scholarly journals Assessment of the Mechanical Parameters of Resin Composites with the Addition of Various Types of Fibres

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1378 ◽  
Author(s):  
Bernardeta Dębska ◽  
Lech Lichołai ◽  
Guilherme Jorge Brigolini Silva ◽  
Marina Altoé Caetano
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Brittle Fracture ◽  
Statistical Analyses ◽  
Fibre Content ◽  
Resin Composites ◽  
Mechanical Parameters ◽  
Carbon Fibres ◽  
Polypropylene Fibres ◽  
The Impact

The article describes tests of epoxy mortars after the addition of fibres. The fibres were a substitute for sand in the amount of 0, 1, 2, 3, 4 and 5% by volume, respectively. Three types of mortar were obtained, containing polypropylene, glass and carbon fibres, respectively. Statistical analyses (ANOVA) were carried out to assess the impact of fibre content on the mechanical properties of mortars. Brittle fracture toughness was also tested using the Cracked Straight Through Brazilian Disc method. The addition of each type of fibre improved the assessed parameters. Based on the obtained research results, and also due to availability and price, the most advantageous seems to be the production of composites containing the addition of polypropylene fibres.

Effect of toughened polyamide-coated carbon fiber fabric on the mechanical performance and fracture toughness of CFRP

2021 ◽  
pp. 002199832199945
Author(s):  
Jong H Eun ◽  
Bo K Choi ◽  
Sun M Sung ◽  
Min S Kim ◽  
Joon S Lee
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Photoelectron Spectroscopy ◽  
Mechanical Performance ◽  
Epoxy Composites ◽  
Scanning Calorimetry ◽  
Internal Damage ◽  
Impact Tests ◽  
Flexural Tests ◽  
The Impact

In this study, carbon/epoxy composites were manufactured by coating with a polyamide at different weight percentages (5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.%) to improve their impact resistance and fracture toughness. The chemical reaction between the polyamide and epoxy resin were examined by fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray photoelectron spectroscopy. The mechanical properties and fracture toughness of the carbon/epoxy composites were analyzed. The mechanical properties of the carbon/epoxy composites, such as transverse flexural tests, longitudinal flexural tests, and impact tests, were investigated. After the impact tests, an ultrasonic C-scan was performed to reveal the internal damage area. The interlaminar fracture toughness of the carbon/epoxy composites was measured using a mode I test. The critical energy release rates were increased by 77% compared to the virgin carbon/epoxy composites. The surface morphology of the fractured surface was observed. The toughening mechanism of the carbon/epoxy composites was suggested based on the confirmed experimental data.

scholarly journals Tetragonal-to-Monoclinic Transformation Influence on the Mechanical Properties of CeO2- ZrO2 Ceramics

2005 ◽  
Vol 498-499 ◽  
pp. 506-511 ◽  
Author(s):  
Maria do Carmo de Andrade Nono
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Performance ◽  
Surface Hardness ◽  
X Rays ◽  
Mechanical Parameters ◽  
Bending Tests ◽  
Structural High

CeO2- ZrO2 ceramics are considered a candidate material for applications as structural high performance ceramics. In this work are presented and discussed the tetragonal-to-monoclinic stress-induced transformation influence on the mechanical properties in these ceramics. Sintered ceramics were fabricated from powders mixtures containing ZrO2 and 8 to 14 CeO2 % mol. SEM observations were used to study de ceramic microstructures and X-rays diffraction to identification and determination of tetragonal and monoclinic phases. It was adopted the 4-point bending tests, Vickers surface hardness and fracture toughness technique to the determination of the mechanical parameters. The results showed that the mechanical properties were strongly dependent of the CeO2 content, the microstructure and the fraction of tetragonal-to-monoclinic stress-induced transformation.

scholarly journals Increasing the construction strength of petroleum pipes operating in agressive environment

2021 ◽  
pp. 70-76
Author(s):  
V.S. Chmeliova ◽  
H.I. Perchun
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Hydrogen Sulfide ◽  
Brittle Fracture ◽  
High Resistance ◽  
Structural Strength ◽  
Aggressive Environment ◽  
The Impact ◽  
Resistance To Brittle Fracture ◽  
Hydrogen Sulfide Cracking

