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Articles 31 - 60 of 108

Full-Text Articles in Mechanical Engineering

Development Of Novel, Microscale Fracture Toughness Testing For Adhesives, Dillon S. Watring Jun 2017

Development Of Novel, Microscale Fracture Toughness Testing For Adhesives, Dillon S. Watring

FIU Electronic Theses and Dissertations

The purpose of this thesis was to develop microscale fracture toughness tests to be performed in situ based off previously used macroscale fracture toughness tests. The thesis also was to use these tests to perform in situ analysis and imaging of reinforced adhesives during crack propagation. Two different fracture toughness tests were developed for this thesis through developing fixtures and sample geometry. A microscale double cantilever beam (DCB) test was developed for mode I fracture (opening mode). A microscale end notch flexure (ENF) test was developed for mode II fracture (sliding mode).

Three different types of materials were used as ...


Cellulose–Hemicellulose And Cellulose–Lignin Interactions During Fast Pyrolysis, Jing Zhang, Yong S. Choi, Chang G. Yoo, Tae H. Kim, Robert C. Brown, Brent H. Shanks Jun 2017

Cellulose–Hemicellulose And Cellulose–Lignin Interactions During Fast Pyrolysis, Jing Zhang, Yong S. Choi, Chang G. Yoo, Tae H. Kim, Robert C. Brown, Brent H. Shanks

Brent H. Shanks

Previously, the primary product distribution resulting from fast pyrolysis of cellulose, hemicellulose, and lignin was quantified. This study extends the analysis to the examinations of interactions between cellulose–hemicellulose and cellulose–lignin, which were determined by comparing the pyrolysis products from their native mixture, physical mixture, and superposition of individual components. Negligible interactions were found for both binary physical mixtures. For the native cellulose–hemicellulose mixture, no significant interaction was identified either. In the case of the native cellulose–lignin mixture, herbaceous biomass exhibited an apparent interaction, represented by diminished yield of levoglucosan and enhanced yield of low molecular weight ...


Effect Of Composition And Build Direction On Additively Manufactured Hastelloy X Alloys, Justin A. Spitzer, Jeffrey T. Schloetter, Sarah Zerga Jun 2017

Effect Of Composition And Build Direction On Additively Manufactured Hastelloy X Alloys, Justin A. Spitzer, Jeffrey T. Schloetter, Sarah Zerga

Materials Engineering

Microcracking has caused premature failure and reduction in properties in additively manufactured (AM) Hastelloy X. The purpose of this research is to meet or exceed the mechanical properties of wrought Hastelloy X by modifying the composition and build direction of Hastelloy X manufactured using Direct Metal Deposition (DMD). Tensile testing, scanning electron microscopy (SEM), and metallography were performed on the samples. ANOVA was used to analyze the dependence that the properties had on build direction and composition. The nominal composition wrought samples had a yield strength of 310.1 MPa and a 60.79% Elongation. Alloy P60-X18 in a horizontal ...


An Experimental And Numerical Study Of Nanomechanical Behavior Of Hard/Soft Multilayered Coatings, Benigno Sandoval May 2017

An Experimental And Numerical Study Of Nanomechanical Behavior Of Hard/Soft Multilayered Coatings, Benigno Sandoval

Mechanical Engineering ETDs

Multilayer thin film composites, sometimes referred to as nanolaminates, have emerged as an important subset of materials with novel, and often tunable, properties such as high strength, high toughness, and resistance to wear or corrosion. Often fabricated using alternating layers of two or more materials, these multilayer thin film coatings are typically expensive and time intensive to fabricate and characterize and exhibit novel responses to nanomechanical testing such as plasticity during unloading. This thesis explores the nanoindentation response of hard/soft multilayer coatings through examination of the optical coating Al/SiC and similar coating Al/SiO2. Instrumented indentation was used ...


Peridynamic Models For Fatigue And Fracture In Isotropic And In Polycrystalline Materials, Guanfeng Zhang May 2017

Peridynamic Models For Fatigue And Fracture In Isotropic And In Polycrystalline Materials, Guanfeng Zhang

Mechanical (and Materials) Engineering -- Dissertations, Theses, and Student Research

To improve design and reliability, extensive efforts has been devoted to understanding damage and failure of materials and structures using numerical simulation, as a complement of theory and experiment. In this thesis, peridynamics is adopted to study fatigue and dynamic failure problems.

