Mechanical Engineering Commons^™

Cfrp Delamination Density Propagation Analysis By Magnetostriction Theory, Brandon Eugene Williams

All Dissertations

While Carbon Fiber Reinforced Polymers (CFRPs) have exceptional mechanical properties concerning their overall weight, their failure profile in demanding high-stress environments raises reliability concerns in structural applications. Two crucial limiting factors in CFRP reliability are low-strain material degradation and low fracture toughness. Due to CFRP’s low strain degradation characteristics, a wide variety of interlaminar damage can be sustained without any appreciable change to the physical structure itself. This damage suffered by the energy transfer from high- stress levels appears in the form of microporosity, crazes, microcracks, and delamination in the matrix material before any severe laminate damage is observed. This …

Controlled Manipulation And Transport By Microswimmers In Stokes Flows, Jake Buzhardt

All Dissertations

Remotely actuated microscale swimming robots have the potential to revolutionize many aspects of biomedicine. However, for the longterm goals of this field of research to be achievable, it is necessary to develop modelling, simulation, and control strategies which effectively and efficiently account for not only the motion of individual swimmers, but also the complex interactions of such swimmers with their environment including other nearby swimmers, boundaries, other cargo and passive particles, and the fluid medium itself. The aim of this thesis is to study these problems in simulation from the perspective of controls and dynamical systems, with a particular focus …

Husker Motorsports Active Drag Reduction System, Creighton Hughes, Evan Killian, Micah Busboom, Aj Johnson, Jude Steffen

Honors Program: Senior Projects (Public)

Formula SAE is a multifaceted competition that involves student teams designing and competing with an open-wheel style race car. There are 5 different dynamic events included in the competition. Each event requires a unique aerodynamic setup to have the best performance possible. This design project focuses on a drag reduction system (DRS) that will improve aerodynamic performance, resulting in faster lap times and increased competitiveness. Key features include a direct electronic actuation mechanism that will allow the rear wing to be adjusted during a race. The benefits of the DRS system, include increased speed, improved handling, and greater fuel efficiency …

An Optimization Procedure To Design Nozzle Contours For Hypersonic Wind Tunnels, Omar Antonio Dominguez

Open Access Theses & Dissertations

Supersonic wind tunnels allow scientists and researchers to evaluate and analyze the behaviors of objects under real-life conditions when subjected to supersonic speeds. One of the main complexities when building a wind tunnel is the design of the convergent-divergent nozzle that is used to produce high-speed and high-quality flows. To achieve supersonic speeds, this nozzle adopts a specialized approach that incorporates the complexities of flow compressibility. The compressible effect is accurately evaluated using isentropic relations, allowing for precise determination of stagnation pressure and temperature, and static pressure and temperature relevant to the desired Mach number. Isentropic equations used to define …

Additively Manufactured Cryogenic Engineered Heat Pipe For Lunar Ice Collection, Mahadi Hasan

Open Access Theses & Dissertations

Nowadays, one of the most talked-about subjects in space exploration is cryogenic heat pipes. These heat pipes are made in a way that allows them to operate without the need for additional power or energy. Evaporated vapor and condensed liquid can be moved by buoyancy forces or capillary forces that are subject to gravity because of the phase shifts of the working fluids moving inside. The cooling solution typically entails a phase transition from liquid to vapor, which can dissipate larger heat fluxes because of the fluid's high latent heat of vaporization. Recent developments in additive manufacturing and micro-nano structures …

Ultra Wide Band Gap Oxides For Advanced Optoelectronics And Supercapacitor Applications: A Case Study Of Intrinsic And Doped Germanium Dioxide, Paul Gaurav Nalam

Open Access Theses & Dissertations

Germanium dioxide (GeO2) is a metal oxide semiconductor with multiple polymorphs that has recently garnered a significant amount of scientific attention owing to its novel ultra-wide band gap and pseudo-capacitive properties, which can potentially transcend current power electronic, optoelectronic, and supercapacitor technologies. However, due to the difficulty in the synthesis of stable crystalline phases of individual polymorphs of GeO2 thin films, this material system demands complex and resource-intensive deposition techniques to synthesize. An attempt was made to develop cost-effective and scalable deposition techniques to stabilize specific crystalline phases of GeO2 thin films. These phases were further structurally fine-tuned to state …

