scholarly journals Determination of the parameters of typical multi-link dimensional chains (closing link is tension) using recurrent dependencies

2020 ◽  
Vol 329 ◽  
pp. 03015
Author(s):  
Sergey Shilyaev ◽  
Evgeniy Slashchev ◽  
Vladimir Osetrov ◽  
Igor Voyachek ◽  
Rinat Shaikhov
Keyword(s):  
Economic Feasibility ◽  
Dimensional Chain ◽  
Mathematical Apparatus ◽  
Work In Progress ◽  
Properties Of Materials ◽  
Complex Mechanisms ◽  
Group Interchangeability ◽  
Production Tolerance

The existing approach to the use of the group interchangeability method during assembly, which are concentrated, has a number of significant drawbacks: 1) there are no formulas for calculating the upper and lower deviations of the component parts of the dimensional chain; 2) deviations are selected without taking into account the design of the component links (the method of equal tolerances is used); 3) the method is applicable for the number of links no more than three with a small number of groups. For other types of problems there is no algorithm, mathematical apparatus, and examples of calculation are not considered sequentially; 4) the calculation by the group interchangeability method is limited by the condition of equal tolerances, i.e. excluding compensators and compensating properties of materials as a part of mechanisms; 5) the calculations are based on assumptions about the economic feasibility of increasing the closing link by a factor of n without taking into account the feasibility of such an increase in the component links that is not permissible in complex mechanisms; 6) the size of the batch of parts and the volume of work in progress are not reflected, as one of the factors of economic feasibility of establishing production tolerance. In this regard, it is necessary to improve the method of achieving accuracy by group interchangeability. This article discusses typical problems that rise when solving dimensional chains in which the closing link is a tension.

scholarly journals Rational reduction of work in progress when assembling parts of a product using the group interchangeability method

2020 ◽  
Vol 329 ◽  
pp. 03016
Author(s):  
Sergey Shilyaev ◽  
Evgeniy Slashchev ◽  
Igor Voyachek ◽  
Rinat Shaikhov
Keyword(s):  
Dimensional Chain ◽  
Rational Technology ◽  
Work In Progress ◽  
Group Assembly ◽  
Group Interchangeability ◽  
Informational Advantage

The article discusses the method for interchangeability method. To reduce the volume of work in progress, the design of a fixed combined compensator is developed, which provides stepwise regulation. The article reducing the work in progress by stepwise regulation in multilink dimension chains when assembled using the group proposes a rational technology for the use of combined compensator, taking into account the peculiarities of the group interchangeability method. In order to reduce the work in progress during assembly using the group interchangeability method, two ways of using the combined compensator have been developed: 1 - the inclusion of a compensator in each dimensional chain collected by the group interchangeability method; 2-application of the compensator only at the stage of formation of work in progress during group assembly by replacing one of the parts with it. The peculiarity of the methods is the use of the informational advantage of group assembly — information about the actual dimensions necessary for sorting parts into groups. This eliminates the step of measuring the closing link during assembly and simplifies the design of the compensator, reducing the number of control steps.

scholarly journals Inner Damping of Water in Conduit of Hydraulic Power Plant

2021 ◽  
Vol 13 (13) ◽  
pp. 7125
Author(s):  
Daniel Himr ◽  
Vladimír Habán ◽  
David Štefan
Keyword(s):  
Power Plant ◽  
Operating Conditions ◽  
Mathematical Apparatus ◽  
Pressure Pulsations ◽  
Hydraulic Power ◽  
Economic Operation ◽  
Compression And Expansion ◽  
Rotor Stator Interaction ◽  
Start Ups

The operation of any hydraulic power plant is accompanied by pressure pulsations that are caused by vortex rope under the runner, rotor–stator interaction and various transitions during changes in operating conditions or start-ups and shut-downs. Water in the conduit undergoes volumetric changes due to these pulsations. Compression and expansion of the water are among the mechanisms by which energy is dissipated in the system, and this corresponds to the second viscosity of water. The better our knowledge of energy dissipation, the greater the possibility of a safer and more economic operation of the hydraulic power plant. This paper focuses on the determination of the second viscosity of water in a conduit. The mathematical apparatus, which is described in the article, is applied to data obtained during commissioning tests in a water storage power plant. The second viscosity is determined using measurements of pressure pulsations in the conduit induced with a ball valve. The result shows a dependency of second viscosity on the frequency of pulsations.

