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Maruti Hegde, Viswanath Meenakshisundaram, Nicholas Chartrain, Susheel Sekhar, Danesh Tafti, Christopher B Williams, Timothy E Long
High-performance, all-aromatic, insoluble, engineering thermoplastic polyimides, such as pyromellitic dianhydride and 4,4'-oxydianiline (PMDA-ODA) (Kapton), exhibit exceptional thermal stability (up to ≈600 °C) and mechanical properties (Young's modulus exceeding 2 GPa). However, their thermal resistance, which is a consequence of the all-aromatic molecular structure, prohibits processing using conventional techniques. Previous reports describe an energy-intensive sintering technique as an alternative technique for processing polyimides with limited resolution and part fidelity...
June 19, 2017: Advanced Materials
Qiang Song, Fang Ye, Xiaowei Yin, Wei Li, Hejun Li, Yongsheng Liu, Kezhi Li, Keyu Xie, Xuanhua Li, Qiangang Fu, Laifeng Cheng, Litong Zhang, Bingqing Wei
Materials with an ultralow density and ultrahigh electromagnetic-interference (EMI)-shielding performance are highly desirable in fields of aerospace, portable electronics, and so on. Theoretical work predicts that 3D carbon nanotube (CNT)/graphene hybrids are one of the most promising lightweight EMI shielding materials, owing to their unique nanostructures and extraordinary electronic properties. Herein, for the first time, a lightweight, flexible, and conductive CNT-multilayered graphene edge plane (MLGEP) core-shell hybrid foam is fabricated using chemical vapor deposition...
June 19, 2017: Advanced Materials
B E Franco, J Ma, B Loveall, G A Tapia, K Karayagiz, J Liu, A Elwany, R Arroyave, I Karaman
Despite the recent growth in interest for metal additive manufacturing (AM) in the biomedical and aerospace industries, variability in the performance, composition, and microstructure of AM parts remains a major impediment to its widespread adoption. The underlying physical mechanisms, which cause variability, as well as the scale and nature of variability are not well understood, and current methods are ineffective at capturing these details. Here, a Nickel-Titanium alloy is used as a sensory material in order to quantitatively, and rather rapidly, observe compositional and/or microstructural variability in selective laser melting manufactured parts; thereby providing a means to evaluate the role of process parameters on the variability...
June 15, 2017: Scientific Reports
Mitesh Patel, Miles A Stopher
This is a transcript of the discussion session on the effects of hydrogen in the non-ferrous alloys of zirconium and titanium, which are anisotropic hydride-forming metals. The four talks focus on the hydrogen embrittlement mechanisms that affect zirconium and titanium components, which are respectively used in the nuclear and aerospace industries. Two specific mechanisms are delayed hydride cracking and stress corrosion cracking.This article is part of the themed issue 'The challenges of hydrogen and metals'...
July 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
T P Chapman, D Dye, D Rugg
Titanium is widely used in demanding applications, such as in aerospace. Its strength-to-weight ratio and corrosion resistance make it well suited to highly stressed rotating components. Zirconium has a no less critical application where its low neutron capture cross section and good corrosion resistance in hot water and steam make it well suited to reactor core use, including fuel cladding and structures. The similar metallurgical behaviour of these alloy systems makes it alluring to compare and contrast their behaviour...
July 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Karolina Z Milowska, Mahdi Ghorbani-Asl, Marek Burda, Lidia Wolanicka, Nordin Ćatić, Paul D Bristowe, Krzysztof K K Koziol
Improving the interface between copper and carbon nanotubes (CNTs) offers a straightforward strategy for the effective manufacturing and utilisation of Cu-CNT composite material that could be used in various industries including microelectronics, aerospace and transportation. Motivated by a combination of structural and electrical measurements on Cu-M-CNT bimetal systems (M = Ni, Cr) we show, using first principles calculations, that the conductance of this composite can exceed that of a pure Cu-CNT system and that the current density can even reach 10(11) A cm(-2)...
June 12, 2017: Nanoscale
Xin Lu, Hang Qu, Maksim Skorobogatiy
We demonstrate planar laminated piezoelectric generators and piezoelectric microstructured fibers based on BaTiO3-polyvinylidene and carbon-loaded-polyethylene materials combinations. The laminated piezoelectric generators were assembled by sandwiching the electrospun BaTiO3-polyvinylidene mat between two carbon-loaded-polyethylene films. The piezoelectric microstructured fiber was fabricated via drawing of the multilayer fiber preform, and features a swissroll geometry that have ~10 alternating piezoelectric and conductive layers...
June 6, 2017: Scientific Reports
Ye Yuan, Xianxian Sun, Minglong Yang, Fan Xu, Zaishan Lin, Xu Zhao, Yujie Ding, Jianjun Li, Weilong Yin, Qingyu Peng, Xiaodong He, Yibin Li
Electromagnetic interference (EMI) shielding materials for electronic devices in aviation and aerospace not only need lightweight and high shielding effectiveness, but also should withstand harsh environments. Traditional EMI shielding materials often show heavy weight, poor thermal stability, short lifetime, poor tolerance to chemicals, and are hard-to-manufacture. Searching for high-efficiency EMI shielding materials overcoming the above weaknesses is still a great challenge. Herein, inspired by the unique structure of natural wood, lightweight and highly anisotropic wood-derived carbon composite EMI shielding materials have been prepared which possess not only high EMI shielding performance and mechanical stable characteristics, but also possess thermally stable properties, outperforming those metals, conductive polymers, and their composites...
