scholarly journals Non-linear elastic behavior of carbon fibres of different structural and mechanical characteristic

2007 ◽  
Vol 72 (5) ◽  
pp. 513-521 ◽  
Author(s):  
Isidor Djordjevic ◽  
Daniela Sekulic ◽  
Momcilo Stevanovic
Keyword(s):  
Tensile Strain ◽  
Axial Stress ◽  
Tensile Modulus ◽  
Compression Modulus ◽  
Interlayer Spacing ◽  
Tensile Tests ◽  
Elastic Behavior ◽  
Carbon Fibres ◽  
Single Filament ◽  
Breaking Strain

Five types of polyacrylonitrile, PAN, based carbon fibres, differing in modulus, breaking strain and in crystallite orientation, have been studied. Non-Hookean behavior was investigated by computing the tangent tensile and compression moduli as a function of strain, from the axial stress-strain response obtained in standard tensile, compression, as well as in modified flexural tests of unidirectional carbon/ epoxy composites. The dependences of the tensile modulus on tensile strain of the carbon fibres were extracted from data obtained in single-filament tensile tests. Analytical expressions for the tensile modulus-tensile strain and compression modulus-compression strain dependences in the performed test were deduced. The structural characterization of the carbon fibres was performed by X-ray diffraction on bundle of parallel fibres. The interlayer spacing d 002 and the apparent lateral dimension of the crystallites L c were deduced by processing the 002 diffraction profiles. The established modulus-strain dependences were correlated with the fibre characteristics (breaking strain and mean modulus values), as well as with the characteristic of the 002 difraction profile and the d 002 and L c values.

Effect of Carbon Nanofiber on Thermal and Tensile Properties of Polypropylene

2006 ◽  
Author(s):  
Yuanxin Zhou ◽  
Mohammad Monirul Hasan ◽  
Shaik Jeelani
Keyword(s):  
Thermal Properties ◽  
Yield Strength ◽  
Strain Rate ◽  
Carbon Nanofiber ◽  
Tensile Modulus ◽  
Tensile Tests ◽  
Strain Rate Range ◽  
Mechanical And Thermal Properties ◽  
Single Filament ◽  
Polypropylene Powder

In the present study, effect of vapor grown carbon nanofiber on the mechanical and thermal properties of polypropylene was investigated. Firstly, nanofibers were dry-mixed with polypropylene powder and extruded into filaments by using a single screw extruder. Then the tensile tests were performed on the single filament at the strain rate range from 0.02/min to 2/min. Experiments results show that both neat and nano-phased polypropylene were strain rate strengthening material. The tensile modulus and yield strength both increased with increasing strain rate. Experimental results also show that infusing nanofiber into polypropylene can increase tensile modulus and yield strength, but decrease the failure strain. At the same time, thermal properties of neat and nano-phased polypropylene were characterized by TGA. TGA results have showed that the nanophased system is more thermally stable. At last, a nonlinear constitutive equation has been developed to describe strain rate sensitive behavior of neat and nano-phased polypropylene.

Additive Manufacturing of PA6 with Short Carbon Fibre Reinforcement Using Fused Deposition Modelling

2018 ◽  
Vol 928 ◽  
pp. 26-31 ◽  
Author(s):  
Frantisek Sedlacek ◽  
Václava Lašová
Keyword(s):  
Additive Manufacturing ◽  
Tensile Modulus ◽  
Tensile Tests ◽  
Fused Deposition Modelling ◽  
Fibre Reinforcement ◽  
3D Printer ◽  
Carbon Fibres ◽  
Fused Deposition ◽  
Additive Manufacturing Technology ◽  
Short Carbon

The aim of this research was to determine the influence of the short carbon fibres in nylon PA6 polymer used for fused deposition modelling (additive manufacturing) technology. Specimens from pure PA6 and PA6 with short carbon fibres were fabricated, with both main directions of the material with respect to the build orientation in a 3D printer. Experimental tensile tests of the specimens were carried out at several temperatures according to ISO standards. The strength, tensile modulus and ductility in relation to the temperature were compared. A significant influence of the short carbon fibres on the strength and heat deflection temperature of the part was found in PA6 and also for the orientation of the build in the 3D printer.

scholarly journals Experimentation of the Bilinear Elastic Behavior of Plain-Woven GFRP Composite with Embedded SMA Wires

