scholarly journals Influence of Carbon Fibers on Strain and Damage Sensing of Self Compacting Concrete under External Applied Forces

2019 ◽  
Vol 18 (6) ◽  
pp. 559-565
Author(s):  
Arvind Kumar Cholker ◽  
Bode Venkata Kavyateja ◽  
Panga Narasimha Reddy
Keyword(s):  
Carbon Fibers ◽  
Self Compacting Concrete ◽  
Damage Sensing ◽  
Applied Forces

scholarly journals Enhancing Damage-Sensing Capacity of Strain-Hardening Macro-Steel Fiber-Reinforced Concrete by Adding Low Amount of Discrete Carbons

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 938 ◽  
Author(s):  
Duy-Liem Nguyen ◽  
Dong-Joo Kim ◽  
Duc-Kien Thai
Keyword(s):  
Strain Hardening ◽  
Carbon Fibers ◽  
Mechanical Response ◽  
Steel Fiber ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Damage Sensing ◽  
Softening Behavior ◽  
Multi Walled Carbon Nanotubes

The effects of adding micro-carbon fibers on the electro-mechanical response of macro-steel fiber-reinforced concretes (MSFRCs) under tension were investigated. Two MSFRCs were investigated and they had identical mortar matrix but different fiber contents: MSFRC1 and MSFRC2 contained 1.0 and 1.5 vol.% fibers, respectively. The volume contents of added micro-carbon fibers were 0 to 1.5 vol.% in MSFRC1 and 0 to 0.75 vol.% in MSFRC2, respectively. The addition of 0.5 vol.% micro-carbon fibers, in both MSFRC1 and MSFRC2, produced significantly enhanced damage-sensing capability and still retained their strain-hardening performance together with multiple micro cracks. However, when the content of carbon fibers was more than 0.5 vol.%, the MSFRCs generated tensile strain-softening behavior and reduced damage-sensing capability. Furthermore, the effects of temperature and humidity on the electrical resistivity of MSFRCs were investigated, as were the effects of adding multi-walled carbon nanotubes on the damage-sensing capability of MSFRCs.

In-situ damage sensing in intra-ply glass/carbon laminate composites under interlaminar shear loading

2021 ◽  
pp. 002199832110492
Author(s):  
Matthew Pires ◽  
Vijaya Chalivendra
Keyword(s):  
Carbon Fibers ◽  
Epoxy Matrix ◽  
Electrical Response ◽  
Glass Fibers ◽  
Shear Loading ◽  
Damage Sensing ◽  
Sensing Applications ◽  
Loading Direction ◽  
Interlaminar Shear

An experimental study is preformed to investigate the in-situ damage sensing capabilities of intra-ply hybrid carbon/glass laminate and epoxy composites under quasi-static interlaminar shear loading. A three-dimensional electrical sensory network is generated inside the composites through embedded carbon nanotubes (CNTs) in an epoxy matrix along with the carbon fibers in the intra-ply hybrid laminates. CNTs are dispersed in the epoxy matrix using a combination of ultrasonication and shear mixing techniques. Four circumferential ring probes are used to examine the electrical response under interlaminar shear load. The effect of four different intra-ply orientations (((0–90)C, where carbon fibers are oriented along the loading direction), ((0–90)G, where glass fibers are oriented along the loading direction), ((45/−45, where glass and carbon fibers are oriented at 45o/−45o and the laminates are repeated), and ((45/−45)A, where glass and carbon fibers are oriented at 45o/−45o and the laminates are alternated)) on the shear constitutive behavior and the damage detection are discussed. Intra-ply orientations of (45/−45) and (45/−45)A showed higher interlaminar shear strength and shear strain at break compared to (0/90)C and (0/90)G orientations. Out of all four orientations, (45/−45)A provided a better resolution of electrical response for damage sensing applications.

scholarly journals USING CARBON FIBER STRIPS IN JOINTS STRENGTHING OF BOX SEGMENTAL SELF-COMPACTING CONCRETE BEAMS

2020 ◽  
Vol 24 (06) ◽  
pp. 22-32
Author(s):  
Ahmed H. Hashim ◽  
◽  
Waleed A. Wrayosh ◽  
Keyword(s):  
Carbon Fibers ◽  
Concrete Beams ◽  
Precast Concrete ◽  
Reference Beam ◽  
Concrete Surface ◽  
Self Compacting Concrete ◽  
Cfrp Sheets ◽  
Mode Of Failure ◽  
Cracking Mode ◽  
Self Compact Concrete

