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Mechanical Engineering Faculty Publications

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Full-Text Articles in Mechanical Engineering

Introduction To Data-Driven Systems For Plastics And Composites Manufacturing, Saeed Farahani, Srikanth Pilla, Yun Zhang, Fausto Tucci May 2023

Introduction To Data-Driven Systems For Plastics And Composites Manufacturing, Saeed Farahani, Srikanth Pilla, Yun Zhang, Fausto Tucci

Mechanical Engineering Faculty Publications

Applications of high-performance plastics and composites have widely been expanded to various industries due to their superior properties, such as high strength-to-weight ratio, chemical resistance, and thermal/electrical insulation. However, the numerous possible combinations of polymers and reinforcements/fillers, the variability of these materials, and their complex manufacturing processes pose challenges in terms of efficiently developing new plastics and composites, accurately modeling their properties, and effectively monitoring and controlling their manufacturing processes. Integrating data-driven techniques, such as machine learning, artificial intelligence, and big data analytics, is a promising pathway to overcome these challenges as it is demonstrated by the state-of-the-art research works …

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A Deep-Learning Framework For Spray Pattern Segmentation And Estimation In Agricultural Spraying Systems, Praneel Acharya, Travis Burgers, Kim-Doang Nguyen May 2023

A Deep-Learning Framework For Spray Pattern Segmentation And Estimation In Agricultural Spraying Systems, Praneel Acharya, Travis Burgers, Kim-Doang Nguyen

Mechanical Engineering Faculty Publications

This work focuses on leveraging deep learning for agricultural applications, especially for spray pattern segmentation and spray cone angle estimation. These two characteristics are important to understanding the sprayer system such as nozzles used in agriculture. The core of this work includes three deep-learning convolution-based models. These models are trained and their performances are compared. After the best model is selected based on its performance, it is used for spray region segmentation and spray cone angle estimation. The output from the selected model provides a binary image representing the spray region. This binary image is further processed using image processing …

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Hybrid Fes-Exoskeleton Control: Using Mpc To Distribute Actuation For Elbow And Wrist Movements, Nathan Dunkelberger, Jeffrey Berning, Eric M. Schearer, Marcia K. O'Malley Apr 2023

Hybrid Fes-Exoskeleton Control: Using Mpc To Distribute Actuation For Elbow And Wrist Movements, Nathan Dunkelberger, Jeffrey Berning, Eric M. Schearer, Marcia K. O'Malley

Mechanical Engineering Faculty Publications

Introduction: Individuals who have suffered a cervical spinal cord injury prioritize the recovery of upper limb function for completing activities of daily living. Hybrid FES-exoskeleton systems have the potential to assist this population by providing a portable, powered, and wearable device; however, realization of this combination of technologies has been challenging. In particular, it has been difficult to show generalizability across motions, and to define optimal distribution of actuation, given the complex nature of the combined dynamic system. Methods: In this paper, we present a hybrid controller using a model predictive control (MPC) formulation that combines the actuation of both …

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Coaxial Jets With Disparate Viscosity: Mixing And Laminarization Characteristics, Mustafa Usta, M. R. C. Ahmad, G. Pathikonda, I. Khan, P. Gillis, D. Ranjan, C. K. Aidun Jan 2023

Coaxial Jets With Disparate Viscosity: Mixing And Laminarization Characteristics, Mustafa Usta, M. R. C. Ahmad, G. Pathikonda, I. Khan, P. Gillis, D. Ranjan, C. K. Aidun

Mechanical Engineering Faculty Publications

Mixing of fluids in a coaxial jet is studied under four distinct viscosity ratios, m = 1, 10, 20 and 40, using highly resolved large-eddy simulations (LES), particle image velocimetry and planar laser-induced fluorescence. The accuracy of predictions is tested against data obtained by the simultaneous experimental measurements of velocity and concentration fields. For the highest and lowest viscosity ratios, standard RANS models with unclosed terms pertaining to viscosity variations are employed. We show that the standard Reynolds-averaged Navier-Stokes (RANS) approach with no explicit modelling for variable-viscosity terms is not applicable whereas dynamic LES models provide high-quality agreement with the …