Effects Of Simultaneous Co2 Addition To The Fuel And Oxidizer Streams On Soot Formation In Co-Flow Diffusion Ethylene Flame, Yu Yang, Shu Zheng, Yuzhen He, Hao Liu, Ran Sui, Qiang Lu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Soot formation in a co-flow diffusion ethylene flame with the addition of CO₂ to the fuel (the CO₂-F), oxidizer (the CO₂-O), and fuel/oxidizer (the CO₂-F/O) streams was numerically and experimentally investigated in this study. The effects of different CO₂ addition ways on soot inception, soot condensation, H-abstraction-C₂H₂-addition (HACA) and oxidation by O₂/OH processes, were quantitatively analyzed by introducing the integrated reaction rates over the whole computational domain. The simulated and experimental results showed that the CO₂-F/O was the most effective in inhibiting soot formation …

Gpu Based Monte Carlo Estimation Of Eddy Current Losses In Electromagnetic Coil-Core System, Adwaith Ravichandran

Theses and Dissertations

A novel parallelizable probabilistic approach to model eddy currents in AC electromagnets is presented in this research. Consequently, power loss associated with the formation of these eddy currents is estimated and validated using experimental data. Furthermore, predicting the effect of ferromagnetic alternating field enhancement on power loss in the source excitation winding has been an active area of research. Unlike a stationary field, an alternating sinusoidal field diffuses partially into the ferromagnetic material leading to a predictably sub-optimal field enhancement. To model these physics, finite element techniques employ nonlinear iterative solvers which are time consuming. A novel method is developed …

Safe Navigation Of Quadruped Robots Using Density Functions, Andrew Zheng

All Theses

Safe navigation of mission-critical systems is of utmost importance in many modern autonomous applications. Over the past decades, the approach to the problem has consisted of using probabilistic methods, such as sample-based planners, to generate feasible, safe solutions to the navigation problem. However, these methods use iterative safety checks to guarantee the safety of the system, which can become quite complex. The navigation problem can also be solved in feedback form using potential field methods. Navigation function, a class of potential field methods, is an analytical control design to give almost everywhere convergence properties, but under certain topological constraints and …

A Dynamic Scoring Methodology For Morphing Airfoil Designs With Application To A Stalling Scenario, Stone Wachs

UNLV Theses, Dissertations, Professional Papers, and Capstones

Shape Changing Airfoils (SCAs) are a developing technology with potential aircraft applications. Leading aerospace corporations are actively researching SCA capabilities. The necessity for this technology stems from the requirement of control surfaces for safe aircraft control. However, the process of testing and determining optimal SCA designs can be costly and time-consuming. While methodologies exist, they often require specific scenario examples and lack a standard approach. To address this issue, a standardized methodology is needed that can be applied to various applications and scenarios. This methodology consists of computational/experimentally produced data for airfoils, a subjective and strategic scoring equation, an algorithmic …

Numerical Investigations Of Sco2 Compressor Aerothermodynamics Using A Streamline Curvature Based Throughflow Method, Victor Quintanilla

UNLV Theses, Dissertations, Professional Papers, and Capstones

Supercritical carbon dioxide (sCO₂) has emerged as a promising working fluid for the Brayton power cycle, offering enhanced efficiency due to the high density and low viscosity of carbon dioxide (CO₂) near the critical point. A critical component of the sCO₂ Brayton cycle is the turbomachinery, namely the compressor, which significantly contributes to the efficiency enhancement in the sCO₂ Brayton cycle owing to reduced compression work requirements. Its primary function involves elevating the fluid's pressure, effectively priming it for the subsequent heat addition process from a thermal energy source. However, despite its advantages, challenges …

Kwad - Ksu All Weather Autonomous Drone, Nick Farinacci, Sebastian Gomez, Stewart Baker, Ed Sheridan

Symposium of Student Scholars

"KWAD" or "KSU all-Weather Autonomous Drone" project was sponsored by Ultool, LLC to the KSU Research and Service Foundation to create a lightweight drone capable of capturing HD video during all-weather operations. The conditions of all-weather operation include rainfall of one inch per hour and wind speeds of up to twenty miles per hour. In addition, a global minimum structural safety factor of two is required to ensure the system's integrity in extreme weather conditions. Potential mission profiles include autonomous aerial delivery, topological mapping in high moisture areas, security surveillance, search and rescue operations, emergency transportation of medical supplies, and …

Molecular Dynamics Simulations Of The Spontaneous Deformation And Auxetics Behavior During Tensile Test Of A Nematic Liquid Crystal Elastomer Model, Haoran Wang, Nanang Mahardika

