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Journal ArticleDOI: 10.1115/1.4034095

High-Ampacity Overhead Power Lines With Carbon Nanostructure–Epoxy Composites

01 Oct 2016-Journal of Engineering Materials and Technology-transactions of The Asme (American Society of Mechanical Engineers)-Vol. 138, Iss: 4, pp 041018
Abstract: 30 Design of high-performance power lines with advanced materials is indispensable to effectively eliminate losses in electrical power transmission and distribution (T&D) lines. In this study, aluminum conductor composite core with carbon nanostructure (ACCC–CNS) coating in a multilayered architecture is considered as a novel design alternative to conventional aluminum conductor steel-reinforced (ACSR) transmission line. In the multiphysics approach presented herein, first, electrothermal finite element (FE) analysis of the ACSR line is performed to obtain its steady-state temperature for a given current. Subsequently, the sag distance of the ACSR line due to self-weight and thermal expansion is determined by performing thermostructural analysis employing an analytical model. The results are then verified with those obtained from the FE analysis of the ACSR line. The electrothermal FE model and the thermostructural analytical model are then extended to the ACCC–CNS line. The results indicate that the ACCC–CNS line has higher current-carrying capacity (CCC) and lower sag compared to those of the ACSR line. Motivated by the improved performance of the ACCC–CNS line, a systematic parametric study is conducted in order to determine the optimum ampacity, core diameter, and span length. The findings of this study would provide insights into the optimal design of high-performance overhead power lines. [DOI: 10.1115/1.4034095]

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Topics: Ampacity (63%), Epoxy (50%)
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Journal ArticleDOI: 10.1016/J.MECHMAT.2016.09.002
Abstract: This study is focused on the mechanical properties and stress transfer behavior of multiscale composites containing nano- and micro-scale reinforcements. The distinctive feature of construction of this composite is such that the carbon nanostructures (CNS) are dispersed in the matrix around the continuous microscale fiber to modify microfiber-matrix interfacial adhesion. Such CNS are considered to be made of aligned CNTs (A-CNTs). Accordingly, multiscale models are developed for such hybrid composites. First, molecular dynamics simulations in conjunction with the Mori-Tanaka method are used to determine the effective elastic properties of nano-engineered interphase layer composed of CNS and epoxy. Subsequently, a micromechanical pull-out model for a continuous fiber multi-scale composite is developed, and stress transfer behavior is studied for different orientations of CNS considering their perfect and imperfect interfacial bonding conditions with the surrounding epoxy. Such interface condition was modeled using the linear spring layer model with a continuous traction but a displacement jump. The current pull-out model accounts for the radial as well as the axial deformations of different orthotropic constituent phases of the multiscale composite. The results from the developed pull-out model are compared with those of the finite element analyses and are found to be in good agreement. Our results reveal that the stress transfer characteristics of the multiscale composite are significantly improved by controlling the CNT morphology around the fiber, particularly, when they are aligned along the axial direction of the microscale fiber. The results also show that the CNS-epoxy interface weakening significantly influences the radial stress along the length of the microscale fiber.

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Topics: Multiscale modeling (60%), Fiber-reinforced composite (56%), Micromechanics (55%) ...read more

53 Citations


Journal ArticleDOI: 10.1016/J.COMPOSITESA.2018.07.021
Abstract: Here, we report highly strain-tolerant and sensitive strain sensors based on carbon nanostructures (CNS)-polydimethylsiloxane (PDMS) nanocomposites. CNS consist of clusters of aligned multiwall carbon-nanotubes (MWCNT) with high degree of entanglement and wall sharing between nanotubes. The unique features of CNS result in nanocomposites with very low electrical percolation threshold (0.05 wt% CNS), strong linear-piezoresistive-response up to 110% strain, and high sensitivity with gauge factor ranging from 8 to 47. We also present a simple analytical model for predicting resistivity evolution as a function of stretch considering incompressible hyperelastic behavior of CNS/PDMS nanocomposites. CNS/PDMS nanocomposites also show good hysteresis performance and stability up to 100 repetitive stretch/release cycles for 30% maximum strain. Tunable sensitivity and linear piezoresistivity coupled with high stretchability of CNS/PDMS nanocomposites demonstrated here suggest their potential for applications in wearable health and fitness monitoring devices.

