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Articles 1 - 24 of 24
Full-Text Articles in Engineering
Prediction Of Thermal Conductance At Liquid-Gas Interfaces Using Molecular Dynamics Simulations, James Gonzalez, Josue Ortega, Zhi Liang
Prediction Of Thermal Conductance At Liquid-Gas Interfaces Using Molecular Dynamics Simulations, James Gonzalez, Josue Ortega, Zhi Liang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Using Molecular Dynamics (MD) Simulations and Theoretical Calculations, We Study Heat Transfer Across Liquid-Gas Interfaces within a Planar Heat Pipe. to Determine the Thermal Conductance (Kapitza Conductance), GK, at the Interface, Two Heat Transfer Mechanisms, Namely, Conduction and Evaporation/condensation Are Considered. in the Case of Interfacial Heat Conduction, Gas Molecules, Particularly Non-Condensable Gas Molecules, Exchange Heat with Liquid Surfaces through Gas-Liquid Collisions, and the Theoretical Expression for GK is Derived from the Kinetic Theory of Gases. for Interfacial Heat Transfer by Evaporation or Condensation, the Theoretical Expression for GK is Derived from the Schrage Relationships. to Assess the Accuracies of …
Multifidelity Modeling Of Ultrasonic Testing Simulations With Cokriging, Leifur Leifsson, Xiaosong Du, Slawomir Koziel
Multifidelity Modeling Of Ultrasonic Testing Simulations With Cokriging, Leifur Leifsson, Xiaosong Du, Slawomir Koziel
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Multifidelity methods are introduced to the nondestructive evaluation (NDE) of measurement systems. In particular, Cokriging interpolation metamodels of physics-based ultrasonic testing (UT) simulation responses are utilized to accelerate the uncertainty propagation in model-assisted NDE. The proposed approach is applied to a benchmark test case of UT simulations and compared with the current state-of-the-art techniques. The results show that Cokriging captures the physics of the problem well and is able to reduce the computational burden by over one order of magnitude compared to the state of the art. To the best of the author's knowledge, this the first time multifidelity methods …
Fast Uncertainty Propagation Of Ultrasonic Testing Simulations For Mapod And Sensitivity Analysis, Xiaosong Du, Leifur Leifsson, Praveen Gurrala, Jiming Song, Slawomir Koziel
Fast Uncertainty Propagation Of Ultrasonic Testing Simulations For Mapod And Sensitivity Analysis, Xiaosong Du, Leifur Leifsson, Praveen Gurrala, Jiming Song, Slawomir Koziel
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Model-assisted probability of detection (MAPOD) and sensitivity analysis (SA) are widelyused for measuring the reliability of nondestructive testing (NDT) systems., such as ultrasonictesting (UT), and understanding the effects of uncertainty parameters. In this work, a stochastic expansion-based metamodel is used in lieu of the physics-based NDT simulation model for efficient uncertainty propagation while keeping satisfactory accuracy. The proposed stochasticmetamodeling approach is demonstrated for MAPOD and SA on a benchmark case for UT simulations on a fused quartz block with a spherically-void defect. The proposed approach is compared with direct Monte Carlo sampling (MCS), and MCS with Kriging metamodels. The results …
Effects Of Nearwall Modeling In The Improved-Delayed-Detached-Eddy-Simulation (Iddes) Methodology, Rohit Saini, Nader Karimi, Lian Duan, Amsini Sadiki, Amirfarhang Mehdizadeh
Effects Of Nearwall Modeling In The Improved-Delayed-Detached-Eddy-Simulation (Iddes) Methodology, Rohit Saini, Nader Karimi, Lian Duan, Amsini Sadiki, Amirfarhang Mehdizadeh
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The present study aims to assess the effects of two different underlying RANS models on overall behavior of the IDDES methodology when applied to different flow configurations ranging from fully attached (plane channel flow) to separated flows (periodic hill flow). This includes investigating prediction accuracy of first and second order statistics, response to grid refinement, grey area dynamics and triggering mechanism. Further, several criteria have been investigated to assess reliability and quality of the methodology when operating in scale resolving mode. It turns out that irrespective of the near wall modeling strategy, the IDDES methodology does not satisfy all criteria …
