Analysis of the thermoelastoplastic nonaxisymmetric stress-strain state of laminated circular cylindrical shells

A technique for analysis of the nonaxisymmetric thermoelastoplastic stress-strain state of laminated circular cylindrical shells is developed. It is assumed that the layers in a laminated package do not slip and separate relative to each other. The problem is solved using the geometrically linear theory of shells that is based on the Kirchhoff-Love hypotheses. The equations of thermoplasticity are written in the form of the method of additional strains. The order of the obtained system of partial differential equations is reduced with the help of trigonometric series in the cyclic coordinate. The systems of ordinary differential equations thus obtained are solved by Godunov's method of discrete orthogonalization. As an example, the nonaxisymmetric thermoelastoplastic stress-strain state of a two-layer cylindrical shell is considered. S. P. Timoshenko Institute of Mechanics, National Academy of Sciences of Ukraine, Kiev. Translated from Prikladnaya Mekhanika, Vol. 36, No. 2, pp. 105–110, February, 2000.     

Nonaxisymmetric Thermoviscoelastoplastic Deformation of Shells of Revolution

An analysis is made of the basic results obtained at the S. P. Timoshenko Institute of Mechanics of the National Academy of Sciences of Ukraine in developing a theory and methods for thermoviscoelastic stress—strain analysis of flexible laminated shells of revolution with a thickness variable in two directions under nonaxisymmetric nonisothermal deformation along rectilinear and slightly curved paths, with the loading history taken into account     

Application of the Newton Method for Calculating the Axisymmetric Thermoelastoplastic State of Flexible Laminar Branched Shells Using the Shear Model

A method for calculating the thermoelastoplastic geometrically nonlinear state of branched laminar shells is elaborated. The method is based on the shear kinematic model for the whole package of layers and on the theory of simple loading processes. The linearization of geometrically nonlinear equations is realized using the Newton method.     

Determination of the axisymmetric geometrically nonlinear thermoviscoelastoplastic stress-strain state of shells of revolution

A method is developed for determining the axisymmetric thermoviscoelastoplastic stress-strain state of shells subjected to bending and torsion. The problem is solved in a geometrically nonlinear formulation with allowance for transverse shear. The geometrically nonlinear deformation of an annular plate, the thermoviscoelastoplastic deformation of a cylindrical shell, and the limiting state of a corrugated shell are studied as examples. S. P. Timoshenko Institute of Mechanics, National Academy of Sciences of Ukraine, Kiev. Translated from Prikladnaya Mekhanika, Vol. 35, No. 12, pp. 40–48, December, 1999.     

Isothermal Crystallisation of PCL Studied by Temperature Modulated Dynamic Mechanical and TMDSC Analysis

Temperature modulated dynamic mechanical analysis (TMDMA) was performed in the same way as temperature modulated DSC (TMDSC) measurements. As in TMDSC TMDMA allows the investigation of reversible and non-reversible phenomena during crystallisation of polymers. The advantage of TMDMA compared to TMDSC is the high sensitivity for small and slow changes in crystallinity, e.g. during re-crystallisation. The combination of TMDMA and TMDSC yields new information about local processes at the surface of polymer crystallites. It is shown that during and after isothermal crystallisation the surface of the individual crystallites is in equilibrium with the surrounding melt. This revised version was published online in August 2006 with corrections to the Cover Date.     

Applicability of different approaches to the determination of the axisymmetric stress-strain state of cylindrical shells reinforced by annular ribs

Institute of Mechanics, Ukrainian Academy of Sciences, Kiev. Translated from Prikladnaya Mekhanika, Vol. 26, No. 10, pp. 50–55, October, 1990.     

Determination of the thermoelastoplastic stress-strain state of cylindrical tubes with corrugated inserts

Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Prikladnaya Mekhanika, Vol. 27, No. 8, pp. 59–68, August, 1991.     

Highly nonlinear fundamental mechanisms of excitation and coloring of wide-gap crystals by intense femtosecond laser pulses

Analysis of the spatial distribution of the color centers formed in wide-gap LiF and MgF₂ crystals in a laser beam channel has shown that these centers are formed in numerous longitudinal filaments into which a laser beam splits when propagating in a medium. The luminescence of the produced color centers is photoluminescence, which is excited by the supercontinuum radiation in the filaments.