Mechanical Engineering Commons^™

The Influence Of Varying Fiber Stacking Sequence On The Tensile, Impact, And Water Absorption Properties Of Unidirectional Flax/E-Glass Fiber Reinforced Epoxy Composite, Mohammed F. Al-Edhari

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis includes the study of the mechanical performance of two different types of fibers reinforced hybrid composites. Two kinds of fibers, natural fiber (flax) and synthetic fiber (E-glass), are used to reinforce epoxy resin. To evaluate the effective properties of the hybrid composites, a micromechanical analysis of the structure genome (SG) of a unidirectional fiber hybrid composites is performed using nite element analysis (FEA). Both fibers are assumed to be circular and packed in a hexagonal pattern. The effects of varying volume fractions and fiber locations, of the two fibers, on the elastic properties of the hybrid composites are …

Transient Analysis Of Fracture Initiation In A Coupled Thermoelastic Solid, Louis Milton Brock

Mechanical Engineering Faculty Publications

An isotropic, thermoelastic solid is initially at rest at uniform (absolute) temperature, and contains a semi-infinite, plane crack. Application of in-plane and normal point forces to each face of the crack causes transient 3D growth. The related problem of discontinuities in temperature and displacement that exist on regions that exhibit dynamic similarity is first considered. Asymptotic expressions, whose inverses are valid near the crack edges for short times, are obtained in integral transform space. These lead to equations of the Wiener–Hopf type for the fracture problem. Analytical solutions are obtained and, upon inversion, subjected to a dynamic energy release rate …

Experimental Measurement Of Residual Stress And Distortion In Additively Manufactured Stainless Steel Components With Various Dimensions, M. Ghasri-Khouzani, H. Peng, R. Rogge, R. Attardo, P. Ostiguy, J. Neidig, R. Billo, D. Hoelzle, M. R. Shankar

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Disk-shaped 316L stainless steel parts with various diameters and heights were additively manufactured using a direct metal laser sintering (DMLS) technique. Neutron diffraction was used to profile the residual stresses in the samples before and after removal of the build plate and support structures. Moreover, distortion level of the parts before and after the removal was quantified using a coordinate measuring machine (CMM). Large tensile in-plane stresses (up to ≈ 400 MPa) were measured near the as-built disk top surfaces, where the stress magnitude decreased from the disk center to the edges. The stress gradient was steeper for the disks …

How Spaceflight Affects The Detachment Of Zinc Whiskers, Kayla Capitan

Von Braun Symposium Student Posters

No abstract provided.

Computational Methods For Nonlinear Systems Analysis With Applications In Mathematics And Engineering, Geoffrey Kenneth Rose

Mechanical & Aerospace Engineering Theses & Dissertations

An investigation into current methods and new approaches for solving systems of nonlinear equations was performed. Nontraditional methods for implementing arc-length type solvers were developed in search of a more robust capability for solving general systems of nonlinear algebraic equations. Processes for construction of parameterized curves representing the many possible solutions to systems of equations versus finding single or point solutions were established. A procedure based on these methods was then developed to identify static equilibrium states for solutions to multi-body-dynamic systems. This methodology provided for a pictorial of the overall solution to a given system, which demonstrated the possibility …

Development Of A Data Acquisition System For Unmanned Aerial Vehicle (Uav) System Identification, Donald Joseph Lear

Mechanical & Aerospace Engineering Theses & Dissertations

Aircraft system identification techniques are developed for fixed wing Unmanned Aerial Vehicles (UAV). The use of a designed flight experiment with measured system inputs/outputs can be used to derive aircraft stability derivatives. This project set out to develop a methodology to support an experiment to model pitch damping in the longitudinal short-period mode of a UAV. A Central Composite Response Surface Design was formed using angle of attack and power levels as factors to test for the pitching moment coefficient response induced by a multistep pitching maneuver.

