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802 results on '"Chou, Tsu-Wei"'

160. Graphene-Based Fibers: A Review

Author

Meng, Fancheng, primary, Lu, Weibang, additional, Li, Qingwen, additional, Byun, Joon-Hyung, additional, Oh, Youngseok, additional, and Chou, Tsu-Wei, additional

Published
2015
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163. Multifunctional Flexible Composites Based on Continuous Carbon Nanotube Fiber

Author

DELAWARE UNIV NEWARK DEPT OF MECHANICAL ENGINEERING, Chou, Tsu-Wei, Zhu, Yuntian T, DELAWARE UNIV NEWARK DEPT OF MECHANICAL ENGINEERING, Chou, Tsu-Wei, and Zhu, Yuntian T

Abstract

Continuous carbon nanotube fibers possess high mechanical properties and electrical conductivity, demonstrating the potential of multifunctional applications in various fields. With the support of the Project Multifunctional Flexible Composites Based on Continuous Carbon Nanotube Fiber (grant No. FA9550-11-1-0124), we systematically studied the synthesis and properties of dry-spun CNT fibers with different spinning techniques, including the tensile strength, compressive strength, microstructure evolution, torsional behavior, electromechanical response, failure behavior, and tensile stress relaxation behavior. The potential use of CNT fiber for torsional sensors have been demonstrated. The interfacial behaviors between CNT fibers and graphene film, PDMS, epoxy resins have also been examined. Molecular dynamics simulations of the fiber structural evolution from CNT array to film to fiber and the resulting mechanical behavior were conducted to gain insight into the fundamental strengthening mechanisms. To demonstrate the multifunctional applications of CNT fiber, we further designed and fabricated transparent, stretchable conductors based on CNT fibers and PDMS. Finally, the synthesis and electromechanical behavior of graphene based continuous fibers., The original document contains color images. Prepared in collaboration with the Department of Materials Science & Engineering, North Carolina State University, Raleigh.

Published
2014

166. A nonclassical model for the stresses in 3-d continuous fiber-reinforced composite materials

Author

Chou Tsu-Wei, Michael H. Santare, and Emin Selçuk Ardiç

Subjects
Materials science, Continuum mechanics, Applied Mathematics, Mechanical Engineering, Composite number, Mechanics, Fiber-reinforced composite, Stress distribution, Elasticity (physics), Condensed Matter Physics, Stress (mechanics), Stress field, Mechanics of Materials, Modeling and Simulation, General Materials Science, Composite material, Anisotropic elasticity
Abstract

A nonclassical continuum mechanics model is developed for a unidirectional continuous fiber-reinforced composite under elastic deformation to determine separate stress field expressions for each material in the body. Far-field strain components, measured or calculated by classical methods, are considered as known inputs. By an elasticity analysis the interactions between the adjacent material regions are found. By using a method similar to the nonlocal continuum mechanics theory all the long-range interactions are expressed as heterogeneity effects. By summing the stresses calculated from the far-field strains and the stresses caused by the heterogeneity effects, the stress fields in the different materials of the composite body are determined. Sample results are compared to those of a classical anisotropic elasticity method.

Published
1990

169. High performance solid-state flexible supercapacitor based on Fe3O4/carbon nanotube/polyaniline ternary films.

Author

Li, Jinsong, Lu, Weibang, Yan, Yushan, and Chou, Tsu-Wei

Abstract

A novel flexible nanoarchitecture was fabricated via the facile electropolymerization of a polyaniline (PANI) network on Fe3O4 particles grown axially on carbon nanotubes (CNTs) of a CNT film for supercapacitor electrode applications. The PANI chains serve as a protective shell to improve the structural stability of the Fe3O4 particles. The resulting supercapacitor exhibits a high specific energy density of 28.0 W h kg−1, high specific power density of 5.3 kW kg−1 and specific capacitance of 201 F g−1 at a scan rate of 20 mV s−1, surpassing the performances observed for many recently reported flexible supercapacitors. Furthermore, the CNT film-Fe3O4-PANI supercapacitor demonstrates excellent cyclic stability with only a 3.6% loss of its initial specific capacitance after 10 000 charge–discharge cycles. These results suggest that the CNT film-Fe3O4-PANI composite is very promising for next generation high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Published
2017
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170. A High Performance Stretchable Asymmetric Fiber-Shaped Supercapacitor with a Core-Sheath Helical Structure.

Author

Yu, Jiali, Lu, Weibang, Smith, Joseph P., Booksh, Karl S., Meng, Linghui, Huang, Yudong, Li, Qingwen, Byun, Joon‐Hyung, Oh, Youngseok, Yan, Yushan, and Chou, Tsu‐Wei

Subjects
SUPERCAPACITORS, ENERGY storage equipment, CARBON nanotubes, ANTHOLOGY films, GEL electrophoresis
Abstract

The emerging fiber-shaped supercapacitors (FSSs) have motivated tremendous research interest in energy storage devices. However, challenges still exist in the pursuit of combination of excellent electrochemical performance and mechanical stretchability. Here, a core-sheath asymmetric FSS is first made by wrapping gel electrolyte coated carbon nanotube (CNT)@MnO2 core fiber with CNT@PPy composite film. Then a stretchable helical structure is formed by over-twisting the FSS. The resulted stretchable asymmetric FSS exhibits a specific capacitance of 60.435 mF cm−2 at the scan rate of 10 mV s−1 and the capacitance performance is well maintained during repeated stretching to 20% strain. Furthermore, a high energy density of 18.88 μW h cm−2 is achieved for the stretchable FSS due to its high specific capacitance and extended potential window of 1.5 V. [ABSTRACT FROM AUTHOR]

