Enhanced Electromechanical Responses of IPCNC Actuators

2010 ◽  
Author(s):  
Yang Liu ◽  
Sheng Liu ◽  
Hulya Cebeci ◽  
Roberto G. de Villoria ◽  
Jun-Hong Lin ◽  
...  
Keyword(s):  
High Performance ◽  
Volume Fraction ◽  
High Volume ◽  
Experimental Results ◽  
Composite Electrodes ◽  
Ionic Polymer ◽  
Electromechanical Responses ◽  
Electromechanical Performance ◽  
Vertically Aligned ◽  
Anisotropic Elastic

In this presentation, we will show several progresses in Ionic Polymer Conductor Network Composite Actuators (IPCNC) studies. First of all, we successfully fabricated ultra high volume fraction vertically aligned carbon nanotubes (VA-CNTs)/polymer composite electrodes which markedly improved the electromechanical performance of IPCNC actuators. The experimental results show that the continuous paths through inter-VA-CNT channels and low electrical conduction resistance due to the continuous CNTs lead to fast actuation speed (>10% strain/second). The experimental results also demonstrate that the VA-CNTs create anisotropic elastic property in the composite electrodes, which suppresses the vertical strain and markedly enhances the actuation strain (>8% strain under 4 volts). The data here show the promise of optimizing the electrode morphology in IPCNCs by the ultrahigh volume fraction VA-CNTs for ionic polymer actuators to achieve high performance.

Ionic Electroactive Polymer Actuators with Aligned Carbon Nanotube/Nafion Nanocomposite Electrodes

2011 ◽  
Vol 1304 ◽  
Author(s):  
Yang Liu ◽  
Sheng Liu ◽  
Hülya Cebeci ◽  
Roberto Guzman de Villoria ◽  
Jun-Hong Lin ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Volume Fraction ◽  
Critical Issue ◽  
Composite Electrodes ◽  
Ionic Polymer ◽  
Electromechanical Performance ◽  
Vertically Aligned ◽  
Controlled Morphology ◽  
Fast Ion ◽  
Actuation Strain

ABSTRACTRecent advances in fabricating controlled-morphology vertically aligned carbon nanotube (VA-CNTs) with ultrahigh volume fraction create unique opportunities for markedly improving the electromechanical performance of ionic polymer conductor network composite actuators (IPCNCs). Actuator experiments show that the continuous paths through inter-VA-CNT channels and low electrical conduction resistance due to the continuous CNTs in the composite electrodes of the IPCNC lead to fast ion transport and actuation speed (>10% strain/second). One critical issue in developing advanced actuator materials is how to suppress or eliminate unwanted strains generated under electric stimulation, which reduce the actuation efficiency and also the actuation strains. We observe that the VA-CNTs in the composite electrodes yields non-isotropic elastic modulus that suppresses the unwanted strain and markedly enhances the actuation strain (>8% strain under 4 volts). A transmission line model has been developed to understand the electrical properties of the actuator device.

Theoretical Modeling for Electroactive Polymer-Ceramic Hybrid Actuation Systems

Aerospace ◽  
2004 ◽  
Author(s):  
Tian-Bing Xu ◽  
Ji Su
Keyword(s):  
Performance Optimization ◽  
High Performance ◽  
Electroactive Polymer ◽  
Actuation System ◽  
Electromechanical Responses ◽  
Electromechanical Performance ◽  
New Type ◽  
Hybrid Actuation ◽  
Actuation Systems ◽  
Further Development

An electroactive polymer-ceramic hybrid actuation system (HYBAS) was recently developed. The HYBAS demonstrates significantly-enhanced electromechanical performance by utilizing advantages of cooperative contributions of the electromechanical responses of an electrostrictive copolymer and an electroactive single crystal. The hybrid actuation system provides not only a new type of device but also a concept to utilize different electroactive materials in a cooperative and efficient method for optimized electromechanical performance. In order to develop an effective procedure to optimize the performance of a hybrid actuation system (HYBAS), a theoretical model has been developed, based on the elastic and electromechanical properties of the materials utilized in the system and on the configuration of the device. The model also evaluates performance optimization as a function of geometric parameters, including the length of the HYBAS and the thickness ratios of the constituent components. The comparison between the model and the experimental results shows a good agreement and validates the model as an effective method for the further development of high performance actuating devices or systems for various applications.