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Topics: Gauge factor (53%)

44 Citations


Journal ArticleDOI: 10.1016/J.MSEC.2018.07.029
Abstract: Herein, we report strain- and damage-sensing performance of biocompatible smart CNT/UHMWPE nanocomposites for the first time. CNT/UHMWPE nanocomposites are fabricated by solution mixing followed by compression molding. The surface morphology, microstructural properties, thermal decomposition and stability, glass transition temperature and thermal conductivity of the nanocomposites are characterized. The degree of crystallinity of CNT/UHMWPE nanocomposites is found to have a maximum value of 52% at 0.1 wt% CNT loading. The degree of crystallinity influences the mechanical properties of the CNT/UHMWPE nanocomposites. The electrical percolation threshold is achieved at 0.05 wt% of CNT and it follows a two dimensional conductive network according to percolation theory. The piezoresistive response of CNT/UHMWPE nanocomposites is demonstrated with a gauge factor of ~2.0 in linear elastic regime and that in the range of 3.8–96.0 in inelastic regimes for 0.05 wt% of CNT loading. A simple theoretical model is also developed to predict the resistivity evolution in both elastic and inelastic regimes. High sensitivity of CNT/UHMWPE nanocomposites coupled with linear piezoresistive response up to 100% strain demonstrates their potential for application in artificial implants as a self-sensing material.

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36 Citations


Journal ArticleDOI: 10.1007/S10853-018-2072-3
Abstract: Ultra-high molecular weight polyethylene (UHMWPE)-based conductive nanocomposites with reduced percolation and tunable piezoresistive behavior were prepared via solution mixing followed by compression molding using carbon nanotubes (CNT) and graphene nanoplatelets (GNP). The effect of varying wt% of GNP with fixed CNT content (0.1 wt%) on the mechanical, electrical, thermal and piezoresistive properties of UHMWPE nanocomposites was evaluated. The combination of CNT and GNP enhanced the dispersion in UHMWPE matrix and lowered the probability of CNT aggregation as GNP acted as a spacer to separate the entanglement of CNT with each other. This has allowed the formation of an effective conductive path between GNP and CNT in UHMWPE matrix. The thermal conductivity, degree of crystallinity and degradation temperature of the nanocomposites increased with increasing GNP content. The elastic modulus and yield strength of the nanocomposites were improved by 37% and 33%, respectively, for 0.1/0.3 wt% of CNT/GNP compared to neat UHMWPE. The electrical conductivity was measured using four-probe method, and the lowest electrical percolation threshold was achieved at 0.1/0.1 wt% of CNT/GNP forming a nearly two-dimensional conductive network (critical value, t = 1.20). Such improvements in mechanical and electrical properties are attributed to the synergistic effect of the two-dimensional GNP and one-dimensional CNT which limits aggregation of CNTs enabling a more efficient conductive network at low wt% of fillers. These hybrid nanocomposites exhibited strong piezoresistive response with sensitivity factor of 6.2, 15.93 and 557.44 in the linear elastic, inelastic I and inelastic II regimes, respectively, for 0.1/0.5 wt% of CNT/GNP. This study demonstrates the fabrication method and the self-sensing performance of CNT/GNP/UHMWPE nanocomposites with improved properties useful for orthopedic implants.

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28 Citations


Journal ArticleDOI: 10.1088/2053-1591/AA9F9E
04 Jan 2018-
Abstract: Carbon nanotubes (CNTs) based polymer nanocomposites offer a range of remarkable properties. Here, we demonstrate self-sensing performance of low density polyethylene (LDPE)-multiwalled carbon nanotubes (MWCNTs) nanocomposites for the first time. The dispersion of the CNTs and the morphology of the nanocomposites was investigated using scanning electron microscopy, x-ray diffraction and Raman spectroscopic techniques. The thermal properties were measured using thermal gravimetric analysis and differential scanning calorimetry and were found to increase with increasing wt% of MWCNTs in LDPE matrix. An overall improvement in ultimate tensile strength, yield strength and Young's modulus was found to be 59.6%, 48.5% and 129.3%, respectively for 5.0 wt% loading of MWCNTs. The electrical percolation threshold was observed at 1.0 wt% of MWCNTs and the highest electrical conductivity of 2.8 × 10−2 Scm−1 was observed at 5.0 wt% loading of MWCNTs. These piezo-resistive nanocomposites offer tunable self-sensing capabilities with gauge factors in the ranges of 17–52 and 42–530 in linear elastic (strain ~3%) and inelastic regimes (strain ~15%) respectively. Our demonstration would provide guidelines for the fabrication of low cost, self-sensing MWCNT-LDPE nanocomposites for potential use as civil water pipelines and landfill membranes.

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Topics: Low-density polyethylene (54%), Carbon nanotube (53%), Polymer nanocomposite (52%) ...read more

19 Citations


References
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Journal ArticleDOI: 10.1016/J.PROGPOLYMSCI.2009.09.003
Abstract: Carbon nanotubes have long been recognized as the stiffest and strongest man-made material known to date. In addition, their high electrical conductivity has roused interest in the area of electrical appliances and communication related applications. However, due to their miniscule size, the excellent properties of these nanostructures can only be exploited if they are homogeneously embedded into light-weight matrices as those offered by a whole series of engineering polymers. We review the present state of polymer nanocomposites research in which the fillers are carbon nanotubes. In order to enhance their chemical affinity to engineering polymer matrices, chemical modification of the graphitic sidewalls and tips is necessary. In this review, an extended account of the various chemical strategies for grafting polymers onto carbon nanotubes and the manufacturing of carbon nanotube/polymer nanocomposites is given. The mechanical and electrical properties to date of a whole range of nanocomposites of various carbon nanotube contents are also reviewed in an attempt to facilitate progress in this emerging area.

