Traction-Separation Relationships For Hydrogen-Induced Grain Boundary Embrittlement In Nickel Via Molecular Dynamics Simulations, 2015 University of Arkansas, Fayetteville
Traction-Separation Relationships For Hydrogen-Induced Grain Boundary Embrittlement In Nickel Via Molecular Dynamics Simulations, Wesley Allen Barrows
Graduate Theses and Dissertations
The deleterious effects of atomic and molecular hydrogen on the mechanical properties of metals have long been observed. Although several theories exist describing the mechanisms by which hydrogen negatively influences the failure of materials, a consensus has yet to be reached regarding the exact mechanism or combination of mechanisms. Two mechanisms have gained support in explaining hydrogen’s degradative role in non-hydride forming metals: hydrogen-enhanced localized plasticity and hydrogen-enhanced decohesion. Yet, the interplay between these mechanisms and microstructure in metallic materials has not been explained. Accordingly, for this thesis, the three main objectives are: (i) to develop a numerical methodology to …
Computational Fluid Dynamics Study Of Balloon System Tethered To A Stratosail, 2015 National University of Signapore
Computational Fluid Dynamics Study Of Balloon System Tethered To A Stratosail, Jayakanth Loganathan, Kian-Meng Lim, Heow Pueh Lee, Boo Cheong Khoo
2017 Academic High Altitude Conference
In this paper, we present a numerical study of a stratospheric balloon system tethered to a passive device, known as the Stratosail, for station-keeping operation. For scientific applications, stratospheric balloons that operate at altitudes between 15 and 20 km will need to maintain station over a fixed point above the earth for a prescribed period of time. This is a challenging problem due to the limitation of payloads and lack of an energy source. The present study uses computational fluid dynamics (CFD) simulations to analyze the drift velocity of such a balloon-Stratosail system under typical wind conditions in the stratosphere. …
Human Powered Vehicle Frame Design, 2015 California Polytechnic State University, San Luis Obispo
Human Powered Vehicle Frame Design, Matthew S. Allen, Peter B. Aumann, Trent J. Hellmann
Mechanical Engineering
This report discusses the Human Powered Vehicle Frame Design senior project’s contributions to the design, manufacture, testing, and competition of the Cal Poly Human Powered Vehicle Club’s 2015 vehicle, Sweet Phoenix. The project’s guiding rules and timeline were dictated by the ASME Human Powered Vehicle Challenge (HPVC), held in April 2015. The Club sought to improve upon its previous vehicle, Aria, which suffered from a range of faults including a catastrophic structural failure at the 2014 HPVC. Largely in response to this failure, the Frame Design project’s major focus was Sweet Phoenix’s frame, from concept to manufacturing. During the design …
Freedom Ski, 2015 California Polytechnic State University - San Luis Obispo
Freedom Ski, Toby A. Goldsteinholm, Ashley Scharff, Justin Satnick, Markus Rutner
Mechanical Engineering
The current availability of water skis for people who are paraplegic or quadriplegic is very limited. The aim of our project is to design a system that improves upon the current models of specialized water skis. Our intent is to create a waterski system that is structurally stable and handles responsively, in order to ensure that anyone is capable of effectively using our system to waterski.
The main client of our project is Quality of Life Plus, an organization that aims to aid veterans of the armed forces who have physical disabilities to still enjoy a good quality of life. …
Low Profile Guitar Tuner, 2015 California Polytechnic State University, San Luis Obispo
Low Profile Guitar Tuner, Yaniv Goldobin, Christer Sundstrom, Samuel Cheng
Electrical Engineering
To develop an innovative guitar tuner with emphasis on low profile design
Power Maximization Of A Three-Phase Hydrokinetic Turbine, 2015 Linfield College
Power Maximization Of A Three-Phase Hydrokinetic Turbine, Matthew Carleson
Senior Theses
As Earth`s expendable resources dwindle, the need for alternative, renewable energy sources grows. Out of this need, an old favorite source is rising in popularity: small water turbines. Water-driven turbines first began as a means for turning mills and eventually evolved into massive dams that can power whole regions. This project focused on the construction of, and testing the properties of, a small pico-hydro power turbine. By using compressed air to drive the turbine, a representation of the peak power output was measured, serving as a basis for determining the value of pico-power systems in regards to the world`s current …
Energy Selective Neutron Imaging For The Characterization Of Polycrystalline Materials, 2015 University of Tennessee - Knoxville
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 …
Using Controlled Curing In A Custom Stereolithography-Based 3d Printing Machine To Obtain Graded Property Variations, 2015 University of Nebraska-Lincoln
Using Controlled Curing In A Custom Stereolithography-Based 3d Printing Machine To Obtain Graded Property Variations, Evan S. Schwahn
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
In an effort to construct materially graded parts, a strategy was studied that is based on varying ratios of interpenetrating polymer networks (IPNs) in a manner that can be adapted to 3D printing. Using IPNs has the benefit of allowing access to a broad range of property variation. The strategy used involves controlled partial curing of the first network, followed by washing of that network to remove uncured components, then swelling of the structure with a second polymer component and curing.
