Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Structures and Materials

Series

2016

Institution
Keyword
Publication

Articles 1 - 8 of 8

Full-Text Articles in Engineering

Finite Element Simulation Of Pzt-Aided Interrogation Of Composite Laminates Exhibiting Damage, Amany Micheal, Yehia Bahei-El-Din Nov 2016

Finite Element Simulation Of Pzt-Aided Interrogation Of Composite Laminates Exhibiting Damage, Amany Micheal, Yehia Bahei-El-Din

Centre for Advanced Materials

Piezoelectricity has proved effective in capturing changes in structures caused by various damage mechanisms. In one approach, piezoelectric wafer active sensors (PWAS) are mounted on the surface of the host structure and utilized as both actuators and sensors to interrogate the structure and monitor its health. This is achieved by subjecting the PWAS to a transient electric pulse and reading the resulting voltage. Changes in the stiffness of the substrate due to structural damage affect the response of the PWAS, which could be correlated to integrity of the structure. Applying this technique to fibrous composite laminates encounters particular challenges due …

Go to article

Large Linear Magnetoresistance In Heavily-Doped Nb:Srtio3 Epitaxial Thin Films, Hyunwoo Jin, Keundong Lee, Seung-Hyub Baek, Jin-Sang Kim, Byung-Ki Cheong, Bae Ho Park, Sungwon Yoon, B. J. Suh, Changyoung Kim, Sung S. Ambrose Seo, Suyoun Lee Oct 2016

Large Linear Magnetoresistance In Heavily-Doped Nb:Srtio3 Epitaxial Thin Films, Hyunwoo Jin, Keundong Lee, Seung-Hyub Baek, Jin-Sang Kim, Byung-Ki Cheong, Bae Ho Park, Sungwon Yoon, B. J. Suh, Changyoung Kim, Sung S. Ambrose Seo, Suyoun Lee

Physics and Astronomy Faculty Publications

Interaction between electrons has long been a focused topic in condensed-matter physics since it has led to the discoveries of astonishing phenomena, for example, high-Tc superconductivity and colossal magnetoresistance (CMR) in strongly-correlated materials. In the study of strongly-correlated perovskite oxides, Nb-doped SrTiO3 (Nb:SrTiO3) has been a workhorse not only as a conducting substrate, but also as a host possessing high carrier mobility. In this work, we report the observations of large linear magnetoresistance (LMR) and the metal-to-insulator transition (MIT) induced by magnetic field in heavily-doped Nb:STO (SrNb0.2Ti0.8O3) epitaxial thin …

Go to article

From Xst To F-117a, Alan Brown Sep 2016

From Xst To F-117a, Alan Brown

ERAU Prescott Aviation History Program

Learn the remarkable story of stealth technology from the man often referred to as “Mr. Stealth.” From 1975-1989 Alan Brown was a member of Lockheed “Skunk Works”, becoming program manager & chief engineer for the F-117A Stealth Fighter from initial concept until the first production aircraft was built, 1978 to 1982. Hear the inside story of the many challenges faced by the stealth program and how they were solved.

Go to article

Thermal Transport Properties Of Dry Spun Carbon Nanotube Sheets, Heath E. Misak, James L. Rutledge, Eric D. Swenson, Shankar Mall Feb 2016

Thermal Transport Properties Of Dry Spun Carbon Nanotube Sheets, Heath E. Misak, James L. Rutledge, Eric D. Swenson, Shankar Mall

Faculty Publications

The thermal properties of carbon nanotube- (CNT-) sheet were explored and compared to copper in this study. The CNT-sheet was made from dry spinning CNTs into a nonwoven sheet. This nonwoven CNT-sheet has anisotropic properties in in-plane and out-of-plane directions. The in-plane direction has much higher thermal conductivity than the out-of-plane direction. The in-plane thermal conductivity was found by thermal flash analysis, and the out-of-plane thermal conductivity was found by a hot disk method. The thermal irradiative properties were examined and compared to thermal transport theory. The CNT-sheet was heated in the vacuum and the temperature was measured with an …

