Papers by Keyword: Pressure

Abstract: The problem of jatropha waste that has not been managed optimally has an impact on environmental pollution. Therefore, it is necessary to conduct research to utilize and utilize jatropha waste in products that are beneficial to the community. The purpose of this study was to find the best variation of particle size, time pressure, removal, and drying temperature to produce the best briquettes. The independent variables in this study were particle size (60 mesh, 80 mesh and 100 mesh); pressure (100 kg/cm2, 200 kg/cm2 and 300 kg/cm2); removal time (3 minutes, 6 minutes, 9 minutes) and drying temperature (100 C, 105 C and 110 C). The variables considered in this study were the water content and the compressive strength of the briquettes. The criteria to get the best product using R2 and R Adj. The results showed that the water content of the briquettes was 7.12%, and the best compressive strength was 23,768 kg/cm2. The water content model was declared feasible and valid to predict the water content of quality briquettes as indicated by all independent variables having VIF<10 and TOL> 0.1 and Durbin Watson value: 2.165 in the range of 1.767<D<2.233. Particle size, pressure, removal time, and drying temperature have a percentage contribution to the briquette pressure is 30.769%, respectively; pressure 29.338%; time eliminated 22.315%; drying temperature 7.952% and the remaining factors that are not used in this study and errors. The compressive strength model is declared feasible and valid to predict the compressive strength of quality briquettes as indicated by all independent variables having VIF < 10 and TOL > 0.1 and Durbin Watson value: 2.286 in the range of 2.233 < D < 2.687.

Abstract: In this work the composite made from epoxy resin as a matrix and natural fiber of Cordyline australis was used as reinforcement. The fiber was prepared from the process of water retting in fresh water for 1 weeks followed by drying. The final process was soaked in sea water to understand the effect of soaked in sea water to the adhesion of the fiber and matrix. The fiber was immersed in 5 hour and also 7 hours in sea water to be compared with the fiber that is was not immersed in sea water. The curing process also consist of 2 variation processes namely hand layup and vacuum pressure. The tensile test is conducted to investigate the final product of composite. It is found that the vacuum process resulting better tensile strength (34.610 MPa) in the sample of epoxy without fiber reinforcement (19.818 MPa for hand layup). In general for composite that are made with fiber without immersion in sea water, the tensile strength for the hand layup increase with addition of fiber fraction. In the other hand the tensile strength is decrease with addition of fiber fraction for vacuum process. For the fiber reinforcement, the hand layup resulting in better reinforcement comparing the vacuum process. .

Abstract: Products with varying cross-sectional height are used in various hydraulic pipelines [1-4]. These products are very easy to manufacture. However, when it comes to hydraulic pipelines of fuel systems, it is essential to use materials resistant to aggressive effects, which are rather difficult to handle [5-8]. In this case, one of the possible options for obtaining such products is hot forming, namely crimping. In view of this, the article considers the crimping of shells made of titanium 6Al-4V alloy. Various combinations of technological parameters and their influence on the flow of metal and the geometry of products are considered. Rational deformation-rate conditions of deformation are found.

Abstract: This paper presents the results of the investigation of the grain structure formation in the intermetallic compound Ni₃Al under conditions of its high-temperature synthesis under pressure in a powder mixture of nickel and aluminum of stoichiometric composition and the effect of grain size on the strength properties of the synthesized intermetallic compound. The grain structure was investigated by optical metallography, transmission electron microscopy, and EBSD analysis; the ultimate tensile strength of the intermetallic compound was investigated under the tension of the samples in the temperature range from 20 to 1000 °C. It was found that with a decrease in the grain size, not only does the tensile strength of the intermetallic compound multiply increases but also on the anomalous temperature dependence of the intermetallic compound strength there is a significant shift in the maximum strength value to the region of higher temperatures.