Selecting a high-quality data acquisition platform was critical to the success of the …

Shear Joy Of Watching Paint Dry, Randy Craig Hurd, Nathan B. Spiers, J. Belden, Zhao Pan, B. Lovett, W. G. Robinson, M. A. Zamora, Saberul I. Sharker, Mohammad M. Mansoor, A. Merritt, Tadd T. Truscott

Mechanical and Aerospace Engineering Faculty Publications

This paper is associated with a video winner of a 2016 APS/DFD Milton van Dyke Award for work presented at the DFD Gallery of Fluid Motion.

Self-Propulsion Of Leidenfrost Drops Between Non-Parallel Structures, Cheng Luo, Manjarik Mrinal, Xiang Wang

Mechanical and Aerospace Faculty Publications - Archive

In this work, we explored self-propulsion of a Leidenfrost drop between non-parallel structures. A theoretical model was first developed to determine conditions for liquid drops to start moving away from the corner of two non-parallel plates. These conditions were then simplified for the case of a Leidenfrost drop. Furthermore, ejection speeds and travel distances of Leidenfrost drops were derived using a scaling law. Subsequently, the theoretical models were validated by experiments. Finally, three new devices have been developed to manipulate Leidenfrost drops in different ways.

The Subject Librarian Newsletter, Engineering And Computer Science, Fall 2017, Buenaventura "Ven" Basco

Libraries' Newsletters

No abstract provided.

Conditions For Barrel And Clam-Shell Liquid Drops To Move On Bio-Inspired Conical Wires, Cheng Luo, Xiang Wang

Mechanical and Aerospace Faculty Publications - Archive

It has been reported that, in a foggy environment, water drops with either barrel or clam-shell shapes are capable of self-running on conical wire-like structures, such as cactus spines, spider silk, and water striders’ legs. On the other hand, the corresponding moving mechanisms are still not quite understood. For instance, it is unclear under what conditions clam-shell drops would move from the tip towards the root on a conical wire. In this work, based on the balance of forces, we derive conditions for a drop to self-transport towards or away from the root. We find that, although barrel and clam-shell …

Minimum Induced Power For A Helicopter In High-Speed Forward Flight, Junsoo (Sean) Hong

McKelvey School of Engineering Graduate Student Theses & Dissertations

A dynamic inflow model is used to calculate minimum induced power for a helicopter in high-speed forward flight with infinite and finite number of blades. Comparisons between analytical and numerical results are shown and they show good agreement. Different flow conditions (such as with and without reverse flow or inflow feedback) are used to show how each condition affects optimum induced power. Several results confirm the findings of earlier investigations such as a singularity in rotor power in reverse flow and induced power reduction with increase in blade number. Some of the new findings are that greater inflow feedback (due …

Additive Manufacturing Of High Solids Loading Hybrid Rocket Fuel Grains, Stephen P. Johnson, Michael Baier, Ibrahim E. Gunduz, Steven F. Son

The Summer Undergraduate Research Fellowship (SURF) Symposium

Hybrid rocket motors offer many of the benefits of both liquid and solid rocket systems. Like liquid engines, hybrid rocket motors are able to be throttled, can be stopped and restarted, and are safer than solid rocket motors since the fuel and oxidizer are in different physical states. Hybrid rocket motors are similar to solid motors in that they are relatively simple and have a high density-specific impulse. One of the major drawbacks of hybrid rocket motors is a slower burning rate than solid rocket motors. Complex port geometries provide greater burning surface area to compensate for lower burning rates …

Advanced Methods Of Nondestructive Inspection Of Composite Structures Based On Limited Angle X-Ray Computed Tomography, Ekaterina Bostaph

Mechanical and Aerospace Engineering Dissertations - Archive

This research aimed to study the potential for breaking through object size limitations of current X-ray computed tomography (CT) systems by implementing a limited angle scanning technique. CT stands out among other industrial nondestructive inspection (NDI) methods due to its unique ability to perform 3D volumetric inspection, unmatched micro-focus resolution, and objectivity that allows for automated result interpretation. This work attempts to advance NDI technique to enable microstructural material characterization and structural diagnostics of composite structures, where object sizes often prohibit the application of full 360o CT. Even in situations where the objects can be accommodated within existing micro-CT configuration, …

