scholarly journals Analysis of Synthetic Fiber Pull-Out from a Cement Matrix

1987 ◽  
Vol 114 ◽  
Author(s):  
Youjiang Wang ◽  
Victor C. Li ◽  
Stanley Backer
Keyword(s):  
Fiber Surface ◽  
Synthetic Fiber ◽  
Cement Matrix ◽  
Good Prediction ◽  
Pull Out ◽  
Fiber Matrix ◽  
Pulling Force ◽  
Matrix Shear ◽  
Slippage Distance ◽  
Increasing Function

ABSTRACTExperiments were conducted on specimens containing nylon or polypropylene monofilaments embedded in a precracked matrix. During pull-out tests, it was generally observed that the pulling force continued to increase after one or both sides of the filament had begun to slip out, even though one or both of the embedded filament lengths were decreasing. This indicated that the fiber/matrix shear stress increased with the fiber slippage distance. Examination of the extracted filaments under a scanning electron microscope (SEM) revealed the increased shear resistance to be the result of fiber surface abrasion. The severity of abrasion was observed to increase with the fiber slippage distance before complete pull-out. A theoretical model has been developed to predict the pull-out force versus displacement relationship based on given fiber/matrix shear strength as an increasing function of the slippage distance. The model gives good prediction in comparison with experimental results.

scholarly journals Surface roughness characterization of various ceramic fibers using AFM and low-voltage SEM

1994 ◽  
Vol 52 ◽  
pp. 1066-1067
Author(s):  
K. L. More ◽  
E. Lara-Curzio ◽  
R. A. Lowden
Keyword(s):  
Surface Roughness ◽  
Low Voltage ◽  
Interfacial Shear Stress ◽  
Fiber Surface ◽  
Interfacial Properties ◽  
Matrix Interface ◽  
Ceramic Fibers ◽  
Pull Out ◽  
Fiber Matrix Interface ◽  
Fiber Matrix

The effect of interfacial properties in fiber-reinforced ceramic matrix composites is critical to the overall mechanical behavior of the composite material. The creation of a relatively weak fiber/matrix interface allows for the beneficial actions of debonding and fiber pull-out to occur, thus improving the fracture toughness and, in many cases, the ultimate strength of the composite. To date, the best room temperature interfacial properties have been achieved by coating the fibers with either carbon or boron nitride. There are several factors which contribute to the interfacial properties of a composite, including the residual stress (clamping stress) present at the fiber/matrix interface, which is a result of differences in thermal expansion, and the fiber surface roughness. In this study, the surfaces of several ceramic fibers have been characterized qualitatively using a Hitachi S-4500 FEG SEM operated at low voltages and quantitatively using a Topometrix atomic force microscope (AFM). This study is part of an overall program relating fiber surface roughness to the interfacial shear stress.

scholarly journals Effect of Fiber-Matrix Bond Strength on the Crack Resistance of Synthetic Fiber Reinforced Cementitious Composites

1987 ◽  
Vol 114 ◽  
Author(s):  
Victor C. Li ◽  
Youjiang Wang ◽  
Stanley Backer
Keyword(s):  
Crack Resistance ◽  
Fiber Surface ◽  
Fiber Reinforced Concrete ◽  
Synthetic Fiber ◽  
Fiber Reinforced ◽  
Softening Behavior ◽  
Tension Softening ◽  
Cantilevered Beam ◽  
Fiber Matrix ◽  
Bond Characteristics

ABSTRACTFiber matrix bond characteristics can be changed by treatments of the fiber surface. The effect of such treatments on the fiber reinforced concrete (FRC) tension-softening behavior and crack resistance is studied in this paper. Various R-curve behaviors are predicted based on a simple double cantilevered beam (DCB) model using the experimentally derived tensionsoftening curves. The result suggests that fiber surface treatments can substantially alter the composite fracture resistance as measured by the R-curve.

