scholarly journals ADDITIONAL CHARACTERISTICS OF HYBRID COMPOSITES FOR FILLING TEETH UNDER LOCAL MOUNTING CLOCKS

2021 ◽  
pp. 29-36
Author(s):  
V.F. Makeev ◽  
V.S. Kukhta ◽  
O.S. Kyrmanov ◽  
V.R. Skalsky
Keyword(s):  
Tensile Strength ◽  
Comparative Analysis ◽  
Oral Cavity ◽  
Air Temperature ◽  
Hybrid Composites ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Dental Composites ◽  
Local Loading ◽  
Ball Diameter

For the rational use of materials, it is necessary to have data on their ability to resist deformation and destruction. In particular, in each case it is necessary to have information on the stiffness, strength and resistance to destruction of materials in the specified operating conditions of the elements. To determine such strength characteristics of the material, certain studies are carried out. According to the analysis of literature sources in the study of dental composites mainly determine the tensile strength (bending) and compression [2-10], because it is subjected to restore materials during their operation in the oral cavity. The purpose of the study is to conduct a comparative analysis of the strength of hybrid composites of domestic and imported production during their local loading: Latelux (Latus, Ukraine), TETRIC N-CERAM (Ivoclar Vivadent, Liechtenstein), CHARISMA CLASSIC (Kulzer, Germany). To conduct research, 10 samples of each dental polymer composite were made. Packaging and molding of the material into a specially designed form was performed in laboratory conditions at an air temperature of 18 210 C with their subsequent polymerization with a LED photopolymer lamp Bluephase 20i (G2) (Ivoclar Vivadent). Before the test, the samples were kept for 24 hours at a temperature of 370 C in saline. The samples were loaded on the SVR-5 installation using a ball indenter (ball diameter mm steel SHX15, modulus of elasticity GPa, Poisson's ratio) with a speed of 0.002 mm/s. The purpose of the study is to conduct a comparative analysis of the strength of hybrid composites of domestic and imported production during their local loading. According to the results of experimental studies on the load of PB fracture, the Charisma Classic composite (5.72 ± 0.16 kN) has the highest strength, Latelux (4.23 ± 0.53 kN) the lowest, and Tetric N-Ceram (5, 03 ± 0.71 kN) occupies an intermediate position. To move the indenter, we obtained the following order of materials (in ascending order): Latelux (0.94 ± 0.11 mm); Charisma Classic (1.02 ± 0.04 mm); Tetric N-Ceram (1.03 ± 0.17 mm).

scholarly journals ДОСЛІДЖЕННЯ ГІГІЄНІЧНИХ ВЛАСТИВОСТЕЙ МАТЕРІАЛІВ НАТІЛЬНОЇ ЛІКАРНЯНОЇ БІЛИЗНИ

2020 ◽  
Vol 140 (6) ◽  
pp. 38-47
Author(s):  
І. О. Іванов ◽  
Н. П. Супрун ◽  
Ю. О. Ващенко
Keyword(s):  
Comparative Analysis ◽  
Materials Science ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Raw Material ◽  
Experimental Investigations ◽  
Textile Materials ◽  
Composition And Structure ◽  
Innovative Materials ◽  
Basic Functions

Investigation of the influence of the peculiarities of raw material composition and structure of traditional and innovative linen textile materials on their hygienic properties. Theoretical and experimental investigations are based on the main positions of textile materials science. In experimental studies, modern standardized methods for determining the hygienic properties of textile materials were used, as well as techniques specially developed taking into account the peculiarities of the operating conditions of underwear. The peculiarities of the operating conditions and the basic functions of hospital underwear were determined. The comparative analysis of hygienic properties of traditional and modern fabrics for underwear was carried out. Using the standardized and the developed methods, adapted to the peculiarities of the conditions of use of the products, the indicators characterizing the processes of water absorption of the materials were experimentally determined. On the basis of the obtained values of quality indicators, a comprehensive assessment of the ability of materials to transfer moisture and air, with the calculation of the arithmetic complex quality index was done. This allowed to determine the material that is optimal in properties, which provides thermophysiological comfort when operating hospital underwear. Using the developed methods, which take into account the specifics of the operating conditions, a comparative analysis of the hygienic properties of traditional and innovative materials for underwear was carried out. A new range of textile materials for underwear has been proposed, taking into account the peculiarities of the operational situation of consumption.

scholarly journals Experimental studies of different quenching media on mechanical and wear behavior of Al7075/SiC/Al2O3 hybrid composites

2020 ◽  
Vol 15 (55) ◽  
pp. 20-31
Author(s):  
M. Ravikumar ◽  
H.N. Reddappa ◽  
R. Suresh ◽  
M. Sreenivasa Reddy
Keyword(s):  
Tensile Strength ◽  
Wear Resistance ◽  
Hybrid Composites ◽  
Experimental Studies ◽  
Age Hardening ◽  
Wear Behaviour ◽  
High Wear Resistance ◽  
Al Alloy ◽  
Quenching Media ◽  
Heat Treated

