Key Engineering Materials Vol. 685

Abstract: In this paper the authors describe necessary conditions of optimality for continuous multicriteria optimization problems. It is proved that the existence of effective solutions requires that the gradients of individual criteria were linearly dependent. The set of solutions is given by system of equations. It is shown that for finding necessary and sufficient conditions for multicriteria optimization problems, it is necessary to switch to the single-criterion optimization problem with the objective function, which is the convolution of individual criteria. These results are consistent with non-linear optimization problems with equality constraints. An example can be the study of optimal solutions obtained by the method of the main criterion for Pareto optimality.

Abstract: The article describes basic approaches to conducting an efficiency assessment of a nuclear object physical protection system as well as the possibility of creation of the intruder analytical model to determine time indicators of overcoming nuclear object protection boundaries by an intruder with defined characteristics. An intruder uses different tactics and methods to overcome boundaries of protection. A multivariate analysis lays in a basis of research that taking into account psycho-physiological and physical properties of the human organism, intruder equipment level for overcoming of physical barriers.

Abstract: Analysis of contemporary cyclone gas purification apparatus was carried out in this article Calculation of the characteristics of the counterflow cyclone in application of pressurization system of the LV fuel tanks with gas pressure accumulator has been executed. 3D-model of the counter-flow cyclone was built. Numerical modeling of soot-cleaning process in countercurrent cyclone has been performed using ANSYS Fluent.

Abstract: In the nearest future, pyrolytic conversion of solid fossil fuels may become an important source of energy resources. Due to this fact, the technologies of heating of subterranean formations are created. This article describes the experience of creating the laboratory setup for the investigations of methods and modes for fuels heating in the conditions similar to the underground ones. Applied technical solutions and the results of their application are described.

Abstract: The paper gives a mathematical model of grain evolution and dislocation density during asymmetric cold rolling of aluminum alloy 7075 in an SPD mode. Correlations between the effect of equivalent and shear strain on Al 7075 structure are obtained. An agreement of simulation results with experimental data is shown.

Abstract: The paper presents the software and data transfer method between ProCAST and Deform-3D, which allow to take into account the geometry, temperature, residual stresses and microstructure of semi-finished product in the “casting – forming” processes.

Abstract: Problems of the poroviscodynamics are considered. Theory of poroviscoelasticity is based on Biot’s equations of fluid saturated porous media under assumption that the skeleton is viscoelastic. Viscoelastic effects of solid skeleton are modeled by mean of elastic-viscoelastic correspondence principle, using such viscoelastic models as a standard linear solid model and model with weakly singular kernel. The fluid is taken as original in Biot’s formulation without viscoelastic effects. Boundary integral equations method is applied to solve three-dimensional boundary-value problems. Boundary-element method with mixed discretization and matched approximation of boundary functions is used. Solution is obtained in Laplace domain, and then Durbin’s algorithm of numerical inversion of Laplace transform is applied to perform solution in time domain. An influence of viscoelastic parameters on dynamic responses is studied. Numerical example of the surface waves modelling is considered.

Abstract: The problem of a planar solidification of a material with an additional nonstationary radiant of heat on a semi-infinite plane has been solved. For a solution the condition of Stefan was used. Results have been compared with an analytical solution in case of the absence of an additional radiant of heat, as well as with a solution obtained by perturbations method. A more complicated two-dimensional nonstationary problem of a solidification of a liquid with interface free-boundary has been also solved. The purpose of this problem solution is to predict position of a material phase boundary, as well as the temperature distribution in a layer of PCM (Phase-Change Material) with boundary conditions of Dirichlet.

Abstract: During production of rolled steel strips the quality of the surface of finished strips influences steel consumption considerably. The most critical areas for crack formation during rolling are lateral sides of slabs. Deformation behaviors of the slab edge in roughing rolling process were analyzed by the finite element method with Deform-3D. In this study our focus is the analysis of the influence of edger’s form on the possibility to decrease surface cracking during roughing hot rolling.

Abstract: The paper describes the method of manufacture of profiles in cramped bending conditions using polyurethaneThe scope of studies included stress-strain state of elastic die and parent sheet, as well as the influence of the basic process parameters on characteristics of the produced items using ANSYS software.