The Effect Of Number Of Corrugation On Crashworthiness Of Aluminum Corrugated Tube Under Lateral Loading,
2017
University of Nebraska-Lincoln
The Effect Of Number Of Corrugation On Crashworthiness Of Aluminum Corrugated Tube Under Lateral Loading, Hozhabr Mozafari, Arameh Eyvazian, Abdel Magid Hamouda
Department of Mechanical and Materials Engineering: Faculty Publications
Thin-walled tubes have been developed and are growing in use as new energy absorber structures. The objective of this study is to investigate the energy absorption and crushing characteristics of corrugated tubes with different number of corrugation in a specific length exposed to lateral loading. At the first step, experimental tests were carried out on a corrugated tube with three con'ugations (two inner and one outer) and a tube without corrugation. After that, a finite element model was developed by means of ABAQUS software in order to study the effect of corrugation number on crushing properties of thin-walled tubes. The …
Effects Of Aspect Ratio On The Mode Couplings Of Thin-Film Bulk Acoustic Wave Resonators,
2017
Nanjing University of Aeronautics and Astronautics
Effects Of Aspect Ratio On The Mode Couplings Of Thin-Film Bulk Acoustic Wave Resonators, Nian Li, Zhenghua Qian, Jiashi Yang
Department of Mechanical and Materials Engineering: Faculty Publications
We studied mode couplings in thin film bulk acoustic wave resonators of a piezoelectric film on a dielectric layer operating with the fundamental thickness-extensional mode. A system of plate equations derived in our previous paper was used which includes the couplings to the unwanted in-plane extension, flexure, fundamental and second-order thickness shear modes. It was shown that the couplings depend strongly on the plate length/thickness ratio. For a relatively clean operating mode with weak couplings to unwanted modes, a series of discrete values of the plate length/thickness ratio should be avoided and these values were determined in the present paper. …
Experimental Study Of Corrugated Metal-Composite Tubes Under Axial Loading,
2017
Qatar University
Experimental Study Of Corrugated Metal-Composite Tubes Under Axial Loading, Arameh Eyvazian, Hozhabr Mozafari, Abdel Magid Hamouda
Department of Mechanical and Materials Engineering: Faculty Publications
In this study, crushing behavior of corrugated metal-composite tube was examined experimentally under axial loading condition. Six types of specimens, classified into two groups of metal and metal-composite, were tested under quasi static axial loading. The failure mechanism and failure history of the specimens were presented and discussed. The experimental result showed that corrugated metal composite tubes demonstrate perfect energy absorption characteristics in terms of uniformity of load-displacement diagram, reduction of initial peak load and controlling failure mechanism. Moreover, it was also found that adding filament wound layer of composite on the surface of metallic corrugated tube compensated weakness of …
Clustering On Magnesium Surfaces – Formation And Diffusion Energies,
2017
Shanghai University
Clustering On Magnesium Surfaces – Formation And Diffusion Energies, Haijian Chu, Hanchen Huang, Jian Wang
Department of Mechanical and Materials Engineering: Faculty Publications
The formation and diffusion energies of atomic clusters on Mg surfaces determine the surface roughness and formation of faulted structure, which in turn affect the mechanical deformation of Mg. This paper reports first principles density function theory (DFT) based quantum mechanics calculation results of atomic clustering on the low energy surfaces {0001} and {1011}. In parallel, molecular statics calculations serve to test the validity of two interatomic potentials and to extend the scope of the DFT studies. On a {0001} surface, a compact cluster consisting of few than three atoms energetically prefers a facecentered- cubic stacking, to serve as a …
Review Of Sustainability Issues In Non-Traditional Machining
Processes,
2017
University of Nebraska-Lincoln
Review Of Sustainability Issues In Non-Traditional Machining Processes, Kamlakar Rajurkar, H. Hadidi, J. Pariti, G. C. Reddy
Department of Mechanical and Materials Engineering: Faculty Publications
Non-traditional machining processes (such as EDM and ECM) provide alternatives or sometimes the only alternative in generating highly complex 3-D features in very difficult-to -machine materials. This paper reviews recently published work on sustainability issues related to these processes. For example in Electrochemical machining (ECM) the effect of sludge generation and selection of dielectric in Electrodischarge machining (EDM) need to be investigated from the sustainability point of view. All processes need to be studied not only for resulting productivity and accuracy but also their environmental impact during product generation and usage. This paper addresses process mechanisms, surface integrity, sensing and …
Target Lesion Calcium Arc Influence The Performance Of Stenting,
2017
University of Nebraska-Lincoln
Target Lesion Calcium Arc Influence The Performance Of Stenting, Pengfei Dong, Shengmao Lin, David L. Wilson, Hiram G. Bezerra, Linxia Gu
Department of Mechanical and Materials Engineering: Faculty Publications
