Papers by Keyword: Computer Simulation

Abstract: The modes of hot and cold rolling of plates from an alloy of the Al-Mg system alloy, doped with scandium in the range of 0.10-0.12%, are modeled. At the first stage of work, using the DEFORM-3D software package, we simulated the process of hot sheet rolling at the Quarto 2800 mill, in order to obtain a billet for further cold rolling. Analysis of the simulation data showed that with the adopted compression mode, the metal forming and temperature conditions of rolling make it possible to obtain plates up to 45 mm thick, without defects, with rational power loading of the equipment. Further modeling of the regime of cold rolling of plates with a thickness of up to 31.5 mm showed that cold rolling can be carried out in 4 passes, provided that the stress and rolling force do not exceed the permissible values. At the second stage of work, we conducted an experimental verification of the obtained simulation results both in industrial and in laboratory conditions. It was found that the value of the total compression leading to the destruction of the samples, depending on the rolling conditions, should not exceed 21-30%. At this degree of deformation, the rolled metal from the alloy under study has high strength and plastic properties. Subsequent industrial verification of the research results confirmed that this alloy is quite advanced technologically, while it has high deformability, both during hot and cold rolling, which allows us to recommend it for sheet deformed semi-finished products in the manufacture of structural products for various purposes.

Abstract: Computer simulation of the α/γ phase transformation in multipass weld of duplex stainless steel was made for predicting the distribution of the γ phase fraction in the weld metal (WM) and HAZ. The kinetic equations including rate constants of the dissolution behaviour as well as precipitation behaviour of γ phase were determined by isothermal heat treatment test. Based on the kinetic equations determined, the distribution of the γ phase fraction in multipass weld of duplex stainless steel was calculated applying the incremental method combined with the heat conduction analysis in welding process. The γ phase fraction was reduced in the higher temperature HAZ and WM, however, that in the reheated HAZ and WM was increased and recovered to the base metal level. Microstructural analysis revealed that the calculated results of the γ phase fraction in multipass weld were consistent with experimental ones. Based on the computer prediction, the microstructural improvement welding (“reheat bead welding”) process, with analogous concept to the temper bead welding technique, was newly proposed for recovering the γ phase fraction in weld even in the as-welded situation.

Abstract: The computer simulation method was used to examine condensation of 90124 Cu and Au atoms from the gas phase. To analyze the synthesis processes, there were selected chemical compositions Cu₃Au, Cu-Au, Cu₉₀Au₁₀ and Cu₆₀Au₄₀ being cooled with liquid nitrogen during the condensation. The undertaken simulation showed that the increase in the percentage of gold atoms in the initial couple decreases the number of clusters of a relatively large size. Moreover, the analysis of the external view and the structure of Cu-Au nanoparticles of various chemical composition allowed us to conclude that a large number of binary nanoparticles were of an icosahedral structure.

Abstract: The paper studies applicability of individual particles of Ag-Cu nanoalloys as data bits in the next generation memory devices constructed on the phase change memory principle. To fulfill this task, the structure formation was simulated with the molecular dynamics method on cooling from the melt of Ag-Cu nanoparticles of the diameter of 2.0 – 8.0 nm of different chemical compositions (with copper content in the alloy from 10 to 50 percent), based on the modified tight-binding potential (TB-SMA). The authors investigated the influence of the size effects and the heat removal rate on the formation of the clusters structure. The investigation showed that different internal structures can be developed upon cooling from the liquid phase, so there were determined some criteria of their stability. Clusters with copper content of not more than 10% and diameters of more than 6.0 nm were isolated from the entire set of the considered particles.

Abstract: The current work deals the phenomenon of non-metallic inclusions as a result of the addition of Yttrium as an alloying component. The order of introducing individual components determines its final content in steel. This problem was analyzed using the WYK_Stal program developed at AGH-UST. Individual cases were considered using the accepted thermodynamics models based on Wagner’s formalism. The study of Y₂O3 and Y₂S₃ phase precipitation and the relationship between the addition of Y, Al, Ca, O and S in molten steel was studied using the thermodynamic models. Based on the simulation, the authors stated that, the introduction of aluminum as the final deoxidizer into the liquid steel before the yttrium, results in the formation of non-metallic oxide inclusions. The low oxygen content in the metal bath promotes the formation of yttrium sulphide. In the case of calcium dosing, it is reasonable that, the yttrium is introduced after this element, which limits the losses on the formation of the yttrium sulphide phase.