Fatigue is a major failure mode in engineering structures. Predicting fracture/failure under cyclic loading is a challenging problem. Classical model cannot directly be applied to problems with discontinuities. A peridynamic model is adopted in this work because of important advantages of peridynamics in allowing autonomous crack initiation and propagation. A recently proposed peridynamic fatigue crack model is ...


Redesign Of Computer Keyboards For Hospital And Consumer Use, Kent Williams, Brian Jensen, Anton Bowden Feb 2017

Redesign Of Computer Keyboards For Hospital And Consumer Use, Kent Williams, Brian Jensen, Anton Bowden

Biomedical Engineering Western Regional Conference

Application of carbon nanotube coatings to computer keyboards in order to reduce the spread of bacteria in hospitals and homes.

Keywords: carbon nanotube, bacteria, antimicrobial, keyboard, design, MRSA, biofilm


Composite Cold Expansion Tooling, Andrew Amos Jan 2017

Composite Cold Expansion Tooling, Andrew Amos

All Undergraduate Projects

In the world of aircraft manufacturing, cold expansion products literally hold these aircraft together. The problem faced today is that the Little Brute Hydraulic Puller designed and built by Fatigue Technology Inc. is a handheld steel hydraulic cylinder that is heavy and expensive to produce. In a market that demands continuous improvement, there is a constant push to make the product cheaper, better and lighter. In order to accomplish this demand a composite tube will be substituted in the design as the primary pressure cylinder instead of the traditional steel pressure cylinder in order to create a lighter and cheaper ...


A Simple Embedded Atom Potential For Palladium-Hydride, Yang Zhang Jan 2017

A Simple Embedded Atom Potential For Palladium-Hydride, Yang Zhang

Theses, Dissertations and Capstones

Metal Hydride systems are an important research topic in material science because of their many practical, industrial, and scientific applications. Therefore, the development of reliable and efficient interatomic potentials for metal hydrides systems, to be utilized in atomistic modeling, can be of great value in accelerating the research in this field. The embedded-atom method (EAM), based on the density functional theory (DFT), has the advantage of being both computationally efficient and being well suited for modeling metal hydride systems. In this work, the author has developed an efficient EAM potential for the palladium hydride (Pd-H) alloy system. Contrary to previously ...


Study On Criterion Of Fabricating Columnar Dendrite Structure Dz466 Superalloy Based On Lmc Process, Xun Sun Oct 2016

Study On Criterion Of Fabricating Columnar Dendrite Structure Dz466 Superalloy Based On Lmc Process, Xun Sun

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.


The Influence Of Welding Parameters On Initial Instability Dynamics During Solidification, Fengyi Yu, Yanhong Wei, Xiaohong Zhan Oct 2016

The Influence Of Welding Parameters On Initial Instability Dynamics During Solidification, Fengyi Yu, Yanhong Wei, Xiaohong Zhan

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.


Prediction Of The Graphite Morphology And Nodularity Based On The Quantitative Sample Solidification Cooling Curves, Han Ye, Chao Li, Qingyou Han, Xiangjie Yang Oct 2016

Prediction Of The Graphite Morphology And Nodularity Based On The Quantitative Sample Solidification Cooling Curves, Han Ye, Chao Li, Qingyou Han, Xiangjie Yang

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.


Temperature Filed Numerical Simulation Of Laser Welding For Ta15 Titanium Alloy By Coupling Thermal And Phase Transformation, Wenmin Ou, Yanhong Wei, Xiaohong Zhan, Gaoyang Mi Oct 2016

Temperature Filed Numerical Simulation Of Laser Welding For Ta15 Titanium Alloy By Coupling Thermal And Phase Transformation, Wenmin Ou, Yanhong Wei, Xiaohong Zhan, Gaoyang Mi

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.


Simulation On The Sealing Of Aluminum Ball Joint, Haobin Tian, Xiaohang Liu, Xuelei Li, Jun Feng Oct 2016

Simulation On The Sealing Of Aluminum Ball Joint, Haobin Tian, Xiaohang Liu, Xuelei Li, Jun Feng

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.


Modeling And Simulation Of Dendrite And Porosity Evolution During Solidification In The Molten Pool Of Al–Cu Alloys, Cheng Gu, Yanhong Wei, Xiaohong Zhan Oct 2016

Modeling And Simulation Of Dendrite And Porosity Evolution During Solidification In The Molten Pool Of Al–Cu Alloys, Cheng Gu, Yanhong Wei, Xiaohong Zhan

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.