Characterization of interfaces in CVD-coated nicalon fiber-reinforced SiC

1989 ◽  
Vol 47 ◽  
pp. 556-557
Author(s):  
K.L. More ◽  
R.A. Lowden
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Frictional Stress ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Carbon Coated ◽  
Fiber Matrix

The mechanical properties of fiber-reinforced composites are directly related to the nature of the fiber-matrix bond. Fracture toughness is improved when debonding, crack deflection, and fiber pull-out occur which in turn depend on a weak interfacial bond. The interfacial characteristics of fiber-reinforced ceramics can be altered by applying thin coatings to the fibers prior to composite fabrication. In a previous study, Lowden and co-workers coated Nicalon fibers (Nippon Carbon Company) with silicon and carbon prior to chemical vapor infiltration with SiC and determined the influence of interfacial frictional stress on fracture phenomena. They found that the silicon-coated Nicalon fiber-reinforced SiC had low flexure strengths and brittle fracture whereas the composites containing carbon coated fibers exhibited improved strength and fracture toughness. In this study, coatings of boron or BN were applied to Nicalon fibers via chemical vapor deposition (CVD) and the fibers were subsequently incorporated in a SiC matrix. The fiber-matrix interfaces were characterized using transmission and scanning electron microscopy (TEM and SEM). Mechanical properties were determined and compared to those obtained for uncoated Nicalon fiber-reinforced SiC.

scholarly journals Dynamic Single-Fiber Pull-Out of Polypropylene Fibers Produced with Different Mechanical and Surface Properties for Concrete Reinforcement

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 722
Author(s):  
Enrico Wölfel ◽  
Harald Brünig ◽  
Iurie Curosu ◽  
Viktor Mechtcherine ◽  
Christina Scheffler
Keyword(s):  
Tensile Strength ◽  
Dynamic Loading ◽  
Melt Spinning ◽  
Structural Changes ◽  
High Surface ◽  
Single Fiber ◽  
Scanning Calorimetry ◽  
Matrix Interaction ◽  
Pull Out ◽  
Fiber Matrix

In strain-hardening cement-based composites (SHCC), polypropylene (PP) fibers are often used to provide ductility through micro crack-bridging, in particular when subjected to high loading rates. For the purposeful material design of SHCC, fundamental research is required to understand the failure mechanisms depending on the mechanical properties of the fibers and the fiber–matrix interaction. Hence, PP fibers with diameters between 10 and 30 µm, differing tensile strength levels and Young’s moduli, but also circular and trilobal cross-sections were produced using melt-spinning equipment. The structural changes induced by the drawing parameters during the spinning process and surface modification by sizing were assessed in single-fiber tensile experiments and differential scanning calorimetry (DSC) of the fiber material. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle measurements were applied to determine the topographical and wetting properties of the fiber surface. The fiber–matrix interaction under quasi-static and dynamic loading was studied in single-fiber pull-out experiments (SFPO). The main findings of microscale characterization showed that increased fiber tensile strength in combination with enhanced mechanical interlocking caused by high surface roughness led to improved energy absorption under dynamic loading. Further enhancement could be observed in the change from a circular to a trilobal fiber cross-section.

Effect of Sisal Fiber Surface Treatments on Sisal Fiber Reinforced Polypropylene (PP) Composites

2014 ◽  
Vol 906 ◽  
pp. 167-177 ◽  
Author(s):  
Hou Lei Gan ◽  
Lei Tian ◽  
Chang Hai Yi
Keyword(s):  
Surface Morphology ◽  
Morphological Changes ◽  
Fiber Surface ◽  
Atmospheric Plasma ◽  
Single Fiber ◽  
Sisal Fiber ◽  
Fiber Reinforced ◽  
Polypropylene Composites ◽  
Pull Out ◽  
Debonding Process

Abstract: The Interface of sisal fiber which was treated by using alkali, potassium permanganate, atmospheric plasma and silane reinforced polypropylene composites were investigated by single fiber pull-out testes and surface morphology were studied. The results indicated that the morphological changes observed on the sisal fiber surface were obviously evident. Untreated, permanganate and plasma treated sisal fiber reinforced PP show a stable debonding process. Silane treated sisal fiber reinforced PP show an unstable debonding process. Single fiber pull-out tests indicated that the IFSS value was in the order of FIB < FIBKMnO4 < FIBP < FIBKH-550 < FIBKH-570. As can be seen from surface morphology of pull-out fiber, a little of PP resin was adhered to the pull-out FIB, FIBKMnO4, FIBP of sisal fiber. In contrast, PP resin at the surface of pull-out fiber was flaked off and sisal fibril was drawn out from sisal fiber were observed from pull-out fibers of FIBKH-550 and FIBKH-570.