Published
2017
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180. Advanced Composite Armor: In Situ Sensing with Carbon Nanotube Networks for Improved Damage Tolerance

Author

DELAWARE UNIV NEWARK, Chou, Tsu-Wei, DELAWARE UNIV NEWARK, and Chou, Tsu-Wei

Abstract

The goal of the project is to develop robust sensing methodologies based on carbon nanotube for the detection of damage in advanced army composite systems. The fundamental idea is that carbon nanotubes can function as a network of sensors in traditional laminated fiber composites to detect deformation and damage in situ, using electrical techniques. The novelty of the approach is in the use of carbon nanotube based multifunctional composites which integrate self-sensing function to structural components and can monitor damage initiation and propagation, and elucidate the nature and extent of damage. The objectives have been accomplished through integrated and complementary analytical and experimental studies. The innovative features of the project include: (a) The processing of SC-15 epoxy based glass fiber composites with highly uniform dispersion of carbon nanotubes as electrical conductive network; (b) The characterization of damage sensing capability of the hybrid composite under static and dynamic loading, and (c) The capability in analysis/modeling of 3D electrical percolation behavior and the evolution of damage with deformation.

Published
2013

184. Damage modeling and characterization of a three-dimensional woven composite

Author

Casari, Pascal, Ladevèze, Pierre, Chou, Tsu-Wei, Institut de Recherche en Génie Civil et Mécanique (GeM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), and University of Delaware [Newark]

Subjects
woven composites, mesoscale, mechanical properties, [SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph], damage, [SPI.MAT]Engineering Sciences [physics]/Materials
Abstract

International audience; The characterization and modeling of the inplane damage behavior of a three-dimensional woven composite are conducted with the use of the Mesoscale Composite Damage Theory, developed by Ladevèze. A first analysis of the composite fabric provides the main geometrical properties that can affect the mechanical behavior. A model previously established for aeronautical carbon/epoxy laminates is applied in a simplified version. It assumes an elastic and brittle behavior in the directions of the fibers, and degradation mechanisms like matrix micro-cracking and fiber debonding under a shear stress state. The model utilizes two experimental laws to be identified for the description of damage and inelastic strains. Then, the experimental procedure is presented by means of tensile tests on two relevant kinds of samples. The identification of the elastic, failure, damage and inelastic properties is performed. The comparison between complementary experiments and simulation shows a good fitting for small strains.

Published
1999

185. Multifunctional Carbon Nanotube-Based Sensors for Damage Detection and Self Healing in Structural Composites

Author

DELAWARE UNIV NEWARK, Chou, Tsu-Wei, Thostenson, Erik T., DELAWARE UNIV NEWARK, Chou, Tsu-Wei, and Thostenson, Erik T.

Abstract

During the past year of the research program focusing on developing composites with damage sensing and self-healing functionalities based on carbon nanotubes, improvements to the state-of-the-art in nanocomposite processing have been made. In order to accommodate the processing of thick-section composites, an alternative approach to the traditional calandering method of carbon nanotube dispersion has been developed. A fiber sizing agent containing multiwalled carbon nanotubes was used in the processing of conductive E-glass fabric composites, which were demonstrated to undergo measurable, non-reversible changes in resistivity during the accumulation of damage under quasi-static loading scenarios. These conductively-modified composites possess the potential to sense damage under fatigue tensile and dynamic compressive and impact loadings. A review article describing the design, processing and resultant mechanical, electrical and thermal properties of nanotube-based composites has been published.

Published
2010

196. Highly Sensitive Wearable Textile-Based Humidity Sensor Made of High-Strength, Single-Walled Carbon Nanotube/Poly(vinyl alcohol) Filaments

Author

Zhou, Gengheng, Byun, Joon-Hyung, Oh, Youngseok, Jung, Byung-Mun, Cha, Hwa-Jin, Seong, Dong-Gi, Um, Moon-Kwang, Hyun, Sangil, and Chou, Tsu-Wei

Abstract

Textile-based humidity sensors can be an important component of smart wearable electronic-textiles and have potential applications in the management of wounds, bed-wetting, and skin pathologies or for microclimate control in clothing. Here, we report a wearable textile-based humidity sensor for the first time using high strength (∼750 MPa) and ultratough (energy-to-break, 4300 J g–1) SWCNT/PVA filaments via a wet-spinning process. The conductive SWCNT networks in the filaments can be modulated by adjusting the intertube distance by swelling the PVA molecular chains via the absorption of water molecules. The diameter of a SWCNT/PVA filament under wet conditions can be as much as 2 times that under dry conditions. The electrical resistance of a fiber sensor stitched onto a hydrophobic textile increases significantly (by more than 220 times) after water sprayed. Textile-based humidity sensors using a 1:5 weight ratio of SWCNT/PVA filaments showed high sensitivity in high relative humidity. The electrical resistance increases by more than 24 times in a short response time of 40 s. We also demonstrated that our sensor can be used to monitor water leakage on a high hydrophobic textile (contact angle of 115.5°). These smart textiles will pave a new way for the design of novel wearable sensors for monitoring blood leakage, sweat, and underwear wetting.

Published
2017
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