The effects of SiC-Al2O3 particle in the Al alloy on the mechanical and wear characteristics of stir-casted Composites have been reported. The Al7075 is reinforced with 2, 4, 6 and 8 wt. % of (SiC + Al2O3) to manufacture the hybrid composite. Ceramic particulates were added into Al alloy to achieve the low wear rate and improving mechanical properties. Hardening of casted specimens at 480ºC for the duration of 2 hrs and the specimens were quenched into two different quenching media (water and ice cubes). Finally, age-hardening were carried out at the temperature of 160ºC for the duration of 4 hrs and cooled at room temperature. The tensile strength, hardness and wear behaviour of MMCs are evaluated on the un-treated and heat treated composite. The tensile strength and hardness of MMCs increases by incorporating SiC-Al2O3 particulates. The wear behaviour of the MMCs containing SiC-Al2O3 particulates revealed the high wear-resistance. The heat-treatment had considerably improved the properties when compared to the un-heat treated composites. The composites with the highest tensile strength, hardness and enhanced wear resistance were found in the composites quenched in ice cubes. Worned surfaces of the composite specimens were studied by using SEM and XRD analysis

scholarly journals COMPARATIVE ANALYSIS OF TISSUE EXERTION OF MUCOUS MEMBRANES DURING DIFFERENT STAGES OF TENSION IN PERFORMING ON CLOTTING OPERATION

2018 ◽  
pp. 5-8
Author(s):  
D.V. Kaplun ◽  
V.M. Skrupnik ◽  
S.O. Stavitsky
Keyword(s):  
Tensile Strength ◽  
Comparative Analysis ◽  
Connective Tissue ◽  
Oral Cavity ◽  
Mucous Membrane ◽  
Soft Core ◽  
Elastic Fibers ◽  
Mucous Membranes ◽  
Biomechanical Parameters ◽  
Tissue Tension

Taking into account the development of modern surgical stomatology, the problem of optimizing the closure of the wounds of the mucous membrane in the oral cavity remains relevant. In our opinion, it is important to study the morphological properties of the mucous membranes of the oral cavity and optimal tensions and tissue stresses in the area of suturing. It is known that the most susceptible to the action of mechanical factors area is the mucous membrane of the gums. However, taking into account the biomechanical parameters, the mucous membrane of the gum is practically not described. The aim of the study was to carry out a comparative analysis of mucous membranes of varying degrees of tension during fracture operations in the oral cavity. The material is taken to the bureau of forensic examination from corpses and both sexes and the period of mature age for histological studies of conditionally healthy mucous membrane of gum. The fence is carried out in the area of incisors, canines and first premolars from both halves of the upper and lower jaws with a standard dental instrument set were compared: a periodontological kit for curettage. The material is collected both in the area of papilla gum, and from its fixed part. Polarization microscopy is used to study the fibroarchitectonics of connective tissue formations. We used a contact strain gauge device to study the biomechanical parameters of the mucous membrane of the gums in normal and at different degrees of tensile of the mucous membranes. At various degrees of tension of the mucous membrane of the cavity of the mouth connective tissue plate loses the characteristic spatial orientation of the beams, the deep disruption of the entire fibrous frame occurs. Tissue stress recording was performed taking into account the tensile strength: weak (5%), average (7%) and strong (10%). Regardless of the degree of this pathology there is a decrease in the indicator we have chosen. Thus, with a weak degree of tension, the tissue pressure of the gum mucus decreases to 208.08 + 19.2 [6.07] Pa. At an average degree, the selected indicator is 149.43 + \ - 20.25 [6.4] Pa. A strong tension reduces the tissue tension of this area to 102.77 + 12.32 [3.9] Pa. One of the factors that provides high values of tissue gum voltage in the norm (350.4 · 9.69 Pa) is its fibrous components, which form a three-dimensional structure in the collagen beams of the 1st and 2nd order relative to the poorly developed elastic network. Different degrees of tensile of mucous membranes as a model of disorganization with the subsequent drop in tissue tension of the fibrous core were described. At the same time, the index of tissue voltage reduction is directly dependent on the tensile strength and is 208.08 + 19.2 Pa. The data presented indicate the disorganization of the fiber composition of the gums while tightening them. The expressiveness and nature of the changes depend on the degree of tension. Clinical manifestation of pathological processes in fibrous components of ascetic connective tissue is characterized by a decrease in tissue tension indices. Moreover, there is a direct relationship between the degree of tensile of the mucous membrane and the adequate reduction of the tense state of the soft core. Various degrees of tension of the mucous membrane can be considered as a kind of model of the fiber matrix with the dynamics of changes in the biomechanical parameters of tissues. The obtained data on the example of normal anatomy of the gums confirm the general pattern in the structures of the soft core - the quantitative ratio, the way of interaction of collagen and elastic fibers. Their spatial architectonics determine the deformative and strength properties of the connective tissue. For a detailed study of structural and biomechanical correlations we have selected mucous membranes with a different degree of tension. Our research has revealed structural changes in the fibrous gingival cortex against a background of different tensions with adequate tissue tension reduction.

