scholarly journals Why Should the “Alternative” Method of Estimating Local Interfacial Shear Strength in a Pull-Out Test Be Preferred to Other Methods?

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2406
Author(s):  
Serge Zhandarov ◽  
Edith Mäder ◽  
Uwe Gohs
Keyword(s):  
Shear Strength ◽  
Interfacial Shear Strength ◽  
Traditional Approach ◽  
Interfacial Shear ◽  
Frictional Stress ◽  
Displacement Curve ◽  
Pull Out ◽  
Alternative Method ◽  
Fiber Reinforced Materials ◽  
Force Displacement

One of the most popular micromechanical techniques of determining the local interfacial shear strength (local IFSS, τd) between a fiber and a matrix is the single fiber pull-out test. The τd values are calculated from the characteristic forces determined from the experimental force–displacement curves using a model which relates their values to local interfacial strength parameters. Traditionally, the local IFSS is estimated from the debond force, Fd, which corresponds to the crack initiation and manifests itself by a “kink” in the force–displacement curve. However, for some specimens the kink point is hardly discernible, and the “alternative” method based on the post-debonding force, Fb, and the maximum force reached in the test, Fmax, has been proposed. Since the experimental force–displacement curve includes three characteristic points in which the relationship between the current values of the applied load and the crack length is reliably established, and, at the same time, it is fully determined by only two interfacial parameters, τd and the interfacial frictional stress, τf, several methods for the determination of τd and τf can be proposed. In this paper, we analyzed several theoretical and experimental force–displacement curves for different fiber-reinforced materials (thermoset, thermoplastic and concrete) and compared all seven possible methods of τd and τf calculation. It was shown that the “alternative” method was the most accurate and reliable one, while the traditional approach often yielded the worst results. Therefore, we proposed that the “alternative” method should be preferred for the experimental force–displacement curves analysis.

scholarly journals A Special Single-Fibre Pull-Out Technique for Determining the Fiber/Cement Interfacial Bond Strength

2002 ◽  
Vol 11 (1) ◽  
pp. 096369350201100 ◽  
Author(s):  
J. M. Caceres ◽  
A. N. Netravali
Keyword(s):  
Shear Strength ◽  
Bond Strength ◽  
Interfacial Shear Strength ◽  
Single Fibre ◽  
Interfacial Shear ◽  
Specimen Geometry ◽  
Interfacial Bond ◽  
Interfacial Bond Strength ◽  
Pull Out ◽  
Fibre Cement

The paper discusses a simple specimen geometry to obtain the fibre/cement interfacial shear strength (IFSS). The specimens are easy to prepare and easy to test. The technique gives reliable and reproducible results. IFSS results for five different fibres with cement were measured. Most IFSS values obtained are in the range of 0.15 to 1.5 MPa. Despite the simplicity of the technique presented in this study, the results are in agreement with those obtained by several other researchers using different techniques and specimen geometry.

scholarly journals Shear Behaviors of the Intersurface between Rice Straw Rope and Dredger Fill Silt: Experimental and Mechanism Studies

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Guizhong Xu ◽  
Ji Chen ◽  
Shenjie Shi ◽  
Angran Tian ◽  
Qiang Tang
Keyword(s):  
Shear Strength ◽  
Normal Stress ◽  
Rice Straw ◽  
Immersion Time ◽  
Interfacial Shear Strength ◽  
Land Reclamation ◽  
Tensile Force ◽  
Interfacial Shear ◽  
Pull Out ◽  
Dredger Fill

The further development of land reclamation, port waterway, and wharf construction brings about proper treatments of dredger fill silt, while huge amounts of rice straw set aside in China argument rational disposal every year. Therefore, rice straw is bundled up as ropes, which represent as drainage body and reinforcement, to make eco-friendly treatment for dredger fill silt. This paper investigates the mechanical properties and validity of rice straw rope as certain treating material of dredger fill silt through a series of pull-out test, mass loss test, and tension test on specimens with different water contents and dry densities. The results reveal that peak value of interfacial shear strength rises with the increase of normal stress at the same immersion time, and in particular, it rises by up to 250.0% when the normal stress is 40 kPa. The tensile force of rice straw rope increases slowly with the rise of tensile displacement, and the failure mode changes from brittle to ductile with the rise of immersion time, which witnesses first rapid back slow degradation trend. The proper interfacial shear strength, tensile force, and reasonable degradation rate of rice straw rope make it ideal in drainage and consolidation of dredger fill silt.