Modeling And Measurements Of Thermal Transport In Li-Ion Based Energy Conversion And Storage Devices, Krishna Shah

Mechanical and Aerospace Engineering Dissertations - Archive

Heat transfer is of significant importance in energy conversion and storage devices such as Lithium-ion batteries for its safe operation and performance. Li-ion batteries are considered to be the state of the art among the energy storage devices due to their very high energy density and high power density. However, the safety of Li-ion batteries has become a concern in light of recent incidents, where there have been catastrophic events reported due to overheating of large battery packs. It is imperative to fully understand the nature of thermal transport in Li-ion cells. However, this has not been explored in detail …

Space Access Systems Design: Synthesis Methodology Development For Conceptual Design Of Future Space Access Systems, Loveneesh Rana

Mechanical and Aerospace Engineering Dissertations - Archive

The early Conceptual Design (CD) of a Space Access System (SAS) is the most abstract, innovative, and technologically challenging phase throughout the entire aerospace product development life-cycle. While it is the most important life-cycle phase which influences around 80 percent of the overall life-cycle-cost, it is also the least understood design phase. The history of space access vehicle design provides numerous examples of projects that failed due to lack of a proper technology-hardware-mission assessment in the CD phase. The present dissertation addresses this crucial phase and develops a prototype best practice solution process to advance the current state of the …

Micro/Nanoencapsulated Phase Change Materials (Pcms) Toward High Temperature Thermal Energy Storage Applications, Hanfei Zhang

Mechanical and Aerospace Engineering Dissertations - Archive

Thermal energy is one of the most important renewable energy sources because of its abundancy. However, despite the long history of people practically trying to harvest thermal energy, the efficiency of thermal energy storage and application to daily life utilization is still a major limitation, especially for high temperature (>300oC) applications. Concentrating solar power (CSP) is one of the very few technologies that have been used commercially to produce electricity from solar thermal energy. Benefiting from the extra latent heat stored during melting/freezing, phase change materials (PCMs) with a high melting point are commonly used in these systems functioning …

Field-Directed Fabrication Of Hierarchical Structures Toward Electrochemical Applications, Anirudh Balram

Mechanical and Aerospace Engineering Dissertations - Archive

The ubiquity of hierarchical structures in nature indicates an inherent advantage to having morphological features comprised of multiple length scales. Such structures help maximize interfacial surface area, allowing for efficient chemical reactions and mass transport despite volumetric constraints. In electrochemical applications such as batteries, supercapacitors, electrolysis, fuel cells, catalysis etc. there is a similar necessity to maximize electrochemically active surface area to facilitate facile charge and mass transport. Inspired by examples in nature, this work seeks to develop scalable fabrication techniques to obtain hierarchically structured high-performance electrodes for electrochemical applications, with a focus on energy applications. Particular emphasis was laid …

Numerical Investigation Of Stability Characteristics Of A Jet In Counterflow, Siddarth Chintamani

Mechanical and Aerospace Engineering Dissertations - Archive

A jet in counterflow is a configuration in which a jet is issued into an opposing external stream of fluid. Some of the possible applications of this configuration include study of pollutant discharge into body of water, aerodynamic flame holder in after burner, reduction of drag and cooling of bluff body by ejecting a jet of coolant gas into counterflowing stream, thrust vectoring of supersonic jets, sonic boom mitigation. The instability associated with flow reversal which is observed in this configuration of the jet leads to enhanced mixing. However, a detailed understanding of the dynamics and control is needed to …

Multi-Mesh Reduced-Order Basis Method For Finite Element Analysis, Ashkan Akbariyeh