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Data-Driven Dynamic Motion Planning For Practical Fes-Controlled Reaching Motions In Spinal Cord Injury, Derek N.N. Wolf, Antonie J. Van Den Bogert, Eric M. Schearer Jan 2023

Data-Driven Dynamic Motion Planning For Practical Fes-Controlled Reaching Motions In Spinal Cord Injury, Derek N.N. Wolf, Antonie J. Van Den Bogert, Eric M. Schearer

Mechanical Engineering Faculty Publications

Functional electrical stimulation (FES) is a promising technology for restoring reaching motions to individuals with upper-limb paralysis caused by a spinal cord injury (SCI). However, the limited muscle capabilities of an individual with SCI have made achieving FES-driven reaching difficult. We developed a novel trajectory optimization method that used experimentally measured muscle capability data to find feasible reaching trajectories. In a simulation based on a real-life individual with SCI, we compared our method to attempting to follow naive direct-to-target paths. We tested our trajectory planner with three control structures that are commonly used in applied FES: feedback, feedforward-feedback, and model …

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Ai-Enabled Droplet Detection And Tracking For Agricultural Spraying Systems, Praneel Acharya, Travis A. Burgers, Doang Nguyen Nov 2022

Ai-Enabled Droplet Detection And Tracking For Agricultural Spraying Systems, Praneel Acharya, Travis A. Burgers, Doang Nguyen

Mechanical Engineering Faculty Publications

his work leverages recent advancements in com- puter vision and deep learning to detect and track the motion of droplets captured by a camera. While classical computer vision techniques have been employed for detection and tracking, those approaches have limitations and are not trivially extended to droplets. We approach the problems of droplet detection and tracking through a data-driven framework, in which an annotated database of droplet images is built and object detection and tracking models are trained on this database. The accuracy of the model is evaluated and the whole process is discussed. At this point, droplet geometric properties …

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3d-Printed Piezoelectric Porous Bioactive Scaffolds And Clinical Ultrasonic Stimulation Can Help In Enhanced Bone Regeneration, Prabaha Sikder, Phaniteja Nagaraju, Harsha P.S. Naganaboyina Nov 2022

3d-Printed Piezoelectric Porous Bioactive Scaffolds And Clinical Ultrasonic Stimulation Can Help In Enhanced Bone Regeneration, Prabaha Sikder, Phaniteja Nagaraju, Harsha P.S. Naganaboyina

Mechanical Engineering Faculty Publications

This paper presents a comprehensive effort to develop and analyze first-of-its-kind design-specific and bioactive piezoelectric scaffolds for treating orthopedic defects. The study has three major highlights. First, this is one of the first studies that utilize extrusion-based 3D printing to develop design-specific macroporous piezoelectric scaffolds for treating bone defects. The scaffolds with controlled pore size and architecture were synthesized based on unique composite formulations containing polycaprolactone (PCL) and micron-sized barium titanate (BaTiO3) particles. Second, the bioactive PCL-BaTiO3 piezoelectric composite formulations were explicitly developed in the form of uniform diameter filaments, which served as feedstock material for the fused filament fabrication …

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Estimation Of Joint Moments During Turning Maneuvers In Alpine Skiing Using A Three Dimensional Musculoskeletal Skier Model And A Forward Dynamics Optimization Framework, Dieter Heinrich, Antonie J. Van Den Bogert, Werner Nachbauer Jun 2022

Estimation Of Joint Moments During Turning Maneuvers In Alpine Skiing Using A Three Dimensional Musculoskeletal Skier Model And A Forward Dynamics Optimization Framework, Dieter Heinrich, Antonie J. Van Den Bogert, Werner Nachbauer

Mechanical Engineering Faculty Publications

In alpine skiing, estimation of the joint moments acting onto the skier is essential to quantify the loading of the skier during turning maneuvers. In the present study, a novel forward dynamics optimization framework is presented to estimate the joint moments acting onto the skier incorporating a three dimensional musculoskeletal model (53 kinematic degrees of freedom, 94 muscles). Kinematic data of a professional skier performing a turning maneuver were captured and used as input data to the optimization framework. In the optimization framework, the musculoskeletal model of the skier was applied to track the experimental data of a skier and …