Experimental Investigation of Mechanical Properties of Ceramic Reinforced Al-7075 Metal Matrix Hybrid Composites

2020 ◽  
Vol 979 ◽  
pp. 34-39
Author(s):  
K. Sudhindra Srinivas ◽  
M. Murali Mohan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Metal Matrix ◽  
Hybrid Composites ◽  
Experimental Studies ◽  
Stir Casting ◽  
Matrix Composites ◽  
Weight Percentage ◽  
Particulate Metal ◽  
Al 7075

The epidemic adoption of particulate metal matrix composites (MMCs) for engineering applications has been delay by the high cost of producing components of even minimally complex shape. The aluminum-based composites find its applications widely in transport, aerospace, marine, automobile and mineral processing industries, owing to their improved strength, stiffness and wear resistance properties. This paper, presents the overview of the addition of different reinforcements to aluminium alloy. The reinforcements are added to the Al7075 by using stir casting method. Effect of these reinforcements like Titanium carbide (TiC) and silicon (Si) influencing on the mechanical properties like tensile strength, hardness was studied. Research relevant to these factors which influence particles distribution were noticed by conducting the experimental studies of Al7075 hybrid composites.The mechanical properties and the microstructure of Al–TiC-Si metal matrix composite has shown the significant improvement in Hardness and Tensile strength, with increase in TiC and Si particles in weight percentage of composites.

scholarly journals Experimental studies of the operation of a frameless building made of thin-gauge structural sections

2021 ◽  
Vol 31 (4) ◽  
pp. 110-119
Author(s):  
I. I. Vedyakov ◽  
D. V. Solovyev ◽  
A. V. Smagin
Keyword(s):  
Comparative Analysis ◽  
Construction Industry ◽  
Experimental Studies ◽  
Numerical Data ◽  
Light Metal ◽  
Operating Conditions ◽  
Shell Structures ◽  
Metal Structures ◽  
Promising Direction ◽  
Operational Scheme

Light metal structures (LMS) are widely spread in domestic construction industry. A promising direction for the development of LMS includes prefabricated shell structures made of thin-gauge structural sections. The scope and operating conditions of such structures are quite extensive. In this regard, the development of a competent engineering methodology for calculating buildings using thin-gauge structural sections is required. The present paper describes a method for a full-scale testing of a shell building fragment and provides the results of forces and deformations calculated using the experimental model. In addition, an approach to modeling and dimensioning of finite elements for the profiles under consideration is described. The comparative analysis of numerical data and experimental results is performed. The results of the study can be used both for developing recommendations and engineering methods for calculating similar shell buildings and for determining the actual operational scheme for units and elements of the considered structure.

scholarly journals Ethanol/Gasoline Blends as Alternative Fuel in Last Generation Spark-Ignition Engines: A Review on CO and HC Engine Out Emissions

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4034
Author(s):  
Paolo Iodice ◽  
Massimo Cardone
Keyword(s):  
Physicochemical Properties ◽  
Alternative Fuels ◽  
Experimental Studies ◽  
Alternative Fuel ◽  
Exhaust Emissions ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Spark Ignition Engines ◽  
The Impact

Among the alternative fuels existing for spark-ignition engines, ethanol is considered worldwide as an important renewable fuel when mixed with pure gasoline because of its favorable physicochemical properties. An in-depth and updated investigation on the issue of CO and HC engine out emissions related to use of ethanol/gasoline fuels in spark-ignition engines is therefore necessary. Starting from our experimental studies on engine out emissions of a last generation spark-ignition engine fueled with ethanol/gasoline fuels, the aim of this new investigation is to offer a complete literature review on the present state of ethanol combustion in last generation spark-ignition engines under real working conditions to clarify the possible change in CO and HC emissions. In the first section of this paper, a comparison between physicochemical properties of ethanol and gasoline is examined to assess the practicability of using ethanol as an alternative fuel for spark-ignition engines and to investigate the effect on engine out emissions and combustion efficiency. In the next section, this article focuses on the impact of ethanol/gasoline fuels on CO and HC formation. Many studies related to combustion characteristics and exhaust emissions in spark-ignition engines fueled with ethanol/gasoline fuels are thus discussed in detail. Most of these experimental investigations conclude that the addition of ethanol with gasoline fuel mixtures can really decrease the CO and HC exhaust emissions of last generation spark-ignition engines in several operating conditions.