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 405 ◽  
Author(s):  
Zhiwei Sun ◽  
Yingjie Xu ◽  
Wenzhi Wang
Keyword(s):  
Tensile Strain ◽  
Tensile Tests ◽  
Elastic Behavior ◽  
Uniaxial Tensile ◽  
Stress Strain ◽  
Strain Behavior ◽  
Reinforced Polymer ◽  
Resin Injection ◽  
Stress Threshold ◽  
Gfrp Composite

In this paper, a plain-woven glass-fabric-reinforced polymer (GFRP) composite with embedded shape memory alloy (SMA) wires is investigated by means of experiments. The vacuum-assisted resin injection (VARI) method is utilized to fabricate the composite specimens. Quasi-static uniaxial tensile tests are then carried out to evaluate the influence of SMA reinforcement on the stress–strain behavior of the composite. Only the elastic behavior of the composite is considered in the present study. The tensile strain in all the experiments is kept below 2.5% to avoid debonding of the SMA-resin interface, which would lead to failure of the composite. Stress–strain curves are obtained and shown to present a bilinear behavior due to phase transformation taking place in the SMA wires beyond a certain stress threshold.

scholarly journals Chemical and physical interactions of regenerated cellulose yarns and isocyanate-based matrix systems

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bernhard Ungerer ◽  
Ulrich Müller ◽  
Antje Potthast ◽  
Enrique Herrero Acero ◽  
Stefan Veigel
Keyword(s):  
Mechanical Performance ◽  
Tensile Force ◽  
Tensile Modulus ◽  
Tensile Tests ◽  
Size Exclusion ◽  
Regenerated Cellulose ◽  
Hydrolytic Cleavage ◽  
Yarn Twist ◽  
Exclusion Chromatography ◽  
Physical And Chemical

AbstractIn the development of structural composites based on regenerated cellulose filaments, the physical and chemical interactions at the fibre-matrix interphase need to be fully understood. In the present study, continuous yarns and filaments of viscose (rayon) were treated with either polymeric diphenylmethane diisocyanate (pMDI) or a pMDI-based hardener for polyurethane resins. The effect of isocyanate treatment on mechanical yarn properties was evaluated in tensile tests. A significant decrease in tensile modulus, tensile force and elongation at break was found for treated samples. As revealed by size exclusion chromatography, isocyanate treatment resulted in a significantly reduced molecular weight of cellulose, presumably owing to hydrolytic cleavage caused by hydrochloric acid occurring as an impurity in pMDI. Yarn twist, fibre moisture content and, most significantly, the chemical composition of the isocyanate matrix were identified as critical process parameters strongly affecting the extent of reduction in mechanical performance. To cope with the problem of degradative reactions an additional step using calcium carbonate to trap hydrogen ions is proposed.

BRIDGING OF CARBON FIBERS IN CF/EPOXY COMPOSITES USING ELECTROSTATICALLY INDUCED CNT ALIGNMENT

2021 ◽  
Author(s):  
DANDAN ZHANG ◽  
XINGKANG SHE ◽  
YIPENG HE ◽  
WESLEY A. CHAPKIN, ◽  
VI T. BREGMAN ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Electric Field ◽  
Carbon Fibers ◽  
Hybrid Composites ◽  
Tensile Modulus ◽  
Tensile Tests ◽  
Polymer Mixture ◽  
Ac Electric Field ◽  
Reinforced Polymer ◽  
Electric Field Direction

Carbon fiber reinforced polymer (CFRP) composites are lightweight materials with superior strength but are expensive due to the increased cost of carbon fibers (CFs). The addition of carbon nanotubes (CNTs) to polymer nanocomposites are becoming an excellent alternative to CF due to their unique combination of electrical, thermal, and mechanical properties. With the application of an electric field across the CNT/polymer mixture before curing, CNTs will not only be aligned along the electric field direction, but also form networks after reaching to a certain degree of alignment. In this study, an alternating current (AC) electric field was applied continuously to CNT/CF/Epoxy hybrid composites before curing. By cutting off the applied voltage when the monitored electric current increased, the degree of networking of CNTs between two CF tows was controlled. The relative electric field strength around the end of conductive carbon fiber tows in the epoxy matrix was modeled using COMSOL Multiphysics. It increased after applying AC electric field parallel to the CF tows, thereby increasing the alignment degree of CNTs and building a network to bridge the CF tows. The preliminary results indicate that the microhardness and tensile modulus between two CF tows are increased due to the networking of CNTs in this area. The fracture surface of the specimens after tensile tests were characterized to reveal more details of the microstructure.