Fast Prediction Of Thermal Distortion In Metal Powder Bed Fusion Additive Manufacturing: Part 2, A Quasi-Static Thermo-Mechanical Model, Hao Peng, Morteza Ghasri-Khouzani, Shan Gong, Ross Attardo, Pierre Ostiguy, Ronald B. Rogge, Bernice Aboud Gatrell, Joseph Budzinski, Charles Tomonto, Joel Neidig, M. Ravi Shankar, Richard Billo, David B. Go, David Hoelzle
Fast Prediction Of Thermal Distortion In Metal Powder Bed Fusion Additive Manufacturing: Part 2, A Quasi-Static Thermo-Mechanical Model, Hao Peng, Morteza Ghasri-Khouzani, Shan Gong, Ross Attardo, Pierre Ostiguy, Ronald B. Rogge, Bernice Aboud Gatrell, Joseph Budzinski, Charles Tomonto, Joel Neidig, M. Ravi Shankar, Richard Billo, David B. Go, David Hoelzle
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The additive manufacturing (AM) process metal powder bed fusion (PBF) can quickly produce complex parts with mechanical properties comparable to that of wrought materials. However, thermal stress accumulated during Metal PBF may induce part distortion and even cause failure of the entire process. This manuscript is the second part of two companion manuscripts that collectively present a part-scale simulation method for fast prediction of thermal distortion in Metal PBF. The first part provides a fast prediction of the temperature history in the part via a thermal circuit network (TCN) model. This second part uses the temperature history from the TCN …
Fast Prediction Of Thermal Distortion In Metal Powder Bed Fusion Additive Manufacturing: Part 1, A Thermal Circuit Network Model, Hao Peng, Morteza Ghasri-Khouzani, Shan Gong, Ross Attardo, Pierre Ostiguy, Bernice Aboud Gatrell, Joseph Budzinski, Charles Tomonto, Joel Neidig, M. Ravi Shankar, Richard Billo, David B. Go, David Hoelzle
Fast Prediction Of Thermal Distortion In Metal Powder Bed Fusion Additive Manufacturing: Part 1, A Thermal Circuit Network Model, Hao Peng, Morteza Ghasri-Khouzani, Shan Gong, Ross Attardo, Pierre Ostiguy, Bernice Aboud Gatrell, Joseph Budzinski, Charles Tomonto, Joel Neidig, M. Ravi Shankar, Richard Billo, David B. Go, David Hoelzle
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The additive manufacturing (AM) process metal powder bed fusion (PBF) can quickly produce complex parts with mechanical properties comparable to wrought materials. However, thermal stress accumulated during PBF induces part distortion, potentially yielding parts out of specification and frequently process failure. This manuscript is the first of two companion manuscripts that introduce a computationally efficient distortion and stress prediction algorithm that is designed to drastically reduce compute time when integrated in to a process design optimization routine. In this first manuscript, we introduce a thermal circuit network (TCN) model to estimate the part temperature history during PBF, a major computational …
Tutorial: Determination Of Thermal Boundary Resistance By Molecular Dynamics Simulations, Zhi Liang, Ming Hu
Tutorial: Determination Of Thermal Boundary Resistance By Molecular Dynamics Simulations, Zhi Liang, Ming Hu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Due to the High Surface-To-Volume Ratio of Nanostructured Components in Microelectronics and Other Advanced Devices, the Thermal Resistance at Material Interfaces Can Strongly Affect the overall Thermal Behavior in These Devices. Therefore, the Thermal Boundary Resistance, R, Must Be Taken into Account in the Thermal Analysis of Nanoscale Structures and Devices. This Article is a Tutorial on the Determination of R and the Analysis of Interfacial Thermal Transport Via Molecular Dynamics (MD) Simulations. in Addition to Reviewing the Commonly Used Equilibrium and Non-Equilibrium MD Models for the Determination of R, We Also Discuss Several MD Simulation Methods Which Can Be …
