Bulletin of the American Physical Society
80th Annual Meeting of the APS Southeastern Section
Volume 58, Number 17
Wednesday–Saturday, November 20–23, 2013; Bowling Green, Kentucky
Session DE: Applied Physics |
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Chair: Farhad Ashrafzadeh, Western Kentucky University Room: 5 |
Thursday, November 21, 2013 1:30PM - 1:42PM |
DE.00001: Analysis of residual stress in welds using electronic speckle-pattern interferometry (ESPI) Sean Craft, Saugat Ghimire, Shun Hasagawa, Sanichiro Yoshida, Tomohiro Sasaki, Masaru Baske, Bishwas Ghimire Residual stress is stress locked inside of a material due to the method of manufacturing such as welding, and is independent of external load. It is of consequence because it leads to the acceleration of fatigue, the initiation of cracks, and the separation of dissimilar materials. When two pieces of metal are joined, the welding torch sweeps on the work from the initial point to the final point along the weld line, creating a temperature and volume gradient along the weld line. As the sample cools, it is clamped down to maintain its shape, but this results in residual stress as the welded part is stretched near the initial point of the weld and compressed near the final point. When two dissimilar materials are welded together, the effect is enhanced because of the difference in the thermal expansion coefficient. The technique we use to analyze this residual stress is electronic speckle-pattern interferometry (ESPI): a non-destructive, full mapping, optical interferometric strain measurement. In unrelated experiments, ESPI has been successfully utilized to show areas of concentrated stress when external forces are applied to a sample metal. Our conjecture is that it can also be used to analyze the areas where residual stress is located within a sample such as that described above. The goal of this research is to show that this is a viable method. [Preview Abstract] |
Thursday, November 21, 2013 1:42PM - 1:54PM |
DE.00002: Design of a Fabry-Perot Open Resonator at Radio Frequencies for an MgB$_2$ Testing Platform Lauren Perez A proposal was written to begin R\&D on the use of MgB$_2$, a high-T$_{c}$ superconducting material that can be deposited onto metallic surfaces, for radio frequency (RF) cavities. Materials Science Divisions at Argonne have been studying deposition techniques, including atomic layer deposition (ALD) to coat MgB$_2$ on sample 2'' coupons. A Fabry-Perot open resonator is suggested as a cavity to test the quality of the coupons, while simulation software, Microwave Studios (MWS), is used to design and validate an open resonator model based on a previously reported cavity The MWS simulation will be used to scale open resonator designs to different- operating frequencies in the search for an optimal test structure. The results of the simulation varied with respect to the comparative article only slightly and most probably due to the differences in simulation software used and excitation source. [Preview Abstract] |
Thursday, November 21, 2013 1:54PM - 2:06PM |
DE.00003: Coordinate Transformations for Mapping Magnetic Field Anomalies in 3D Space Utilizing Commodity Hardware Nicole Gagnon The M3S project, derived from Magnetometer 3D Scanner, aims to develop and implement an instrument for the real-time mapping of magnetic field strengths in 3-space over an extended volume. Three-dimensional digital mapping enables a closer study of the real world and should aid in the detection and identification of magnetic field anomalies. To accomplish this, a quaternion optimization algorithm is used to map points in a two-dimensional image of an object to the points of that object in three-dimensional space. Creating Python libraries for projection, calibration, plotting, and light tracking will allow for the desired mapping. A working prototype, a unique coupled device consisting of a Wii remote and magnetometer, is to be developed in the near future. This novel device has potential applications for diagnostics in many fields related to electrical engineering, quality control, medical imaging, and possibly other unrealized applications. [Preview Abstract] |
Thursday, November 21, 2013 2:06PM - 2:18PM |
DE.00004: Investigation of Basalt Fibres in Concrete Jahi Palmer, Edward Kintzel, Keith Andrew Mechanical properties of concrete are most commonly determined using destructive tests including: compression, flexure, and fracture notch specimen tests. However, nondestructive tests exist for evaluating the properties of concrete such as ultrasonic pulse velocity and impact echo tests. One of major issues with concrete is that unlike steel it is quasi-brittle material. It tends to want to crack when tensile stresses develop. Fibers have been added to concrete for many years to help with temperature and shrinkage cracks. In more recent years, the concepts of adding fibers to concrete have been explored. Some possibilities include developing concrete that may be more durable, flexible, stronger, less permeable, and potentially ``crack free'' than traditional concrete. It has become important test to improvements that the fibres make to the concrete as well as testing the general strength of concrete to stand up to constant pressure at varied strengths. Increasing the rate at which a stress load is added to concrete will lessen the amount of time it takes for the concrete to fail. [Preview Abstract] |
Thursday, November 21, 2013 2:18PM - 2:30PM |
