Wyniki wyszukiwania - BazTech

1

Method for calculation of the carrying capacity of the bottomhole zone of a gas-bearing formation

Rizo Zakhar, Vasyliev Leonid, Vasyliev Dmytro, Avramenko Stanislav

Mining Science

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2023

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Vol. 30

135--145

EN

This paper presents a method for calculating vertical and horizontal stresses in gas-bearing coal seams based on a set of equations developed by the authors. The method describes the experimental curve of rock pressure as a convex quadratic function, with the initial value of the function equal to the normal stress at the top of the bottom hole crack. The method also considers the variation of gas pressure as the crack moves towards the interior of the formation. In addition, the method employs the relationship between active tangential stresses at points on the edges of the bottomhole crack, derived from Coulomb’s strength criteria for brittle materials. The accuracy of the method was confirmed by experimental data on the maximum shear strength of marble and brown coal at various levels of confining pressure and pore pressure. The paper also presents analytical expressions for the strength limit of the bottomhole zone of gas-bearing coal seams as a function of gas pressure gradient.

2

Granica wytrzymałości konstrukcji zmechanizowanej obudowy ścianowej na przykładzie badań numerycznych

Szurgacz Dawid, Chyrowski Piotr, Trzop Konrad

Bezpieczeństwo Pracy i Ochrona Środowiska w Górnictwie

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2023

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nr 9

2--8

EN

The process of designing a longwall powered support is extremely complex and requires many operations related to the creation of a complete machine. The powered support section is one of the basic elements of the longwall system. The implementation of the support that meets the guidelines of the manufacturer and user, requires an endurance analysis at the design stage conducted according to the regulations in force. The main objective of the research was to perform the analysis of the ultimate strength of selected elements of the designed powered support section. The research was carried out with the use of special software that uses the finite element method. The article presents the analysis of the strength limits done with the help of the finite element method, determining the strength of selected elements of the longwall support section. The solutions proposed included changes in the structure and properties of the material in the design process. The aim of the proposed solution was to obtain a model with strength value that meets safety standards. The research results are a valuable source of knowledge for designers. Solutions of this type set examples for spatial models of the longwall support section being designed nowadays. The analysis presented in the article, together with the results of the research and the conclusions resulting from them, may improve the safety and effectiveness of powered supports.

PL

W artykule przedstawiono badania, których celem jest analiza wytrzymałości granicznych konstrukcji obudowy zmechanizowanej. Przeprowadzono je z wykorzystaniem metody elementów skończonych. W oparciu o wyniki badań zaproponowano model spełniający normy bezpieczeństwa.

3

A Study of The Properties of Forming Mixtures Containing Polystyrene Wastes

Dan Olena, Trofimova Larysa

Journal of Casting & Materials Engineering

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2021

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Vol. 5, no. 2

14--19

EN

Expanded polystyrene is widely used as a material for packaging, in modern construction as a heat and sound insulation layer, in thermal insulation systems for buildings, as well as tanks and pipelines. It is additionally used in foundry engineering for the production of models which are gasified during the production of castings from ferrous and non-ferrous alloys under the contact with liquid metal. The use of expanded polystyrene products is associated with waste generation, both in production and in consumption. About 40–50 kg/person of polystyrene waste is generated per year. The peculiarity of polymeric wastes is their resistance to aggressive environments. They do not rot and the destruction processes in natural conditions proceed rather slowly, with the formation of harmful substances that poison the environment. Therefore, the problem of the processing of waste from polymeric materials is of great importance, not only from the standpoint of environmental protection, but also due to the fact that in conditions of a shortage of polymer raw materials, this waste becomes a powerful raw material resource. This article describes the prospects for recycling expanded polystyrene wastes in foundry engineering. In this work, the properties of molding and core sands containing a combined binder, consisting of a solution of expanded polystyrene wastes in turpentine and clay were investigated, and their main characteristics (weight during stretching and crumbling) were determined. Molding and core mixtures, which contain only a binder in the form of a solution of expanded polystyrene in turpentine, have a crude strength of not more than 0.01 MPa. The introduction of a mixture of clay in the amount of 2–3% allows a crude strength of the mixture of up to 0.05 MPa to be obtained. After drying, the investigated mixtures containing a solution of expanded polystyrene wastes and clay have a tensile strength of up to 2.1 MPa. Mixtures into which a solution of polystyrene wastes and clay was introduced have an insignificant gas capacity and satisfactory gas permeability.

4

Influence of effectiveness speed in mechanical properties of AW6060 T66 (PA38) alloy

Panasiuk K.

Journal of KONES

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2017

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Vol. 24, No. 4

219--226

EN

The article examines the effect of the change in the speed of deformation on the mechanical properties of AW 6060 alloy specimens, characterized by high mechanical strength, which is a material used in the shipbuilding industry. The theoretical basis for the influence of load speed on the mechanical properties of materials is presented. Static and dynamic tensile test was conducted on a universal testing machine. Dynamic stretching was performed on samples at 10–1 s–1 – 102 s–1. Done charts and tables showing results. Calculated in accordance with DIN EN ISO 6892-1 2010P total elongation and contraction of the sample. Comparison of the results of the study with the current knowledge of the subject. Material studies have shown that increasing the deformation rate results in an increase in the yield point and tensile strength. On the basis of calculations of the narrowing and elongation of the total sample, the material can be strengthened. The rate of deformation of the materials is favourable for their strengthening by increasing the limit of tensile strength. Given that most of the design is subject to dynamic loads and the aluminum alloy AW 6060 finds extensive use in shipbuilding and beyond, these are satisfactory results.