Method of Testing of Sound Absorption Properties of Materials Intended for Ultrasonic Noise Protection

2013 ◽  
Vol 38 (2) ◽  
pp. 191-195 ◽  
Author(s):  
Dariusz Pleban
Keyword(s):  
Sound Absorption ◽  
Free Field ◽  
Tone Burst ◽  
Mineral Wool ◽  
Frequency Range ◽  
Absorption Properties ◽  
Open Cell Foam ◽  
Properties Of Materials ◽  
Cell Foam

Abstract Efficient ultrasonic noise reduction by using enclosures requires the knowledge of absorbing properties of materials in the frequency range above 4 kHz. However, standardized methods enable determination of absorption coefficients of materials in the frequency range up to 4 kHz. For this reason, it is proposed to carry out measurements of the sound absorption properties of materials in the free field by means of a tone-burst technique in the frequency range from 4 kHz to 40 kHz at angles of incidence varying from 0° to 60°. The absorption coefficient of a material is calculated from the reflection coefficient obtained by reflecting a tone-burst from both a perfectly reflecting panel and a combination of this panel and the sample of the tested material. The tests results show that mineral wool and polyurethane open-cell foam possess very good absorbing properties in this frequency range.

scholarly journals Determination of geometric accuracy and surface roughness of small parts of circular and square sections, obtained depending on the printer location in the working space using selective laser melting technology from steel grade 12KH18N10T

2019 ◽  
pp. 59-67
Author(s):  
I. V. Gorbatov ◽  
Y. A. Orlov ◽  
V. A. Antiufeev ◽  
T. V. Telgerekova ◽  
N. Y. Orlova
Keyword(s):  
Selective Laser Melting ◽  
Physical And Mechanical Properties ◽  
Steel Grade ◽  
Geometric Accuracy ◽  
Laser Melting ◽  
Working Space ◽  
Properties Of Materials ◽  
Number Of Publications ◽  
Small Parts

The introduction of additive technologies for the manufacture of parts will significantly improve the efficiency and mobility of production. The technology of selective laser melting has the greatest accuracy in the manufacture of metal and alloyed parts. There are a number of publications on the physical and mechanical properties of such products, which often exceed the properties of materials obtained by traditional technology, but there is no data on the geometric accuracy of manufacturing. This paper provides explicit data on geometric accuracy, depending on various factors.

scholarly journals DETERMINATION OF CREEP PARAMETERS IN LAYERS OF BUILDING COMPOSITES/SLUOKSNIUOTŲJŲ STATYBINIŲ KOMPOZITŲ VALKŠNUMO PARAMETRŲ NUSTATYMAS

1998 ◽  
Vol 4 (2) ◽  
pp. 101-108 ◽  
Author(s):  
Gediminas Marčiukaitis
Keyword(s):  
Force Action ◽  
Building Product ◽  
Creep Coefficient ◽  
Deformation Properties ◽  
Linear Creep ◽  
Modulus Of Deformation ◽  
Composite Product ◽  
Properties Of Materials ◽  
Creep Deformations