Model-Assisted Probability Of Detection Of Flaws In Aluminum Blocks Using Polynomial Chaos Expansions, Xiaosong Du, Leifur Leifsson, Robert Grandin, William Meeker, Ronald Roberts, Jiming Song
Model-Assisted Probability Of Detection Of Flaws In Aluminum Blocks Using Polynomial Chaos Expansions, Xiaosong Du, Leifur Leifsson, Robert Grandin, William Meeker, Ronald Roberts, Jiming Song
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Probability of detection (POD) is widely used for measuring reliability of nondestructive testing (NDT) systems. Typically, POD is determined experimentally, while it can be enhanced by utilizing physics-based computational models in combination with model-assisted POD (MAPOD) methods. With the development of advanced physics-based methods, such as ultrasonic NDT testing, the empirical information, needed for POD methods, can be reduced. However, performing accurate numerical simulations can be prohibitively time-consuming, especially as part of stochastic analysis. In this work, stochastic surrogate models for computational physics-based measurement simulations are developed for cost savings of MAPOD methods while simultaneously ensuring sufficient accuracy. The stochastic …
Direct Metal Laser-Sintered Stainless Steel: Comparison Of Microstructure And Hardness Between Different Planes, M. Ghasri-Khouzani, H. Peng, R. Attardo, P. Ostiguy, J. Neidig, R. Billo, D. Hoelzle, M. R. Shankar
Direct Metal Laser-Sintered Stainless Steel: Comparison Of Microstructure And Hardness Between Different Planes, M. Ghasri-Khouzani, H. Peng, R. Attardo, P. Ostiguy, J. Neidig, R. Billo, D. Hoelzle, M. R. Shankar
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Microstructural analysis and micro-hardness measurements were performed on different planes of 316L stainless steel fabricated by direct metal laser sintering (DMLS) technique. A fine cellular network was observed within the steel microstructure, where morphology of most cells changed from columnar on XZ-plane (vertical section) to equiaxed on XY-plane (horizontal section). Correspondingly, morphology of most grains was found to alter from columnar for the XZ-plane to equiaxed in the case of the XY-plane. Moreover, X-ray diffraction (XRD) analysis revealed a fully austenitic structure for both the planes. The average micro-hardness value for the XZ-plane and XY-plane was insignificantly (≈ 3%) different, …
Ultra-Broadband Infrared Absorption By Tapered Hyperbolic Multilayer Waveguides, Huixu Deng, Cherian J. Mathai, Shubhra Gangopadhyay, Jie Gao, Xiaodong Yang
Ultra-Broadband Infrared Absorption By Tapered Hyperbolic Multilayer Waveguides, Huixu Deng, Cherian J. Mathai, Shubhra Gangopadhyay, Jie Gao, Xiaodong Yang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Ultra-broadband strong absorption over 92% covering the infrared wavelength range of 1 ~ 6μm is demonstrated by using the tapered hyperbolic Au-SiO2 multilayer waveguides on glass substrates. Such broadband absorption is formed by the stop-light modes at various wavelengths located at different waveguide widths. A planar hyperbolic waveguide model is built to determine the stop-light modes by considering both forward and backward guided modes. The stop-light modes located inside the Au-SiO2 multilayer waveguide are simulated at the absorption peaks by reducing the Au loss. Tapered multilayer waveguides with varying top widths are further simulated, fabricated and measured, indicating …
Wavelength-Selective Mid-Infrared Metamaterial Absorbers With Multiple Tungsten Cross Resonators, Zhigang Li, Liliana Stan, David A. Czaplewski, Xiaodong Yang, Jie Gao
Wavelength-Selective Mid-Infrared Metamaterial Absorbers With Multiple Tungsten Cross Resonators, Zhigang Li, Liliana Stan, David A. Czaplewski, Xiaodong Yang, Jie Gao
