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Investigation of Strength and Buckling of Orthotropic Conical Shells and Conical Panels

Authors: Lapina E. O., Semenov A. A.

In the construction, thin-walled shell structures are used to cover the buildings of large areas, such as stadiums, hangars, circuses, airports. In this paper, the strength and buckling of closed conical shells as well as their panels are studied. The geometric nonlinearity and transverse shifts are taken into account. A mathematical model is used in the form of a functional of the total potential energy of deformation. Also expressions for deformations, forces and moments are given. The calculation program is implemented in the MatLab environment.

Stability of Periodic Billiard Trajectories in Triangle

Authors: Kirillov A. N., Alkin R. V.

The problem of stability of periodic billiard trajectories in triangles is considered. The notion of stability means the preservation of a period and qualitative structure of a trajectory (its combinatorial type) for sufficiently small variations of a triangle. The geometric, algebraic and fan unfoldings are introduced for stable trajectories description. The new method of fan coding, using these unfoldings, is proposed. This method permits to simplify the stability analysis.

Analyticity Conditions of Characteristic and Disturbing Quasipolynomials of Hybrid Dynamical Systems

Authors: Portenko M. S., Melnichuk D. V., Andreichenko D. K.

Hybrid dynamical systems (HDS) are connected by means of the boundary conditions and the constraint’s conditions systems of ordinary differential equations and partial differential equations with the corresponding initial conditions. Check the stability of HDS can be performed on the basis of the "fast"algorithm for the application which requires analytic characteristic and disturbing quasipolynomials of HDS in the right half-plane and near the imaginary axis.

On Functional Stability of the Solution for the Problem of Convex Body Best Approximating by a Ball with Fixed Radius

Authors: Dudov S. I., Osipcev M. A.

A finite-dimensional problem of finding a uniform estimate (approximation in the Hausdorff metric) of a convex body by a fixed-radius ball in an arbitrary norm is considered. It is known that this problem can be reduced to a linear programming problem in the case, when the convex body and the norm ball are polytops. Therefore, we prove the functional stability of the optimal value of the objective function with respect to accuracy of the given convex body and accuracy of the unit ball for the norm used. The stability rating is derived.

Mathematical modelling of loss of stability of system of step and homogeneous cores at blow about the rigid barrier Tymoshenko's method

Authors: Bityurin A. A.

Mathematical modeling of longitudinal elastic central blow of system of step and homogeneous cores about a rigid barrier is carried out, at not holding communications by a solution of the wave equation by Dalamber's method. On the basis of the law of conservation of energy by Tymoshenko's method the size of critical compressing loading according to which, the size of critical pretonic speed leading to loss of stability of considered rod system further pays off. 

Mathematical modelling of critical speed of the multistage core at longitudinal blow

Authors: Bityurin A. A.

Mathematical modeling of longitudinal elastic central blow of a multistage core about a rigid barrier is carried out, at not keeping communications. Mathematical modeling is carried out by the exact analytical decision of the wave differential equation by a method of Dalamber with the task of necessary initial and boundary conditions. With application of the formula of Euler analytical expression for calculation of critical pretonic speed at which there comes loss of stability of a step core is received.