DE.00005: Innovative Energy Harvesting Nanostructures for Organic-based Solar Cells Hemali Rathnayake Linear conjugated polymers (LCPs) exhibit very complex self-assembly behavior due to their structural flexibility, longer chain length, and wide molecular weight distribution. It is essential to develop LCPs having both improved optoelectronic and organizable self-assembly properties. To improve the progress of organic-based devices, synthetic methods need to be developed to make well-defined three-dimensional structures with a controlled size and shape in conjunction with delicately organized self-assembly properties. Here I will discuss a series of donor- and acceptor-functionalized nanostructures having both improved optoelectronic and well defined self-assembly properties for low-cost, high efficiency, and flexible solar cells. This work will contribute to the fundamental knowledge in this discipline by developing better synthetic methodologies, designing novel hybrid nanostructures, and fabricating low-cost, flexible solar panels. Incorporating linear conjugated polymers to self-guidable three-dimensional structures avoid the formation of micrometer-sized phase segregated domains and improved the photovoltaic parameters of these donor/acceptor systems. Improvements in efficiency are realized by obtaining nanoscale phase separation using these hybrid materials. [Preview Abstract] |
Thursday, November 21, 2013 2:30PM - 2:42PM |
DE.00006: Investigation of Asymmetric Impacts on Protective Head Gear using the Large Chamber Scanning Electron Microscope Kristina Medero, Edward Kintzel This study will interrogate the effect of asymmetric impacts on gridiron football helmets using the Large Chamber Scanning Electron Microscope (LC-SEM). As new materials are developed, the ability to predict and test in ``real world'' collisions is key to maximum protection of the athlete. Materials that compose the headgear are put under conditions of extreme stress, and after multiple collisions, must maintain their integrity. Better understanding of the damage caused by the impact vibrations is key to developing a strategy to reduce the number of injuries. Controlled impacts utilizing standard issued football helmets made of polycarbonates, and carbon fiber composite were carried out in air using a pendulum apparatus. Subsequent measurements were performed using the LC-SEM in variable pressure mode to interrogate changes to the helmet surface structure. Results of this investigation will show the progression of changes in the surface due to multiple impacts. This study may provide new insights for developing novel materials and helmet architectures for improved protective headgear in sports. Although numerous recent studies exist on improved safety in athletics, this project will explore these impacts from a unique perspective. [Preview Abstract] |
Thursday, November 21, 2013 2:42PM - 2:54PM |
DE.00007: Probing Confinement and Interfacial Effects on Multilayer Ferroelectric Polymer Thin Films Jennifer Jones, Anthony Mayo, Lei Zhu, Norman Tolk, Eugene Collins, Richard Mu Electrical energy storage plays a key role in mobile electronic devices, stationary power systems, and hybrid electrical vehicles. High energy density capacitors based on dielectric polymers are a focus of increasing research effort motivated by the possibility to realize compact and flexible energy storage devices. Multilayered ferroelectric PVDF systems are fabricated using enabling technology in co-extrusion for increased energy storage efficiency. These micro- and nano-layered polymeric systems result in much improved device performance and a three-time enhancement of capacitive electrical energy density has been demonstrated. To understand the physics of why these multilayered systems perform better than a single layer we are developing characterization techniques using confocal second harmonic generation (SHG), electric field induced second harmonic (EFISH) and Raman laser spectroscopy. Our results have shown that the combination of Raman and SHG is a very sensitive, non-destructive and versatile technique that can be used to study the ferroelectric and structural properties of layered systems. The addition of EFISH this technique allows the interrogation of structural and dielectric properties within the individual layers and at the interfaces between the layers. [Preview Abstract] |
Thursday, November 21, 2013 2:54PM - 3:06PM |
DE.00008: Evaluation of thin-film adhesion with Opto-Acoustic System Sushovit Adhikari, David Didie, Daniel Didie, Sanichiro Yoshida An opto-acoustic technique has been applied to evaluate the adhesion strength of a thin-film (Au/Ti, Pt/Ti or Ti) coating on silicon wafers. The specimens have been configured with a Michelson Interferometer as the end mirror, and are driven from the rear with an acoustic transducer so that the specimen oscillates in the direction of the optical axis at frequencies ranging 2 kHz -- 30 kHz. Interferometric fringes are formed behind the beam splitter. The resulting film-surface displacement causes a shift in fringe (dark stripe) locations occurring at the driving frequency. For a given input power to the transducer, the amplitude of the oscillatory fringe-shift varies depending on the adhesion strength. On the fringe image formed by a digital imaging system at a sampling rate much lower than the driving frequency, the fringe oscillation is detected as a change in the fringe contrast (weaker adhesion makes the fringes blurrier), and its amplitude is quantified. Specimens with different pre-coating surface treatments have been tested. They are clearly differentiated by difference in the peak height and position in the frequency dependence of the fringe contrast. [Preview Abstract] |
Thursday, November 21, 2013 3:06PM - 3:18PM |
DE.00009: Enhancing Photovoltaic Performance of P3HT/PDIB-silsesquioxanes Donor-Acceptor using Spray-Coating Fabrication Technique Venkata Manda, Hemali Rathnayake Organic photovoltaic devices of a blend of perylenediimide-functionalized silsesquioxane nanoparticles with poly(3-hexylthiophenes) were fabricated using a spray-painting technique. The photovoltaic performance of these blends with two different film thicknesses of the active layer and PEDOT.PSS layer was evaluated and compared with the test devices made from spin-coated samples. The film thickness of the layers was characterized under the scanning electron microscope. Through the spray-painting techniques, the photovoltaic performance of P3HT/PDI blend is enhanced with the power conversion efficiency of 2.05{\%} at open circuit voltage of 1.05 V. [Preview Abstract] |
Thursday, November 21, 2013 3:18PM - 3:30PM |
DE.00010: Cavity Acoustics using OVERFLOW Maxwell Henry |
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