Purpose. Questions about ways to increase the structural strength of oil country tubular goods are considered. Alloying and heat treatment of medium-alloy steels should ensure: pro-carbonization to the structure of martensite and lower bainite with a minimum carbon content (C ≤ 0.3 %), high resistance to brittle fracture and hydrogen embrittlement, the formation of uniformly distributed finely dispersed carbides and sulphides of a round shape to reduce diffusion mobile hydrogen is absorbed by steel. Propose modes of thermal treatment of casing pipes that provide the required level of mechanical and operational properties. Methodology. We used standard techniques for determining the mechanical properties in tension, dynamic bending tests and fracture studies. Results. The modes of heat treatment of casing pipes of strength category E, L are proposed, which provide the required level of mechanical and operational properties and an increase in structural strength. Originality. A systematic analysis of the influence of various factors on the structural strength of oil country tubular goods operating in an aggressive environment has been carried out. The highest degree of correlation between the value of the impact toughness and the tough component in the fracture is shown. Cooling of pipes with a nozzle sprayer of the design of the Department of Heat Treatment of Metals of NMetAU, which provides high resistance to brittle fracture by increasing the proportion of the viscous component and changing the microrelief of the cup fracture. Practical value. The proposed technology of heat treatment of oil pipes, working in an aggressive environment, provides the required level of mechanical properties and resistance to hydrogen sulfide cracking. Keywords: structural strength; oil country tubular goods; alloying; heat treatment; strength categories;temperature and deformation parameters; hydrogen sulfide cracking; brittle fracture resistance

scholarly journals Evaluation of the Degree of Conversion, Residual Monomers and Mechanical Properties of Some Light-Cured Dental Resin Composites

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2109 ◽  
Author(s):  
Marioara Moldovan ◽  
Robert Balazsi ◽  
Andrada Soanca ◽  
Alexandra Roman ◽  
Codruta Sarosi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Properties ◽  
Degree Of Conversion ◽  
Resin Composites ◽  
Mechanical Parameters ◽  
Dental Resin ◽  
Posterior Teeth ◽  
Commercial Resin ◽  
Diametral Tensile Strength

The novelty of this study consists in the formulation and characterization of three experimental dental composites (PM, P14M, P2S) for cervical dental lesion restoration compared to the commercial composites Enamel plus HRi® - En (Micerium S.p.A, Avengo, Ge, Italy), G-ænial Anterior® - Ge, (GC Europe N.V., Leuven, Belgium), Charisma® - Ch (Heraeus Kulzer, Berkshire, UK). The physio-chemical properties were studied, like the degree of conversion and the residual monomers in cured samples using FTIR-ATR (attenuated total reflectance) and HPLC-UV (ultraviolet detection), as well as the evaluation of the mechanical properties of the materials. The null hypothesis was that there would be no differences between experimental and commercial resin composites regarding the evaluated parameters. Statistical analysis revealed that water and saliva storage induced significant modifications of all mechanical parameters after three months for all tested materials, except for a few comparisons for each type of material. Storage medium seemed not to alter the values of mechanical parameters in comparison with the initial ones for: diametral tensile strength (DTS-saliva for Ge and PM, compressive strength (CS)-water for Ch, DTS-water and Young’s modulus YM-saliva for P14M and YM-water/ saliva for P2S (p > 0.05). Two of the experimental materials showed less than 1% residual monomers, which sustains good polymerization efficiency. Experimental resin composites have good mechanical properties, which makes them recommendable for the successful use in load-bearing surfaces of posterior teeth.

On the Methods for Assessing the Resistance of Steels to Brittle Fracture

2021 ◽  
pp. 59-64
Author(s):  
A.P. Korchagin ◽  
◽  
K.A. Kuznetsov ◽  
A.M. Kuznetsov ◽  
S.I. Kirillov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Brittle Fracture ◽  
Impact Strength ◽  
Low Temperatures ◽  
Physical And Mechanical Properties ◽  
Correct Choice ◽  
Temperature Dependences ◽  
And Control ◽  
The Impact ◽  
Resistance To Brittle Fracture

The problem of assessing steels durability, their resistance to brittle fracture in the structures used in various branches of industry, remains relevant at the development of the new equipment and control of the old equipment. Standard strength calculations do not give a complete picture of the ability of steels due to their physical and mechanical properties to resist the formation and further development of defects and cracks under the action of actual stresses. The correct choice of a structural material for technical devices operating at low temperatures, knowledge of its characteristics of resistance to brittle fracture, understanding of brittle fracture mechanism at low temperatures and research in this area are of great importance. Since 1980s, JSC IrkutskNIIkhimmash systematically conducts the research works related to impact strength characteristics. These works are carried out in connection with the need for assessing the resistance to brittle fracture of metal of the equipment for storing oil products, vessels and pipelines, drill pipes and tubing, etc. As a result of many years of research, the authors accumulated significant experimental material in the form of temperature dependences of impact strength - both for the material of various types of blanks (sheets, pipes, forgings) in the state of delivery, and for the metal of technical devices elements after their operation of various duration. The main objective of the article is to assist specialists in establishing the correct choice of steel for the new or old structures in terms of their resistance to brittle fracture without conducting special studies. Specialists can select the closest steel analogue (on chemical composition, mechanical properties, and the type of product without making cuts from the structure or blanks for additional research), and set the numerical value of the impact strength, critical temperature of brittleness and the stress intensity factor for any temperature in the range from –40 to 20° С in order to use them in further calculations.

