Determination of the residual stresses in the welded joints of glass structures

We propose a computational model for determining the residual stresses in a welded glass structure taking account of the properties of the formation of residual stresses in glass. The problem is solved in displacements using Galerkin's method in conjunction with a finite-element model. A numerical solution is obtained for the axisymmetric case. Translated fromMatematichni Metodi ta Fiziko-mekhanichni Polya, Vol. 39, No. 1, 1996, pp. 131–134.     

Computation of thermal residual stresses in optic fibers

We propose an analytic method of determining all the components of the residual stress tensor in optic fibers. The method is based on solving a plane problem for a cylindrical structure with singular stresses. We obtain closed-form solutions of the problem in the case of a piecewise-constant distribution of free deformations that model the presence of inclusions in the fiber with different values of the thermal coefficient of expansion. We also consider inclusions with cross sections in the shape of a circle, a central ellipse and a central annular sector. We describe the results obtained on this basis in the computation of residual thermal stresses.Translated fromMatematicheskie Metody i Fiziko-Mekhanicheskie Polya, Issue 34, 1991, pp. 79–83.     

Diagnostics of residual stresses and estimation of their influence on the static strength of welded joints of pipes with different thicknesses with crack-type defects

Within the framework of the calculation-experimental method suggested by Pidstryhach and his followers, a athematical model for definition of residual stresses in the zone of circular welded joints of pipes with different thicknesses is developed. We constructed a functional to determine the residual thermoplastic strains on the basis of theoretical relations and experimental data obtained by a nondestructive (semidestructive) methods. Using the two-parametric criterion R6 of fracture mechanics and a failure assessment diagram constructed on its basis, the strength reserve coefficients of a welded joint of the main pipeline with different thicknesses under internal pressure and the presence of a surface crack in the thinner pipe wall are determined. The influence of residual stresses on the strength reserve coefficients is estimated.     

A nondestructive numerical-experimental method of determining the residual stresses in welded shells of revolution

We propose a numerical-experimental method of determining the residual stresses in welded shells of revolution. We solve the inverse conditionally correct problem of recovering the complete picture of the residual stress state from part of the experimental values obtained by the method of photoelasticity. We apply the numerical spline-collocation method. Translated fromMatematichni Metodi ta Fiziko-mekhanichni Polya, Vol. 39, No. 1, 1996, pp. 149–151.     

The inverse conditionally correct problem of determining the residual stresses in compound welded shells of revoltuion

We solve the inverse conditionally correct problem of recovering the complete picture of the residual stressed state for a compound shell welded from two parts, one cylindrical and the othe conical. We apply the partial values of the stresses obtained experimentally by the method of photoelasticity. We also apply the numerical method of spline-collocations. Translated fromMatematichni Metodi i Fiziko-mekhanichni Polya, Vol. 40, No. 1, 1997, pp. 130–134.     

Analytic investigation of features of stresses in plane nonstationary contact problems with moving boundaries

We propose a technique for the analytic investigation of features of contact stresses in the vicinity of the nonstationary moving boundary of a contact region in plane nonstationary contact problems with moving boundaries, which is based on the reduction of a boundary two-dimensional singular integral equation resolving the problem to a system of two one-dimensional singular equations. As tools of research, a method for the reduction of singular integral equations to an equivalent Riemann type problem for piecewise analytic functions and a technique of fractional integro-differentiation are used. It is shown that, on the moving boundary of the contact region, a power singularity, the order of which depends on the velocity of the boundary, takes place.     

Results of an experimental investigation of the residual stresses in wound glass-reinforced plastics

The results of an experimental investigation of the residual stresses in wound glass-reinforced plastic rings are presented. The residual stresses were determined by the Davidenkov method. The dependence of the maximum tensile and compressive circumferential stresses on ring thickness and polymerization temperature is investigated. The experimental data are compared with the results of calculations based on the theory proposed in [1, 2].Moscow Power Engineering Institute. Translated from Mekhanika Polimerov, No. 6, pp. 1116–1119, November–December, 1970.     

Experimental study of the effect of technological parameters on the residual stresses in thin-walled coiled parts

The effect of the parameters of heat treatment and programmed winding under tension on the residual stresses in thin-walled coiled parts made from glass plastic by the "dry" winding of a heated glass strip on an unheated mandrel is studied experimentally. The effect of the thickness of the parts on the maximum radial residual stresses is considered. A method is proposed for regulating the residual stresses in parts with very thick walls.Translated from Mekhanika Polimerov, No. 1, pp. 75–80, January–February, 1972.     

