Journal of Theoretical and Applied Mechanics
Volume 36, Number 3, 2006
G. Bontchev Str., Bl. 4,
84/32, Profsousnaya, 117811
Mathematics and Physics,
2, V. Holesovickach, 18000
Interpretation of satellite magnetosheath plasma measurements using a magnetosheath-magnetosphere numerical model
Abstract. We consider a specific implementation of a numerical
magnetosheath model, where the preliminary computation of the angle between
solar wind flow and Sun-Earth direction at the spacecraft trajectory points is
utilized for better implementation of the angular diagram of the device. The
goal is better determination of the relation between the “real” and “measured”
parameters. The parameter under consideration is ion flux, measured by VDP
instrument on board Interball-1 satellite. A new numerical three dimensional
model of the system magnetosphere – magnetosheath, lately developed in the
Key words: model, magnetosheath, magnetosphere, gas dynamic satellite.
Department of Theoretical Mechanics,
29, Komsomolskii prospect, 614000,
Department of Civil Engineering,
8/E2063, Wiedner-Hauptstrasse, A-1040,
Abstract: Many problems in continuum mechanics rely on the concept of eigenstrain. The authors proved the theorem on decomposition of eigenstrain (when imposed in an elastic body) into two parts, namely into its stress-free and deformation-free constituents. Individual determination of these constituents is crucial to keep the control of deformation and of stress by eigenstrain independent. General conditions for eigenstrain to be stress-free are derived. The generalized statement of the appropriate boundary value problem with eigenstrain is applied that becomes important for discrete and discretized systems. The relation between the criterion for such stress-free eigenstrain and Duhamel’s analogy is established.
Key words: eigenstrain decomposition, generalized solution, optimal shape control, elastic body.
Acad. G. Bontchev Str., Bl. 4, 1113
Interphase model for a multilayer structures in heat conduction problems. Non-perfect contact
Abstract. In the present paper the thermal behaviour of the interphase layer, disposed between two bodies in the case of non-perfect contact on the interfaces is analyzed by Biot’s variational principle. The main aim is to find the local partial differential equations for interphase layer for two types of distribution of the temperature - linear and quadratic. The comparisons of the temperatures in the interphase layer are done for effective thermal and elastic characteristics of a layer, composed by and . The non-perfect contact conditions for temperatures are assumed along the interfaces. The application example for elastic isotropic interphase layer with finite length is performed. One part of the interfaces allows the perfect contact condition. On the rest part of the interface length a non-perfect contact for temperatures thought Kapitza thermal resistance is assumed.
The layer is assumed elastic on the first part while on the rest part the thermal stress reaches its yield limit. The critical length of the perfect contact condition is analytically found.
The results are illustrated in figures and discussed.
Key words: heat conduction, interphases layer, FGMs, non-perfect contact, thermal stresses.
Angel S. Mladensky, Victor I. Rizov
FRACTURE BEHAVIOUR OF UNIDIRECTIONAL FIBER REINFORCED COMPOSITE MATERIALS UNDER MIXED MODE I/II/III LOADING
Abstract. In the present study a crack problem under mixed Mode I/II/III loading conditions in a rectangular composite beam is considered in the terms of the total strain energy release rate. The beam structure is made of two unidirectional composite materials. The crack is situated between them and propagates longitudinally to the beam axis. An analytical solution of the problem for determination of the strain energy release rate is obtained. For this purpose the values of the crack front internal forces are used. The solution is based on the linear elastic fracture mechanics. The correctness of the formula derived is checked by comparison with a known linear elastic beam theory solution. An extensive investigation of the influence of some material, geometrical and load parameters on the strain energy release rate is also carried-out.
Key words: fracture mechanics, strain energy release rate, unidirectional fiber reinforced composite materials, internal forces.
8, Kl. Ohridski Blvd, 1000,
Finite element modelling of semi-compensated overhead contact line system
Abstract. A finite element model of semi-compensated overhead contact line system is under consideration in this paper. Numerical results are obtained and analyzed. A university-licensed version of finite element code ANSYS is used to perform the numerical experiments. Results for the deflection of the overhead contact line and the tensile force in the catenary wire are given for some typical values of the temperature conditions. On the other hand, a laboratory model of semi-compensated overhead contact line system is investigated. The numerical and experimental data are compared with analytically obtained results for the same temperature conditions. There is a good agreement between computed results and experimental data from the laboratory model. In the cases of loaded and unloaded support droppers some advantages of the finite element modelling are established.
Key words: electric railways, semi-compensated overhead contact line system, finite element analyses, experimental investigations.
Acad. G. Bonchev Str., Bl. 4, 1113
MECHANICAL PROPERTIES OF HERNIA MESHES
structural, physical and mechanical properties of three commercially available in
Key words: hernia meshes, fascia, tensile strength, elasticity.