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Amplitude And Wavelength Scaling Of Sinusoidal Roughness Effects In Turbulent Channel Flow At Fixed ReΤ, Sparsh Ganju, Sean C. C. Bailey, Christoph Brehm Feb 2022

Amplitude And Wavelength Scaling Of Sinusoidal Roughness Effects In Turbulent Channel Flow At Fixed ReΤ, Sparsh Ganju, Sean C. C. Bailey, Christoph Brehm

Mechanical Engineering Faculty Publications

Direct numerical simulations are performed for incompressible, turbulent channel flow over a smooth wall and different sinusoidal wall roughness configurations at a constant Reτ = 720. Sinusoidal walls are used to study the effects of well-defined geometric features of roughness-amplitude, a, and wavelength, λ, on the flow. The flow in the near-wall region is strongly influenced by both a and λ. Establishing appropriate scaling laws will aid in understanding the effects of roughness and identifying the relevant physical mechanisms. Using inner variables and the roughness function to scale the flow quantities provides support for Townsend’s hypothesis, …

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Volumetric Lattice Boltzmann Method For Wall Stresses Of Image-Based Pulsatile Flows, Xiaoyu Zhang, Joan Gomez-Paz, Xi Chen, James M. Mcdonough, Md Mahfuzul Islam, Yiannis Andreopoulos, Luoding Zhu, Huidan Yu Feb 2022

Volumetric Lattice Boltzmann Method For Wall Stresses Of Image-Based Pulsatile Flows, Xiaoyu Zhang, Joan Gomez-Paz, Xi Chen, James M. Mcdonough, Md Mahfuzul Islam, Yiannis Andreopoulos, Luoding Zhu, Huidan Yu

Mechanical Engineering Faculty Publications

Image-based computational fluid dynamics (CFD) has become a new capability for determining wall stresses of pulsatile flows. However, a computational platform that directly connects image information to pulsatile wall stresses is lacking. Prevailing methods rely on manual crafting of a hodgepodge of multidisciplinary software packages, which is usually laborious and error-prone. We present a new computational platform, to compute wall stresses in image-based pulsatile flows using the volumetric lattice Boltzmann method (VLBM). The novelty includes: (1) a unique image processing to extract flow domain and local wall normality, (2) a seamless connection between image extraction and VLBM, (3) an en-route …

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A Novel Approach For Real-Time Quality Monitoring In Machining Of Aerospace Alloy Through Acoustic Emission Signal Transformation For Dnn, David Adeniji, Kyle Oligee, Julius Schoop Jan 2022

A Novel Approach For Real-Time Quality Monitoring In Machining Of Aerospace Alloy Through Acoustic Emission Signal Transformation For Dnn, David Adeniji, Kyle Oligee, Julius Schoop

Mechanical Engineering Faculty Publications

Gamma titanium aluminide (γ-TiAl) is considered a high-performance, low-density replacement for nickel-based superalloys in the aerospace industry due to its high specific strength, which is retained at temperatures above 800 °C. However, low damage tolerance, i.e., brittle material behavior with a propensity to rapid crack propagation, has limited the application of γ-TiAl. Any cracks introduced during manufacturing would dramatically lower the useful (fatigue) life of γ-TiAl components, making the workpiece surface’s quality from finish machining a critical component to product quality and performance. To address this issue and enable more widespread use of γ-TiAl, this research aims to develop a …

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A Novel Approach For Real-Time Quality Monitoring In Machining Of Aerospace Alloy Through Acoustic Emission Signal Transformation For Dnn, David Adeniji, Kyle Oligee, Julius Schoop Jan 2022

A Novel Approach For Real-Time Quality Monitoring In Machining Of Aerospace Alloy Through Acoustic Emission Signal Transformation For Dnn, David Adeniji, Kyle Oligee, Julius Schoop

