scholarly journals Use of Onion-Like Carbon to Reinforce Carbon Composites

2018 ◽  
Vol 20 (3) ◽  
pp. 201
Author(s):  
A. Galiguzov ◽  
A. Malakho ◽  
S. Minchuk ◽  
L. Oktiabrskaia ◽  
V. Lepin
Keyword(s):  
Solid Lubricant ◽  
Carbon Matrix ◽  
Carbon Composite ◽  
Bending Test ◽  
Nanoindentation Test ◽  
Friction Mechanism ◽  
Three Point Bending ◽  
Lubricating Film ◽  
Nanoindentation Testing ◽  
Porosity Analysis

Onion-like carbon reinforced carbon-carbon composite was fabricated, and the influence of onion-like carbon (OLC) on the microstructure and mechanical and friction properties was investigated by porosity analysis, scanning electron microscopy, three-point bending test, nanoindentation test and ring-on-ring friction test. The results show that the sample containing OLC has a higher flexural strength (by 7.3%) and compressive strength (by 29.3%), hardness (by 2.1 times) and apparent density (by 1.1%) and smaller open porosity (7.9% vs 9.8%) and mesopore volume, which is confirmed by porosity analysis and is attributed to improved fiber/ matrix interface performance. The presence of OLC results in higher hardness and elastic modulus of carbon matrix under nanoindentation testing, which leads to modification of friction mechanism and a decrease in the wear rate under friction (by 3.3 times). Besides, OLC particles form self-lubricating film and show a graphitic carbon solid lubricant properties.

scholarly journals Tribological properties of MoS2 coating for ultra-long wear-life and low coefficient of friction combined with additive g-C3N4 in air

Friction ◽  
2020 ◽  
Author(s):  
Yupeng Zhang ◽  
Panpan Li ◽  
Li Ji ◽  
Xiaohong Liu ◽  
Hongqi Wan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Solid Lubricant ◽  
Sliding Friction ◽  
Friction Mechanism ◽  
X Ray ◽  
Lubricating Film ◽  
Valence States ◽  
Transmission Electron ◽  
Wear Life

Abstract The solid lubricant MoS2 demonstrates excellent lubricating properties, but it spontaneously oxidizes and absorbs moisture in air, and thus results in poor wear resistance and short wear-life. In this study, the additive g-C3N4 (CN) was successfully combined with MoS2 via hydrothermal synthesis as a solid lubricant for the first time. Meanwhile, a low friction coefficient (COF, μ = 0.031) and ultra-long wear-life of CN/MoS2 compared to pure MoS2 in air were demonstrated. The functional groups and good crystallinity of the lubricant material were characterized via Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The formed valence states in CN/MoS2 were analyzed via X-ray photoelectron spectroscopy (XPS). The characterized results of the scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) show the morphology and interior crystal phase structure of CN/MoS2. From the cross-section analysis, the presence of iron oxide nanoparticles lubricating film is synergistic with CN/MoS2 film during the friction process, resulting in its ultra-long wear-life. In particular, the friction mechanism of interlayer sliding friction combined with energy storage friction was analyzed and proposed.

Optimal Elastic Design of CFCs

2011 ◽  
Vol 488-489 ◽  
pp. 295-298 ◽  
Author(s):  
Galyna Stasiuk ◽  
Romana Piat ◽  
Yuriy Sinchuk
Keyword(s):  
Elastic Properties ◽  
Material Properties ◽  
Bulk Material ◽  
Carbon Composite ◽  
Bending Test ◽  
Three Point Bending ◽  
Design Variables ◽  
Tension And Compression ◽  
Elastic Design ◽  
Analytical Homogenization

The aim of the proposed studies is the development of the carbon/carbon composite with prescribed elastic properties. To achieve this, a microstructure optimisation problem for estimation of the microstructure with prescribed stiffness is formulated. The design variables of the posed problem are the local fibers distribution and porosity. The volume fractions of the fibers and pores in the whole microstructure are fixed. Material properties of the local microstructure of the composite are calculated using virtual models. Semi-analytical homogenization procedures were used for the development of these models. Modeling results are compared with elastic properties obtained experimentally by tension and compression test and ultrasonic studies of the bulk material. Approach to design microstructure for three point bending test is proposed.

