A spectroscopic examination of carbon fiber cross sections using XPS and ISS

Carbon ◽  
1996 ◽  
Vol 34 (10) ◽  
pp. 1221-1228 ◽  
Author(s):  
S.D. Gardner ◽  
G. He ◽  
C.U. Pittman
Keyword(s):  
Carbon Fiber ◽  
Cross Sections ◽  
Spectroscopic Examination

scholarly journals Electrodeposited Platinum Iridium Enables Microstimulation With Carbon Fiber Electrodes

2021 ◽  
Vol 3 ◽  
Author(s):  
Elena della Valle ◽  
Beomseo Koo ◽  
Paras R. Patel ◽  
Quentin Whitsitt ◽  
Erin K. Purcell ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Cross Sections ◽  
Minimal Scarring ◽  
Pulse Testing ◽  
Implant Tests ◽  
Before And After ◽  
Voltage Transients ◽  
Scanning Electron

Ultrasmall microelectrode arrays have the potential to improve the spatial resolution of microstimulation. Carbon fiber (CF) microelectrodes with cross-sections of less than 8 μm have been demonstrated to penetrate cortical tissue and evoke minimal scarring in chronic implant tests. In this study, we investigate the stability and performance of neural stimulation electrodes comprised of electrodeposited platinum-iridium (PtIr) on carbon fibers. We conducted pulse testing and characterized charge injection in vitro and recorded voltage transients in vitro and in vivo. Standard electrochemical measurements (impedance spectroscopy and cyclic voltammetry) and visual inspection (scanning electron microscopy) were used to assess changes due to pulsing. Similar to other studies, the application of pulses caused a decrease in impedance and a reduction in voltage transients, but analysis of the impedance data suggests that these changes are due to surface modification and not permanent changes to the electrode. Comparison of scanning electron microscope images before and after pulse testing confirmed electrode stability.

Effect of kidney-type and circular cross sections on carbon fiber surface and composite interface

2008 ◽  
Vol 39 (2) ◽  
pp. 301-307 ◽  
Author(s):  
Zhiwei Xu ◽  
Jialu Li ◽  
Xiaoqing Wu ◽  
Yudong Huang ◽  
Li Chen ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Cross Sections ◽  
Fiber Surface ◽  
Composite Interface ◽  
Carbon Fiber Surface

scholarly journals Pulse Ultrasonic Cure Monitoring of the Pultrusion Process

2018 ◽  
Author(s):  
Patrick Scholle ◽  
Michael Sinapius
Keyword(s):  
Carbon Fiber ◽  
Cross Sections ◽  
Ultrasonic Transducers ◽  
Adhesively Bonded ◽  
Carbon Fiber Reinforced Plastics ◽  
Pultrusion Process ◽  
Cure Monitoring ◽  
Reinforced Plastics ◽  
Series Of Experiments ◽  
Fiber Reinforced Plastics

This article discusses the results of a series of experiments on pulse ultrasonic cure monitoring of carbon fiber reinforced plastics applied to the pultrusion process. The aim of this study is to validate the hypothesis that pulse ultrasonic cure monitoring can be applied a) for profiles having small cross sections such as 7x0.5 mm and b) within the environment of the pultrusion process. Ultrasonic transducers are adhesively bonded to the pultrusion tool as actuators and sensors. The time-of-flight and the amplitude of an ultrasonic wave are analyzed to deduce the current curing state of the epoxy matrix. The experimental results show that ultrasonic cure monitoring is indeed applicable even to very thin cross sections. However, significant challenges can be reported when the techniques are used during the pultrusion process.

scholarly journals Fundamental Investigation on Seismic Retrofitting Method of Aging Concrete Structural Wall Using Carbon Fiber Sheet-Constitutive Law of Rectangular Section

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Kazuhiro Hayashi ◽  
Tomoya Matsui ◽  
Taiki Saito ◽  
Roy Reyna
Keyword(s):  
Carbon Fiber ◽  
Cross Section ◽  
Cross Sections ◽  
Constitutive Law ◽  
Seismic Retrofitting ◽  
Short Side ◽  
Structural Wall ◽  
Strain Relationship ◽  
Fiber Sheet ◽  
Concrete Elements

