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.

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.

scholarly journals A Study of the Mechanical Behavior and Crystal Structure of UHMWPE/HDPE Blend Fibers Prepared by Melt Spinning

2018 ◽  
Vol 13 (3) ◽  
pp. 155892501801300
Author(s):  
Fei Wang ◽  
Lichao Liu ◽  
Ping Xue ◽  
Mingyin Jia ◽  
Hua Sun
Keyword(s):  
Crystal Structure ◽  
Mechanical Properties ◽  
Tensile Strength ◽  
Mechanical Behavior ◽  
Melt Spinning ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Melt Flow Index ◽  
Flow Index ◽  
Scanning Calorimetry ◽  
Spinning Process

Ultrahigh molecular weight polyethylene (UHMWPE) and high-density polyethylene (HDPE) blend fibers with the highest tensile strength of 1.13 GPa were prepared by a melt spinning process. The crystal structure and mechanical behavior of the as-spun filaments and fibers were studied by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), atomic force microscope (AFM), X-ray diffraction (XRD), sound velocity orientation test and tensile strength test. The results suggested that the degree of molecular chain orientation, crystallinity and mechanical properties of the blend fibers were improved by blending with the low melt flow index (MFI) HDPE. The crystal grains of low MFI HDPE blend fibers that were formed by more highly oriented molecular chains could be stretched more effectively in the drawing direction, and the improved mechanical properties were due to the more regular and compact crystal structure.

Electromechanical study of carbon fiber composites

1998 ◽  
Vol 13 (11) ◽  
pp. 3081-3092 ◽  
Author(s):  
Xiaojun Wang ◽  
Xuli Fu ◽  
D. D. L. Chung
Keyword(s):  
Carbon Fiber ◽  
Electrical Resistance ◽  
Fiber Composites ◽  
Single Fiber ◽  
Fiber Direction ◽  
Carbon Fiber Composites ◽  
Fiber Waviness ◽  
Pull Out ◽  
The Matrix ◽  
Fiber Matrix

Electromechanical testing involving simultaneous electrical and mechanical measurements under load was used to study the fiber-matrix interface, the fiber residual compressive stress, and the degree of marcelling (fiber waviness) in carbon fiber composites. The interface study involved single fiber pull-out testing while the fiber-matrix contact electrical resistivity was measured. The residual stress study involved measuring the electrical resistance of a single fiber embedded in the matrix while the fiber was subjected to tension through its exposed ends. The marcelling study involved measuring the electrical resistance of a composite in the through-thickness direction while tension within the elastic regime was applied in the fiber direction.

Electromechanical Study of Carbon Fiber Composites

1997 ◽  
Vol 500 ◽  
Author(s):  
Xiaojun Wang ◽  
Xuli Fu ◽  
D.D.L. Chung
Keyword(s):  
Residual Stress ◽  
Carbon Fiber ◽  
Fiber Composites ◽  
Single Fiber ◽  
Fiber Direction ◽  
Carbon Fiber Composites ◽  
Fiber Waviness ◽  
Pull Out ◽  
The Matrix ◽  
Fiber Matrix

ABSTRACTElectromechanical testing involving simultaneous electrical and mechanical measurements under load was used to study the fiber-matrix interface, fiber residual stress and marcelling (fiber waviness) in carbon fiber composites. The interface study involved single fiber pull-out while the fiber-matrix contact resistivity was measured. The residual stress study involved measuring the resistance of a single fiber embedded in the matrix while the fiber was tensioned at its exposed ends. The marcelling study involved measuring the resistance of a composite in the through-thickness direction while tension was applied in the fiber direction.

scholarly journals Numerical simulation of fiber-matrix debonding in single fiber pull-out tests

2020 ◽  
Vol 2 (1) ◽  
pp. 21-35
Author(s):  
Lukas Hoppe
Keyword(s):  
Crack Initiation ◽  
Cohesive Zone ◽  
Single Fiber ◽  
Displacement Curve ◽  
Fe Model ◽  
Pull Out ◽  
Peridynamic Model ◽  
Reference Experiment ◽  
Fiber Matrix ◽  
Force Displacement