Percutaneous coronary intervention (PCI) is the most common revascularization procedure, in which, fibrocalcific plaques are found in 17–35% of patients undergoing PCI [1]. Numbers will rise with population aging and prolonged statin treatment. Calcifications often lead to stent under expansion and strut malapposition, with increased risk of thrombosis and in-stent restenosis [2]. Presence of calcium strongly inhibits stent performance, a well-documented metric for outcome [3]. The goal of this work is to develop the finite element models for inspecting the influence of the calcium arc extent on the stenting outcomes, such as the stress and strain distribution within the plaque, …
Accommodation Of The Human Lens Capsule Using A Finite Element Model Based On Nonlinear Regionally
Anisotropic Biomembranes,
2017
University of the Philippines
Accommodation Of The Human Lens Capsule Using A Finite Element Model Based On Nonlinear Regionally Anisotropic Biomembranes, G. David, Ryan M. Pedrigi, J. D. Humphrey
Department of Mechanical and Materials Engineering: Faculty Publications
Accommodation of the eyes, the mechanism that allows humans to focus their vision on near objects, naturally diminishes with age via presbyopia. People who have undergone cataract surgery, using current surgical methods and artificial lens implants, are also left without the ability to accommodate. The process of accommodation is generally well known; however the specific mechanical details have not been adequately explained due to difficulties and consequences of performing in vivo studies. Most studies have modeled the mechanics of accommodation under assumptions of a linearly elastic, isotropic, homogenous lens and lens capsule. Recent experimental and numerical studies showed that the …
Micro/Nanostructures Formation By Femtosecond Laser Surface Processing On Amorphous And Polycrystalline Ni60nb40,
2017
University of Nebraska-Lincoln
Micro/Nanostructures Formation By Femtosecond Laser Surface Processing On Amorphous And Polycrystalline Ni60nb40, Edwin Peng, Alfred Tsubaki, Craig A. Zuhlke, Meiyu Wang, Ryan Bell, Michael J. Lucis, Troy P. Anderson, Dennis R. Alexander, George Gogos, Jeffrey E. Shield
Department of Mechanical and Materials Engineering: Faculty Publications
Femtosecond laser surface processing is a technology that can be used to functionalize many surfaces, imparting specialized properties such as increased broadband optical absorption or superhydrophilicity/superhydrophobicity. In this study, two unique classes of surface structures, below surface growth (BSG) and above surface growth (ASG) mounds, were formed by femtosecond laser surface processing on amorphous and polycrystalline Ni60Nb40 with two different grain sizes. Cross sectional imaging of these mounds revealed thermal evidence of the unique formation processes for each class of surface structure. BSG mounds formed on all three substrates using the same laser parameters had similar surface …
Growth Mechanisms Of Multiscale, Mound-Like Surface Structures
On Titanium By Femtosecond Laser Processing,
2017
University of Nebraska-Lincoln
Growth Mechanisms Of Multiscale, Mound-Like Surface Structures On Titanium By Femtosecond Laser Processing, Edwin Peng, Ryan Bell, Craig A. Zuhlke, Meiyu Wang, Dennis R. Alexander, George Gogos, Jeffrey E. Shield
Department of Mechanical and Materials Engineering: Faculty Publications
Femtosecond laser surface processing (FLSP) can be used to functionalize many surfaces, imparting specialized properties such as increased broadband optical absorption or superhydrophobicity/-hydrophilicity. In this study, the subsurface microstructure of a series of mound-like FLSP structures formed on commercially pure titanium using five combinations of laser fluence and cumulative pulse counts was studied. Using a dual beam Scanning Electron Microscope with a Focused Ion Beam, the subsurface microstructure for each FLSP structure type was revealed by cross-sectioning. The microstructure of the mounds formed using the lowest fluence value consists of the original Ti grains. This is evidence that preferential laser …
Robotic Surgical Devices, Systems, And Related Methods,
2017
University of Nebraska-Lincoln
Robotic Surgical Devices, Systems, And Related Methods, Shane M. Farritor, Erik Mumm, Philip Chu, Nishant Kumar, Jason Dumpert, Yutaka Tsutano
Department of Mechanical and Materials Engineering: Faculty Publications
The embodiments disclosed herein relate to various medical device components, including components that can be incorporated into robotic and/or in vivo medical devices. Certain embodiments include various modular medical devices for in vivo medical procedures.
Methods , Systems , And Devices
Relating To Surgical End Effectors,
2017
University of Nebraska-Lincoln
Methods , Systems , And Devices Relating To Surgical End Effectors, Shane M. Farritor, Tom Fredrick, Joe Bartels
Department of Mechanical and Materials Engineering: Faculty Publications
The embodiments disclosed herein relate to various medical device components, including components that can be incorporated into robotic and/or in vivo medical devices, and more specifically including end effectors that can be incorporated into such devices. Certain end effector embodiments include various vessel cautery devices that have rotational movement as well as cautery and cutting functions while maintaining a relatively compact structure. Other end effector embodiments include various end effector devices that have more than one end effector.
