Applied Mechanics and Materials Vol. 756

Abstract: The processes of high-velocity interaction of a projectile with a metal-intermetallic laminate (MIL) composite target were numerically investigated in axisymmetrical geometry using the finite element method. To simulate the failure of the material under high velocity impact, we applied the active-type kinetic model determining the growth of microdamages, which continuously changes the properties of the material and induce the relaxation of stresses. To simulate the brittle-like failure of the intermetallic material under high velocity impact, we modified the kinetic model of failure and included the possibility of failure above Hugoniot elastic limit in the shock wave and sharp drop in strength characteristics if the failure begins. The results show that the depth of penetration depends on the thicknesses of intermetallic and titanium alloy layers. The Al₃Ti/Ti-6-4 MIL composite target withstands the impact loading in the case of the ratio about 4/1.

Abstract: The paper studies issues of the cross impact of tension and strip gauge at the rolling in the continuous roughing sub-train of the wide strip hot-rolling mill. Functional dependencies and chart of the mathematical model defining interrelation between the specific tension and strip gauge increment are provided. Based on the example of the 2,000 mm hot rolling mill of OJSC Magnitogorsk Iron and Steel Works (OAO MMK), it has been proved that rolling is carried out with tension values which exceed several times allowable values. The paper also considers new technical solutions enhancing the speed mode control algorithms and systems of the electric drives of the wide strip hot-rolling mill continuous subgroup.

Abstract: Generated model of the temperature pattern in the lamellate system takes into account system structure, thermo-physical parameters of the each layer material, and process factors: acting heat source duration and intensity, heat dissipation to process liquid, allowing calculating cutting modes, maximum allowed per heating temperature for each layer of the system.

Abstract: Tessellation methods are a relatively new approach for modeling the structure of a material. In this paper, such structures are interpreted as sphere packing models, where molecules and atoms represent spheres of equal or different size. Based on the review of the literature, it is shown that the tessellation approach is a powerful method for modeling and simulating such structures with desirable metric and topological properties. Two basic tessellation methods are considered more in detail: the Delaunay tessellation and the Voronoi diagram in Laguerre geometry, as well as some of their generalizations. The principal concepts of both tessellation methods are briefly explained for a better understanding of the application details. It is noted that packing models created by tessellation methods are not based on the use of the gravity camp effect, which is a difference to numerical and mathematic programming modeling approaches. Therefore, tessellation methods permit the development of structures without taking into account the gravitation, what is important for modeling the structure on the microscopic and nano levels, where the influence of the gravitation is studied insufficiently. A review of the related literature is given, focusing on the details of the tessellation method and the particle size distribution.

Abstract: We consider the control problem for two-dimensional model of the electromagnetic field which describes the scattering E-polarized electromagnetic waves in an infinite homogeneous medium containing permeable dielectric obstacle with a partially covered (for masking) boundary. The role of control function is played by surface conductivity entering the impedance boundary condition on the covered part of the boundary and the index of refraction of the dielectric obstacle. We prove the solvability of the control problem, derive the optimality system which describes the necessary conditions of an extremum and develop an efficient numerical algorithm for the solution of the control problem.

Abstract: We consider a gear with parallel rotation axes of an input and output part (spur gear), the input part having so-called arch teeth. We found the equation of the surfaces family for the arch tooth, the envelope of which is the tooth surface of the output part. We obtained an analytical solution of the equation that results from the condition of enveloping, which allowed to record parametric equations of the envelope determining the tooth surfaces of the output part.

Abstract: In article the problem of automatic distribution of spatial objects to layers is considered. The result of the distribution is multi-layered vector map. Hierarchical model of topological relations has been developed. It is the basis for implementation of objects distribution algorithms. The practical significance of the work is processing of spatial objects in navigation systems.

Abstract: Today, the LED illumination takes one of the leading positions in the segment of lighting equipment. This is due to the lighting market demanding energy-efficient and ecologically safe sources of light. The purpose of this project was to investigate the temperature conditions of Сree LEDs, depending on impressed current. The basic idea was to obtain dependencies that could be used to select the optimal operating mode for getting the most LED lamp efficiency. Calculation of thermal conditions was held with the help of a special software application SolidWorks Flow Simulation. In the course of research 5 PCBs mounted on the aluminum housing of the designed luminaire were calculated. On each board different current from 0.35A to 1.5A was impressed. LED quantity on PCBs was chosen so that the luminous flux was the same on all the boards - 5klm. After the calculations the graphs and experiments, reflecting energy efficient characteristics of the luminaire were obtained. The analysis of obtained results elucidates that the operating heat regimes at LED supply currents varying from 0.35 A to 0.7 A are most suitable for the effective work of a lamp. At currents higher than 1 A, there is a considerable drop of the light output. The calculation of LEDs thermal condition (especially, powerful) and the choice of a suitable cooling system is one of the main criteria in the design of a reliable and durable LED lighting system.

Abstract: For the model of the nonlinear elastic medium with inhomogeneous properties represented by a continuous change of the elastic moduli and density, the motion problems of a plane longitudinal or transverse shock waves are considered. The matched asymptotic expansions method allows to determine the evolution equations reflecting the nonlinearity of the wave processes and the inhomogeneity of the medium. The transition to the limiting inner problem of the small parameter method is dictated by the chain of inner problems, the solutions of which require a changes in all of the independent variables and their scales.

Abstract: The paper presents a numerical study of the interaction of a shock wave with a protective stopping. It addresses the effect of the type of setting on dangerous stresses emergences under the explosion. The types of setting are evaluated depending on the nature of the load on the sopping. Heavy concrete of B15 grade was taken as the material for evaluation.