Gelation-Assisted Layer-by-Layer Deposition of High Performance Nanocomposites

2018 ◽  
Vol 232 (9-11) ◽  
pp. 1383-1398 ◽  
Author(s):  
Jian Zhu ◽  
Douglas Watts ◽  
Nicholas A. Kotov
Keyword(s):  
High Performance ◽  
Volume Fraction ◽  
High Volume ◽  
Nanometer Scale ◽  
Layer By Layer ◽  
Lbl Assembly ◽  
Layer Deposition ◽  
Fine Control ◽  
Nanofiber Alignment ◽  
Functional Components

Abstract Layer-by-layer (LBL) assembly produces nanocomposites with distinctively high volume fractions of nanomaterials and nanometer scale controlled uniformity. Although deposition of one nanometer scale layer at a time leads to high performance composites, this deposition mode is also associated with the slow multilayer build-up. Exponential LBL, spin coating, turbo-LBL and other methods tremendously accelerate the multilayer build-up but often yield lower, strength, toughness, conductivity, etc. Here, we introduce gelation assisted layer-by-layer (gaLBL) deposition taking advantage of a repeating cycle of hydrogel formation and subsequent polymer infiltration demonstrated using aramid nanofiber (ANF) and epoxy resin (EPX) as deposition partners. Utilization of ANF gels increases the thickness of each deposited layer from 1–10 nm to 30–300 nm while retaining fine control of thickness in each layer, high volume fraction, and uniformity. While increasing the speed of the deposition, the high density of interfaces associated with nanofiber gels helps retain high mechanical properties. The ANF/EPX multilayer composites revealed a rare combination of properties that was unavailable in traditional aramid-based and other composites, namely, high ultimate strength of 505±47 MPa, high toughness of 50.1±9.8 MJ/m3, and high transparency. Interestingly, the composite also displayed close-to-zero thermal expansion. The constellation of these materials properties is unique both for quasi-anisotropic composites and unidirectional materials with nanofiber alignment. gaLBL demonstrates the capability to resolve the fundamental challenge between high-performance and scalability. The gelation-assisted layered deposition can be extended to other functional components including nanoparticle gels.

scholarly journals Finite Element Simulation Study of Ultrasonic Vibration-Assisted Tensile High-Volume Fraction SiCp/Al Composite

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3841 ◽  
Author(s):  
Zhang ◽  
Xiang ◽  
Wu ◽  
Feng ◽  
Shi ◽  
...  
Keyword(s):  
Finite Element ◽  
Tensile Strength ◽  
Finite Element Simulation ◽  
Ultrasonic Vibration ◽  
Stress Reduction ◽  
Volume Fraction ◽  
Aluminum Matrix ◽  
High Volume ◽  
Experimental Results ◽  
Element Simulation

Silicon carbide particle-reinforced aluminum matrix composite (SiCp/Al) has been widely used in the military and aerospace industry due to its special performance; however, there remain many problems in the processing. The present paper introduces an ultrasonic vibration tensile apparatus and a composite tensile specimen and performs Abaqus finite element simulation on high-volume SiCp/Al. The results show that the stress-strain curve increases linearly during conventional tensile strength; the intermittent vibration tensile strength is similar to the full course vibration tensile strength: The magnitude of the stress reduction increases as the amplitude of the ultrasound increases and the vibration frequency increases. The tensile rate is inversely proportional to the magnitude of the stress reduction, and in the ultrasonic parameters, the amplitude has the greatest influence on the magnitude of the stress reduction, followed by the tensile rate; additionally, the frequency has the least influence on the magnitude of the stress reduction. The experimental results show that the simulation results are consistent with the experimental results.

scholarly journals Flexural Behavior of High-Volume Steel Fiber Cementitious Composite Externally Reinforced with Basalt FRP Sheet

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Seungwon Kim ◽  
Cheolwoo Park
Keyword(s):  
High Performance ◽  
Volume Fraction ◽  
High Volume ◽  
Cement Composite ◽  
High Energy ◽  
Absorption Capacity ◽  
Flexural Behavior ◽  
Fiber Reinforced ◽  
Externally Bonded ◽  
Energy Absorbing