System For Imaging And Measuring
Rail Deflection,
2017
University of Nebraska-Lincoln
System For Imaging And Measuring Rail Deflection, Shane M. Farritor
Department of Mechanical and Materials Engineering: Faculty Publications
Devices, systems, and methods for imaging and measuring deflections in structures such as railroad rail are disclosed. One exemplary embodiment relates to a vision system having a high-speed, visible-light imaging camera and an evaluation unit configured for analyzing images from the camera to detect geometric variations in the structure. In a second example, additional sensors are used to identify the wheel location(s) in the same reference frame as the mea Surement system. In analyzing structures Such as railroad track rail, the imaging camera can be coupled to a moving rail vehicle and configured for generating images of the rail as …
Local And Segmental Motions Of The Mobile Amorphous Fraction In Semi-Crystalline Polylactide Crystallized Under Quiescent And Flow-Induced Conditions,
2017
Normandie Université
Local And Segmental Motions Of The Mobile Amorphous Fraction In Semi-Crystalline Polylactide Crystallized Under Quiescent And Flow-Induced Conditions, Xavier Monnier, Laurence Chevalier, Antonello Esposito, Lucia Fernandez-Ballester, Allisson Saiter, Eric Dargent
Department of Mechanical and Materials Engineering: Faculty Publications
The molecular dynamics of the constrained and unconstrained mobile amorphous fractions in semicrystalline polylactide (PLA) was investigated in the presence of both flow-induced crystalline structures and spherulites by fast scanning calorimetry (FSC) through cooperativity and physical aging concepts. First, the shear rate conditions leading to flow-induced crystallization were characterized by examining the relaxation of shear-induced precursors. At a temperature of 150 °C, the critical relaxation time is so long that cooling down the sheared melt to the crystallization temperature does not affect significantly the precursors. Therefore, highly oriented structures develop. The arrangement of the crystalline fraction, either in flow-induced crystalline …
Effect Of Random Ethylene Comonomer On Relaxation Of Flow-Induced Precursors In Isotactic Polypropylene,
2017
University of Nebraska-Lincoln
Effect Of Random Ethylene Comonomer On Relaxation Of Flow-Induced Precursors In Isotactic Polypropylene, Benjamin Schammé, Eric Dargent, Lucia Fernandez-Ballester
Department of Mechanical and Materials Engineering: Faculty Publications
The effect of comonomer on structure and relaxation of flow-induced precursors was investigated in a series of isotactic polypropylene and random propylene−ethylene copolymers. The polymers were subjected to flow by fiber pulling and allowed to relax above their nominal melting temperature for specific times. The type of morphology developed after cooling revealed whether flow-induced precursors were still present or the melt had fully reequilibrated. Precursors were long-lived and, at fixed temperature, decayed significantly faster with higher ethylene content. The critical time for precursor relaxation followed an Arrhenius-type dependence with temperature. The apparent energy of activation for precursor dissolution decreased with …
Rapidly Solidified Rare-Earth Permanent Magnets: Processing, Properties, And Applications,
2017
Indian Institute of Technology Kharagpur
Rapidly Solidified Rare-Earth Permanent Magnets: Processing, Properties, And Applications, Shampa Aich, Dillip K. Satapathy, Jeffrey E. Shield
Department of Mechanical and Materials Engineering: Faculty Publications
Rapidly solidified rare-earth-based permanent magnets are considered to have better potential as permanent magnets compared to the conventional bulk materials, which can be attributed to their improved microstructure and better magnetic properties compared to rare-earth magnets synthesized by the conventional (powder metallurgy) routes. The performance (quality) of these magnets depends on the thermodynamics and kinetics of the different processing routes, such as atomization, melt spinning, and melt extraction. Here, we review the various processing routes of rapidly solidified rare-earth permanent magnets and the related properties and applications. In the review, some specific alloy systems, such as Sm–Co-based alloys, Nd–Fe–B, and …
Biodegradable Elastic Nanofibrous
Platforms With Integrated Flexible
Heaters For On-Demand Drug
Delivery,
2017
Harvard Medical School
Biodegradable Elastic Nanofibrous Platforms With Integrated Flexible Heaters For On-Demand Drug Delivery, Ali Tamayol, Alireza Hassani Najafabadi, Pooria Mostafalu, Ali K. Yetisen, Mattia Commotto, Musab Aldhahri, Mohamed Shaaban Abdel-Wahab, Zeynab Izadi Najafabadi, Shahrzad Latifi, Mohsen Akbari, Nasim Annabi, Seok Hyun Yun, Adnan Memic, Mehmet R. Dokmeci, Ali Khademhosseini
Department of Mechanical and Materials Engineering: Faculty Publications