Browse all Datasets

Nematic liquid crystal elastomers (LCEs) are advanced materials known for their shape-changing capability in response to external stimuli such as heat, light and electromagnetic fields. This makes them excellent candidates for applications like soft robotics and energy harvesting. While studies on their physical behavior have shed light on the complex nonlinear mechanics of LCEs, investigations through all-atom molecular dynamics (MD) simulations remain an underutilized avenue compared to experimental and theoretical analyses. This limited use is primarily due to the lack of well-established frameworks for conducting high-fidelity atomistic simulations of LCEs. To bridge this gap, we introduce an all-atom MD simulation …

Steady And Transient Study Of Conjugate Heat Transfer In Regenerative Cooled Nozzle, Khaled Bensayah, Khadidja Kamri

Emirates Journal for Engineering Research

The Heat transfer is one of the most serious challenges that exist in a supersonic nozzle flow. The combustion chamber wall and the nozzle are exposed to high-temperature gases during combustion and gas expansion, which can eventually lead to structural failure. This paper reports a computational study of steady and transient conjugate heat transfer in regenerative water cooled nozzle. Numerical computation solved Reynolds-averaged equations based on RSM-Omega turbulence model coupling with solid-phase heat conduction equation and with coolant-phase. The effect of four inlet cooled approach length 0 inch, 6 inch, 12 inch and 18 inch are studied and validated against …

The Effect Of Vortex Cooling And Injection Parameters On A Bipropellant 3d Printed Thermoplastic Thruster, Mousa A. Aqailan

Thesis/ Dissertation Defenses

This research reports an experimental investigation of the efficiency and cooling performance of a 10Nvortex cooled Propane/Gox bi-propellent thruster designed and tested with different fabrication materials including a thermoplastic combustion chamber, and metal faceplate and nozzle. The study proposes vortex as a possible solution for cooling thrusters made from partially 3D-printed thermoplastic. This enables the vortex injection method to be 3D printed in a single solid piece thruster to minimize the design complexity and reduce weight, production time, and cost compared to conventional cooling methods. Vortex cooling is simply made by changing the direction of propellant injection rather than using …

Aerodynamic & Aeroacoustic Performance Of Wind Turbine Blades Featuring Enhanced, Md Zishan Akhter

Thesis/ Dissertation Defenses

Wind energy, being one of the cleanest and most sustainable sources, has undergone remarkable growth in recent years due to advancements in aerodynamics and increased power output. The research community is actively pursuing the development of cutting-edge solutions to further optimize wind turbine technology, ensuring its maximum efficiency and revolutionizing the landscape of wind power.
This research aims to design and develop flow-control devices for wind turbine blades, employing both active and passive control mechanisms, namely morphing trailing-edge and slot-profile, respectively. The objective is to enhance wind turbine performance across a wide range of wind speeds. The morphing trailing-edge mechanism …

Comparative Evaluation Of Investigation Methods For Estimating The Load-Dependent State Of Charge And End Of Discharge Of A Multirotor Uav Battery, Hanna Dibbern, Morten Roßberg, Claudia Werner

Journal of Aviation Technology and Engineering

As the scope of multirotor unmanned aerial vehicle (UAV) applications increases, more attention is being paid to UAV energy requirements, which vary depending on the mission profile. To obtain accurate information about the UAV battery during flight, the idea of a digital twin including a battery state estimation model is promising. For battery state estimation, a Kalman filter combination is the preferred approach in the literature. Comparing different Kalman filters, the unscented Kalman filter has a more accurate estimation for nonlinear systems compared to the extended Kalman filter. In the application of UAV flight with load-dependent flight missions, the comparison …

Development, Implementation, And Evaluation Of Swirl-Combustion Strategies For Optimal Performance Of Ammonia As A Fuel For Gas Turbine Engines, Varun Nanjunda Rao Viswamithra

LSU Doctoral Dissertations

In an effort to reduce harmful effects of greenhouse gas emissions, ammonia is being pursued as a fuel for power generation as it is a carbon-free energy source. However, the use of ammonia-air mixtures in premixed swirl combustors poses challenges due to low flame speed and reactivity resulting in combustor stability issues in addition to high Nitrous Oxide (NOx) emissions due to the presence of fuel-bound Nitrogen. The first part of this study attempts to overcome lean blowout limits of methane-ammonia-air mixtures using a novel, multi-point () injection strategy, whereby micron-sized holes on the swirler vanes generate a co-flowing stream …

Development Of A Vortex-Cooled Bipropellant Thruster And Evaluation Of Performance Characteristics With Respect To Injection Parameters, Mousa Adnan Aqailan