Fe Simulation For Accuracy Evolution And Control In Hot Forging Of Non-Circular Spur Bevel Gear, Wuhao Zhuang, Xinghui Han Oct 2016

Fe Simulation For Accuracy Evolution And Control In Hot Forging Of Non-Circular Spur Bevel Gear, Wuhao Zhuang, Xinghui Han

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.


High Strain Rate Experiments Of Energetic Material Binder, Roberto Rangel Mendoza, Michael Harr, Weinong Chen Aug 2016

High Strain Rate Experiments Of Energetic Material Binder, Roberto Rangel Mendoza, Michael Harr, Weinong Chen

The Summer Undergraduate Research Fellowship (SURF) Symposium

Energetic materials, in particular HMX, is widely used in many applications as polymer bonded explosives (PBX) and rocket propellant. However, when damaged, HMX is known to be an unstable substance which renders it a hazardous material and in some cases unreliable. Finding critical mechanical conditions at high rates that render various forms of energetic materials as unreliable would be vital to understand the effects that vibrations and compression forces have on energetic materials. A better understanding would enable the ability to develop improvements in the manufacturing of PBX and rocker propellant. The method utilized to evaluate the mechanical properties of ...


Metals Additive Manufacturing Powder Aging Characterization, Thomas Russell Lovejoy, Nicholas Karl Muetterties, David Takeo Otsu Jun 2016

Metals Additive Manufacturing Powder Aging Characterization, Thomas Russell Lovejoy, Nicholas Karl Muetterties, David Takeo Otsu

Mechanical Engineering

The metallic additive manufacturing process known as selective laser melting requires highly spherical, normally distributed powder with diameters in the range of 10 to 50 microns. Previous observations have shown a degradation in powder quality over time, resulting in unwanted characteristics in the final printed parts. 21-6-9 stainless steel powder was used to fabricate test parts, with leftover powder recycled back into the machine. Powder samples and test specimens were characterized to observe changes across build cycles. Few changes were observed in the physical and mechanical properties of the specimens, however, there were indications of chemical changes across cycles. Potential ...


Phased Array Ultrasonic Inspection Method For Homogeneous Tube Inspection Over Wide Oblique Angle Range, Benoit Lepage, Guillaume Painchaud-April Jan 2016

Phased Array Ultrasonic Inspection Method For Homogeneous Tube Inspection Over Wide Oblique Angle Range, Benoit Lepage, Guillaume Painchaud-April

Review of Progress in Quantitative Nondestructive Evaluation

As seamless tube manufacturers push quality requirements for their products, automated phased array Rotating Tube Inspection Systems (RTIS) are now required to provide continuous NDE detection performances over a wide angular range of oblique flaws. One major impact of this new reality is a paradigm shift for the calibration method driven by the requirement to meet homogeneous detection over broad oblique flaw angle intervals, whereas standard practice only requires calibration at specific discrete angles. An innovative method specifically designed to obtain high productivity and homogeneous inspection measurements over an oblique flaw range extending from -45 to 45 degrees is presented ...


Multi-Use Fireline Handtool, Bruce W. Bernard Jr Jan 2016

Multi-Use Fireline Handtool, Bruce W. Bernard Jr

All Undergraduate Projects

A wildland firefighter is a valuable resource to protecting public lands and managing fuels. The many hand tools used by firefighters aid in their ability to complete any required tasks effectively. Several of the tools available are specially purposed for individually grubbing, scraping, or liming. A small squad of firefighters could become a more effective resource if the tools they carried could perform several of these purposes as one single tool. To improve the effectiveness of an individual on the fireline a multi-use hand tool was designed to include an axe for liming and a heavy duty scraper for grubbing ...


Mechanical Testing Of Fused Filament 3-D Printed Components For Distributed Manufacturing, Nagendra Gautam Tanikella Jan 2016

Mechanical Testing Of Fused Filament 3-D Printed Components For Distributed Manufacturing, Nagendra Gautam Tanikella

Dissertations, Master's Theses and Master's Reports

Fused filament fabrication (FFF)-based open-source 3-D printers offer the potential of decentralized manufacturing both in developing and developed countries. Unfortunately, a severe lack of data and standards relating to material properties and printed components limit this potential. This thesis first investigates the mechanical properties of a wide-range of FFF materials and provides a database of mechanical strength of the materials tested. The results demonstrate that the tensile strength of a 3-D printed specimen depends largely on the mass of the specimen, which provides a means to estimate the strength of 3-D printed components. Then this information is used to ...


