Applied Mechanics and Materials Vol. 756

Abstract: The mathematical model based on system of momentum and energy equations for free convection flow along a vertical surface in porous media under boundary conditions of the third sort is solved analytically using the method of matched asymptotic expansions. The region of validity for boundary layer model and expansions for stream function and temperature with parameter of perturbations were defined. The dependence of characteristic flow from governing dimensionless parameters and was analyzed numerically. The influence of viscous and convective terms of momentum equation in the proposed mathematical model significantly increases the rate of heat transfer on plate in porous media in comparison with Darsy flow model.

Abstract: It is shown that principal amplitude waveforms in the magnetic vibrations of a string can be expressed by complex (two-wave) functions. The research results can be used in the design of mechatronic systems with vibrating elements.

Abstract: The paper presents numerical solution of the problem of acoustic waves attenuation in metal barriers. We investigated separately the plates from steel, lead or copper as metal barriers. The acoustic wave attenuation was compared after passing the barrier, depending on the quantity of plates of the particular barrier and the distance between them.

Abstract: In this paper the modern methods of cable products insulation control are referred. A comparison of efficiency of the cable insulation defects control by changing in cable area capacitance is carried out in the strong and weak electric fields. The electric cable can be represented as a cylindrical capacitor, but to simplify the issue the insulation area is represented as a plate capacitor with anisotropic dielectric. The cable insulation model is created in the software Comsol Multyphysic. The effect of the defect dimension on the cable area electric capacitance in a strong and weak electric field is described. Also, the control sensitivity of both methods was assessed and compared with each other. The control sensitivity in a weak electric field is slightly higher for the defects with small size (less than 70% from insulation thickness). The control sensitivity in a strong electric field is considerably higher for the defects with big size (more than 70% from insulation thickness).

Abstract: The article presents the results of a numerical study of the compression wave attenuation (CW) in water barriers. The impact of barriers thickness, their quantity and concentration of water particles in the barrier have been analyzed in the process of CW attenuation.

Abstract: The present study provides structural synthesis, designing of 3D models and kinematic analysis of the developed spatial one-and two-movable mechanisms with imposed constraints. These mechanisms have an opportunity of technological application as mechanisms for cutting the complex internal surfaces of machine elements. The mechanisms produce a special kind of screw motion which is the most suitable means for cutting of complex spatial surfaces. Structural synthesis was based on mathematical solution of universal structural system where numbers of kinematic pairs and movable links were calculated. 3D-modelling analysis allowed to identify motion paths of their output links with machining tools. This investigation results gave an opportunity to analyze the tools motion, optimize their constructions and use of relevant parameters, and design their motions to obtain specified surfaces of machine elements.

Abstract: In this article, the proposed approaches to continuous process simulation via E-network are considered in order to construct analytical and simulation models using unified methodology. Principals of continuous process simulation via E-networks using Block Function Diagram programming technology are presented. The construction of continuous process dynamic models is based on the state space method and is implemented using E-network algorithmic simulation scheme.

Abstract: The article deals with the problem of calculating the fault tolerance of neural network components of industrial controlling and measuring systems used in mechanical engineering. We have formulated a general approach to developing methods for quantitative determination of the level of the fault tolerance of artificial neural networks with any structure and function. We have studied the fault tolerance of four artificial feedforward neural networks as well as the correlation between the result of determining the fault tolerance level and a selected performance parameter of artificial neural networks.

Abstract: Processes of high-speed orthogonal cutting of metal workpieces are numerically investigated with modified finite element method in the framework of the elastic-plastic model in the range of cutting speeds 1-200 m/s. To simulate the failure of the material under high-velocity impact, we applied an active-type kinetic model determining the growth of microdamages, which continuously changes the properties of the material and induce the relaxation of stresses. The threshold value of specific energy of shear deformations is used as a criterion of chip separation. Necessity of using an additional criterion of chip formation is revealed, the threshold value of specific volume of microdamages is offered as the additional criterion.

Abstract: The Ritz method is used for the buckling analysis of stiffened plates under compressive load. Suggested approximations of displacements allow taking into account the features of system wave formation. The results are compared with data, received by finite element method.