Mechanical Engineering Faculty Publications

Gamma titanium aluminide (γ-TiAl) is considered a high-performance, low-density replacement for nickel-based superalloys in the aerospace industry due to its high specific strength, which is retained at temperatures above 800◦C. However, low damage tolerance, i.e., brittle material behavior with a propensity to rapid crack propagation, has limited the application of γ-TiAl. Any cracks introduced during manufacturing would dramatically lower the useful (fatigue) life of γ-TiAl components, making the workpiece surface’s quality from finish machining a critical component to product quality and performance. To address this issue and enable more widespread use of γ-TiAl, this research aims to develop a real-time …

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Vision And Radar Steering Reduces Agricultural Sprayer Operator Stress Without Compromising Steering Performance, Travis A. Burgers, Kelly J. Vanderwerff Jan 2022

Vision And Radar Steering Reduces Agricultural Sprayer Operator Stress Without Compromising Steering Performance, Travis A. Burgers, Kelly J. Vanderwerff

Mechanical Engineering Faculty Publications

Self-propelled agricultural sprayer operators work an average of 15 h d-1 in peak season, and steering is the task that causes the operator the most stress because of the large number of stimuli involved. Automatic guidance systems help reduce stress and fatigue for operators by allowing them to focus on tasks other than steering. Physiological signals like skin conductance (electrodermal activity, EDA) change with stress and can be used to identify stressful events. The objective of this study was to determine if using a commercially available vision and radar guidance system (VSN®, Raven Industries) reduces agricultural sprayer operators’ stress …

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Antagonistic Co-Contraction Can Minimize Muscular Effort In Systems With Uncertainty, Anne D. Koelewijn, Antonie J. Van Den Bogert Jan 2022

Antagonistic Co-Contraction Can Minimize Muscular Effort In Systems With Uncertainty, Anne D. Koelewijn, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

Muscular co-contraction of antagonistic muscle pairs is often observed in human movement, but it is considered inefficient and it can currently not be predicted in
simulations where muscular effort or metabolic energy are minimized. Here, we investigated the relationship between minimizing effort and muscular co-contraction
in systems with random uncertainty to see if muscular co-contraction can minimize effort in such system. We also investigated the effect of time delay in the muscle, by varying the time delay in the neural control as well as the activation time constant.We solved optimal control problems for a one-degree-of-freedom pendulum actuated by two identical …

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Numerical Investigation On The Effect Of Spectral Radiative Heat Transfer Within An Ablative Material, Raghava S. C. Davuluri, Rui Fu, Kaveh A. Tagavi, Alexandre Martin Dec 2021

Numerical Investigation On The Effect Of Spectral Radiative Heat Transfer Within An Ablative Material, Raghava S. C. Davuluri, Rui Fu, Kaveh A. Tagavi, Alexandre Martin

Mechanical Engineering Faculty Publications

The spectral radiative heat flux could impact the material response. In order to evaluate it, a coupling scheme between KATS - MR and P1 approximation model of radiation transfer equation (RTE) is constructed and used. A Band model is developed that divides the spectral domain into small bands of unequal widths. Two verification studies are conducted: one by comparing the simulation computed by the Band model with pure conduction results and the other by comparing with similar models of RTE. The comparative results from the verification studies indicate that the Band model is computationally efficient and can be used to …

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Fully Coupled Internal Radiative Heat Transfer For The 3d Material Response Of Heat Shield, Raghava S. C. Davuluri, Rui Fu, Kaveh A. Tagavi, Alexandre Martin Jul 2021

Fully Coupled Internal Radiative Heat Transfer For The 3d Material Response Of Heat Shield, Raghava S. C. Davuluri, Rui Fu, Kaveh A. Tagavi, Alexandre Martin

Mechanical Engineering Faculty Publications

The radiative transfer equation (RTE) is strongly coupled to the material response code KATS. A P-1 approximation model of RTE is used to account for radiation heat transfer within the material. First, the verification of the RTE model is performed by comparing the numerical and analytical solutions. Next, the coupling scheme is validated by comparing the temperature profiles of pure conduction and conduction coupled with radiative emission. The validation study is conducted on Marschall et al. cases (radiant heating, arc-jet heating, and space shuttle entry), 3D Block, 2D IsoQ sample, and Stardust Return Capsule. The validation results agree well for …