Theses

This study presents an experimental assessment of the cooling performance and efficiency of a 10N-vortex-cooled Propane/Gox bi-propellant thruster that was fabricated using metal and thermoplastic material. The proposal of injecting an oxidizer in a vortex pattern was suggested as a potential cooling method for semi-thermoplastic constructed thrust engines. This method has been demonstrated as a promising candidate for integrated cooling and can be manufactured using 3D printing technology. In contrast to typical complicated cooling systems and their attributed common downsides; the vortex injection can be 3D printed as a single solid piece thruster, thereby reducing design complexity, weight, and manufacturing …

Electromagnetic Mems Safety And Arming Devices, Fatima Rashed Alnuaimi

Theses

This thesis aims to investigate the design of safety and arming devices within artillery fuzes, which rely on the spin velocity and setback acceleration of the weapon. These systems consist of two critical components: the spin lock and the inertia lock. The spin velocity and setback acceleration of the weapon induce deformations in these components, serving as key criteria for determining whether the weapon is in an armed or safe state.

The primary objective of this thesis is to comprehensively analyze and assess the design of both the spin lock and inertia lock. The research will delve into multiple factors …

Design And Fem Modelling Of Mems Capacitive Accelerometer And Gyroscope For Quadcopter/Uav Applications, Shaikha Rashid Alnaqbi

Theses

This study presents the design, simulation, and analysis of Micro Electromechanical Systems (MEMS) sensors, constituting the principal components of MEMS-based Inertial Measurement Units (IMUs). The main objective of the study is to design, simulate and analyze 3-axis capacitive accelerometer and 3-axis gyroscope. The MEMS-based capacitive accelerometers and gyroscope are analyzed using Ansys Workbench. Modal, Static Structural and harmonic analysis are used to obtain resonant frequencies, deformation/stress and profile of amplitude over a wide range of frequencies. Mechanical sensitivity analysis of the designed accelerometer and gyroscope is performed using the Finite Element Method (FEM). Analytical Equations are developed to calculate mechanical …

Aerodynamic & Aeroacoustic Performance Of Wind Turbine Blades Featuring Enhanced Flow-Control, Md Zishan Akhter

Dissertations

Wind energy, being one of the cleanest and most sustainable sources, has undergone remarkable growth in recent years due to advancements in aerodynamics and increased power output. The research community is actively pursuing the development of cutting-edge solutions to further optimize wind turbine technology, ensuring its maximum efficiency and revolutionizing the landscape of wind power.
/="/">This research aims to design and develop flow-control devices for wind turbine blades, employing both active and passive control mechanisms, namely morphing trailing-edge and slot-profile, respectively. The objective is to enhance wind turbine performance across a wide range of wind speeds. The morphing trailing-edge …

Implementation Of Experimental Static Recrystallization Of High Strength Steel Into Computational Simulation Of Multi-Pass Slab Hot Rolling, S. K. Dasari, S. Ganguly, A. Abutunis, K. Chandrashekhara, M. F. Buchely, S. N. Lekakh, R. J. O'Malley, T. Natarajan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Microstructural changes and softening due to static recrystallization have a critical influence on thermo-mechanical behavior of high strength steels during industrial multi-pass hot rolling. Numerical simulation using finite element analysis (FEA) can be used to accurately predict the softening behavior during the hot rolling process. Therefore, the implementation of an experimentally defined static recrystallization model into FEA is necessary to get realistic simulation prediction. in this study, the extent of softening during static recrystallization in Si and Mn alloyed high strength steel was measured using double hit tests. a Gleeble™ thermo-mechanical simulator was used to perform the double hit tests …

Design Of Impact-Free Gaits For Planar Bipeds And Their Stabilization Using Impulsive Control, Aakash Khandelwal, Nilay Kant, Ranjan Mukherjee

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The problem of designing and stabilizing impact-free gaits is considered for point-foot planar bipeds. A set of geometric constraints, which eliminate impact forces at the time of leg interchange, are used to design the gaits. A family of gaits, where the stride length and walking speed can be chosen independently for each gait, is guaranteed to exist. A continuous controller is used to enforce the constraints associated with a desired gait and intermittent impulsive inputs are applied to stabilize the gait. A five-link biped example is used to illustrate the procedure for designing impact-free gaits. The effectiveness of the continuous …

