymer composites have promising applications in infrastructures due to their low cost, high specific stiffness/strength, and corrosion resistance. The pultrusion process is often used to manufacture glass fiber-reinforced polyurethane (PU) composite. The objective of this study is to use thermoset PU resin to manufacture high quality composites for infrastructure applications using vacuum assisted resin transfer molding (VARTM) process. Using VARTM to fabricate PU resins presents unique challenges. Several modifications however have helped with overcoming these problems. In part I of the research, the mechanical performance of two different PU resin not only evaluated but also compared to one …

Numerical Modeling Of Infrared Thermography Techniques Via Ansys, Hayder Abdulnabi Thajeel

Masters Theses

"Several inspection techniques have been developed over years. Recently, infrared thermography (IRT) technology has become a widely accepted as a nondestructive inspection (NDI) technique for different fields and various applications as well. Infrared thermography stands as one of the most an attractive and a successful NDI technique that has ability to detect the object's surface/subsurface defects remotely based on observing and measuring the surface's emitted infrared heat radiation by using an infrared camera. The finite element modeling FEM ANSYS was successfully used for the modelling of several IRT techniques; such as Pulsed Thermography (PT) and Lock-in Thermography (LT) that can …

Waveguiding Of Surface Phonon Polariton, Franklin Manene, Brian A. Lail, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Metal losses lead to unacceptably low propagation lengths in THz and LWIR waveguides. While SPP based waveguides provide relatively good confinement and attenuation in the near-IR and visible these are insufficiently bound to the surface in the THz and LWIR. We study using surface phonon polaritons for waveguiding at these frequencies. An eigenmode approach was applied to model a hybrid waveguide structure at λ=10.6 μm. The results show that phonon-coupled hybrid waveguide of silicon carbide BCB and gold exhibit enhanced propagation length and confinement at LWIR. © 2013 IEEE.

Liquid Phase Stability Under An Extreme Temperature Gradient, Zhi Liang, Kiran Sasikumar, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Using Nonequilibrium Molecular Dynamics Simulations, We Subject Bulk Liquid to a Very High-Temperature Gradient and Observe a Stable Liquid Phase with a Local Temperature Well above the Boiling Point. Also, under This High-Temperature Gradient, the Vapor Phase Exhibits Condensation into a Liquid at a Temperature Higher Than the Saturation Temperature, Indicating that the Observed Liquid Stability is Not Caused by Nucleation Barrier Kinetics. We Show that, Assuming Local Thermal Equilibrium, the Phase Change Can Be Understood from the Thermodynamic Analysis. the Observed Elevation of the Boiling Point is Associated with the Interplay between the "Bulk" Driving Force for the Phase …

Development Of An Experimental Testbed For Research In Lithium-Ion Battery Management Systems, Nima Lotfi, Poria Fajri, Samuel Novosad, Jack Savage, Robert G. Landers, Mehdi Ferdowsi

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Advanced electrochemical batteries are becoming an integral part of a wide range of applications from household and commercial to smart grid, transportation, and aerospace applications. Among different battery technologies, lithium-ion (Li-ion) batteries are growing more and more popular due to their high energy density, high galvanic potential, low self-discharge, low weight, and the fact that they have almost no memory effect. However, one of the main obstacles facing the widespread commercialization of Li-ion batteries is the design of reliable battery management systems (BMSs). An efficient BMS ensures electrical safety during operation, while increasing battery lifetime, capacity and thermal stability. Despite …

Computational Modeling And Experimental Study On Optical Microresonators Using Optimal Spherical Structure For Chemical Sensing, Hanzheng Wang, Lei Yuan, Jie Huang, Xinwei Lan, Cheol-Woon Kim, Lan Jiang, Hai Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

Chemical sensors based on optical microresonators have been demonstrated highly sensitive by monitoring the refractive index (RI) changes in the surrounding area near the resonator surface. In an optical resonator, the Whispering Gallery Modes (WGMs) with high quality (Q) factor supported by the spherical symmetric structure interacts with the contiguous background through evanescent field. Highly sensitive detection can be realized because of the long lifetime of the photons. The computational models of solid glass microspheres and hollow glass spheres with porous wall (PW-HGM) were established. These two types of microresonators were studied through simulations. The PWHGM resonator was proved as …