Effects of Air Temperature on Combustion Characteristics of LPG Diffusion Flame

2020 ◽  
Vol 1008 ◽  
pp. 128-138
Author(s):  
Ahmed M. Salman ◽  
Ibrahim A. Ibrahim ◽  
Hamada M. Gad ◽  
Tharwat M. Farag
Keyword(s):  
Air Temperature ◽  
Diffusion Flame ◽  
Nitrogen Addition ◽  
Flame Length ◽  
Combustion Characteristics ◽  
Operating Conditions ◽  
Low Oxygen ◽  
Air Temperatures ◽  
Air Stream ◽  
Wide Range

In the present study, the combustion characteristics of LPG gaseous fuel diffusion flame at elevated air temperatures were experimentally investigated. An experimental test rig was manufactured to examine a wide range of operating conditions. The investigated parameters are the air temperatures of 300, 350, 400, 450, and 500 K with constant percentage of nitrogen addition in combustion air stream of 5 % to give low oxygen concentration of 18.3 % by mass at constant air swirl number, air to fuel mass ratio, and thermal load of 1.5, 30, and 23 kW, respectively. The gaseous combustion characteristics were represented as axial and radial temperatures distributions, temperatures gradient, visible flame length and species concentrations. The results indicated that as the air temperature increased, the chemical reaction rate increased and flame volume decreased, the combustion time reduced leading to a reduction in flame length. The NO concentration reaches its maximum values near the location of the maximum centerline axial temperature. Increasing the combustion air temperature by 200 K, the NO consequently O2 concentrations are increased by about % 355 and 20 % respectively, while CO2 and CO concentrations are decreased by about % 21 and 99 % respectively, at the combustor end.

scholarly journals Effects of water absorption on the mechanical properties of hybrid natural fibre/phenol formaldehyde composites

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sekar Sanjeevi ◽  
Vigneshwaran Shanmugam ◽  
Suresh Kumar ◽  
Velmurugan Ganesan ◽  
Gabriel Sas ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Impact Strength ◽  
Water Absorption ◽  
Hybrid Composites ◽  
Phenol Formaldehyde ◽  
Natural Fibre ◽  
The Other ◽  
Fibre Reinforcement ◽  
Dry Conditions

AbstractThis investigation is carried out to understand the effects of water absorption on the mechanical properties of hybrid phenol formaldehyde (PF) composite fabricated with Areca Fine Fibres (AFFs) and Calotropis Gigantea Fibre (CGF). Hybrid CGF/AFF/PF composites were manufactured using the hand layup technique at varying weight percentages of fibre reinforcement (25, 35 and 45%). Hybrid composite having 35 wt.% showed better mechanical properties (tensile strength ca. 59 MPa, flexural strength ca. 73 MPa and impact strength 1.43 kJ/m2) under wet and dry conditions as compared to the other hybrid composites. In general, the inclusion of the fibres enhanced the mechanical properties of neat PF. Increase in the fibre content increased the water absorption, however, after 120 h of immersion, all the composites attained an equilibrium state.

Diametral tensile strength and dental composites

1987 ◽  
Vol 3 (1) ◽  
pp. 46-48 ◽  
Author(s):  
R.W. Penn ◽  
R.G. Craig ◽  
J.A. Tesk
Keyword(s):  
Tensile Strength ◽  
Dental Composites ◽  
Diametral Tensile Strength

Pulsed NMR for Molecular Structure Analysis of EPDM

1989 ◽  
Vol 62 (4) ◽  
pp. 643-655
Author(s):  
Richard W. Tomlinson ◽  
Daniel F. Sheridan
Keyword(s):  
Tensile Strength ◽  
Relaxation Times ◽  
Operating Conditions ◽  
Test Method ◽  
Major Contributor ◽  
Nmr Analysis ◽  
Pulsed Nmr ◽  
Molecular Structure Analysis ◽  
Separate Calibration ◽  
Comparison Data

Abstract The use of pulsed NMR analysis under proper operating conditions has proven to be useful for controlling various polymer compositions in the manufacture of EPDM. It can be used in determining the amount of oil incorporated into oil-extended EPDMs. At higher oil contents, the differences in EPDM properties will affect this test method, which will require a separate calibration curve for each type of polymer. It can be used to measure the propylene content of EPDM. Comparison data have shown that this technique is more accurate in predicting crystallinity or propylene content than the standard IR method within the propylene range of 22 to 41%. Pulsed NMR can also be used to predict uncured EPDM compound tensile strength and EPDM/PP compression-molded tensile strength. Since these properties are affected by the crystallinity of EPDM, of which percent ethylene is the major contributor, then tensile strength can be determined indirectly. Based on the tensile and SER correlation, it seems obvious that this technique is measuring the spin-spin relaxation times of the crystalline phase, whereas the ir method is only measuring propylene content.

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