The system of indicators of the quality of the carbon-carbon composite materials and technologies of their production

2018 ◽  
pp. 127-132
Author(s):  
T. N. Antipova ◽  
D. S. Shiroyan
Keyword(s):  
Composite Material ◽  
Low Cost ◽  
Experimental Studies ◽  
Carbon Matrix ◽  
Carbon Composite ◽  
Optimal Number ◽  
Laboratory Equipment ◽  
Carbon Composite Material ◽  
Carbon Composite Materials

The system of indicators of quality of carbon-carbon composite material and technological operations of its production is proved in the work. As a result of the experimental studies, with respect to the existing laboratory equipment, the optimal number of cycles of saturation of the reinforcing frame with a carbon matrix is determined. It was found that to obtain a carbon-carbon composite material with a low cost and the required quality indicators, it is necessary to introduce additional parameters of the pitch melt at the impregnation stage.

scholarly journals Additive Manufacturing-Based In Situ Consolidation of Continuous Carbon Fibre-Reinforced Polycarbonate

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2450
Author(s):  
Andreas Borowski ◽  
Christian Vogel ◽  
Thomas Behnisch ◽  
Vinzenz Geske ◽  
Maik Gude ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Carbon Fibre ◽  
Bending Test ◽  
Thermoplastic Composites ◽  
Experimental Investigations ◽  
Material Structure ◽  
Three Point Bending ◽  
Continuous Fibre ◽  
Local Material

Continuous carbon fibre-reinforced thermoplastic composites have convincing anisotropic properties, which can be used to strengthen structural components in a local, variable and efficient way. In this study, an additive manufacturing (AM) process is introduced to fabricate in situ consolidated continuous fibre-reinforced polycarbonate. Specimens with three different nozzle temperatures were in situ consolidated and tested in a three-point bending test. Computed tomography (CT) is used for a detailed analysis of the local material structure and resulting material porosity, thus the results can be put into context with process parameters. In addition, a highly curved test structure was fabricated that demonstrates the limits of the process and dependent fibre strand folding behaviours. These experimental investigations present the potential and the challenges of additive manufacturing-based in situ consolidated continuous fibre-reinforced polycarbonate.

Effect of Concrete Mixture Composition on Acoustic Emission and Fracture Parameters Obtained from Three-Point Bending Test

2015 ◽  
Vol 1100 ◽  
pp. 152-155
Author(s):  
Libor Topolář ◽  
Hana Šimonová ◽  
Petr Misák
Keyword(s):  
Acoustic Emission ◽  
Bending Test ◽  
Mixture Composition ◽  
Three Point Bending ◽  
Concrete Mixtures ◽  
Fracture Parameters ◽  
Fracture Tests ◽  
Stress Behaviour ◽  
Bending Fracture ◽  
Fracture Processes

This paper reports the analysis of acoustic emission signals captured during three-point bending fracture tests of concrete specimens with different mixture composition. Acoustic emission is an experimental tool well suited for monitoring fracture processes in material. The typical acoustic emission patterns were identified in the acoustic emission records for three different concrete mixtures to further describe the under-the-stress behaviour and failure development. An understanding of microstructure–performance relationships is the key to true understanding of material behaviour. The acoustic emission results are accompanied by fracture parameters determined via evaluation of load versus deflection diagrams recorded during three-point bending fracture tests.

scholarly journals Experimental and Numerical simulation of a Three Point Bending Test of a Stainless Steel Beam

2021 ◽  
Vol 55 ◽  
pp. 1114-1121
Author(s):  
Daniel Jindra ◽  
Zdeněk Kala ◽  
Jiří Kala ◽  
Stanislav Seitl
Keyword(s):  
Numerical Simulation ◽  
Stainless Steel ◽  
Bending Test ◽  
Steel Beam ◽  
Three Point Bending

scholarly journals Fracture and Size Effect of PFRC Specimens Simulated by Using a Trilinear Softening Diagram: A Predictive Approach

