Papers by Keyword: Computer Modelling

Abstract: The paper presents the results of the computer modelling of the stressed state and relative density when burnishing a porous hollow cylinder, made from copper sintered powder material. The mathematical model, based on the theory of porous bodies’ plasticity, is used for the analysis. The paper researches the impact of the initial porosity of the material on the effective stresses distribution, relative density and force change when free burnishing of hollow cylinders. It is ascertained that with the decrease of the initial porosity of the sintered material there is the increase of the burnishing force, stresses rate and relative density on the inner sur-face of a hollow cylinder. For porous materials at a certain stage of burnishing, the deformation zone is transformed into the compaction zone with a high relative density which de-creases while moving away from the inner surface of hollow cylinders. The maximum value of the relative density is implemented directly on the inner surface of hollow cylinders; along with this the density value is evenly distributed on the inner wall.

Abstract: When selecting the compositions and studying the properties of the activated mineral powders based on superacid fly ash, mineral and organic activating agents, the computer modelling was performed. The activated mineral powders compositions corresponding to the properties of GOST 32761 2014 requirements to the MP-1 activated mineral powders of carbonate rocks were selected using the experiment mathematical planning method. When processing the experimental data for obtaining the adequate mathematical model, optimizing the compositions and constructing the graphical dependencies, the Maple package was used. The software for the personal computer including the algorithm and se-lection program of the activated mineral powders compositions was developed. The software makes it possible to automate the calculation of the activated mineral powders formulas with the specified technical properties.

Abstract: In the sintering of ceramics, cracks are inevitably encountered after sintering. But very few studies have been presented in the literature for qualifying and quantifying effects of inhomogeneity on sintering kinetics. Therefore, a series of detailed sintering variables such as grain size, surface tension and diffusivity are chosen to study the effects of their inhomogeneity on sintering kinetics through a computational model calculated by computer.Furthermore, there are two main achievements in this computational model that first one is providing a numerical solution for the curvature at triple junction (pore tip) of microscopic particles, and second one is considering the effect of surface diffusion on first-stage sintering where diffusion mechanism is coupled by grain-boundary and surface diffusion.

Abstract: The rising demand for high quality castings necessitates that vast amount of manufacturing knowledge be incorporated in manufacturing system like computer aided design and manufacturing. Rotary furnace fabrication involves several critical parameters like, capacity of furnace, flame length, length of furnace due to the available installation space and determination of type and thickness of materials needed. A complex relationship exists between these fabrication parameters and hence there is a need to develop models which can capture this complex interrelationship and enable fast computation. In this project a computer model is designed and run, taking a 5kg rotary furnace calculated parameters as prototype to facilitate the production of a rotary furnace, using Microsoft visual basic language embedded with the necessary and required design and analysis formulae needed to fabricate different sizes of rotary furnaces.

Abstract: The computer model that allows predicting the temperature distribution during local ion nitriding with hollow cathode effect (HCE) and depth of the diffusion zone after the treatment was developed. The influence of the HCE on the temperature distribution for the gear was studied. Investigation results of the hollow cathode effect influence on the hardened layer depth for a sample of 38KhMYuA steel are presented.

Abstract: LNG (Liquefied Natural Gas) submerged combustion vaporiser is applied to convert Liquefied natural gas to gas phase natural gas through using the hot combustion gas generated from submerged combustion. This paper investigated the vaporisation and heat transfer process of a single horizontal tube, a simplified model, to simulate the heat transfer of circular tube heat exchanger used in LNG submerged combustion vaporiser. This work provides a useful computer model for the design of heat exchanger used in LNG submerged combustion vaporiser. The overall heat transfer and vaporisation process of the tube was separated into single-phase liquid, two-phase mixture and single-phase vapour heat transfer regions for calculation and analysis. Through development of a dedicated computer model, a parametric study was carried out to analyse the effects of geometrical size and operating conditions on inner surface convective heat transfer of tube. The results of study suggested that the preferable tube surface temperature for design was found between 280 K and 288 K in order to avoid frost deposition. The minimum tube length required for the overall vaporisation is predicted to be about 16 m when the inner tube diameter set between 0.24 m and 0.28 m.

Abstract: The paper deals with problems of computer modelling of heat treatment processes. The effect of the choice of the coefficient of heat transfer between the coolant and components was quantified. The oil Isorapid HM 277 was chosen as the coolant. Two cases of application of the convective boundary condition were studied through numerical experiment. In the first of the cases, a real functional dependence of the heat transfer coefficient (HTC) was applied on the surface temperature. In the second case, it was used constant and temperature independent values of HTC on the surface temperature. Cooling curves were obtained through numerical experiment. Derived variables such as cooling rate, the density of the thermal flows are shown in the paper. Code ANSYS was used as interpretative tool of the numerical experiment.

Abstract: A new model of strain induced precipitation in niobium microalloyed austenite is proposed. This is based on the experimental observation of formation of microbands during hot deformation of iron – 30% nickel, which remains austenitic to room temperature. Precipitates are preferentially nucleated on nodes in the dislocation network in the microbands. This geometry enables features of earlier models to be simply explained, and facilitates extension of the model to multipass deformation. It is shown that the model captures all the essential features of previous experimental observations on microalloyed C – Mn steels. Currently, sensitivity analysis of the model and systematic experimental work are being undertaken to quantitatively validate the model.