Solid State Phenomena Vol. 243

Abstract: This work is devoted to experimental-theoretical analysis of mechanical properties of sandwich panels made of fibrous polymer composite materials. The structures with tubular core were considered. Numerical simulations of the mechanical behaviour and tensile testing of full-scale samples of sandwich panels were done. The analysis of influence of perforation on mechanical properties of fiberglass laminates and sandwich panels was alsoperformed.

Abstract: New approach to construction curve of salt rock’s long-term strength based on the diagram’s analysis of the earth surface subsidence growth under the influence of underground mining has been proposed. Performed verification of received estimation showed acceptable fit of mathematical modeling results of interchamber pillars’ deformation and fracture processes with in-situ data.

Abstract: Approaches to mathematical modeling of waterproof strata stress-strain state modification under the influence of large-scale mining have been considered. The level of anthropogenic impact on waterproof strata (WPS) was controlled by realized parameters of movement trough. Mechanism of forming tensile and shearing cracks in waterproof strata has been determined. Retrospective numerical analysis of the reasons for WPS discontinuity at abnormal flood of the First Bereznikovsky potassium mine has been done.

Abstract: This paper’s purpose is analyzing a problem of optimal control of vitrifying polymers cooling process. A solution methodology is suggested targeting at decreasing technological residual stresses, which predetermine major operating characteristics of polymer structures. The criteria function to be minimized is maximum intensity of technological residual stresses under minimum cooling process time. To determine technological residual stresses, a problem of thermoviscoelasticity is solved in finite-elemental formulation. The chosen mathematical model of mechanical behavior of viscoelastic bodies under thermorelaxation transition allows to formulate and to solve the problem of cooling process optimal control. Obtained results show that application of optimal control methods to vitrifying polymers cooling process lead to tenfold decrease of technological residual stresses when compared to an uncontrolled process.

Abstract: The results of experiments related to torsion of uniform cylindrical specimen at the fixed length between the specimens ends are presented in this paper. Axial stress has been found, initially stretching and then compressing the sample which has an oscillatory component with the period of one turn. Reasons of this nonlinear effect that are not described in the references are discussed here.

Abstract: The paper presents an experimental and theoretical approach to the modeling of non-stationary thermal processes in the elements of MHD-devices. The theoretical part of the approach is based on a mathematical formulation of the non-stationary heat conduction problem and its numerical implementation by the finite-element method. The experimental part involves a series of preliminary and verification tests. A comparison of the results obtained in these experiments with the calculated data allowed us to specify heat conduction coefficients and to pick up space-time parameters of the algorithm to ensure a high degree of adequacy of mathematical description of thermal fields. The approach made it possible to set the process conditions under which the necessary level of preliminary heating of a conduit of the MHD-pump can be achieved without loss of its mechanical strength.

Abstract: This work is devoted to the development of a constitutive model for the simulation of dissipated and stored energy evolutions under irreversible (plastic) deformation of metals. The efficiency of the model was demonstrated by the calculation of the energy balance in 304(L) austenitic steel under quasistatic deformation. The results of the numerical simulation are in a good agreement with the experimental data. The additional theoretical result of the study has established (based on the numerical and experimental data) a correlation between energy storage rate and rate of strain hardening.

Abstract: This paper presents the results of numerical solution of the 3D spectral problem on natural vibrations of two parallel identical rectangular plates interacting with a quiescent fluid confined between them. Based on the developed finite element algorithm several examples have been considered to analyze the influence of the fluid height and boundary conditions on the natural frequencies and vibration modes.

Abstract: The work deal with numerical modeling of the air cooling of cylindrical billet. The solution is carried out taking into account the dynamics of environmental air, radiation heat transfer, turbulence of the flow and conjugate heat transfer. The modeling process was realized in the accordance with a scheme of manufacturing of alloys with the structure of lower carbide-free bainite. A mathematical model has been developed by means of the finite-volume software Ansys CFX. The most effective mechanisms to control the cooling speed of the billet have been identified during numerical experiments.