High-performance fiber-reinforced cementitious composites (HPFRCCs) are characterized by unique tensile strain hardening and multiple microcracking behaviors. The HPFRCC, which demonstrates remarkable properties such as strength, ductility, toughness, durability, stiffness, and thermal resistance, is a class of fiber cement composite with fine aggregates. It can withstand tensile stresses by forming distributed microcracks owing to the embedded fibers in the concrete, which improve the energy absorption capacity and apparent ductility. This high energy absorbing capacity can be enhanced further by an external stiff fiber-reinforced polymer (FRP). Basalt fabric is externally bonded as a sheet on concrete materials to enhance the durability and resistance to fire and other environmental attacks. This study investigates the flexural performance of an HPFRCC that is externally reinforced with multiple layers of basalt FRP. The HPFRCC considered in the study contains steel fibers at a volume fraction of 8%.

Gel Casting and Properties of SiCp/Al Composite

2016 ◽  
Vol 697 ◽  
pp. 551-554
Author(s):  
Hai Lin Liu ◽  
Xiao Ting Huang ◽  
Yan Li Huo ◽  
Chuan Qi Hu ◽  
Chun Peng Wang ◽  
...  
Keyword(s):  
High Performance ◽  
Volume Fraction ◽  
Casting Process ◽  
High Volume ◽  
High Volume Fraction ◽  
Solid Loading ◽  
Low Viscosity ◽  
Gel Casting ◽  
Al Composite ◽  
Infiltration Technique

In this paper, high volume fraction SiCp/Al composite was fabricated by pressureless technique with silicon carbide porous preform which fabricated through gel casting process. The effects of solid loading on the rheological properties of SiC slurry were discussed. High solid loading SiC slurry of 65vol% with low viscosity and high stability was fabricated. Also microstructure, flexural strength of the SiC preform and SiCp/Al composite were studied, the results showed gel casting process and pressureless infiltration technique were suitable for fabricating high volume fraction, homogeneous structure and high performance SiCp/Al composite.

scholarly journals Severely Damaged Reinforced Concrete Circular Columns Repaired by Turned Steel Rebar and High-Performance Concrete Jacketing with Steel or Polymer Fibers

2018 ◽  
Vol 8 (9) ◽  
pp. 1671 ◽  
Author(s):  
Junqing Xue ◽  
Davide Lavorato ◽  
Alessandro V. Bergami ◽  
Camillo Nuti ◽  
Bruno Briseghella ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Volume Fraction ◽  
Plastic Hinge ◽  
High Volume ◽  
Polymer Fibers ◽  
Rc Columns ◽  
Steel Rebar ◽  
Transverse Steel

A new strategy that repairs severely damaged reinforced concrete (RC) columns after an earthquake is proposed as a simpler and quicker solution with respect to the strategies currently available in the literature. The external concrete parts are removed from the column surface along the whole plastic hinge region to uncover the steel reinforcement. The transverse steel is cut away, and each longitudinal rebar is locally substituted by steel rebar segments connected by welding connections to the original undamaged rebar pieces outside the intervention zone. The new rebar segments have a reduced diameter achieved by turning to ensure plastic deformation only in the plastic hinge, protecting the original rebar and the welding connections. The connection is specifically designed to be effective and simple, and is directly realized on column reinforcement. Finally, the removed concrete is restored by a jacket built with high-performance concrete with steel or polymer fibers. The use of concrete with high volume fraction of polymer fibers to repair the column is investigated for the first time in this paper. This concrete was characterized by compression and flexural tests in the laboratory and its mechanical characteristics were compared with those of the concrete with steel fibers, which are being increasingly used in construction. The repair strategy was applied to two RC columns (1:6 scaled bridge piers), tested by asymmetric cyclic tests. The results show that the column strength, stiffness, and ductility were restored, and the energy dissipation capacity improved. The experimental evidence was investigated by fiber models in OpenSees.