Mechanical and Aerospace Engineering Dissertations - Archive

Reduced order modeling of differential equations parametrized over a parameter space can be used to accelerate optimization and parameter estimation problems. The method of snapshots or reduced order basis is well established among researchers as a tool to build reduced order models of ordinary differential equations. The reduced order basis method has been utilized for numerical solution of parametric PDE problems by researchers in recent years and has many advantages over response surface methods. The application of ROB to finite element analysis has been restricted to using a fixed mesh for snapshots. In this work, a new method is developed …

Thermal Measurement And Optimization Of Materials And Processes In A Li-Ion Cell, Vivek Vishwakarma

Mechanical and Aerospace Engineering Dissertations - Archive

Applications of Lithium-ion cells range from consumer electronics to electric cars because of their excellent electrochemical performance and energy density. However, a Li-ion cell also suffers from poor thermal transport characteristics, which reduces performance, causes overheating and thermal runaway. This work contributes towards thermal characterization of key Li-ion battery materials and identifies and improves the rate-limiting, material-level thermal conduction process in a Li-ion cell. Among the various materials within a Li-ion cell, the separator is expected to have the lowest thermal conductivity. In this work, we have carried out first-ever measurements of thermal conductivity and heat capacity of the separator …

Flexible-Continuum Robot For Bladder Tissue Diagnostics, Samson Abimbola Adejokun

Mechanical and Aerospace Engineering Theses - Archive

The aim of this thesis is to investigate and develop a robotic system capable of a transurethral palpation of any targeted area on the bladder interior wall tissue to determine the biomechanical properties of the tissue considering the urinary tract geometric constraints and to demonstrate the motion kinematics of such robot to achieve a desired robot pose normal to any localized region throughout the bladder workspace. Current technologies have, to varied degree of success, provide approximate, global diagnostics information to bladder tissue elasticity. However, no direct access qualitative methods to measure the bladder tissue properties are known. For this reason, …

Enhancing Indirect / Direct Evaporative Heat Exchanger In Data Center Cooling By Using Phase Change Material, Ahmed Ali Abuklam

Mechanical and Aerospace Engineering Theses - Archive

Electrical usage in data center continues to grow and recent projection estimate that it contributes 2% in the electricity use in the U.S. One method of controlling the electrical usage during cooling is to reduce or eliminate mechanical cooling; however, using indirect/direct evaporative (IDE) cooling system is starting to be quite popular. IDE has limitations and in this paper we will show how phase change material (PCM) can extend the cooling capacity of IDE. The PCM has been used for temperature control operations. Latent heat storage is one of the most efficient ways of storing thermal energy in PCM. The …

Cfd Simulation And Design Optimization To Improve Cooling Performance Of Open Compute ‘Big Sur’ Server, Mangesh Mohan Dhadve

Mechanical and Aerospace Engineering Theses - Archive

In recent years, there have been a phenomenal increase in Artificial Intelligence and Machine Learning that require data collection, mining and using data sets to teach computers certain things to learn, analyze image and speech recognition. Machine Learning tasks require a lot of computing power to carry out numerous calculations. Therefore, most servers are powered by Graphics Processing Units (GPUs) instead of traditional CPUs. GPUs provide more computational throughput per dollar spent than traditional CPUs. Open Compute Servers forum has introduced the state-of-the-art machine learning servers “Big Sur” recently. Big Sur unit consists of 4OU (OpenU) chassis housing eight NVIDIA …

Analysis Of Composite Structures With Curvature Under Temperature Environment, Muthu Ram Prabhu Elenchezhian

Mechanical and Aerospace Engineering Theses - Archive

Composite structures are frequently exposed to environments with change in temperatures during their service life. The thermal behaviours of the laminated composite structures are more pronounced than that of the structures made of isotropic materials. For the structures under thermal environment, extensive studies have been conducted to investigate the induced thermal stresses and deformation of composite laminated plates by linear/non-linear analysis and composite structures by finite element analysis. The main focus of this study is concentrated on development of an analytical method for analyzing composite thin shells and/or moderate curved beam structures under temperature environment. This includes the derivation of …