This method was utilized to control final IPN properties by controlling the extent of crosslinking of the initial network, …
Effects Of Temperature Change On Interfacial Delamination In Thermal Barrier Coatings, 2015 University of Central Florida
Effects Of Temperature Change On Interfacial Delamination In Thermal Barrier Coatings, Hossein Ebrahimi, Soheil Nakhodchi
Hossein Ebrahimi
No abstract provided.
In-Vivo Corrosion And Fretting Of Modular Ti-6al-4v/Co-Cr-Mo Hip Prostheses: The Influence Of Microstructure And Design Parameters, 2015 Florida International University
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 micromotion were also shown …
Design, Fabrication, And Properties Of 2-2 Connectivity Cement/Polymer Based Piezoelectric Composites With Varied Piezoelectric Phase Distribution, 2015 University of South Carolina, United States
Design, Fabrication, And Properties Of 2-2 Connectivity Cement/Polymer Based Piezoelectric Composites With Varied Piezoelectric Phase Distribution, Xu Dongyu, Cheng Xin, Sourav Banerjee, Huang Shifeng
Sourav Banerjee
The laminated 2-2 connectivity cement/polymer based piezoelectric composites with variedpiezoelectric phase distribution were fabricated by employing Lead Zirconium Titanate ceramicas active phase, and mixture of cement powder, epoxy resin, and hardener as matrix phase with a mass proportion of 4:4:1. The dielectric, piezoelectric, and electromechanical coupling properties of the composites were studied. The composites with large total volume fraction ofpiezoelectric phase have large piezoelectric strain constant and relative permittivity, and thepiezoelectric and dielectric properties of the composites are independent of the dimensional variations of the piezoelectric ceramic layer. The composites with small total volume fraction of piezoelectric phase have large …
Elastic Wave Field Computation In Multilayered Nonplanar Solid Structures: A Mesh-Free Semianalytical Approach, 2015 University of South Carolina, United States
Elastic Wave Field Computation In Multilayered Nonplanar Solid Structures: A Mesh-Free Semianalytical Approach, Sourav Banerjee, Tribikram Kundu
Sourav Banerjee
Multilayered solid structures made of isotropic, transversely isotropic, or general anisotropic materials are frequently used in aerospace, mechanical, and civil structures. Ultrasonic fields developed in such structures by finite size transducers simulating actual experiments in laboratories or in the field have not been rigorously studied. Several attempts to compute the ultrasonic field inside solid media have been made based on approximate paraxial methods like the classical ray tracing and multi-Gaussian beam models. These approximate methods have several limitations. A new semianalytical method is adopted in this article to model elastic wave field in multilayered solid structures with planar or nonplanar …
Phonon Confinement Using Spirally Designed Elastic Resonators In Discrete Continuum, 2015 University of South Carolina, United States
Phonon Confinement Using Spirally Designed Elastic Resonators In Discrete Continuum, Sourav Banerjee, Raiz U. Ahmed
Sourav Banerjee
Periodic and chiral orientation of microstructures, here we call phononic crystals, have extraordinary capabilities to facilitate the innovative design of new generation metamaterials. Periodic arrangements of phononic crystals are capable of opening portals of non-passing, non-dispersive mechanical waves. Defying conventional design of regular periodicity, in this paper spirally periodic but chiral orientation of resonators are envisioned. Dynamics of the spirally connected resonators and the acoustic wave propagation through the spirally connected multiple local resonators are studied using fundamental physics. In present study the spiral systems with local resonators are assumed to be discrete media immersed in fluid. In this paper …
Parker Hannifin Chainless Challenge 2014-15 Senior Design Project, 2015 California Polytechnic State University - San Luis Obispo
Parker Hannifin Chainless Challenge 2014-15 Senior Design Project, Matt Pallotta, Nathan Klammer, Kemper Whaley, Jack Rechtin
Mechanical Engineering
California Polytechnic State University has been invited to compete in the Parker Hannifin Chainless Challenge Competition in 2014-15. Cal Poly has chosen a team of mechanical engineering students to take part. We have named our team “Bike Under Pressure” and all references as such refer to the team.