Evaluation of Progressive Changes in Elastomer Properties during Vulcanization

1961 ◽  
Vol 34 (3) ◽  
pp. 777-789
Author(s):  
W. E. Claxton ◽  
F. S. Conant ◽  
J. W. Liska
Keyword(s):  
Induction Time ◽  
Tensile Modulus ◽  
Compression Modulus ◽  
Test Methods ◽  
Screening Tests ◽  
Time Saving ◽  
Physical Test ◽  
Polymeric Compounds ◽  
Cure Time ◽  
Selection Of

Abstract An apparatus and method are described for evaluating state of cure, optimum cure time, rate of cure, induction time for cure, scorch time, induction time for reversion, reversion rate and degree of reversion of elastomeric compounds. Coincident with these determinations vulcanizate specimens are prepared on which more conventional physical test data may be obtained; e.g., compression modulus, compression set, hardness, specific gravity, tensile modulus and elongation. In essence, the method described provides a progressive measure of modulus change during cure or reversion through the change in deformation of a periodically loaded plunger, one end of which is embedded into the specimen. Typical results are given which show application of the apparatus to screening tests, millroom control, reversion studies and to compounds which are too stiff for conventional test methods. Demonstrated advantages for the apparatus include time saving, stock saving and better cure information on a wider range of polymeric compounds than is obtainable from tensile test methods. In a laboratory where a large selection of test instruments is not feasible, the versatility of the apparatus described should prove very advantageous.

scholarly journals Experimental Study on Compression Deformation and Permeability Characteristics of Grading Broken Gangue under Stress

Processes ◽  
2018 ◽  
Vol 6 (12) ◽  
pp. 257 ◽  
Author(s):  
Yu Zhang ◽  
Wei Zhou ◽  
Ming Li ◽  
Zhanqing Chen
Keyword(s):  
Axial Stress ◽  
Compression Modulus ◽  
Raw Material ◽  
Compression Rate ◽  
Lateral Compression ◽  
Seepage Velocity ◽  
Permeability Characteristics ◽  
Backfill Mining ◽  
Important Test ◽  
Overlying Strata

As the important raw material for backfill mining, broken gangue’s deformation and permeability characteristics directly affect the deformation of the overlying strata above the filling space. In this paper, through lateral compression and pressed seepage tests, the deformation and permeability characteristics of broken gangue as a function of the stress level and grading features were studied. This research indicates that the stress of broken gangue increases exponentially with an increase in strain, and the compression modulus and compression rate present a positive correlation. The samples with discontinuous grading are more difficult to compress than the continuous grading samples, and the discontinuous grading samples are tighter in accordance with the increase in compression rate. At the same time, the change range of the seepage velocity and permeability of the broken gangue decreases. Positive correction between the grading index of the broken gangue and the effect of reducing the permeability of samples is more obvious under axial compression, and less axial stress is needed to achieve the same permeability level for discontinuous grading. This paper can provide an important test basis for the design of grading parameters and the prediction of filling effects of broken gangue on backfill mining.

scholarly journals Preparation And Properties Of Bionanocomposite Films Reinforced With Nanocellulose Isolated From Moroccan Alfa Fibres

2015 ◽  
Vol 15 (3) ◽  
pp. 164-172 ◽  
Author(s):  
Benyoussif Youssef ◽  
Aboulhrouz Soumia ◽  
El Achaby Mounir ◽  
Cherkaoui Omar ◽  
Lallam Abdelaziz ◽  
...  
Keyword(s):  
Carboxymethyl Cellulose ◽  
Food Packaging ◽  
Fourier Transforms ◽  
Tensile Modulus ◽  
Tensile Tests ◽  
X Ray Diffraction ◽  
Vapour Permeability ◽  
Force Microscopy ◽  
Atomic Force ◽  
Bionanocomposite Films

AbstractNanocellulose (NC) were extracted from the Moroccan Alfa plant (Stipa tenacissima L.) and characterised. These Alfa cellulosic nanoparticles were used as reinforcing phase to prepare bionanocomposite films using carboxymethyl cellulose as matrix. These films were obtained by the casting/evaporation method. The crystallinity of NC was analysed by X-ray diffraction, the dimension of NC by atomic force microscopy, molecular interactions due to incorporation of NC in carboxymethyl cellulose (CMC) matrix were supported by Fourier transforms infrared (FTIR) spectroscopy. The properties of the ensuing bionanocomposite films were investigated using tensile tests, water vapour permeability (WVP) study and thermogravimetric analysis. With the progress of purification treatment of cellulose, the crystallinity is improved compared to the untreated fibres; this can be explained by the disappearance of the amorphous areas in cellulose chain of the plant. Consequently, the tensile modulus and tensile strength of CMC film increased by 60 and 47%, respectively, in the bionanocomposite films with 10 wt% of NC, and decrease by 8.6% for WVP with the same content of NC. The NC obtained from the Moroccan Alfa fibres can be used as a reinforcing agent for the preparation of bionanocomposites, and they have a high potential for the development of completely biodegradable food packaging materials.