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2,561 Citations


Journal ArticleDOI: 10.1109/TPWRD.2005.848736
A. Alawar1, E.J. Bosze1, S.R. Nutt1Institutions (1)
Abstract: A new type of overhead conductor with a polymer composite core is evaluated in terms of the mechanical properties and operating characteristics. The conductor is composed of trapezoidal O'-tempered aluminum wires helically wound around a hybrid glass/carbon composite core produced by pultrusion. The conductor is intended for electrical power transmission, and is designated ACCC/TW, for aluminum conductor composite core/trapezoidal wire. Measurements of core properties and conductor sag at high temperatures were compared to conventional ACSR (aluminum conductor, steel-reinforced) of the same diameter. The tensile strength of the ACCC/TW was /spl sim/1.5 times greater than conventional ACSR of the same outer diameter. The CTE of the composite core was approximately 4 times lower than the steel core in ACSR. The ACCC/TW conductor exhibited a six-fold reduction in high-temperature sag compared with conventional ACSR (Drake) when operated at the same current. The ACCC/TW conductor also exhibited greater ampacity than ACSR conductor at all operating temperatures.

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Topics: Conductor (51%), Ampacity (51%)

117 Citations


Journal ArticleDOI: 10.1016/J.MATDES.2015.09.105
05 Jan 2016-Materials & Design
Abstract: Epoxy matrix reinforced with conventional microscale short carbon fibers (SCFs) and carbon nanotubes (CNTs) form a hybrid material system where the characteristic length scales of SCFs and CNTs differ by multiple orders of magnitude. Several recent studies show that the addition of CNTs into a non-conducting polymer matrix improves both structural performance such as modulus, strength and fracture toughness and functional response such as electrical and thermal conductivities of the resulting nano-composite. In this study, a physics-based hierarchical multiscale modeling approach is presented to calculate the effective electrical conductivity of SCF-CNT-polymer hybrid composites. A dual step procedure is adopted to couple the effects of nano- and micro-scale so as to estimate the effective electrical properties of the composite. First, CNTs are dispersed into the non-conducting polymer matrix to obtain an electrically conductive CNT-epoxy composite. The effective electrical conductivity of CNT-epoxy composite is modeled using a physics-based formulation for both randomly distributed and vertically aligned cases of CNTs and the results are verified with the measured data available in the literature. In the second step, SCFs are randomly distributed in the CNT-epoxy composite and the effective electrical conductivity of the resulting SCF-CNT-epoxy hybrid composite is estimated using a micromechanics based self-consistent approach considering SCFs as microscopic inhomogeneities.

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Topics: Carbon nanotube (55%), Micromechanics (54%), Composite number (52%) ...read more

73 Citations


Journal ArticleDOI: 10.1016/J.CARBON.2011.10.040
01 Mar 2012-Carbon
Abstract: The axial mechanical, electrical and thermal properties of carbon nanotubes (CNTs) can be exploited macroscopically by assembling them parallel to each other into a fibre during their synthesis by chemical vapour deposition. Multifunctional composites with high volume fraction of CNT fibres are then made by direct polymer infiltration of an array of aligned fibres. The fibres have a very high surface area, causing the polymer to infiltrate them and resulting in a hierarchical composite structure. The electrical and thermal conductivities of CNT/epoxy composites are shown to be superior to those of equivalent specimens with T300 carbon fibre (CF) which is widely used in industry. From measurements of longitudinal coefficient of thermal expansion (CTE) of the composites we show that the CTE of CNT fibres is approximately −1.6 × 10 −6 K −1 , similar to in-plane graphite. The combination of electrical, thermal and mechanical properties of CNT fibre composites demonstrates their potential for multifunctionality.

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Topics: Carbon nanotube (56%), Epoxy (51%), Graphite (50%)

64 Citations


Journal ArticleDOI: 10.1109/MPER.2001.4311194
C. Mensah-Bonsu, U. Fernandez, Gerald T. Heydt1, Y. Hoverson1  +2 moreInstitutions (3)
Abstract: This paper describes a method to directly measure the physical sag of overhead electric power transmission conductors. The method used relies on the Global Positioning System (GPS) used in the differential mode. The direct measurement of sag is a main advantage of the concept. The digital signal processing required is described in detail in a four-level configuration. The typical accuracy, response time, problems, strengths and weaknesses of the method are also described.

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Topics: Overhead (computing) (55%), Electric power transmission (54%), Power transmission (54%) ...read more

60 Citations