Finite Element Analysis On Hybrid Boron-Carbon Composites, Amruta Rupa Nemani

Mechanical and Aerospace Engineering Theses - Archive

Adaptability to different situations and the ease of combination makes composites one of the most extensively used materials in the engineering industries. One of the ways of managing properties of composites is hybridization of different fibers in one composite. This work merely focuses upon the analysis of effective stiffness of Hybrid materials which is carried out using Finite Element Method. A series of models were experimented in a sequence by imposing various conditions on each of them. Boron and Carbon fibers were used primarily for these experiments because of their better compatibility than other combinations of fibers. Due to the …

Thermal Modeling Of 3-Dimensionally Stacked Dram Memory, Ratnesh Raj

Mechanical and Aerospace Engineering Theses - Archive

A large fraction of energy consumed in modern microelectronic devices and systems is taken up by memory access operations, which is expected to cause significant temperature rise. Since memory access operations are very short this is expected to inherently be a transient thermal phenomenon. Despite the critical importance of thermal management in microelectronics, not much work exists on understanding the nature of thermal transport during memory access operations. In this work, a mathematical model to predict the transient temperature rise within a 3D layered memory chip is presented. Most heat-generating memory access processes occur over a short timescale for which …

Numerical Simulation Of Flow In Fluidic Valves In Rotating Detonation Engines, Nandini Gopalakrishnan

Mechanical and Aerospace Engineering Theses - Archive

Rotating detonation engines (RDE) have received considerable research attention in recent times for use in propulsion systems. The cycle frequency of operation of an RDE can be as high as 10,000 Hz. Conventional mechanical valves cannot operate at such high frequencies, leading to the need for propellant injectors or valves with no moving parts. A fluidic valve is such a valve and is the focus of this study. The valve consists of an orifice connected to a constant area plenum cavity which operates at constant pressure. The fluidic valve supplies propellants to the detonation tube through the orifice. Hydrogen – …

Experimental And Computational Study Of Multi-Level Cooling Systems At Elevated Coolant Temperatures In Data Centers, Manasa Sahini

Mechanical and Aerospace Engineering Dissertations - Archive

Data centers house a variety of compute, storage, network IT hardware where equipment reliability is of utmost importance. Heat generated by the IT equipment can substantially reduce its service life if T_(J,Max), maximum temperature that the microelectronic device tolerates to guarantee reliable operation, is exceeded. Hence, data center rooms are bound to maintain continuous conditioning of the cooling medium. This approach often results in over-provisioned cooling systems. In 2014, U.S. Data center electricity consumption is about 1.8% of the total electrical energy in the country. Hence, data center power and cooling have become significant issues facing the IT industry. The …

Prediction Of Process-Induced Defects By Ply-Drops In The Design Optimization Of A Complex Composite Laminate, Sitanshu Pandya

Mechanical and Aerospace Engineering Theses - Archive

The objective of this work is to characterize manufacturing process-induced warping defects due to ply drops in composite laminates to guide composite laminate design. Composite laminate optimization seeks weight efficient models, but the process can also generate complex ply geometry, which compounds the challenges of the already rigorous composite laminate manufacturing process. Increased design complexity enhances the likelihood of manufacturing process-induced defects like warping; therefore, it is important to predict such defects in the design phase to make the product more efficient yet producible and thereby avoid such defects. This work study is manufacturing process induced warpage in complex composite …

Development Of Empirical And Virtual Tools For The Study Of Bicycle Safety, Brent Kostich

Masters Theses

Bicycles have been used as a form of non-motorized transportation for several hundred years. Recently, their use in the transportation realm has been reinvigorated because of growing population densities and efforts to improve environmental sustainability. However, a large deterrent for public use of the bicycle is concern over its level of safety in the transportation environment. The goal of this thesis is to develop two complementary research tools that advance the study of bicycle safety factors.

First, an instrumented probe bicycle (IPB) is constructed from the ground up. The bicycle is outfitted with an array of sensors that are integrated …