Abstract: In Thailand, the sheet metal products that were produced by rolling process have high demand and the consumption trend to grow in the future. Many new products, which made from rolling steel sheet, had been developed with various design. Thus the manufacturers have to improve the productivity through the investigation and analysis of different process parameters, which affect to the quality during the production. In this paper, finite volume method FVM had been applied to analyze different effects of processes parameters such as temperature, roller speed, friction, size and capacity of rolling machine. The commercial software MSC.SuperForge was used in the modeling and simulation of metal deformation under the flat rolling process. Considering the predicted results compared with the experimental data, the different in dimension error data were within an acceptable range of quality specification. The error in width of finished steel sheet was 1.17%, the length was error of 1.50%, and the thickness was error of 2.32%. By using this technique, different factors affected during rolling process can be investigated and controlled such as the metal flow, the distribution of stress and strain, and the deformation zone.

Abstract: The current high-geared developments within the automotive sector have triggered a series of performance, comfort, safety and design-related issues. Hence, oftentimes manufacturers are challenged to combine various elements so as to achieve an attractive design, without diminishing the vehicle’s dynamic performance. Under the circumstances, the shape of the vehicle body becomes the key element that connects the design component with the performance requirement, since it directly influences the value of the resistance forces, and, respectively the air resistance. Aerodynamics is the branch of mechanical engineering that deals with the movement of gases (especially the air) and their effects on fluids. As far as the automotive sector is concerned, aerodynamics focuses mainly on the flow of the air currents over the vehicle body. When designing vehicle, the positive or negative displacement of the airflow is studied in aerodynamic tunnels. It is preferable for the negative displacement to push the vehicle as close to the ground as possible. In what follows we set out to study the influence of the drag coefficient and, implicitly, of the air resistance on vehicle performance. Hence, we will carry out comparative analysis of two vehicles with similar technical characteristics, but with different bodies, i.e. a hatchback and a sedan. The results obtained are then compared both by means of the analytical determination of the air resistance and via a simulation performed within the Virtual Crash software platform. The results recorded show that of the two vehicles, with the considered aerodynamic coefficients, hatchback type vehicle displays lower values in terms of air resistance.

Abstract: This paper deals with the geometric and kinematic analysis of the circular-arc profile cams with one connection arc. If the maximum lift of the follower is required, it is shown that it is possible to connect two circular-arcs – that are defined by center of curvature and radius – through a single circular-arc, and the connection points result. But, if the connection points of two given circular-arcs of the cam profile are required, at least two circular-arcs are needed to connect them. The specific equations for the geometric analysis for one circular-arc profile are described. Also, for two mechanisms, one with straight-line profile and another with one circular-arc connection profile, the geometric and kinematic analysis and simulations of the movements using SolidWorks and ADAMS programs are presented

Abstract: In this paper the task of the study of the deformation during helical piercing of the metal was set and solved with the use of the DEFORM-3D software. Methodology, that allows to calculate the length of helix lead along the deformation zone, as well as determine for each lead absolute and relative reduction, the width of the contact area and the metal strain refinement indicator was developed. Based on the developed methodology application the following variation regularities were established: helix lead length (l_i), quotient reduction (Δr/r₀), ratio of the billet radius to the width of the contact area (r₀/b), as well as the length of the billet contact surface (l₀) with the roll in dependence of the feed angle (β), the roll number of revolutions (N) and the plug nose advancement over the gorge (C_g).

Abstract: The paper presents the results of a computer simulation of the drawing process in the step-wedge dies of two configurations: with wedge-shaped protrusions in the first and second sections of the top and bottom dies, and with a wedge-shaped protrusion in the first and second sections of the top die and wedge-shaped cavity in the first and second sections of the bottom die. A comparative analysis of the stress-strain state and energy-power parameters is carried out. Based on the analysis conclusions about the feasibility of choosing a specific configuration of step-wedge dies depending on the set aim were made.