The present work deals with the numerical crack simulation of fiber-matrix debonding in single fiber pull-out tests. For this purpose, two models are used: a finite element model (FE model) with the cohesive zone approach and a peridynamic model. For calibration a reference experiment is applied. In addition analytical equations are used for reference values. The influence of the model parameters and the material parameters of the cohesive zone model on the force-displacement curve is investigated. Besides the free fiber length, the critical interface strength, the critical energy release rate as well as the initial interface stiffness have a great influence on the force-displacement curve of the pull-out test. From the crack simulation it can be seen that Mode I has an influence on the crack initiation, but further crack growth after initiation is dominated by Mode II. The FE model can be calibrated in a way that the crack initiation point and the maximum force correspond to the reference experiment. The peridynamic model depicts a comparable crack formation process.

scholarly journals Effect of Interface Coating on High Temperature Mechanical Properties of SiC–SiC Composite Using Domestic Hi–Nicalon Type SiC Fibers

Coatings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 477 ◽  
Author(s):  
Enze Jin ◽  
Wenting Sun ◽  
Hongrui Liu ◽  
Kun Wu ◽  
Denghao Ma ◽  
...  
Keyword(s):  
Tensile Strength ◽  
High Temperature ◽  
Theoretical Analysis ◽  
Fracture Mode ◽  
Radial Stress ◽  
Matrix Interface ◽  
Preparation Temperature ◽  
Pull Out ◽  
Fiber Matrix Interface ◽  
Fiber Matrix

Here we show that when the temperature exceeded 1200 °C, the tensile strength drops sharply with change of fracture mode from fiber pull-out to fiber-break. Theoretical analysis indicates that the reduction of tensile strength and change of fracture mode is due to the variation of residual radial stress on the fiber–matrix interface coating. When the temperature exceeds the preparation temperature of the composites, the residual radial stress on the fiber–matrix interface coating changes from tensile to compressive, leading to the increase of the interface strength with increasing temperature. The fracture behavior of SiC–SiC composites changes from ductile to brittle when the strength of fiber–matrix interface coating exceeds the critical value. Theoretical analysis predicts that the high temperature tensile strength can increase with a decrease in fiber–matrix interface thickness, which is verified by experiments.

Investigation of the fiber-matrix interaction in carbon fiber-reinforced polyether ether ketone by cyclic single fiber push-out and push-back tests

2019 ◽  
Vol 27 (2) ◽  
pp. 227-247 ◽  
Author(s):  
Judith Moosburger-Will ◽  
Michael Greisel ◽  
Michael Schulz ◽  
Mario Löffler ◽  
Wolfgang M. Mueller ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Single Fiber ◽  
Fiber Reinforced ◽  
Matrix Interaction ◽  
Polyether Ether Ketone ◽  
Ether Ketone ◽  
Fiber Matrix ◽  
Carbon Fiber Reinforced ◽  
Push Out

Interface Properties for Ceramic Composites from a Single-Fiber Pull-Out Test

1989 ◽  
Vol 170 ◽  
Author(s):  
Elizabeth P. Butler ◽  
Edwin R. Fuller ◽  
Helen M. Chan
Keyword(s):  
Friction Coefficient ◽  
Shear Resistance ◽  
Ceramic Composites ◽  
Single Fiber ◽  
Displacement Curve ◽  
Interface Properties ◽  
Model Composite ◽  
Pull Out ◽  
Fiber Matrix ◽  
Clamping Pressure

AbstractAn experimental approach has been developed using a single-fiber pullout test to measure intrinsic interface properties for ceramic composites. The properties are determined from a pull-out, force-displacement curve, which is directly related to reinforcement toughening via fiber/matrix debonding and frictional pull-out. They were evaluated for a model composite system of continuous SiC fibers with various surface treatments in a borosilicate glass matrix. For the processing conditions used, the interface fracture toughness and the interface frictional shear resistance were found to be 1.0 ± 0.5 J/m2 and 3.3 ± 0.6 MPa, respectively, for as-received fibers. Experiments conducted with long embedded fiber lengths allowed the shear resistance to be deconvolved into an interface friction coefficient of 0.05 ± 0.01 and an initial fiber-clamping pressure of 65 ± 6 MPa. Nitric acidwashed fibers gave an increased interface toughness of 3.6 ± 0.1 J/m2 and friction coefficient of 0.08 ± 0.02, but nearly the same initial clamping pressure, 72 ± 12 MPa. Calculations of the clamping pressure from the fiber/matrix thermal expansion mismatch and from stress birefringence measurements in the glass were in general agreement with this value.

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.

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