The challenge is to build a bicycle which does not have a solid mechanical connection between the power input of the rider to the power output of the wheel(s). After conducting research into different previous designs and brainstorming designs of their own, Bike Under Pressure developed two conceptual designs. One design featured …
Fully Electronic Method Of Measuring Post-Release Gap And Gradient/Residual Stress Of A Mems Cantilever, 2015 Purdue University
Fully Electronic Method Of Measuring Post-Release Gap And Gradient/Residual Stress Of A Mems Cantilever, Andrew Stephen Kovacs
Open Access Dissertations
Smartphones and other wireless devices have become ubiquitous over the past decade, and the RF front-end inside of them has become more complex and disproportionately consumes more power compared to other components. Micro-electromechanical systems (MEMS) have a huge potential to reduce these problems while simultaneously offering superior performance compared to current leading-edge technology. However, MEMS technology has difficulty transitioning from the lab to large-scale manufacturing due to the unpredictability of device lifetime and manufacturability issues. This can be mitigated by investigating how critical material or physical parameters (gap, stress, Young's modulus, material thickness, etc.) vary from manufacturing uncertainties and how …
Asymptotic Modelling Of A Thermopiezoelastic Anisotropic Smart Plate, 2015 Purdue University
Asymptotic Modelling Of A Thermopiezoelastic Anisotropic Smart Plate, Yufei Long
Open Access Theses
Motivated by the requirement of modelling for space flexible reflectors as well as other applications of plate structures in engineering, a general anisotropic laminated thin plate model and a monoclinic Reissner-Mindlin plate model with thermal deformation, two-way coupled piezoelectric effect and pyroelectric effect is constructed using the variational asymptotic method, without any ad hoc assumptions. Total potential energy contains strain energy, electric potential energy and energy caused by temperature change. Three-dimensional strain field is built based on the concept of warping function and decomposition of the rotation tensor. The feature of small thickness and large in-plane dimension of plate structure …
Effects Of Nano Additives On Hydrogen Storage Behavior Of The Multinary Complex Hydride Libh4/Linh2/Mgh2., 2015 University of South Carolina - Columbia
Effects Of Nano Additives On Hydrogen Storage Behavior Of The Multinary Complex Hydride Libh4/Linh2/Mgh2., Sesha Srinivasan, Michael Niemann, Jason Hattrick-Simpers, Kimberly Mcgrath, Prakash Sharma, D. Goswami, Elias Stefanakos
Jason R. Hattrick-Simpers
No abstract provided.
Exploration Of Magnetoelectric Thin-Film Sensors Using Supperlattice Composition Spreads, 2015 University of South Carolina - Columbia
Exploration Of Magnetoelectric Thin-Film Sensors Using Supperlattice Composition Spreads, K.-S. Chang, M. Aronova, C. Gao, C. Lin, Jason Hattrick-Simpers, M. Murakami, I. Takeuchi
Jason R. Hattrick-Simpers
No abstract provided.
Acoustic Manipulation And Alignment Of Particles For Applications In Separation, Micro-Templating, And Device Fabrication, 2015 Florida International University
Acoustic Manipulation And Alignment Of Particles For Applications In Separation, Micro-Templating, And Device Fabrication, Kamran Moradi
FIU Electronic Theses and Dissertations
This dissertation studies the manipulation of particles using acoustic stimulation for applications in microfluidics and templating of devices. The term particle is used here to denote any solid, liquid or gaseous material that has properties, which are distinct from the fluid in which it is suspended. Manipulation means to take over the movements of the particles and to position them in specified locations.
Using devices, microfabricated out of silicon, the behavior of particles under the acoustic stimulation was studied with the main purpose of aligning the particles at either low-pressure zones, known as the nodes or high-pressure zones, known as …
Banded Microstructure In 2024-T351 And 2524-T351 Aluminum Friction Stir Welds: Part Ii. Mechanical Characterization, 2015 University of South Carolina - Columbia
Banded Microstructure In 2024-T351 And 2524-T351 Aluminum Friction Stir Welds: Part Ii. Mechanical Characterization, Michael Sutton, Bangcheng Yang, Anthony Reynolds, Junhui Yan
Anthony P. Reynolds
No abstract provided.