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3795
Author(s):  
Fernando Suárez ◽  
Jaime C. Gálvez ◽  
Marcos G. Alberti ◽  
Alejandro Enfedaque
Keyword(s):  
Reinforced Concrete ◽  
Size Effect ◽  
A Priori ◽  
Plain Concrete ◽  
Specimen Size ◽  
Bending Test ◽  
Orientation Factor ◽  
Fibre Reinforced Concrete ◽  
Softening Function ◽  
Three Point Bending

The size effect on plain concrete specimens is well known and can be correctly captured when performing numerical simulations by using a well characterised softening function. Nevertheless, in the case of polyolefin-fibre-reinforced concrete (PFRC), this is not directly applicable, since using only diagram cannot capture the material behaviour on elements with different sizes due to dependence of the orientation factor of the fibres with the size of the specimen. In previous works, the use of a trilinear softening diagram proved to be very convenient for reproducing fracture of polyolefin-fibre-reinforced concrete elements, but only if it is previously adapted for each specimen size. In this work, a predictive methodology is used to reproduce fracture of polyolefin-fibre-reinforced concrete specimens of different sizes under three-point bending. Fracture is reproduced by means of a well-known embedded cohesive model, with a trilinear softening function that is defined specifically for each specimen size. The fundamental points of these softening functions are defined a priori by using empirical expressions proposed in past works, based on an extensive experimental background. Therefore, the numerical results are obtained in a predictive manner and then compared with a previous experimental campaign in which PFRC notched specimens of different sizes were tested with a three-point bending test setup, showing that this approach properly captures the size effect, although some values of the fundamental points in the trilinear diagram could be defined more accurately.

Experimental and Numerical Investigation of Critical Buckle Load of Composite Specimens

2015 ◽  
Vol 732 ◽  
pp. 85-90
Author(s):  
Lukáš Bek ◽  
Radek Kottner ◽  
Jan Krystek ◽  
Tomáš Kroupa
Keyword(s):  
Static Analysis ◽  
Glass Fibre ◽  
Large Deformations ◽  
Bending Test ◽  
Test Results ◽  
Beam Test ◽  
Three Point Bending ◽  
Box Beams ◽  
Buckle Beam ◽  
Thin Walled

Different carbon and glass fibre strips were subjected to the double clamp buckle beam test. Furthermore, thin-walled glass fibre box-beams were subjected to the three-point bending test. Results of experiments were compared to different numerical simulations using buckling analysis or static analysis considering large deformations.

Influence of Honeycomb Core Compression on the Mechanical Properties of the Sandwich Structure

2013 ◽  
Vol 486 ◽  
pp. 283-288
Author(s):  
Ladislav Fojtl ◽  
Soňa Rusnáková ◽  
Milan Žaludek
Keyword(s):  
Mechanical Properties ◽  
Impact Test ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Low Velocity Impact ◽  
Bending Test ◽  
Honeycomb Core ◽  
Low Velocity ◽  
Three Point Bending ◽  
Core Technology

This research paper deals with an investigation of the influence of honeycomb core compression on the mechanical properties of sandwich structures. These structures consist of prepreg facing layers and two different material types of honeycomb and are produced by modified compression molding called Crush-Core technology. Produced structures are mechanically tested in three-point bending test and subjected to low-velocity impact and Charpy impact test.

Three-Point Bending Test Evaluation of Concrete Specimens by Non-Traditional Analysis of Acoustic Emission Method

2016 ◽  
Vol 837 ◽  
pp. 198-202
Author(s):  
Luboš Pazdera ◽  
Libor Topolář ◽  
Tomáš Vymazal ◽  
Petr Daněk ◽  
Jaroslav Smutny
Keyword(s):  
Acoustic Emission ◽  
Signal Analysis ◽  
Measurement Data ◽  
Bending Test ◽  
Test Evaluation ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
Three Point Bending ◽  
Time Frequency ◽  
Emission Signal

The aim of the paper is focused on the analysis of the mechanical properties of the concrete specimens with plasticizer at three point bending test by the signal analysis of the acoustic emission signal. The evaluations were compared the measurement and the results obtained with theoretical presumptions. The Joint Time Frequency Analysis applied on measurement data and its evaluation is described. It is well known that the Acoustic Emission Method is a very sensitive method to determine active cracks into structure. However, evaluation of acoustic emission signals is very difficult. A non-traditional method was used to signal analysis of burst acoustic emission signals recorded during three point bending test.

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