Abstract: The engineering method of analysis of pressure of a ground on flat walls is offered at presence of combine strip superficial loading in view of seismic influences. It is recommended to determine a situation of an internal slip surface dividing an elastic zone from area of limiting balance, on the basis of the technical theory of the ultimate stress condition. Proceeding from a situation of an internal and external slip plane, size of strip loading on the fill, the pressure of a ground which is taking place in an ultimate condition, on an internal slip surface of is determined on developed by P. Yakovlev to the specified Coulomb's method [1], and on an internal side of a retaining structure on the basis of the Boussinesq decision. In comparison with the earlier developed way it is offered specified according to the Boussinesq theory a method of definition of pressure transmitted by bed on a ground of the basis and, as a consequence more reasonable definition of safety factor of stability of a structure. Thus, curvilinear normal pressure diagram in a ground under a sole of lay is replaced on isosides trapeziform.

Abstract: In the framework of this study, compressed earth blocks (CEB) were produced using waste materials and various parameters. Material parameters included waste soil, recycled concrete, fly ash, cement, admixtures and water contents. Manufacturing parameters were vibration during manufacturing, confinement pressure, curing environment and curing time. Specimens used in this study were cubes and compressive strength testing was used to evaluate different mixtures and manufacturing methods. In terms of compressive strength, compressed earth blocks made of these materials could be used for manufacturing bricks and other structural elements.

Abstract: In this work, relations have been obtained that allow one to estimate the effect of pressure on the temperature of the liquid phase transition between different nanofilms and nanoparticles. It is shown that the external forces lead to a rise in phase transition temperature which should be considered during the contact-reactive soldering in electronics.

Abstract: In the article the results of the finite element modeling of cold extrusion of carbon steel, the stress-strain state of massive dies at high cyclic stresses characteristic of the cold extrusion of steel are presented. The possibility of significant amplification of dies in their working area by creating a variable external pressure from the rims of a special design is shown. Dies banding with variable external pressure, proportional to the internal pressure in the die, is aimed at increasing the technical resource of the tool.

Abstract: This article is focused on solving the problem of power supply for the mining and industrial regions of Ukraine. This problem is caused by a significant import dependence on natural gas, the lack of efficient technologies in the integrated development of the energy resources of gas-coal deposits and the deterioration of social and economic, as well as environmental conditions in mining regions. As a promising direction for solving the problem of rational use of methane from coal mines and reducing the hazardous gas emissions into the atmosphere, the implementation of gas hydrate technologies into the technological complex of a coal mine has been proposed. The Clausius-Clapeyron equation has been improved for the conditions of gas hydrates formation, which considers the presence of an excess in non-equilibrium defects and is supplemented, taking into account the thermal effect of phase transformations, with all the time positive thermal effect of the defects relaxation. It has been revealed that one can intentionally control the relaxation energy of defects by the thermodynamic stimulus of phase transformations in the process of hydrate formation. The experimental dependences have been determined of the change in hydrate accumulation on the time of hydrate formation, with the methane hydrates production and taking into account the parameters of pressure and temperature. It has been revealed that the maximum fast time of hydrate formation at T = 1°C and P = 10 MPa is the time which amounts to 2.5 hours. The experimental dependences have been determined of the gas hydrates formation out of a methane-air mixture of degassing holes, on the methane concentration, on pressure and temperature parameters. It has been determined that the greater the methane concentration in the mixture, the greater must be the pressure in the system for the gas hydrates formation.

Abstract: The method and unit for experimental research of membrane formation from titanium alloys under conditions of superplastic is developed, which allows to determine necessary parameters of deformation. The unit is designed to deform titanium sheets in isothermal conditions by applying a uniform distributed load. When membrane is formed by a gas medium, a biaxial tension is realized. This type of test is used to assess the plastic properties of metals. In this work, the limiting deformations of the sheet titanium alloy OT4-0 have been evaluated in the formation of the membrane. Installed during the process of superplastic deformation the connection between the external parameters of deformation (force, temperature) with the depth of formation of the membrane in time and strain distribution along its generatrix.