Dynamics of a cylindrical shell with a locally damaged protective coating

An approximate solution of a problem on the dynamic behavior of a thin elastic circular cylindrical shell with the damaged heat-protective layer section is presented. The influence of the fracture zone size and its mass on the frequencies of shell natural vibrations and its dynamic deflections is analyzed.     

Analysis of stress state in a root-airfoil transition zone of hollow wide chord fan blades

In this paper, under consideration is the complex approach to analyzing the operation of a simulator for the hollow blade made from the VT6 titanium alloy. The stress state parameters in the hollow-monolithic part transition zone of the cantilevered simulator at bending under the distributed load are determined.     

Antenna systems of radio equipment for advanced UAVs: Problems and lines of development

The paper deals with the problem of creating airborne antenna systems for advanced unmanned aerial vehicles (UAVs). The ways of solving the basic problems, based on a combination of empirical approaches, electrodynamic simulation, and experimental results are proposed.     

Experimental study of pressure fields in a multilobe journal bearing

An experimental pressure field in operating clearance and flowrate parameters analysis for different eccentricities, inlet oil pressures, and journal rotating velocities are presented for a radial multilobe journal bearing. Lubricating film breakdown zones in bearing oil ducts caused by complicated construction and journal rotation are observed.     

Formation of required transfer zero location in the multiconnected dynamic system

A method for providing the required location of a transfer zero set in the linear multiconnected dynamic system with an equal number of inputs and outputs is considered.     

Experimental study of strain for plates discretely connected to a cylindrical shell

We present the results of an experimental study of deflections for the loaded plates that are discretely connected to a circular cylindrical shell along the generatrix lines. The influence of structure element connection elasticity on these deflections has been examined. The unique experimental setup and three specimens being tested are described. Satisfactory agreement is shown between the experimental results and the calculation data obtained by the simplified mechanical model of a plane problem.     

Control of spacecraft turns in scheduled time using rocket engines

We obtained an on-off control law for two spacecraft (SC) rocket engines creating the angular acceleration in the opposite directions considering that SC is controlled by the rocket engines with an exponential increase of thrust at starting and decrease at shutdown. This control law provides the change-over of SC from the initial angular position to the final one in the scheduled time. A special trajectory consisting of eight typical segments is proposed to identify the angular acceleration and delay of its formation in the rocket engines. Both problems are solved by the method of analytical construction of composite trajectories for the angular turn from the typical segments on which the differential equations of angular motion have analytical solutions. The results are applicable for the development of promising space interceptors and design of onboard control systems.     

Divergence of a plate discretely supported by the stringer system

An approximate solution of the divergence problem, that is, of the static instability of a plate discretely supported by a system of stiffening ribs (stringers) in the gas flow. The critical velocity of divergence is determined in one-term approximation and the influence of stringers on it is analyzed.     

Construction of an airfoil with an irregularity in the flow

Using the method of quasisolutions for inverse boundary-value problems of aerohydrodynamics, a problem of constructing an airfoil was solved by the specified velocity distribution along the sought airfoil contour when there is an irregularity in the flow such as a vorticity source. The cases of a source (sink) and vortex are obtained as particular ones. The airfoils are constructed numerically and analytically and conclusions are made about an influence of the irregularity position and type on the shape and aerodynamic characteristics of the airfoil.     

Analysis of chaotic vibrations for the distributed systems in the form of the Bernoulli-Euler beams using the wavelet transform

A problem on chaotic vibrations of the Bernoulli-Euler beams is formulated. The wavelet transform was first applied to investigate the complex beam vibrations. The validity of results was provided by using two methods of solution, namely, the finite element method and finite difference method.