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Wavelength-selective metamaterial absorbers in the mid-infrared range are demonstrated by using multiple tungsten cross resonators. By adjusting the geometrical parameters of cross resonators in single-sized unit cells, near-perfect absorption with single absorption peak tunable from 3.5 µm to 5.5 µm is realized. The combination of two, three, or four cross resonators of different sizes in one unit cell enables broadband near-perfect absorption at mid-infrared range. The obtained absorption spectra exhibit omnidirectionality and weak dependence on incident polarization. The underlying mechanism of near-perfect absorption with cross resonators is further explained by the optical mode analysis, dispersion relation and equivalent RLC circuit …
Molecular Simulation Of Steady-State Evaporation And Condensation In The Presence Of A Non-Condensable Gas, Zhi Liang, Pawel Keblinski
Molecular Simulation Of Steady-State Evaporation And Condensation In The Presence Of A Non-Condensable Gas, Zhi Liang, Pawel Keblinski
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Using Molecular Dynamics Simulations, We Study Evaporation and Condensation of Fluid Ar in the Presence of a Non-Condensable Ne Gas in a Nanochannel. the Evaporation and Condensation Are Driven by the Temperature Difference, ΔTL, between the Evaporating and Condensing Liquid Surfaces. the Steady-State Evaporation and Condensation Fluxes (JMD) Are Also Affected by the Ne Concentration, ΡNe, and the Nanochannel Length. We Find that Across a Wide Range of ΔTL and ΡNe, JMD is in Good Agreement with the Prediction from Stefan's Law and from Schrage Relationships. Furthermore, for ΔTL Less Than ∼20% of the Absolute Average Temperature, We Find that …
Nano-Graphene Oxide And Vitamin D Delivery, Reza Mahdavi, Mehran Solati-Hashjin, Meisam Omidi, Arash Khojasteh, Fateme Fayyazbakhsh
Nano-Graphene Oxide And Vitamin D Delivery, Reza Mahdavi, Mehran Solati-Hashjin, Meisam Omidi, Arash Khojasteh, Fateme Fayyazbakhsh
Mechanical and Aerospace Engineering Faculty Research & Creative Works
One of the Most Interesting and Recent Insights into Biomimetic Scaffold Nano-Biomaterial is Smart Scaffolding with Targeted Drug Delivery Ability. in Recent Decades, the Use of Graphene-Based Materials, Such as Nano-Graphene Oxide (NGO), as a Drug Carrier with Amphiphilic Properties, Has Attracted Considerable Attention of Scientists and Researchers in This Field. in Addition, One of the Important Global Problems is Increased Vitamin D Deficiency, Particularly in Pregnant and Postmenopausal Women. Therefore, in This Work, by Considering Hydrophobic Properties of Vitamin D, We Attempted to Examine its Loading and Release Both in the Presence of Surfactant and Surfactant-Free NGO-Aqueous Solution. at …
Thermal Analysis And Control Of Small Satellites In Low Earth Orbit, Katelyn Elizabeth Boushon
Thermal Analysis And Control Of Small Satellites In Low Earth Orbit, Katelyn Elizabeth Boushon
Masters Theses
"Small satellites are becoming more popular in the space sector, primarily due to their lower cost and shorter development time. Much of the information available about satellite thermal analysis and control refers to larger spacecraft. Sorting through this information to find the practices specifically applicable for small satellites can be a daunting task, particularly for inexperienced engineers. This thesis study is intended to inform the reader about basic thermal control and analysis methods that relate specifically to small satellites in low Earth orbit. A case study involving a satellite designed by the Missouri University of Science and Technology Satellite Research …
Investigation Of Additively Manufactured Polymer And Transparent Polymer Composites, Gregory Taylor
Investigation Of Additively Manufactured Polymer And Transparent Polymer Composites, Gregory Taylor
Doctoral Dissertations
"The objective of this study is an investigation of both the characterization of fused deposition modeling (FDM) of polymer thermoplastics and the manufacture of glass-reinforced transparent composites. The flexural behavior and fracture toughness of FDM parts are critical for the evaluation and optimization of both material and process. This study focuses on the performance of FDM Ultem 1010 specimens intended to be used as composite tooling due the material's high heat resistance. A three-point bend test is performed for flexure properties while a single edge notch bend test is performed for fracture toughness. For each of the tests, the build …