The main objective of this research is to study the effect of carbon fibers used to strengthen the joints of the box segmental beams. For this research, four beams were produced and tested. One of these beams, monolithically, was cast as a reference beam and the three others were segmental beams. All beams were produced with Self-Compact Concrete (SCC) and box cross section. Each segmental beam consisted of three precast concrete segments were connected by post tensioning tendons. The three segmental beams have same characteristics, but different in joint types between the segments. The types of joints used were (dried , epoxied and dried strengthen by CFRP sheets). All beams were tested under static two point loads up to failure. For each test, deflections at mid-span location were recorded for each (5kN). Also, first cracking, mode of failure and ultimate loads values were recorded as well as the concrete surface strains at the specified locations for both loadings.

Damage sensing in multi-functional glass fiber composites under mode-I fracture loading

2020 ◽  
Vol 54 (30) ◽  
pp. 4821-4829
Author(s):  
Jacob O’Donnell ◽  
Vijaya Chalivendra ◽  
Asha Hall ◽  
Yong Kim
Keyword(s):  
Carbon Fiber ◽  
Crack Initiation ◽  
Glass Fiber ◽  
Carbon Fibers ◽  
Mode I ◽  
Initiation Toughness ◽  
Mode I Fracture ◽  
Conductive Composites ◽  
Damage Sensing ◽  
Conductive Glass

A detailed experimental study is performed for piezo resistance damage sensing on conductive glass fiber/epoxy composites under mode-I fracture conditions. The conductive composites are fabricated by homogeneously dispersing carbon nanotubes (CNTs) within the epoxy matrix and electro-flocking short carbon fibers onto the laminates along with a vacuum infusion process. A parametric study is done on the in-situ damage sensing properties by varying the carbon fiber lengths (150 µm and 350 µm) and the carbon fiber areal densities (500, 1000, 1500, and 2000 fibers/mm2). The change in resistance is captured with a four-point probe measuring methodology by measuring the resistance through the thickness of the composite. The crack initiation toughness value of the composites containing carbon fibers showed improvement over control composites. Composites containing 350 µm length carbon fibers and 2000 fiber/mm2 not only showed the best crack initiation toughness but also provided sensitive network for detecting crack growth.

EXELFS Studies of Carbon Fibers

1990 ◽  
Vol 48 (2) ◽  
pp. 72-73
Author(s):  
V. Serin ◽  
K. Hssein ◽  
G. Zanchi ◽  
J. Sévely
Keyword(s):  
Carbon Fibers ◽  
Energy Analysis ◽  
Electron Excitation ◽  
Complex Structures ◽  
High Modulus ◽  
Promising Technique ◽  
X Ray ◽  
Fine Structures ◽  
X Ray Absorption

The present developments of electron energy analysis in the microscopes by E.E.L.S. allow an accurate recording of the spectra and of their different complex structures associated with the inner shell electron excitation by the incident electrons (1). Among these structures, the Extended Energy Loss Fine Structures (EXELFS) are of particular interest. They are equivalent to the well known EXAFS oscillations in X-ray absorption spectroscopy. Due to the EELS characteristic, the Fourier analysis of EXELFS oscillations appears as a promising technique for the characterization of composite materials, the major constituents of which are low Z elements. Using EXELFS, we have developed a microstructural study of carbon fibers. This analysis concerns the carbon K edge, which appears in the spectra at 285 eV. The purpose of the paper is to compare the local short range order, determined by this way in the case of Courtauld HTS and P100 ex-polyacrylonitrile carbon fibers, which are high tensile strength (HTS) and high modulus (HM) fibers respectively.

The effects of scaling height and scaling bar design on applied forces and bilateral muscle activity of the back and shoulders

2006 ◽  
Author(s):  
William Porter ◽  
Sean Gallagher ◽  
Carrie Reinholtz ◽  
Janet Torma-Krajewski
Keyword(s):  
Muscle Activity ◽  
Applied Forces
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