Aging building structure has become a world problem. This problem is particularly serious in developing and underdeveloped countries. The multihazard resilience and sustainability (e.g., seismic performance) decrease at the aging building. A construction method for strengthening aging-reinforced concrete buildings by wrapping structural members with carbon fiber sheets has been proposed and implemented in recent years. Authors aim to develop a seismic retrofitting method of aging concrete structural wall with a rectangular cross section using carbon fiber sheets. In this paper, authors examined the stress-strain relationship of concrete elements with rectangular cross sections reinforced by wrapping with carbon fiber sheets. Monotonic uniaxial compression tests were performed on 21 specimens using the ratio of the long side to the short side and the ratio of the element height to the short side of the concrete cross section, the weight of the carbon fiber sheet, and the chamfer radius of section corners as variables. The tests revealed that (1) the compressive strength decreases and ultimate strain increases as the ratio of the long to short side (longitudinal ratio) of the cross section increases even in a range the ratio exceeds 2 and (2) the ratio of the element height to the short side does not significantly affect the stress-strain relationship. Furthermore, authors proposed evaluation formulas for the constitutive law of concrete elements with rectangular cross sections including the longitudinal ratio which exceeds 2 reinforced by carbon fiber sheets and confirmed that the formulas can reproduce the test results with good accuracy.

Basic Study on Reinforced Concrete Shear Walls Without Boundary Columns Retrofitted by Carbon Fiber Sheets

2014 ◽  
Vol 9 (6) ◽  
pp. 1008-1014 ◽  
Author(s):  
Tomoya Matsui ◽  
◽  
Taiki Saito ◽  
Roy Reyna
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Cross Sections ◽  
Shear Walls ◽  
Shear Wall ◽  
Wire Mesh ◽  
Structural Elements ◽  
Basic Study ◽  
Flexural Mode ◽  
Strength Deterioration

Reinforced concrete (RC) buildings in Peru use low ductility walls, with rectangular cross-sections and reinforced with wire mesh and vertical reinforcement bars at boundary ends, as structural elements. These structural elements have no columns, have small amounts of reinforcing bars and are expected to fail in a brittle manner. In this study, a performance verification test is conducted on the use of carbon fiber sheets (CFS) as a retrofitting method for shear walls without boundary columns. The focus is on retrofitting walls that fail in flexural mode. In other words, although an increase in strength cannot be expected, CFS retrofitting can delay the concrete crushing of the shear wall base that occurs during flexural failure; and the aim is to verify this improvement in deformation performance due to CFS retrofitting. From the test, by retrofitting the RC shear wall without boundary columns with CFS, it was found that postmaximum strength deterioration was more gradual, and deformation performance was improved. And Ultimate limit deformation of specimen which was partially retrofitted at the boundary ends of the wall was larger than that of specimen which was retrofitted over the entire wall span.

scholarly journals The use of FRP of increased thickness for strengthening structures

2021 ◽  
Vol 263 ◽  
pp. 02033
Author(s):  
Oleg Simakov
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Cross Sections ◽  
Experimental Studies ◽  
Calculation Methods ◽  
Reinforcement System ◽  
External Reinforcement ◽  
Concrete Elements

The external reinforcement system based on carbon fiber has been used for decades to strengthen reinforced concrete elements. At the same time, it is impossible not to recognize that the existing calculation methods are largely based on empirical dependencies obtained from experimental studies. One of these issues is related to the application of the methodology for materials of heterogeneous origin-tapes and laminates. In general, the possibility of applying the calculation methods accepted in the norms for laminates of generally accepted thicknesses up to 1.6 mm is determined. The question related to the possibility of using laminates of greater thickness is not sufficiently studied. This article deals with the calculation of the reinforcement of the normal cross sections of the bent reinforced concrete elements with the reinforcement of laminates with a thickness of 5 mm.