Three-Dimensional Microstructural Effects On Multi-Site Fatigue Crack Nucleation Behaviors Of High Strength Aluminum Alloys, Yan Jin Jan 2016

Three-Dimensional Microstructural Effects On Multi-Site Fatigue Crack Nucleation Behaviors Of High Strength Aluminum Alloys, Yan Jin

Theses and Dissertations--Chemical and Materials Engineering

An experimental method was further developed to quantify the anisotropy of multi-site fatigue crack initiation behaviors in high strength Al alloys by four-point bend fatigue testing under stress control. In this method, fatigue crack initiation sites (fatigue weak-links, FWLs) were measured on the sample surface at different cyclic stress levels. The FWL density in an alloy could be best described using a three-parameter Weibull function of stress, though other types of sigmoidal functions might also be used to quantify the relationship between FWL density and stress. The strength distribution of the FWLs was derived from the Weibull function determined by ...


Energy Selective Neutron Imaging For The Characterization Of Polycrystalline Materials, Robin Woracek May 2015

Energy Selective Neutron Imaging For The Characterization Of Polycrystalline Materials, Robin Woracek

Doctoral Dissertations

This multipart dissertation focuses on the development and evaluation of advanced methods for material testing and characterization using neutron diffraction and imaging techniques. A major focus is on exploiting diffraction contrast in energy selective neutron imaging (often referred to as Bragg edge imaging) for strain and phase mapping of crystalline materials. The dissertation also evaluates the use of neutron diffraction to study the effect of multi-axial loading, in particular the role of applying directly shear strains from the application of torsion. A portable tension-torsion-tomography loading system has been developed for in-situ measurements and integrated at major user facilities around the ...


In-Vivo Corrosion And Fretting Of Modular Ti-6al-4v/Co-Cr-Mo Hip Prostheses: The Influence Of Microstructure And Design Parameters, Jose Luis Gonzalez Jr Apr 2015

In-Vivo Corrosion And Fretting Of Modular Ti-6al-4v/Co-Cr-Mo Hip Prostheses: The Influence Of Microstructure And Design Parameters, Jose Luis Gonzalez Jr

FIU Electronic Theses and Dissertations

The purpose of this study was to evaluate the incidence of corrosion and fretting in 48 retrieved titanium-6aluminum-4vanadium and/or cobalt-chromium-molybdenum modular total hip prosthesis with respect to alloy material microstructure and design parameters. The results revealed vastly different performance results for the wide array of microstructures examined. Severe corrosion/fretting was seen in 100% of as-cast, 24% of low carbon wrought, 9% of high carbon wrought and 5% of solution heat treated cobalt-chrome. Severe corrosion/fretting was observed in 60% of Ti-6Al-4V components. Design features which allow for fluid entry and stagnation, amplification of contact pressure and/or increased ...


Characterization Of High-Pressure-Die-Cast Magnesium Alloy Am60, Hooman Baghaei Anaraki Mar 2015

Characterization Of High-Pressure-Die-Cast Magnesium Alloy Am60, Hooman Baghaei Anaraki

Electronic Thesis and Dissertation Repository

The primary goal of this study is the characterization of high pressure die cast magnesium alloys AM60 so that the failure model which is proposed by J.Weiler can be validated for two new castings. The input variables of failure model can be determined by characterization of different regions within the castings. Based on the location of gate system, the desired regions are identified across both castings and tensile specimens are extracted from various regions. Therefore the local mechanical properties are determined, and fracture strain of samples ranges from 1.2 to 9.5%. The area fraction of porosities and ...


Nanoindentation Of A Zinc Metal Soap Mixture For Use In A Laser Printer, George A. Nimick Jan 2015

Nanoindentation Of A Zinc Metal Soap Mixture For Use In A Laser Printer, George A. Nimick

Theses and Dissertations--Chemical and Materials Engineering

At the start of this project, the possible choices of metal soaps had already been narrowed to include some of the zinc soaps used in this project. These zinc soaps are mixtures of zinc stearate and zinc palmitate of varying ratios purchased from a supplier. Zinc soap was chosen as result of its common use in various industries as a lubricant and mold release, which implied potential benefits in an electrophotographic printing system. These potential benefits include, but are not limited to, a more efficient transfer from a photoconductive drum and protection of the drum from mechanical and chemical degradation ...