Various composite building products consisting of layers of different physical-mechanical properties being tied rigidly together are manufactured and used in construction. In many cases such products curve, become flaky, crack and their thermo-insulating capability suffers. It occurs because deformation properties are not adjusted, different layers of such products deform differently under the load. And the deformation effects the behaviour of the whole structure. A correct adjustment of deformations can be achieved with allowance for creep of different layers and of the whole composite. Determination of creep parameters—creep coefficient and specific creep—depends on the orientation of layers in respect of the direction of force action. When layers are situated transverselly in respect of the direction of action of forces (stresses), creep parameters of composite depend on creep parameters of materials of separate layers and on relative volumes of these layers. Creep deformations of a composite can be described by equations describing creep of individual layers. Appropriate equations and formulas ((17)-(25)) are presented for determining such deformations. When layers are parallel to the direction of stresses, redistribution of these stresses between layers takes place. Compression stresses increase in a layer with higher modulus of deformation and decrease in that with lower modules. Proposed equations (37)-(42) enable to determine redistribution of stresses between layers, the main creep parameters of composite, their modulus of deformations and creep deformations themselves when strength of a composite product is reached, E(t0)=E(t)=const and stresses produce linear creep. Such loading of a composite product is the most common in practice. Presented formulas ((46), (52)) and diagrams show that it is possible to design a composite building product or material with creep parameters given in advance by means of appropriate distribution of product layers, selecting ratios between layers and properties of materials.

scholarly journals Analysis of operating variables for Yerba mate leaves supercritical carbon dioxide extraction

2018 ◽  
Vol 24 (3) ◽  
pp. 231-238 ◽  
Author(s):  
Branislava Teofilovic ◽  
Nevena Grujic-Letic ◽  
Strahinja Kovacevic ◽  
Sanja Podunavac-Kuzmanovic ◽  
Slobodan Gadzuric
Keyword(s):  
Potassium Chloride ◽  
Current Source ◽  
Economic Feasibility ◽  
Superior Performance ◽  
Yerba Mate ◽  
Operating Variables ◽  
Carbon Dioxide Extraction ◽  
Increasing Demand ◽  
Positive Results

Given the increasing demand for potassium in Brazil, the mining and use of carnallite is becoming increasingly important, because the current source of potassium, sylvinite, is being depleted and there is a risk of shortages. Based on theoretical and practical data available in existing literature, this work describes the development, simulation, and economic feasibility of a process for dissolution and crystallization of potassium chloride from carnallite ore. Positive results were obtained following the application of the Hoffman diagram and determination of the corresponding equation. The proposed process provided over 85% potassium chloride crystallization, demonstrating its superior performance, compared to existing procedures.

Determination of rock hardness at the chrysotile - asbestos deposit

2020 ◽  
Author(s):  
P.I. Zuev ◽  
◽  
V.S. Vedernikov ◽  
D.V. Grigoriev ◽  
◽  
...  
Keyword(s):  
Economic Feasibility ◽  
Open Pit ◽  
Open Pit Mining ◽  
Chrysotile Asbestos ◽  
Calculation Methods ◽  
Rock Hardness ◽  
Technological Improvement

The article presents field and calculation methods for determining the rock hardness at the chrysotile-asbestos deposit mined by the open–pit mining. The methods presented are necessary for technological improvement of mining (including optimization of drilling and blasting operations), which, in the turn, improves the economic feasibility of the chrysotile-asbestos mining.

ASSESSMENT OF DEFORMABILITY BY EXPERIMENTAL METHODS

2019 ◽  
Vol 33 (1) ◽  
pp. 7-14
Author(s):  
Elena Pop ◽  
Keyword(s):  
Experimental Study ◽  
Physical Simulation ◽  
Copper Wire ◽  
Experimental Methods ◽  
Test Methods ◽  
Degree Of Deformation ◽  
Properties Of Materials

The paper presents a theoretical and experimental study of experimental methods for the determination of deformability. Thus we determined the degree of deformation of copper wire by testing to traction, the fragility by means of fragility testing and the elongation of the spire sample. The experimental attempts have highlighted the fact that the properties of materials are determined with the help of the experimental methods. These The indicated test methods show the deformability of the material in the process ofplastic deformation and they are representative of physical simulation attempts.

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