scholarly journals Experimental analysis and design strength models adopted by international guides for FRP-confined concrete columns subjected to axial compression

2021 ◽  
Vol 71 (344) ◽  
pp. e266
Author(s):  
J.P. Gutiérrez ◽  
S. Martínez ◽  
A. De Diego ◽  
V.J. Castro ◽  
L. Echevarría
Keyword(s):  
Carbon Fiber ◽  
Cross Sections ◽  
Rectangular Cross Section ◽  
Effective Strain ◽  
Plain Concrete ◽  
Experimental Program ◽  
Design Strength ◽  
Analysis And Design ◽  
Intermediate Size ◽  
Strength Models

Carbon fiber jacketing is an efficient technique for increasing the strength and strain capacity of concrete circular and square section columns subjected to axial load, although confinement efficiency decreases for rectangular cross-section members. The research project BIA 2016-80310-P includes an experimental program on intermediate-size plain concrete specimens strengthened with carbon fiber jackets, mostly with square and rectangular cross-sections. The results, alongside others with similar characteristics from two databases published, are compared to predictions of four international guides. The incidence of the key parameters in the experimental results is analyzed, such as the aspect ratio of the section, the effective strain in FRP jacket attained at failure or the rounded corner radius. As a result, two efficiency strain factors are proposed, one for circular and another for rectangular specimens. The predictions contained in certain guides, based on a simple linear design-model, are improved by using the proposed efficiency strain factor for rectangular sections.

scholarly journals Pulse Ultrasonic Cure Monitoring of the Pultrusion Process

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3332 ◽  
Author(s):  
Patrick Scholle ◽  
Michael Sinapius
Keyword(s):  
Carbon Fiber ◽  
Cross Sections ◽  
Ultrasonic Transducers ◽  
Adhesively Bonded ◽  
Carbon Fiber Reinforced Plastics ◽  
Pultrusion Process ◽  
Cure Monitoring ◽  
Reinforced Plastics ◽  
Series Of Experiments ◽  
Fiber Reinforced Plastics

This article discusses the results of a series of experiments on pulse ultrasonic cure monitoring of carbon fiber reinforced plastics applied to the pultrusion process. The aim of this study is to validate the hypothesis that pulse ultrasonic cure monitoring can be applied (a) for profiles having small cross sections such as 7 mm × 0.5 m m and (b) within the environment of the pultrusion process. Ultrasonic transducers are adhesively bonded to the pultrusion tool as actuators and sensors. The time-of-flight and the amplitude of an ultrasonic wave are analyzed to deduce the current curing state of the epoxy matrix. The experimental results show that ultrasonic cure monitoring is indeed applicable even to very thin cross sections. However, significant challenges can be reported when the techniques are used during the pultrusion process.

scholarly journals Strengthening Prestressed Concrete Bridge Girders and Building Beams with Carbon Fiber Reinforced Polymer Sheets

2021 ◽  
Vol 6 (1) ◽  
pp. 55-57
Author(s):  
Herish A. Hussein ◽  
Zia Razzaq
Keyword(s):  
Carbon Fiber ◽  
Flexural Strength ◽  
Cross Sections ◽  
Prestressed Concrete ◽  
Concrete Strength ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Carbon Fiber Reinforced

The effect of Carbon Fiber Reinforced Polymer (CFRP) retrofitting and concrete type on the flexural strength of prestressed concrete I-section girders used in bridges and beams in buildings is investigated. Non-linear moment-curvature relationships are predicted using an iterative algorithm for both non-retrofitted and CFRP-retrofitted prestressed concrete girder and beam cross-sections with various concrete types. Two different CFRP-retrofitting schemes are analyzed for comparing their effectiveness. It is found that although non-retrofitted beam section exhibits greater ductility, the use of CFRP retrofitting in both tension and compression regions simultaneously results in a significant increase in flexural strength. It is also found that the higher the ultimate concrete strength, the higher is the influence of CFRP-retrofitting on increasing flexural strength.

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