A Study To Evaluate Non-Uniform Phase Maps In Shape Memory Alloys Using Finite Element Method, Naren Motte Jan 2015

A Study To Evaluate Non-Uniform Phase Maps In Shape Memory Alloys Using Finite Element Method, Naren Motte

Theses and Dissertations

The unique thermo-mechanical behavior of Shape Memory Alloys (SMAs), such as their ability to recover the original shape upon heating or being able to tolerate large deformations without undergoing plastic transformations, makes them a good choice for actuators.

This work studies their application in the aerospace and defense industries where SMA components can serve as release mechanisms for gates of enclosures that have to be deployed remotely. This work provides a novel approach in evaluating the stress and heat induced change of phase in a SMA, in terms of the transformation strain tensor. In particular, the FEA tool

ANSYS has ...


Effects Of Magnetic Field On The Shape Memory Behavior Of Single And Polycrystalline Magnetic Shape Memory Alloys, Ali S. Turabi Jan 2015

Effects Of Magnetic Field On The Shape Memory Behavior Of Single And Polycrystalline Magnetic Shape Memory Alloys, Ali S. Turabi

Theses and Dissertations--Mechanical Engineering

Magnetic Shape Memory Alloys (MSMAs) have the unique ability to change their shape within a magnetic field, or in the presence of stress and a change in temperature. MSMAs have been widely investigated in the past decade due to their ability to demonstrate large magnetic field induced strain and higher frequency response than conventional shape memory alloys (SMAs). NiMn-based alloys are the workhorse of metamagnetic shape memory alloys since they are able to exhibit magnetic field induced phase transformation. In these alloys, martensite and austenite phases have different magnetization behavior, such as the parent phase can be ferromagnetic and martensite ...


Shape Memory Behavior Of Single Crystal And Polycrystalline Ni-Rich Nitihf High Temperature Shape Memory Alloys, Sayed M. Saghaian Jan 2015

Shape Memory Behavior Of Single Crystal And Polycrystalline Ni-Rich Nitihf High Temperature Shape Memory Alloys, Sayed M. Saghaian

Theses and Dissertations--Mechanical Engineering

NiTiHf shape memory alloys have been receiving considerable attention for high temperature and high strength applications since they could have transformation temperatures above 100 °C, shape memory effect under high stress (above 500 MPa) and superelasticity at high temperatures. Moreover, their shape memory properties can be tailored by microstructural engineering. However, NiTiHf alloys have some drawbacks such as low ductility and high work hardening in stress induced martensite transformation region. In order to overcome these limitations, studies have been focused on microstructural engineering by aging, alloying and processing.

Shape memory properties and microstructure of four Ni-rich NiTiHf alloys (Ni50.3Ti29 ...


Increasing Efficiency Of Thermal Desalination, Jarrod A. Edwards, Mackinzie Washington, Chan Jung, Ben Garrison Jan 2015

Increasing Efficiency Of Thermal Desalination, Jarrod A. Edwards, Mackinzie Washington, Chan Jung, Ben Garrison

Chancellor’s Honors Program Projects

No abstract provided.


Cellulose–Hemicellulose And Cellulose–Lignin Interactions During Fast Pyrolysis, Jing Zhang, Yong S. Choi, Chang G. Yoo, Tae H. Kim, Robert C. Brown, Brent H. Shanks Jan 2015

Cellulose–Hemicellulose And Cellulose–Lignin Interactions During Fast Pyrolysis, Jing Zhang, Yong S. Choi, Chang G. Yoo, Tae H. Kim, Robert C. Brown, Brent H. Shanks

Chemical and Biological Engineering Publications

Previously, the primary product distribution resulting from fast pyrolysis of cellulose, hemicellulose, and lignin was quantified. This study extends the analysis to the examinations of interactions between cellulose–hemicellulose and cellulose–lignin, which were determined by comparing the pyrolysis products from their native mixture, physical mixture, and superposition of individual components. Negligible interactions were found for both binary physical mixtures. For the native cellulose–hemicellulose mixture, no significant interaction was identified either. In the case of the native cellulose–lignin mixture, herbaceous biomass exhibited an apparent interaction, represented by diminished yield of levoglucosan and enhanced yield of low molecular weight ...