scholarly journals Experimental and Numerical Study of the Interfacial Shear Strength in Carbon Fiber/Epoxy Resin Composite under Thermal Loads

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Hongxiao Wang ◽  
Xiaohui Zhang ◽  
Yugang Duan ◽  
Lingjie Meng
Keyword(s):  
Shear Strength ◽  
Carbon Fiber ◽  
Epoxy Resin ◽  
Interfacial Shear Strength ◽  
Numerical Study ◽  
Resin Composite ◽  
Interfacial Shear ◽  
Thermal Loads ◽  
Mechanical Coupling ◽  
Pull Out

This study examined the influence mechanism of temperature on the interfacial shear strength (IFSS) between carbon fiber (CF) and epoxy resin (EP) matrices under various thermal loads using experimental and numerical simulation methods. To evaluate the change in IFSS as a function of the increase in temperature, a microbond test was performed under controlled temperature environment from 23°C to 150°C. The experimental results showed that IFSS values of CF/EP reduce significantly when the temperature reaches near glass transition temperature. To interpret the effect of thermal loads on IFSS, a thermal-mechanical coupling finite element model was used to simulate the process of fiber pull-out from EP. The results revealed that temperature dependence of IFSS is linked to modulus of the matrix as well as to the coefficients of thermal expansion of the fiber and matrix.

Pull-out method for direct measuring the interfacial shear strength between short plant fibers and thermoplastic polymer composites (TPC)

Holzforschung ◽  
2014 ◽  
Vol 68 (1) ◽  
pp. 17-21 ◽  
Author(s):  
Hao Wang ◽  
Genlin Tian ◽  
Hankun Wang ◽  
Wanju Li ◽  
Yan Yu
Keyword(s):  
Shear Strength ◽  
Polymer Composites ◽  
Interfacial Shear Strength ◽  
Interfacial Shear ◽  
Thermoplastic Polymer ◽  
Plant Fibers ◽  
Important Indicator ◽  
Pull Out ◽  
Research Activities ◽  
The Matrix

Abstract Thermoplastic polymer composites reinforced with short plant fiber are worldwide in focus of research activities. Interfacial shear strength (IFSS) is an important indicator for evaluating the bonding quality between the fiber and the matrix polymer. However, the direct measurement of IFSS is especially difficult in the case of short fibers. In the present article, a method is proposed to this purpose, which is related to the known “fiber pulling out” methodology. In the case of single bamboo fibers, the IFSS in a polypropylene (PP) matrix was on, an average, of 5 MPa, which can be considered as weak. Scanning electron microscopy images revealed a rough inner surface in PP cavities left after fiber pulling out. This is direct evidence that a mechanical interlocking mechanism is active in the interphase between the hydrophilic fibers and the hydrophobic matrix.

Influence of Unsizing and Carbon Nanotube Grafting of Carbon Fibre on Fibre Matrix Interfacial Shear Strength of Carbon Fibre and Polyamide 6

2019 ◽  
Vol 827 ◽  
pp. 178-183
Author(s):  
Kazuto Tanaka ◽  
Kanako Yamada ◽  
Yoshitake Hinoue ◽  
Tsutao Katayama
Keyword(s):  
Shear Strength ◽  
Carbon Fibre ◽  
Interfacial Shear Strength ◽  
Chemical Vapour ◽  
Polyamide 6 ◽  
Interfacial Shear ◽  
Morphological Observation ◽  
Production Cycle ◽  
Pull Out ◽  
Fibre Matrix