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A Model-Based Approach To Predict Neuromuscular Control Patterns That Minimize Acl Forces During Jump Landing, Dieter Heinrich, Antonie J. Van Den Bogert, Robert Csapo, Werner Nachbauer May 2021

A Model-Based Approach To Predict Neuromuscular Control Patterns That Minimize Acl Forces During Jump Landing, Dieter Heinrich, Antonie J. Van Den Bogert, Robert Csapo, Werner Nachbauer

Mechanical Engineering Faculty Publications

Jump landing is a common situation leading to knee injuries involving the anterior cruciate ligament (ACL) in sports. Although neuromuscular control is considered as a key injury risk factor, there is a lack of knowledge regarding optimum control strategies that reduce ACL forces during jump landing. In the present study, a musculoskeletal model-based computational approach
is presented that allows identifying neuromuscular control patterns that minimize ACL forces during jump landing. The approach is demonstrated for a jump landing maneuver in downhill skiing, which is one out of three main injury mechanisms in competitive skiing.

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Comparison Of Three Commercial Automatic Boom Height Systems For Agricultural Sprayers, Travis A. Burgers, John D. Gaard, Brian J. Hyronimus Apr 2021

Comparison Of Three Commercial Automatic Boom Height Systems For Agricultural Sprayers, Travis A. Burgers, John D. Gaard, Brian J. Hyronimus

Mechanical Engineering Faculty Publications

Automatic boom height systems reduce the variability of agricultural sprayer boom height. Consistent boom height is important for three key reasons: to reduce uneven spray dispersion if the boom is too low, to reduce spray droplet drift if the boom is too high, and to reduce damage to the boom or crop if the boom is too low. No data is available comparing commercial boom height systems. Three leading North American automatic boom height systems were compared: John Deere BoomTrac Pro (System A), Raven AutoBoom® XRT (System B), and Norac UC5TM Passive Roll (System C) on a John Deere R4045 …

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In-Situ Calibrated Modeling Of Residual Stresses Induced In Machining Under Various Cooling And Lubricating Environments, Julius M. Schoop Mar 2021

In-Situ Calibrated Modeling Of Residual Stresses Induced In Machining Under Various Cooling And Lubricating Environments, Julius M. Schoop

Mechanical Engineering Faculty Publications

Although many functional characteristics, such as fatigue life and damage resistance depend on residual stresses, there are currently no industrially viable ‘Digital Process Twin’ models (DPTs) capable of efficiently and quickly predicting machining-induced stresses. By leveraging advances in ultra-high-speed in-situ experimental characterization of machining and finishing processes under plane strain (orthogonal/2D) conditions, we have developed a set of physics-based semi-analytical models to predict residual stress evolution in light of the extreme gradients of stress, strain and temperature, which are unique to these thermo-mechanical processes. Initial validation trials of this novel paradigm were carried out in Ti-6Al4V and AISI 4340 alloy …

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Numerical Reconstruction Of Spalled Particle Trajectories In An Arc-Jet Environment, Raghava S. C. Davuluri, Sean C. C. Bailey, Kaveh A. Tagavi, Alexandre Martin Jan 2021

Numerical Reconstruction Of Spalled Particle Trajectories In An Arc-Jet Environment, Raghava S. C. Davuluri, Sean C. C. Bailey, Kaveh A. Tagavi, Alexandre Martin

Mechanical Engineering Faculty Publications

To evaluate the effects of spallation on ablative material, it is necessary to evaluate the mass loss. To do so, a Lagrangian particle trajectory code is used to reconstruct trajectories that match the experimental data for all kinematic parameters. The results from spallation experiments conducted at the NASA HYMETS facility over a wedge sample were used. A data-driven adaptive methodology was used to adapts the ejection parameters until the numerical trajectory matches the experimental data. The preliminary reconstruction results show that the size of the particles seemed to be correlated with the location of the ejection event. The size of …

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Wetting And Brazing Of Yig Ceramics Using Ag–Cuo–Tio2 Metal Filler, Wanqi Zhao, Shuye Zhang, Jian Yang, Tiesong Lin, Dusan P. Sekulic, Peng He Jan 2021