Multi-Axis Planning Of A Hybrid Material Deposition And Removal Combined Process, J. Zhang, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Study Of A Molten Carbonate Fuel Cell Combined Heat, Hydrogen And Power System: End-Use Application, Tarek A. Hamad, Abdulhakim Amer A. Agll, Yousif M. Hamad, Sushrut Bapat, Mathew Thomas, Kevin B. Martin, John W. Sheffield

Engineering Management and Systems Engineering Faculty Research & Creative Works

To address the problem of fossil fuel usage and high greenhouse gas emissions at the Missouri University of Science and Technology campus, using of alternative fuels and renewable energy sources can lower energy consumption and greenhouse gas emissions. Biogas, produced by anaerobic digestion of wastewater, organic waste, agricultural waste, industrial waste, and animal by-products is a potential source of renewable energy. In this work, we have discussed the design of CHHP system for the campus using local resources. An energy flow and resource availability study is performed to identify the type and source of feedstock required to continuously run the …

Vision-Based Process Monitoring For Laser Metal Deposition Processes, Sreekar Karnati, Niroop Matta, Todd E. Sparks, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laser Metal deposition is a process with immense scope and promise for becoming a robust manufacturing technology in the near future. Monitoring process variables is very instrumental in process planning and output monitoring. The current work deals with realizing the effect of power modulation on size of the high temperature region during deposition with varying powder feed. A thermal camera was used to visualize and analyze the deposition process. The area of the high temperature region through the deposition was identified and compared to realize the effect of each variable parameter during deposition. The power modulation was fruitful in modulating …

Effect Of Architecture And Porosity On Mechanical Properties Of Borate Glass Scaffolds Made By Selective Laser Sintering, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas, Taylor Comte

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The porosity and architecture of bone scaffolds, intended for use in bone repair or replacement, are two of the most important parameters in the field of bone tissue engineering. The two parameters not only affect the mechanical properties of the scaffolds but also aid in determining the amount of bone regeneration after implantation. Scaffolds with five different architectures and four porosity levels were fabricated using borate bioactive glass (13-93B3) using the selective laser sintering (SLS) process. The pore size of the scaffolds varied from 400 to 1300 μm. The compressive strength of the scaffolds varied from 1.7 to 15.5 MPa …

Additive Manufacturing Laser Deposition Of Ti‐6al‐4v For Aerospace Repair Applications, Nanda Kumar Dey, Frank W. Liou, C. Nedic

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Parts or products from high performance metal are very expensive, partly due to the processing complexities during manufacturing. The purpose of this project is to use additive laser deposition and machining processes to repair titanium parts, thus extending the service life of these parts. The study broadly included preparing the defects, laser deposition, machining, sample preparation and mechanical tests. Comparative study of mechanical properties (UTS, YS, percentage elongation) of the repaired samples to the ideal conditions was undertaken. The research throws up interesting facts where the data from the test sample shows enhancement of properties of the repaired part.

Development Of Freeze-Form Extrusion Fabrication With Use Of Sacrificial Material, Ming-Chuan Leu, Diego A. Garcia

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The development of Freeze-form Extrusion Fabrication (FEF) process to fabricate three-dimensional (3D) ceramic parts with use of sacrificial material to build support sections during the fabrication process is presented in this paper. FEF is an environmentally friendly, additive manufacturing process that builds 3D parts in a freezing environment layer-by-layer by computer controlled extrusion and deposition of aqueous colloidal pastes based on computer-aided design (CAD) models. Methyl cellulose was identified as the support material, and alumina was used as the main material in this study. After characterizing the dynamics of extruding alumina and methyl cellulose pastes, a general tracking controller was …