June 15, 2017: ACS Applied Materials & Interfaces
Stanton A Glantz, John D Rutherford
Dr Glantz is Professor of Medicine in the Division of Cardiology, the Truth Initiative Distinguished Professor of Tobacco Control, and Director of the Center for Tobacco Control Research and Education at the University of California, San Francisco School of Medicine. He obtained a BSc in aerospace engineering from the University of Cincinnati in 1969 and an MSc and PhD in applied mechanics from Stanford University. He is the author of 4 books, including The Cigarette Papers and Primer of Biostatistics He is also a member of the University of California, San Francisco Cardiovascular Research Institute and Institute for Health Policy Studies and Co-leader of the University of California, San Francisco Comprehensive Cancer Center Tobacco Program...
June 6, 2017: Circulation
Loyd V Allen
3D printing is a standard tool in the automotive, aerospace, and consumer goods in industry and is gaining traction in pharmaceutical manufacturing, which has introduced a new element into dosage-form development. This article, which represents part 2 of a 3-part article on the topic of 3D printing, discusses the different technologies available for 3D printing.
May 2017: International Journal of Pharmaceutical Compounding
Sampada Bodkhe, Gabrielle Turcot, Frederick P Gosselin, Daniel Therriault
Development of a 3D printable material system possessing inherent piezoelectric properties to fabricate integrable sensors in a single-step printing process without poling is of importance to the creation of a wide variety of smart structures. Here, we study the effect of addition of barium titanate nanoparticles in nucleating piezoelectric β-polymorph in 3D printable polyvinylidene fluoride (PVDF) and fabrication of the layer-by-layer and self-supporting piezoelectric structures on a micro- to millimeter scale by solvent evaporation-assisted 3D printing at room temperature...
June 21, 2017: ACS Applied Materials & Interfaces
Zhenhua Tang, Ziwei Gao, Shuhai Jia, Fei Wang, Yonglin Wang
3D structure assembly in advanced functional materials is important for many areas of technology. Here, a new strategy exploits IR light-driven bilayer polymeric composites for autonomic origami assembly of 3D structures. The bilayer sheet comprises a passive layer of poly(dimethylsiloxane) (PDMS) and an active layer comprising reduced graphene oxides (RGOs), thermally expanding microspheres (TEMs), and PDMS. The corresponding fabrication method is versatile and simple. Owing to the large volume expansion of the TEMs, the two layers exhibit large differences in their coefficients of thermal expansion...
May 2017: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
(no author information available yet)
No abstract text is available yet for this article.
June 1, 2017: Aerospace Medicine and Human Performance
(no author information available yet)
No abstract text is available yet for this article.
April 1, 2017: Aerospace Medicine and Human Performance
(no author information available yet)
No abstract text is available yet for this article.
April 1, 2017: Aerospace Medicine and Human Performance
Elisa Boatti, Nikolaos Vasios, Katia Bertoldi
Materials with engineered thermal expansion, capable of achieving targeted area/volume changes in response to variations in temperature, are important for a number of aerospace, optical, energy, and microelectronic applications. While most of the proposed structures with engineered coefficient of thermal expansion consist of bi-material 2D or 3D lattices, here it is shown that origami metamaterials also provide a platform for the design of systems with a wide range of thermal expansion coefficients. Experiments and simulations are combined to demonstrate that by tuning the geometrical parameters of the origami structure and the arrangement of plates and creases, an extremely broad range of thermal expansion coefficients can be obtained...
May 3, 2017: Advanced Materials
S Ehsan Moosavimehr, A Srikantha Phani
Sandwich panels are extensively used in constructional, naval, and aerospace structures due to the high stiffness and strength-to-weight ratios. In contrast, the sound transmission properties are adversely influenced by the low effective mass. Phase velocity matching of structural waves propagating within the panel and the incident pressure waves from the fluid medium leads to coincidence effects resulting in reduced impedance and high sound transmission. Truss-like lattice cores with porous microarchitecture and reduced inter panel connectivity offer the potential to satisfy the conflicting structural and vibroacoustic response requirements...
April 2017: Journal of the Acoustical Society of America
Michelle J Creech-Eakman, P Scott Carney, David F Buscher, Michael Shao
Aperture synthesis methods allow the reconstruction of images with the angular resolutions exceeding that of extremely large monolithic apertures by using arrays of smaller apertures together in combination. In this issue we present several papers with techniques relevant to amplitude interferometry, laser radar, and intensity interferometry applications.
May 1, 2017: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Binu P Thomas, S Annamala Pillai, C S Narayanamurthy
Sandwich structures, in the modern aerospace industry, are more sought after due to their high strength to stiffness ratio resulting in significant weight gains. Optical techniques like time-average holography and shearography are preferred in industries for inspection of huge sandwich and composite panels because of whole-field (full coverage) inspection in a lesser time leading to large savings in cost. These techniques conventionally use sinusoidal frequency sweep to capture the local resonance of defective regions...
May 1, 2017: Applied Optics
Valerio Oddone, Benji Boerner, Stephanie Reich
High thermal conductivity, low thermal expansion and low density are three important features in novel materials for high performance electronics, mobile applications and aerospace. Spark plasma sintering was used to produce light metal-graphite composites with an excellent combination of these three properties. By adding up to 50 vol.% of macroscopic graphite flakes, the thermal expansion coefficient of magnesium and aluminum alloys was tuned down to zero or negative values, while the specific thermal conductivity was over four times higher than in copper...
2017: Science and Technology of Advanced Materials
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