Searching For Unknown Material Properties For Am Simulations, Aaron Flood, Rachel Boillat, Sriram Praneeth Isanaka, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Additive manufacturing (AM) simulations are effective for materials that are well characterized and published; however, for newer or proprietary materials, they cannot provide accurate results due to the lack of knowledge of the material properties. This work demonstrates the process of the application of mathematical search algorithms to develop an optimized material dataset which results in accurate simulations for the laser directed energy deposition (DED) process. This was performed by first using a well-characterized material, Ti-64, to show the error in the predicted melt pool was accurate, and the error was found to be less than two resolution steps. Then, …

Towards A Virtual Test Framework To Predict Residual Compressive Strength After Lightning Strikes, Scott L.J. Millen, Xiaodong Xu, Juhyeong Lee, Suparno Mukhopadhyay, Michael R. Wisnom, Adrian Murphy

Mechanical and Aerospace Engineering Faculty Publications

A novel integrated modelling framework is proposed as a set of coupled virtual tests to predict the residual compressive strength of carbon/epoxy composites after a lightning strike. Sequentially-coupled thermal-electric and thermo-mechanical models were combined with Compression After Lightning Strike (CAL) analyses, considering both thermal and mechanical lightning strike damage. The predicted lightning damage was validated using experimental images and X-ray Computed Tomography. Delamination and ply degradation information were mapped to a compression model, with a maximum stress criterion, using python scripts. Experimental data, in which artificial lightning strike and compression testing were performed, was used to assess the predictive capabilities …

On Quantifying Uncertainty In Lightning Strike Damage Of Composite Laminates: A Hybrid Stochastic Framework Of Coupled Transient Thermal-Electrical Simulations, R. S. Chahar, J. Lee, T. Mukhopadhyay

Mechanical and Aerospace Engineering Faculty Publications

Lightning strike damage can severely affect the thermo-mechanical performance of composite laminates. It is essential to quantify the effect of lightning strikes considering the inevitable influence of material and geometric uncertainties for ensuring the operational safety of aircraft. This paper presents an efficient support vector machine (SVM)-based surrogate approach coupled with computationally intensive transient thermal-electrical finite element simulations to quantify the uncertainty in lightning strike damage. The uncertainty in epoxy matrix thermal damage and electrical responses of unprotected carbon/epoxy composite laminates is probabilistically quantified considering the stochasticity in temperature-dependent multi-physical material properties and ply orientations. Further, the SVM models are …

Atomic Insights Into The Structural Properties And Displacement Cascades In Ytterbium Titanate Pyrochlore (Yb2ti2o7) And High-Entropy Pyrochlores, M. Mustafa Azeem, Qingyu Wang

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Pyrochlore oxides ((Formula presented.) are potential nuclear waste substrate materials due to their superior radiation resistance properties. We performed molecular dynamics simulations to study the structural properties and displacement cascades in ytterbium titanate pyrochlore ((Formula presented.)) and high-entropy alloys (HEPy), e.g., (Formula presented.), (Formula presented.), and (Formula presented.). We computed lattice constants (LC) ((Formula presented.)) and threshold displacement energy (Ed). Furthermore, the calculation for (Formula presented.) and ionic radius ((Formula presented.)) were performed by substituting a combination of cations at the A and B sites of the original pyrochlore structure. Our simulation results have demonstrated that the lattice constant is …

Studies Of Flowfields And Dynamic Stability Characteristics Of A Quadrotor, Engin Baris

Mechanical & Aerospace Engineering Theses & Dissertations

Electric multirotor air vehicles have become a pervasive technology and research topic in industry, academia, and daily life, and small quadrotors are one of the most preferred designs in the multirotor marketplace. However, the configuration of the quadrotors makes aerodynamic interaction effects one of the key factors of the vehicle performance in both hover and non-axial forward flight conditions.

In the present work, aerodynamic characteristics of the cross-configured small quadrotor in hover, edgewise, and maneuvering flight modes were investigated in detail by performing static and dynamic wind tunnel tests at various RPM levels, wind speeds, pitch and yaw angles, and …

Additive Manufacturing And Characterization Of Auxetic Structures, Jayesh P. Moore, Stephanie R. Ruzicka

College of Engineering Summer Undergraduate Research Program

An auxetic structure is an arrangement of unit cells that under a uniaxial load experiences expansion in both the longitudinal and transverse directions, resulting in a negative Poisson’s ratio (NPR). Research in auxetics has led to new insights into how non-linear mechanical reactions can be applied to various engineering fields. This project utilized stereolithography (SLA) 3D printing to manufacture auxetic test specimens to analyze of geometry-driven NPRs. With the distinctive mechanical properties of auxetic structures and vast applications, the future of product development of these geometries seems promising.