Wetting And Brazing Of Yig Ceramics Using Ag–Cuo–Tio2 Metal Filler, Wanqi Zhao, Shuye Zhang, Jian Yang, Tiesong Lin, Dusan P. Sekulic, Peng He

Mechanical Engineering Faculty Publications

The wetting and brazing of Y3Fe5O12 (YIG) ceramics with a Ag–8CuO–2TiO2 filler was investigated for the first time. For comparison, the wettability of a Ag–10CuO filler on YIG ceramics was similarly investigated. The Ag–8CuO–2TiO2 filler has an equilibrium contact angle of approximately 31 °C on the YIG substrate at 1000 °C; thus, its wettability is excellent. Moreover, its wettability exceeds that of Ag–10CuO. The microstructure and the interfacial structure between the filler and the substrate were determined using scanning electron microscopy, X-ray diffraction, EPMA and transmission electron microscopy. The liquid Ag–8CuO–2TiO2 filler …

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Data Generated During The 2018 Lapse-Rate Campaign: An Introduction And Overview, Gijs De Boer, Adam Houston, Jamey D. Jacob, Phillip B. Chilson, Suzanne W. Smith, Brian Argrow, Dale Lawrence, Jack Elston, David Brus, Osku Kemppinen, Petra Klein, Julie K. Lundquist, Sean Waugh, Sean C. C. Bailey, Amy E. Frazier, Michael P. Sama, Christopher Crick, David G. Schmale Iii, James Pinto, Elizabeth A. Pillar-Little, Victoria Natalie, Anders Jensen Dec 2020

Data Generated During The 2018 Lapse-Rate Campaign: An Introduction And Overview, Gijs De Boer, Adam Houston, Jamey D. Jacob, Phillip B. Chilson, Suzanne W. Smith, Brian Argrow, Dale Lawrence, Jack Elston, David Brus, Osku Kemppinen, Petra Klein, Julie K. Lundquist, Sean Waugh, Sean C. C. Bailey, Amy E. Frazier, Michael P. Sama, Christopher Crick, David G. Schmale Iii, James Pinto, Elizabeth A. Pillar-Little, Victoria Natalie, Anders Jensen

Mechanical Engineering Faculty Publications

Unmanned aircraft systems (UASs) offer innovative capabilities for providing new perspectives on the atmosphere, and therefore atmospheric scientists are rapidly expanding their use, particularly for studying the planetary boundary layer. In support of this expansion, from 14 to 20 July 2018 the International Society for Atmospheric Research using Remotely piloted Aircraft (ISARRA) hosted a community flight week, dubbed the Lower Atmospheric Profiling Studies at Elevation – a Remotely-piloted Aircraft Team Experiment (LAPSE-RATE; de Boer et al., 2020a). This field campaign spanned a 1-week deployment to Colorado's San Luis Valley, involving over 100 students, scientists, engineers, pilots, and outreach coordinators. These …

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Experimental And Mathematical Tools To Predict Droplet Size And Velocity Distribution For A Two-Fluid Nozzle, Sadegh Poozesh, Nelson K. Akafuah, Heather R. Campbell, Faezeh Bashiri, Kozo Saito Dec 2020

Experimental And Mathematical Tools To Predict Droplet Size And Velocity Distribution For A Two-Fluid Nozzle, Sadegh Poozesh, Nelson K. Akafuah, Heather R. Campbell, Faezeh Bashiri, Kozo Saito

Mechanical Engineering Faculty Publications

Despite progress in laser-based and computational tools, an accessible model that relies on fundamentals and offers a reasonably accurate estimation of droplet size and velocity is lacking, primarily due to entangled complex breakup mechanisms. Therefore, this study aims at using the integral form of the conservation equations to create a system of equations by solving which, the far-field secondary atomization can be analyzed through predicting droplet size and velocity distributions of the involved phases. To validate the model predictions, experiments are conducted at ambient conditions using water, methanol, and acetone as model fluids with varying formulation properties, such as density, …