The Separation Of Shear-Driven Liquid Films From A Sharp Corner, Zahra Sadeghizadeh
The Separation Of Shear-Driven Liquid Films From A Sharp Corner, Zahra Sadeghizadeh
Doctoral Dissertations
"The separation of shear-driven liquid films occurs in many engineering applications such as port fuel injected engines, demisters, and gas transfer lines. Despite the importance of this problem, the details of the interaction between operating parameters such as liquid flow rate, gas velocities and liquid film properties on the forces at the expanding corner are still not clear. To enhance the insight on the complicated interaction between the gas and liquid phases, the shear-driven liquid flow around a corner has been studied both experimentally and analytically in this work. The effect of the complex liquid film structure on liquid mass …
Characterization Of Ionic Liquid Monopropellants For A Multi-Mode Propulsion System, Alex J. Mundahl
Characterization Of Ionic Liquid Monopropellants For A Multi-Mode Propulsion System, Alex J. Mundahl
Masters Theses
"Multi-mode micropropulsion is a potential game-changing technology enabling rapidly composable small satellites with unprecedented mission flexibility. Maximum mission flexibility requires one shared propellant between the chemical and electric systems. A deep eutectic 1:2 molar ratio mixture of choline-nitrate and glycerol ([Cho][NO3] - glycerol) is investigated as a fuel component in a binary mixture propellant for such a multi-mode micropropulsion. Specifically, binary mixtures of the novel ionic liquid fuel with hydroxyl-ammonium nitrate (HAN) and ammonium nitrate (AN) are considered and compared against the previously investigated propellant [Emim][EtSO4]-HAN. Chemical rocket performance simulations predict this new propellant to have …
Quantifying On-Orbit Performance Of Cubesat Micropropulsion Systems By Observing Orbital Element Variations, Bradyn William Morton
Quantifying On-Orbit Performance Of Cubesat Micropropulsion Systems By Observing Orbital Element Variations, Bradyn William Morton
Masters Theses
"The Advanced Propulsion Experiment mission in development by the Missouri University of Science and Technology's satellite research team (M-SAT) is a technology demonstration mission of a multi-mode propulsion system. The true test of any satellite propulsion system is the on-orbit performance. The purpose of this research is to develop methods for quantifying the on-orbit performance of the multi-mode propulsion system. This performance can be determined by observing the small variations in the orbital element parameters and using a differential corrector with the Gauss Variation of Parameter equations. Furthermore, this research could be used to determine and quantify a propulsion system's …
Developing Computational Models For Pulsed-Inductive Plasma Formation, Zachary Aaron Gill
Developing Computational Models For Pulsed-Inductive Plasma Formation, Zachary Aaron Gill
Masters Theses
"Pulsed-inductive discharges are a common method of producing a plasma. They provide a mechanism for quickly and efficiently generating a large volume of plasma for rapid use and are seen in applications including propulsion, fusion power, and high-power lasers. However, some common designs see a delayed response time due to the plasma forming when the magnitude of the magnetic field in the device is at a minimum. New designs are difficult to evaluate due to the amount of time needed to construct a new geometry and the high monetary cost of changing the power generation circuit. To more quickly evaluate …
Development Of A Cfd Model Of The Catalytic Combustion Of A Microtube Multi-Mode Propulsion System, Andrew Paul Taylor
Development Of A Cfd Model Of The Catalytic Combustion Of A Microtube Multi-Mode Propulsion System, Andrew Paul Taylor
Masters Theses