Delivery of drugs with controlled temporal profiles is essential for wound treatment and regenerative medicine applications. For example, bacterial infection is a key challenge in the treatment of chronic and deep wounds. Current treatment strategies are based on systemic administration of high doses of antibiotics, which result in side effects and drug resistance. On-demand delivery of drugs with controlled temporal profile is highly desirable. Here, we have developed thermally controllable, antibiotic-releasing nanofibrous sheets. Poly(glycerol sebacate)- poly(caprolactone) (PGS-PCL) blends were electrospun to form elastic polymeric sheets with fiber diameters ranging from 350 to 1100 nm and substrates with a tensile modulus …
Nondestructive Testing System Design For Biological
Product Based On Vibration Signal Analysis Of
Acceleration Sensor,
2017
Northeastern University
Nondestructive Testing System Design For Biological Product Based On Vibration Signal Analysis Of Acceleration Sensor, Xiaohao Li, Tao Shen
Department of Mechanical and Materials Engineering: Faculty Publications
In order to reduce the disadvantages of current biological product quality testing methods, taking the quality testing in cocoon trade markets as an example, this paper has proposed a quality nondestructive testing method for biological products based on the analysis of vibration signal from acceleration sensors. According to the wavelet transformation analysis on the random vibration signal acquired from the acceleration sensor, the random vibration signal related to the silkworm chrysalis quality has been analyzed and reconstructed; then the characteristic values such as: mean value, variance, mean square root, waveform index, pulse factor, and so on of the quality signal …
Solution Nuclear Magnetic Resonance Spectroscopy On A Nanostructured Diamond Chip,
2017
Harvard University & University of New Mexico
Solution Nuclear Magnetic Resonance Spectroscopy On A Nanostructured Diamond Chip, P. Kehayias, A. Jarmola, N. Mosavian, I. Fescenko, F.M. Benito, A. Laraoui, J. Smits, L. Bougas, D. Budker, A. Neumann, S.R.J. Brueck, V.M. Acosta
Department of Mechanical and Materials Engineering: Faculty Publications
Sensors using nitrogen-vacancy centers in diamond are a promising tool for small-volume nuclear magnetic resonance (NMR) spectroscopy, but the limited sensitivity remains a challenge. Here we show nearly two orders of magnitude improvement in concentration sensitivity over previous nitrogen-vacancy and picoliter NMR studies. We demonstrate NMR spectroscopy of picoliter-volume solutions using a nanostructured diamond chip with dense, high-aspect-ratio nanogratings, enhancing the surface area by 15 times. The nanograting sidewalls are doped with nitrogen-vacancies located a few nanometers from the diamond surface to detect the NMR spectrum of roughly 1 pl of fluid lying within adjacent nanograting grooves. We perform 1H …
Quantification Of Re-Absorption And Re-Emission
Processes To Determine Photon Recycling Efficiency
In Perovskite Single Crystals,
2017
University of Nebraska-Lincoln
Quantification Of Re-Absorption And Re-Emission Processes To Determine Photon Recycling Efficiency In Perovskite Single Crystals, Yanjun Fang, Haotong Wei, Qingfeng Dong, Jinsong Huang
Department of Mechanical and Materials Engineering: Faculty Publications
Photon recycling, that is, iterative self-absorption and re-emission by the photoactive layer itself, has been speculated to contribute to the high open-circuit voltage in several types of high efficiency solar cells. For organic–inorganic halide perovskites that have yielded highly efficient photovoltaic devices, however, it remains unclear whether the photon recycling effect is significant enough to improve solar cell efficiency. Here we quantitatively evaluate the re-absorption and re-emission processes to determine photon recycling efficiency in hybrid perovskite with its single crystals by measuring the ratio of the re-emitted photons to the initially excited photons, which is realized by modulating their polarization …
Low-Drag Events In Transitional Wall-Bounded Turbulence,
2017
Newcastle University
Low-Drag Events In Transitional Wall-Bounded Turbulence, Richard D. Whalley, Jae Sung Park, Anubhav Kushwaha, David J.C. Dennis, Michael D. Graham, Robert J. Poole
Department of Mechanical and Materials Engineering: Faculty Publications
Intermittency of low-drag pointwise wall shear stress measurements within Newtonian turbulent channel flow at transitional Reynolds numbers (friction Reynolds numbers 70 – 130) is characterized using experiments and simulations. Conditional mean velocity profiles during low-drag events closely approach that of a recently discovered nonlinear traveling wave solution; both profiles are near the so-called maximum drag reduction profile, a general feature of turbulent flow of liquids containing polymer additives (despite the fact that all results presented are for Newtonian fluids only). Similarities between temporal intermittency in small domains and spatiotemporal intermittency in large domains is thereby found.