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Subsystem Identification Of Feedback And Feedforward Systems With Time Delay, S. Alireza Seyyed Mousavi, Xingye Zhang, Thomas M. Seigler, Jesse B. Hoagg Dec 2020

Subsystem Identification Of Feedback And Feedforward Systems With Time Delay, S. Alireza Seyyed Mousavi, Xingye Zhang, Thomas M. Seigler, Jesse B. Hoagg

Mechanical Engineering Faculty Publications

We present an algorithm for identifying discrete-time feedback-and-feedforward subsystems with time delay that are interconnected in closed loop with a known subsystem. This frequency-domain algorithm uses only measured input and output data from a closed-loop discrete-time system, which is single input and single output. No internal signals are assumed to be measured. The orders of the unknown feedback and feedforward transfer functions are assumed to be known. We use a two-candidate-pool multi-convex-optimization approach to identify not only the feedback and feedforward transfer functions but also the feedback and feedforward time delay. The algorithm guarantees asymptotic stability of the identified closed-loop …

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Laser Powder Bed Fusion Of Nitihf High-Temperature Shape Memory Alloy: Effect Of Process Parameters On The Thermomechanical Behavior, Mohammadreza Nematollahi, Guher P. Toker, Keyvan Safaei, Alejandro Hinojos, S. Ehsan Saghaian, Othmane Benafan, Michael J. Mills, Haluk E. Karaca, Mohammad Elahinia Nov 2020

Laser Powder Bed Fusion Of Nitihf High-Temperature Shape Memory Alloy: Effect Of Process Parameters On The Thermomechanical Behavior, Mohammadreza Nematollahi, Guher P. Toker, Keyvan Safaei, Alejandro Hinojos, S. Ehsan Saghaian, Othmane Benafan, Michael J. Mills, Haluk E. Karaca, Mohammad Elahinia

Mechanical Engineering Faculty Publications

Laser powder bed fusion has been widely investigated for shape memory alloys, primarily NiTi alloys, with the goal of tailoring microstructures and producing complex geometries. However, processing high temperature shape memory alloys (HTSMAs) remains unknown. In our previous study, we showed that it is possible to manufacture NiTiHf HTSMA, as one of the most viable alloys in the aerospace industry, using SLM and investigated the effect of parameters on defect formation. The current study elucidates the effect of process parameters (PPs) on the functionality of this alloy. Shape memory properties and the microstructure of additively manufactured Ni-rich NiTiHf alloys were …

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Efficient Trajectory Optimization For Curved Running Using A 3d Musculoskeletal Model With Implicit Dynamics, Marlies Nitschke, Eva Dorschky, Dieter Heinrich, Heiko Schlarb, Bjoern M. Eskofier, Anne D. Koelewijn, Antonie J. Van Den Bogert Oct 2020

Efficient Trajectory Optimization For Curved Running Using A 3d Musculoskeletal Model With Implicit Dynamics, Marlies Nitschke, Eva Dorschky, Dieter Heinrich, Heiko Schlarb, Bjoern M. Eskofier, Anne D. Koelewijn, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

Trajectory optimization with musculoskeletal models can be used to reconstruct measured movements and to predict changes in movements in response to environmental changes. It enables an exhaustive analysis of joint angles, joint moments, ground reaction forces, and muscle forces, among others. However, its application is still limited to simplified problems in two dimensional space or straight motions. The simulation of movements with directional changes, e.g. curved running, requires detailed three dimensional models which lead to a high-dimensional solution space. We
extended a full-body three dimensional musculoskeletal model to be specialized for running with directional changes. Model dynamics were implemented implicitly …

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Elmer Fem-Dakota: A Unified Open-Source Computational Framework For Electromagnetics And Data Analytics, Anjali Sandip Aug 2020

Elmer Fem-Dakota: A Unified Open-Source Computational Framework For Electromagnetics And Data Analytics, Anjali Sandip

Mechanical Engineering Faculty Publications

Open-source electromagnetic design software, Elmer FEM, was interfaced with data analytics toolkit, Dakota. Furthermore, the coupled software was validated against a benchmark test. The interface developed provides a unified open-source computational framework for electromagnetics and data analytics. Its key features include uncertainty quantification, surrogate modelling and parameter studies. This framework enables a richer understanding of model predictions to better design electric machines in a time sensitive manner.