Effect of Rare Earth Oxide and Rare Earth-Alumina-Silica Glass on Mechanical Properties of Liquid Phase Sintered Alumina Ceramics

2005 ◽  
Vol 290 ◽  
pp. 246-249 ◽  
Author(s):  
Jaroslav Sedláček ◽  
Dušan Galusek ◽  
Pavol Šajgalík
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Rare Earth ◽  
Liquid Phase ◽  
Rare Earth Oxide ◽  
Aluminosilicate Glass ◽  
Alumina Ceramics ◽  
Beneficial Effects ◽  
Rare Earth Addition ◽  
The Impact

The microstructure evolution and mechanical properties of alumina doped with rare earth oxide and rare earth-aluminosilicate glass has been investigated in order to understand better the impact of rare earth addition on hardness and fracture toughness. The aims of the present work are to examine the possibly beneficial effects of selected rare earth oxide added to alumina by two different routes in enhancing mechanical properties. The specific systems considered in this work were as follows: liquid phase sintered alumina containing RE2O3 (RE = La, Y) and RE2O3 – Al2O3 – SiO2 glassy phase up to 5 wt. %. The Vickers hardness and fracture toughness have been compared with the undoped alumina.

Effect of Fly Ash Content on Mechanical Properties of Cement-Fly Ash Stabilized Crushed Stones

2014 ◽  
Vol 548-549 ◽  
pp. 228-232 ◽  
Author(s):  
Xiao Chen ◽  
Ji Wei Liu ◽  
Ming Kai Zhou
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Crack Resistance ◽  
Unconfined Compressive Strength ◽  
Resilient Modulus ◽  
Ash Content ◽  
Mechanical Parameters ◽  
Cleavage Strength ◽  
The Impact

To improve the impact of fly ash on the properties of cement-fly ash stabilized crushed stone, and promote it popularize and apply better. This paper investigated the effect of fly ash content on unconfined compressive strength, cleavage strength and resilient modulus of cement-fly ash stabilized crushed stones, and those relationships between mechanical parameters. The results showed that with increasing of the fly ash content, the unconfined compressive strength and cleavage strength increased at first, then decreased, the resilient modulus decreased, and The brittleness index increased. We can conclude that the optimal fly ash content is between 10% and 15%, and increment of fly ash content can improve its crack-resistance.

scholarly journals Mechanical and Heterogeneous Properties of Coal and Rock Quantified and Mapped at the Microscale

2020 ◽  
Vol 10 (1) ◽  
pp. 342 ◽  
Author(s):  
Changlun Sun ◽  
Guichen Li ◽  
Suhui Zhang ◽  
Jiahui Xu ◽  
Houqiang Yang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Convenient Method ◽  
Elastic Moduli ◽  
Averaging Method ◽  
Sample Volume ◽  
Small Sample ◽  
Mechanical Parameters ◽  
Experimental Technology ◽  
Small Sample Volume

Due to the impossibility of obtaining intact standard experimental samples, it is difficult to test the mechanical properties of soft and broken coal and rock obtained from deep coal mines. So, an advanced experimental technology based on a small sample volume, nanoindentation technology, was introduced and used to measure the mechanical parameters of them. By using the averaging method, the hardness of shale, mudstone and coal are 1191.90 MPa, 674.95 MPa and 424.30 MPa, respectively; their elastic moduli are 20.39 GPa, 11.72 GPa and 5.47 GPa; and their fracture toughness were 1.66 MPa·m0.5, 1.28 MPa·m0.5 and 0.77 MPa·m0.5. These three mechanical parameters were used to quantify and map the heterogeneous properties of coal and rock for convenience and accuracy. For example, the inter quartile range (IQR) of the hardness of shale, mudstone, and coal are 1502.10 MPa, 1016.20 MPa and 54.64 MPa, respectively, meaning that coal has the best homogeneity among them. Nanoindentation technology provides researchers with a convenient method to conduct mechanical experiments at the microscale.

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