Morphology, Distribution and Identification of Micro-Constituents Along Grain Boundaries in Nickel-Base Alloys

1973 ◽  
Vol 31 ◽  
pp. 176-177
Author(s):  
D. E. Fornwalt ◽  
A. R. Geary ◽  
B. H. Kear
Keyword(s):  
Electron Microscope ◽  
Grain Boundaries ◽  
Volume Fraction ◽  
Rupture Life ◽  
Stress Rupture ◽  
High Volume ◽  
Precipitate Morphology ◽  
Stress Rupture Life ◽  
Nickel Base ◽  
Scanning Electron

A systematic study has been made of the effects of various heat treatments on the microstructures of several experimental high volume fraction γ’ precipitation hardened nickel-base alloys, after doping with ∼2 w/o Hf so as to improve the stress rupture life and ductility. The most significant microstructural chan§e brought about by prolonged aging at temperatures in the range 1600°-1900°F was the decoration of grain boundaries with precipitate particles.Precipitation along the grain boundaries was first detected by optical microscopy, but it was necessary to use the scanning electron microscope to reveal the details of the precipitate morphology. Figure 1(a) shows the grain boundary precipitates in relief, after partial dissolution of the surrounding γ + γ’ matrix.

Macroprobe Mode for the Study of Segregation in Steels

1990 ◽  
Vol 48 (2) ◽  
pp. 260-261
Author(s):  
Auclair Gilles ◽  
Benoit Danièle
Keyword(s):  
Mechanical Properties ◽  
Spatial Distribution ◽  
High Performance ◽  
Volume Fraction ◽  
Sheet Steel ◽  
Acquisition Time ◽  
Chemical Information ◽  
X Ray ◽  
Accurate Quantitative Analysis ◽  
Optical Micrographs

During these last 10 years, high performance correction procedures have been developed for classical EPMA, and it is nowadays possible to obtain accurate quantitative analysis even for soft X-ray radiations. It is also possible to perform EPMA by adapting this accurate quantitative procedures to unusual applications such as the measurement of the segregation on wide areas in as-cast and sheet steel products.The main objection for analysis of segregation in steel by means of a line-scan mode is that it requires a very heavy sampling plan to make sure that the most significant points are analyzed. Moreover only local chemical information is obtained whereas mechanical properties are also dependant on the volume fraction and the spatial distribution of highly segregated zones. For these reasons we have chosen to systematically acquire X-ray calibrated mappings which give pictures similar to optical micrographs. Although mapping requires lengthy acquisition time there is a corresponding increase in the information given by image anlysis.

HOT CORROSION OF CERIA-YTTRIA STABILIZED ZIRCONIA PLASMA SPRAYED THERMAL BARRIER COATING BY EUTECTIC VANDIUM PENTAOXIDE-SODIUM SULFATE

2018 ◽  
Vol 18 (1) ◽  
pp. 182-192 ◽  
Author(s):  
Mohammed J Kadhim ◽  
Mohammed H Hafiz ◽  
Maryam A Ali Bash
Keyword(s):  
Thermal Barrier Coating ◽  
Hot Corrosion ◽  
Monoclinic Phase ◽  
Volume Fraction ◽  
High Volume ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Plan View ◽  
Barrier Coating ◽  
Plasma Sprayed

The high temperature corrosion behavior of thermal barrier coating (TBC) systemconsisting of IN-738 LC superalloy substrate, air plasma sprayed Ni24.5Cr6Al0.4Y (wt%)bond coat and air plasma sprayed ZrO2-20 wt% ceria-3.6 wt% yttria (CYSZ) ceramic coatwere characterized. The upper surfaces of CYSZ covered with 30 mg/cm2 , mixed 45 wt%Na2SO4-55 wt% V2O5 salt were exposed at different temperatures from 800 to 1000 oC andinteraction times from 1 up to 8 h. The upper surface plan view of the coatings wereidentified for topography, roughness, chemical composition, phases and reaction productsusing scanning electron microscopy, energy dispersive spectroscopy, talysurf, and X-raydiffraction. XRD analyses of the plasma sprayed coatings after hot corrosion confirmed thephase transformation of nontransformable tetragonal (t') into monoclinic phase, presence ofYVO4 and CeVO4 products. Analysis of the hot corrosion CYSZ coating confirmed theformation of high volume fraction of YVO4, with low volume fractions of CeOV4 and CeO2.The formation of these compounds were combined with formation of monoclinic phase (m)from transformation of nontransformable tetragonal phase (t').

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