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University Of Kentucky Measurements Of Wind, Temperature, Pressure And Humidity In Support Of Lapse-Rate Using Multisite Fixed-Wing And Rotorcraft Unmanned Aerial Systems, Sean C. C. Bailey, Michael P. Sama, Caleb A. Canter, Luis Felipe Pampolini, Zachary S. Lippay, Travis J. Schuyler, Jonathan D. Hamilton, Sean B. Macphee, Isaac S. Rowe, Christopher D. Sanders, Virginia G. Smith, Christina N. Vezzi, Harrison M. Wight, Jesse B. Hoagg, Marcelo I. Guzman, Suzanne Weaver Smith Aug 2020

University Of Kentucky Measurements Of Wind, Temperature, Pressure And Humidity In Support Of Lapse-Rate Using Multisite Fixed-Wing And Rotorcraft Unmanned Aerial Systems, Sean C. C. Bailey, Michael P. Sama, Caleb A. Canter, Luis Felipe Pampolini, Zachary S. Lippay, Travis J. Schuyler, Jonathan D. Hamilton, Sean B. Macphee, Isaac S. Rowe, Christopher D. Sanders, Virginia G. Smith, Christina N. Vezzi, Harrison M. Wight, Jesse B. Hoagg, Marcelo I. Guzman, Suzanne Weaver Smith

Mechanical Engineering Faculty Publications

In July 2018, unmanned aerial systems (UASs) were deployed to measure the properties of the lower atmosphere within the San Luis Valley, an elevated valley in Colorado, USA, as part of the Lower Atmospheric Profiling Studies at Elevation – a Remotely-piloted Aircraft Team Experiment (LAPSE-RATE). Measurement objectives included detailing boundary layer transition, canyon cold-air drainage and convection initiation within the valley. Details of the contribution to LAPSE-RATE made by the University of Kentucky are provided here, which include measurements by seven different fixed-wing and rotorcraft UASs totaling over 178 flights with validated data. The data from these coordinated UAS flights …

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An Iterative Size Effect Model Of Surface Generation In Finish Machining, Ian S. Brown, Julius M. Schoop Jul 2020

An Iterative Size Effect Model Of Surface Generation In Finish Machining, Ian S. Brown, Julius M. Schoop

Mechanical Engineering Faculty Publications

In this work, a geometric model for surface generation of finish machining was developed in MATLAB, and subsequently verified by experimental surface roughness data gathered from turning tests in Ti-6Al4V. The present model predicts the behavior of surface roughness at multiple length scales, depending on feed, nose radius, tool edge radius, machine tool error, and material-dependent parameters—in particular, the minimum effective rake angle. Experimental tests were conducted on a commercial lathe with slightly modified conventional tooling to provide relevant results. Additionally, the model-predicted roughness was compared against pedigreed surface roughness data from previous efforts that included materials 51CrV4 and AL …

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Characterization And Modeling Of Surface Roughness And Burr Formation In Slot Milling Of Polycarbonate, David Adeniji, Julius M. Schoop, Shehan Gunawardena, Craig Hanson, Muhammad Jahan Jun 2020

Characterization And Modeling Of Surface Roughness And Burr Formation In Slot Milling Of Polycarbonate, David Adeniji, Julius M. Schoop, Shehan Gunawardena, Craig Hanson, Muhammad Jahan

Mechanical Engineering Faculty Publications

Thermoplastic materials hold great promise for next-generation engineered and sustainable plastics and composites. However, due to their thermoplastic nature and viscoplastic material response, it is difficult to predict the properties of surfaces generated by machining. This is especially problematic in micro-channel machining, where burr formation and excessive surface roughness lead to poor component-surface integrity. This study attempts to model the influence of size effects, which occur due to the finite sharpness of any cutting tool, on surface finish and burr formation during micro-milling of an important thermoplastic material, polycarbonate. Experimental results show that the depth of cut does not affect …

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