"This thesis presents the process and results of the development of a computational fluid dynamics (CFD) model in ANSYS Fluent 18.1 on the catalytic decomposition of a novel liquid monopropellant in a microtube in order to gain deeper insights than what is available through the experimental data. The CFD model was created using the Euler- Euler Multiphase model in conjunction with the Heterogeneous Reaction submodel. Such a choice of modeling setting was backed up by theory and benchmark computations on multiphase and compressible flow, shown in Section 3 and Appendix A. It was found that the previously determined one-step reaction …
Effects Of Terrain-Based Altimetry On Navigation Performance, Kenneth Michael Kratzer
Effects Of Terrain-Based Altimetry On Navigation Performance, Kenneth Michael Kratzer
Masters Theses
"Navigation filters used during an entry, descent, and landing scenario often receive measurements related to the terrain over which the vehicle is traversing. Models of the terrain can be presented in varying degrees of fidelity, providing increasingly realistic and accurate models of the surface. While it is ideal to provide the filter with the most realistic model possible, the performance is limited by the strict nature of the real time scenario. Therefore, it is of interest to determine what level of fidelity is necessary to achieve an accurate filtering solution. Determining how best to incorporate terrain-related data into navigation solutions …
Direct Numerical Simulation Of Pressure Fluctuations Induced By Supersonic Turbulent Boundary Layers, Chao Zhang
Direct Numerical Simulation Of Pressure Fluctuations Induced By Supersonic Turbulent Boundary Layers, Chao Zhang
Doctoral Dissertations
"Direct Numerical Simulations are used to generate a database of high-speed zero-pressure-gradient turbulent boundary layers developing spatially over a flat plate with nominal freestream Mach number ranging from 2:5 to 14 and wall-to-recovery temperature ranging from 0:18 to 1:0. The flow conditions of the DNS are representative of the operational conditions of the Purdue Mach 6 quiet tunnel, the Sandia Hypersonic Wind Tunnel at Mach 8, and the AEDC Hypervelocity Tunnel No. 9 at Mach 14. The DNS database is used to gauge the performance of compressibility transformations, including the classical Morkovin's scaling and strong Reynolds analogy as well as …
Efficient Inverse Design Of Transonic Airfoils Using Variable-Resolution Models And Manifold Mapping, Xiaosong Du, Leifur Leifsson, Slawomir Koziel
Efficient Inverse Design Of Transonic Airfoils Using Variable-Resolution Models And Manifold Mapping, Xiaosong Du, Leifur Leifsson, Slawomir Koziel
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper presents an efficient approach for simulation-based inverse design of airfoil shapes using variable-fidelity computational fluid dynamics models and manifold mapping (MM). Inverse design involves determining an airfoil shape fulfilling a given target performance characteristic. In particular, the pressure coefficient distribution is typically used in aerodynamic inverse design. Such a task can be challenging when using computationally expensive simulations. In the context of local optimization, the MM technique searches for a new design in the vicinity of the current design by constructing a fast multi-fidelity model, which is setup by the available evaluations of each of the high- and …
Multitarget Tracking And Terrain-Aided Navigation Using Square-Root Consider Filters, James Samuel Mccabe
Multitarget Tracking And Terrain-Aided Navigation Using Square-Root Consider Filters, James Samuel Mccabe
Doctoral Dissertations
"Filtering is a term used to describe methods that estimate the values of partially observed states, such as the position, velocity, and attitude of a vehicle, using current observations that are corrupted due to various sources, such as measurement noise, transmission dropouts, and spurious information. The study of filtering has been an active focus of research for decades, and the resulting filters have been the cornerstone of many of humankind's greatest technological achievements. However, these achievements are enabled principally by the use of specialized techniques that seek to, in some way, combat the negative impacts that processor roundoff and truncation …