Numerical investigation of thermal characteristics of spray cooling with minimum quantity lubrication in milling process

This study explores the cooling performance associated with spray cooling with minimum quantity lubrication (MQL) in milling of Ti6Al4V using tungsten carbide (WC) cutting tool. Vegetable oil is used as a cutting fluid, and it impacts the cutting zone. A numerical model using sliding mesh and discrete phase model (DPM) is developed to calculate the flow field and the temperature distributions in both WC and Ti6Al4V subjected to conjugated heat transfer. The effect of spray angle relative to the feed direction on cooling performance is examined by analyzing the flow field and droplet behavior when nozzle is oriented to the tool or tool flute. The result shows that the temperature of both WC and Ti6Al4V for 0 and 90° of spray angle is lower than that for 45° of spray angle. However, 90° of spray angle is not suitable for lubrication purpose in milling process since MQL droplets hardly penetrate into the cutting zone.     

Numerical and experimental investigation of thermal convection in an inclined narrow gap

The knowledge of the fluid behaviour in inclined cavities is of fundamental importance as far as heat and mass transfer are concerned. The interest in this subject is particularly increasing due to the rapid process in micro technologies. We therefore studied the flow- and temperature field of such flows numerically as well as experimentally using CFD and PIV/T, respectively. We present and discuss the numerical and experimental results of our investigations and explain the applied techniques. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Analysis of contact stresses in structural joints of composite shell with steel banding

Based on the generalized Timoshenko-type shell theory, a numerical-analytical procedure for determining contact stresses from the interaction between a cylindrical composite shell and rigid bandings is proposed. Specific cases of loading and contact interaction (ideal contact through an adhesive interlayer) are considered. The contact problems are reduced to the solution of a Fredholm integral equation of the second-kind. A calculation analysis is performed. Translated from Mekhanika Kompozitnykh Materialov, Vol. 35, No. 1, pp. 109–120, January–February, 2000.     

Method of calculating the macroscopic shrinkage stresses in cylindrical glass-reinforced plastic shells with allowance for certain technological factors

The effect of certain technological factors, in particular, the thermophysical characteristics of the mandrel material, the degree of anisotropy of the fabricated article, and the inelastic properties of the matrix, on the magnitude and distribution of the macroscopic shrinkage stresses is examined in the case of cylindrical glass-reinforced plastic (GRP) shells.     

Revised analysis of the thermal stresses in a shallow spherical shell with a foreign inclusion

We carry out a revised analysis of the concentration of thermal stresses in a shallow spherical shell with a small foreign inclusion. We show that near the interface of the materials the stressed state has a sharply expressed three-dimensional character; thus the stresses differ significantly (both qualitatively and quantitatively) from the shells predicted by the standard theories. Translated fromMatematichni Metody i Fiziko-Mekhanichni Polya, Vol. 38, 1995.     

Numerical analysis of stresses and strains in flexible cylindrical shells with variable rigidity in two directions

The paper analyzes the stress-strain state in a cylindrical shell with variable rigidity in two directions. The shell is analyzed in a geometrically nonlinear framework under different loads and boundary conditions. The proposed approach reduces the nonlinear system of partial differential equations to a sequence of linear systems of ordinary differential equations. The latter are solved by discrete orthogonalization.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 57, pp. 62–67, 1985.     

Numerical simulation of the distribution of charge carrier in nanosized semiconductor heterostructures with account for polarization effects

A three-level scheme for modeling nanosized semiconductor heterostructures with account for spontaneous and piezoelectric polarization effects is presented. The scheme combines quantummechanical calculations at the atomic level for obtaining the charge density on heterointerfaces, calculation of the distribution of carriers in the heterostructure based on the solution to the Schrödinger and Poisson equations, and the calculation of electron mobility in the two-dimensional electron gas with account for various scattering mechanisms. To speed up the computations of electron density in the heterostructure, the approach based on the approximation of the nonlinear dependence of the electron density on the potential in combination with the linearization of the Poisson equation is used. The efficiency of this approach in problems of the class in question is demonstrated.