scholarly journals Cementitious Composites Reinforced with Polypropylene, Nylon and Polyacrylonitile Fibres

2012 ◽  
Vol 730-732 ◽  
pp. 271-276
Author(s):  
H.R. Pakravan ◽  
M. Jamshidi ◽  
M. Latifi ◽  
F. Pacheco-Torgal
Keyword(s):  
Absorption Capacity ◽  
Cement Matrix ◽  
Cementitious Composites ◽  
Scanning Electron Micrographs ◽  
Energy Absorption Capacity ◽  
Cement Ratio ◽  
Pull Out ◽  
Water To Cement Ratio ◽  
Before And After ◽  
Scanning Electron

This paper compares the adhesion strength between three polymeric fibres (polypropylene (PP), nylon66 (N66) and polyacrylonitrile (PAN)) embedded in a cement paste. The specimens were prepared at a water to cement ratio (w/c) of 0.5 and tested after 7, 14 and 28 curing days. It was found that although the adhesion between the polymeric fibres to the cement matrix is an important factor, the energy absorption capacity or energy dissipation ability of the fibres, plays a more important role in the improvement of the cementitious composites fracture toughness. Scanning electron micrographs were used to characterize the fibres surface before and after the Pull-out tests.

scholarly journals Model Test Research on the Influence of Gate Blocking in Siltation Environment

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Hua Li ◽  
Yifeng Wang ◽  
Jingyu Zhang ◽  
Liangpeng Wan ◽  
Qiao Jiang ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Model Test ◽  
Significant Influence ◽  
High Water ◽  
Deep Hole ◽  
Analysis Model ◽  
Pull Out ◽  
Test Study ◽  
Similarity Ratio ◽  
Pulling Force

Aiming at the clogging problems encountered in the operation of deep-hole gates in high water level reservoirs and dams, this paper carried out a model test study on the influence of different materials and different siltation environments on the lifting of the gates and analyzed the rules of the effects of blockages in different siltation environments. An analysis model of the pull-out force of the gate (blocked object) considering the siltation environment was proposed in an innovative way and the similarity ratio relationship was verified. The results of the study show that (1) the size and time of the siltation and other factors have a significant influence on the pulling force of the blocked object. It increases with the increase of the siltation area. The longer the siltation goes on, the greater the pulling force will be. (2) As the similarity ratio n increases, the calculation result of the analysis model is closer to the target value n 2 and it indicates that the theoretical model is reliable. The research results of this paper can provide certain guidance for deep-hole siltation dispatch to ensure project safety.

scholarly journals Influence of Oxidation Damages on Mechanical Properties of SiC/SiC Composite Using Domestic Hi-Nicalon Type SiC Fibers

Scanning ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Enze Jin ◽  
Denghao Ma ◽  
Zeshuai Yuan ◽  
Wenting Sun ◽  
Hao Wang ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Tensile Modulus ◽  
Treatment Temperature ◽  
Matrix Interface ◽  
Oxidation Treatment ◽  
Pull Out ◽  
Special Surface ◽  
Higher Temperature ◽  
Fiber Matrix Interface ◽  
Fiber Matrix

Here, we show that when the oxidation treatment temperature exceeded 600°C, the tensile strength of SiC/SiC begins to decrease. Oxidation leads to the damages on the PyC fiber/matrix interface, which is replaced by SiO2 at higher temperature. The fracture mode converts from fiber pull-out to fiber-break as the fiber/matrix interface is filled with SiO2. Oxidation time also plays an important role in affecting the tensile strength of SiC/SiC. The tensile modulus decreases with temperature from RT to 800°C, then increases above 800°C due to the decomposition of remaining CSi x O y and crystallization of the SiC matrix. A special surface densification treatment performed in this study is confirmed to be an effective approach to reduce the oxidation damages and improve the tensile strength of SiC/SiC after oxidation.

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