Experimental Investigation Of Different Cellular Lattice Structures Manufactured By Fused Deposition Modeling, Osman Iyibilgin, Cemil Yigit, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Experimental tests were conducted to evaluate the compressive properties (yield strength and compressive modulus) and build time for five different cellular lattice structures fabricated by the Fused Deposition Modeling (FDM) process. The lattice structures had repeating unit cells, and the shapes of the unit cell under study included honeycomb, square, diamond, triangle, and circle. Test specimens were manufactured by a Stratasys Fortus 400mc machine using ABS (Acrylonitrile Butadiene Styrene) as the part material. The five different lattice structures were compared with each other and also with the sparse and sparse-double dense build styles that are directly available from the Fortus …

Probabilistic Simulation Of Solidification Microstructure Evolution During Laser-Based Metal Deposition, Jingwei Zhang, Frank W. Liou, William Seufzer, Joseph William Newkirk, Zhiqiang Fan, Heng Liu, Todd E. Sparks

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A predictive model, based on a Cellular Automaton (CA) - Finite Element (FE) method, has been developed to simulate microstructure evolution during metal solidification for a laser based additive manufacturing process. The macroscopic FE calculation was designed to update the temperature field and simulate a high cooling rate. In the microscopic CA model, heterogeneous nucleation sites, preferential growth orientation and dendritic grain growth kinetics were simulated. The CA model was able to show the entrapment of neighboring cells and the relationship between undercooling and the grain growth rate. The model predicted the dendritic grain size, structure, and morphological evolution during …

Numerical Analysis Of Thermal Stress And Deformation In Multi-Layer Laser Metal Deposition Processes, Heng Liu, Todd E. Sparks, Frank W. Liou, David M. Dietrich

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct metal deposition (DMD) has gained increasing attention in the area of rapid manucooling rate, resulting in residual stresses and distortion. This paper presents a 3D sequentially coupled thermo-mechanical finite element model to predict residual stresses and deformations. The temperature distribution, thermal stress field and geometry deformation across domain are illustrated. The effect of deposition parameters on residual stress and deflections are also explored. A set of validation experiments for mechanical effects were conducted using laser displacement sensor. The comparisons between the simulated and experimental results show good agreement

Hybrid System For Enhancing Algal Growth Using Vertical Membranes, David J. Bayless, Ben J. Stuart

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A method for enhancing gas-to-liquid transfer rate and algal growth using vertical membranes suspended over a pond, wherein the membranes are formed of fibers. An aqueous solution is applied to the top edges of the membranes through a series of headers. The membranes are exposed to a stream of gas containing soluble gas species as the aqueous solution migrates downwardly through the membranes by virtue of gravity-assisted capillary action. The aqueous solution collects the soluble gases from the gas stream, thus promoting the growth of photosynthetic organisms on the membranes and in the pond. The membranes facilitate a gradual introduction …

Near- And Far-Field Spectroscopic Imaging Investigation Of Resonant Square-Loop Infrared Metasurfaces, J. D'Achangel, E. Tucker, Edward C. Kinzel, E. A. Muller, H. A. Bechtel, M. B. Martin, G. Boreman

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Apparatus And Method For Growing Biological Organisms For Fuel And Other Purposes, David J. Bayless, Morgan Lefay Vis-Chiasson, Ben J. Stuart, Gregory G. Kremer

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A bioreactor apparatus in which a container has sidewalls, a floor and a ceiling defining a chamber that contains a slurry of water, nutrients and photosynthetic microorganisms. A plurality of optical fibers, each of which has a first end disposed outside the chamber and a second end in the mixture. A light collector spaced from the container has light incident on it and focuses the light onto the first ends of the plurality of optical fibers, thereby permitting the light to be conveyed into the mixture to promote photosynthesis. At least one nozzle is in fluid communication with a source …

Structural Health Monitoring Data Transmission For Composite Hydrokinetic Turbine Blades, A. Heckman, Joshua L. Rovey, K. Chandrashekhara, Steve Eugene Watkins, Daniel S. Stutts, Arindam Banerjee, Rajiv S. Mishra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.