Stress-Strain Equations for Some Near-Eutectic Tin-Lead Solders

1991 ◽  
Vol 113 (4) ◽  
pp. 475-484 ◽  
Author(s):  
K. P. Jen ◽  
J. N. Majerus
Keyword(s):  
Strain Rate ◽  
Printed Circuit Boards ◽  
Volume Fraction ◽  
Total Error ◽  
Tensile Tests ◽  
Elastic Behavior ◽  
Plastic Behavior ◽  
Strain Rates ◽  
Stress Strain ◽  
Engineering Strain

This paper presents the evaluation of the stress-strain behavior, as a function of strain-rate, for three tin-lead solders at room temperature. This behavior is critically needed for reliability analysis of printed circuit boards (PCB) since handbooks list minimal mechanical properties for the eutectic solder used in PCBs. Furthermore, most handbook data are for stable eutectic microstructure whereas PCB solder has a metastable microstructure. All three materials were purchased as “eutectics.” However, chemical analysis, volume fraction determination, and microhardness tests show some major variations between the three materials. Two of the materials have a eutectic composition, and one does not. The true stress-strain equations of one eutectic and the one noneutectic material are determined from compressive tests at engineering strain-rates between 0.0002/s and 0.2/s. The second eutectic material is evaluated using tensile tests with strain-rates between 0.00017/s and 0.042/s. The materials appear to exhibit linear elastic behavior only at extremely small strains, i.e., less than 0.0005. However, this “elastic” behavior showed considerable variation, and depended upon the strain rate. In both tension and compression the eutectic alloy exhibits nonlinear plastic behavior, i.e., strain-softening followed by strain-hardening, which depends upon the strain rate. A quadratic equation σy = σy(ε˚/ε˚0) + A(ε˚/ε˚0)ε + B(ε˚/ε˚0)ε2 fit to the data gives correlation coefficients R2 > 0.91. The coefficients σy(ε˚/ε˚0), A(ε˚/ε˚0), B(ε˚/ε˚0) are fitted functions of the normalized engineering strain rate ε˚/ε˚0. Replicated experiments are used at each strain-rate so that a measure of the statistical variation could be estimated. Measures of error associated with the regression analysis are also obtained so that an estimate of the total error in the stress-strain relations can be made.

scholarly journals Enhancement of Mechanical Properties of Flax-Epoxy Composite with Carbon Fibre Hybridisation for Lightweight Applications

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 109 ◽  
Author(s):  
Hom Nath Dhakal ◽  
Mohini Sain
Keyword(s):  
Carbon Fibre ◽  
Tensile Properties ◽  
Composite Laminates ◽  
Failure Modes ◽  
Epoxy Composite ◽  
Hybrid Composites ◽  
Environmental Scanning Electron Microscopy ◽  
Tensile Modulus ◽  
Tensile Tests ◽  
Flax Fibre

The effect of unidirectional (UD) carbon fibre hybridisation on the tensile properties of flax fibre epoxy composite was investigated. Composites containing different fibre ply orientations were fabricated using vacuum infusion with a symmetrical ply structure of 0/+45/−45/90/90/−45/+45/0. Tensile tests were performed to characterise the tensile performance of plain flax/epoxy, carbon/flax/epoxy, and plain carbon/epoxy composite laminates. The experimental results showed that the carbon/flax fibre hybrid system exhibited significantly improved tensile properties over plain flax fibre composites, increasing the tensile strength from 68.12 MPa for plain flax/epoxy composite to 517.66 MPa (670% increase) and tensile modulus from 4.67 GPa for flax/epoxy to 18.91 GPa (305% increase) for carbon/flax hybrid composite. The failure mechanism was characterised by examining the fractured surfaces of tensile tested specimens using environmental scanning electron microscopy (E-SEM). It was evidenced that interactions between hybrid ply interfaces and strain to failure of the reinforcing fibres were the critical factors for governing tensile properties and failure modes of hybrid composites.

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