Go to article

Growth Control Of Oxygen Stoichiometry In Homoepitaxial Srtio3 Films By Pulsed Laser Epitaxy In High Vacuum, Ho Nyung Lee, Sung S. Ambrose Seo, Woo Seok Choi, Christopher M. Rouleau Jan 2016

Growth Control Of Oxygen Stoichiometry In Homoepitaxial Srtio3 Films By Pulsed Laser Epitaxy In High Vacuum, Ho Nyung Lee, Sung S. Ambrose Seo, Woo Seok Choi, Christopher M. Rouleau

Physics and Astronomy Faculty Publications

In many transition metal oxides, oxygen stoichiometry is one of the most critical parameters that plays a key role in determining the structural, physical, optical, and electrochemical properties of the material. However, controlling the growth to obtain high quality single crystal films having the right oxygen stoichiometry, especially in a high vacuum environment, has been viewed as a challenge. In this work, we show that, through proper control of the plume kinetic energy, stoichiometric crystalline films can be synthesized without generating oxygen defects even in high vacuum. We use a model homoepitaxial system of SrTiO3 (STO) thin films on …

Go to article

Expedient Airfield Runway Repair Using Folded Fiberglass Mat, Christopher Y. Tuan, Willaim C. Dass Jan 2016

Expedient Airfield Runway Repair Using Folded Fiberglass Mat, Christopher Y. Tuan, Willaim C. Dass

Department of Civil and Environmental Engineering: Faculty Publications

For expedient airfield runway repair, the US Air Force has developed a folded fiberglass mat to cover craters repaired with a well-compacted granular base material. The objective of this study was to evaluate the adequacy of using polymer plugs to anchor the mat to a repaired asphalt pavement for heavy aircraft operations. The effort consisted of materials testing, field experiments and analytical modeling. An 89,800-kg (198,000-pound) load cart having the footprint of a single C-5 main gear was pulled on a mat with wheels locked to simulate full braking forces. Anchor bushings were instrumented to measure anchor loads. A simplified …

Go to article

Distinction In Corrosion Resistance Of Selective Laser Melted Ti-6al-4v Alloy On Different Planes, Nianwei Dai, Laichang Zhang, Junxi Zhang, Xin Zhang, Qingzhao Ni, Yang Chen Jan 2016

Distinction In Corrosion Resistance Of Selective Laser Melted Ti-6al-4v Alloy On Different Planes, Nianwei Dai, Laichang Zhang, Junxi Zhang, Xin Zhang, Qingzhao Ni, Yang Chen

Research outputs 2014 to 2021

Electrochemical measurements and microstructural analysis were performed to study the corrosion resistance of different planes of Ti-6Al-4V alloy manufactured by selective laser melting (SLM). The electrochemical results suggest that its XY-plane possesses a better corrosion resistance compared to XZ-plane in 1 M HCl solution, in spite of slight difference in 3.5 wt.% NaCl solution, suggesting that the different planes exhibit more pronounced distinction in corrosion resistance in harsher solution system. The inferior corrosion resistance of XZ-plane is attributed to the presence of more α′ martensite and less β-Ti phase in microstructure for XZ-plane than for XY-plane of the SLM-produced Ti-6Al-4V …

Go to article

Constructal Alkaline Membrane Fuel Cell (Amfc) Design, E. M. Sommer, J. V. C. Vargas, Lauber De Souza Martins, J. C. Ordonez Jan 2016

Constructal Alkaline Membrane Fuel Cell (Amfc) Design, E. M. Sommer, J. V. C. Vargas, Lauber De Souza Martins, J. C. Ordonez

Faculty Publications

This paper introduces a structured procedure to optimize the internal structure (relative sizes, spacing) and external shape (aspect ratios) of a single alkaline membrane fuel cell so that net power is maximized. The optimization of flow geometry is conducted for the smallest (elemental) level of a fuel cell stack, i.e., the single alkaline membrane fuel cell, which is modeled as a unidirectional flow system. The polarization curve, total and net power, and efficiency are obtained as functions of temperature, pressure, electrolyte solution concentration (KOH), geometry and operating parameters. The optimization is subjected to fixed total volume. There are two levels …

Go to article