Carbon Fibre Reinforced Thermoplastics (CFRTP) are expected to be applied to the automotive industry instead of CFRP which require curing time, due to the expected short production cycle time of CFRTP, which is using thermoplastic as a matrix. We reported that the grafting of carbon nanotubes (CNTs) on the carbon fibre improves the fibre matrix interfacial shear strength. In our process to graft CNTs on carbon fibre, chemical vapour deposition (CVD) method was used and Ni, which was used as the catalyst, was electrically plated onto carbon fibres. Since commercially available carbon fibre was sized, which may affect the plating behaviour of Ni, the effects of sizing agents on CNT deposition have to be clarified. In this study, Ni for catalytic metal was plated by electrolytic plating using a watt bath on spread PAN-based carbon fibre and unsized carbon fibre, and the influence of the sizing agent to the distribution of Ni was evaluated. The morphological observation of carbon fibre and single fibre pull-out test were conducted to clarify the influence of sizing agent on the CNT deposition and the interfacial shear strength between the CNT grafted carbon fibre and Polyamide 6 (PA6). Uniform distribution of small sized Ni particles can be obtained on unsized carbon fibre and uniform Ni particles results in uniform CNT distribution. The CNT grafted unsized carbon fibre showed higher interfacial shear strength with PA6 than that of sized carbon fibre.

Improving the Flexural Strength of Fibre Reinforced Oil Well Cementsby Addition of a Polymer Latex

1994 ◽  
Vol 370 ◽  
Author(s):  
Demosthenis G. Pafitis
Keyword(s):  
Shear Strength ◽  
Flexural Strength ◽  
Glass Fibre ◽  
Interfacial Shear Strength ◽  
Interfacial Shear ◽  
Cement Matrix ◽  
Oil Well ◽  
Pull Out ◽  
Glass Fibre Reinforced ◽  
Polymer Latex

AbstractFibre-reinforced cements are proving to be useful in various oilfield applications. Low cost and increased toughness render glass fibre reinforced cements of particular interest. In most cases, improvements in toughness are the result of extensive fibre pull-out and this can be clearly observed in electron micrographs of fracture surfaces. This observation implies that there is much scope for improving the interfacial shear strength between the hydrated cement and glass fibres.Experiments have shown that increases in flexural strength and in energy to fracture can be achieved by incorporating small amounts of a polymer latex. Improvements of a factor of four in energy to fracture have been measured when approximately 0.8% by volume of a styrenebutadiene copolymer latex is added to a glass fibre reinforced class G oilwell cement. Experimental results suggest that this effect is not due to improvements in the strength of the cement matrix but due to an enhancement of the interfacial shear strength between fibre and cement.

scholarly journals Interfacial Debonding Force and Shear Strength of Sugar Palm (Arenga pinnata) Fiber Reinforced Composites by Pull-Out Test

2013 ◽  
Vol 634-638 ◽  
pp. 1931-1936 ◽  
Author(s):  
L.S. Khor ◽  
Leman Zulkiflle ◽  
C. H. Lee
Keyword(s):  
Shear Strength ◽  
Interfacial Shear Strength ◽  
Phenol Formaldehyde ◽  
Unsaturated Polyester ◽  
Interfacial Shear ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Remarkable Improvement ◽  
Pull Out ◽  
Fiber Matrix Interface

An experimental investigation was performed to understand the pulling out behaviour of sugar palm (Arenga pinnata) fibers from unsaturated polyester (UP) composites. The effect of embedded length on the fiber-matrix interface was studied. Fibers were treated with UP and phenol formaldehyde (PF). Untreated fibers were used as the control. Single fiber pull-out tests were carried out for 360 specimens to determine the debonding force and interfacial shear strength (IFSS). Significant increase in debonding force of untreated fiber and UP-impregnated fiber was observed from embedded length of 2 mm to 3 mm. However, no significant increase was observed for the embedded length of more than 3 mm. Debonding force showed remarkable improvement with ascending order of untreated fibers, PF-impregnated fibers, and UP-impregnated fibers. The optimum embedded lengths of untreated fibers and UP fibers were determined. Additional finding showed that the interfacial shear strength decreased as the embedded length increased. However, UP-impregnated fibers showed the highest IFSS value, followed by PF fibers and untreated fibers. Analysis using Scanning Electron Microscope (SEM) was also included to justify the result.

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