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Marat Aksanovich Ilgamov.
Scientific interests
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M.A.Ilgamov is a specialist in the area of mechanics of
hydroelastic systems such as dynamics and stability of shells
interacting with continuous and loose media.
He developed a theory of strong interaction of thin-walled
structures with fluids taking into account large displacement of
the contact surface.
Effective analitic and numerical methods
developed by M.A.Ilgamov are being used in analysis of
thin-walled shells, dynamic phenomena in pipe-line systems and
working processes in flight vehicle engines.
M.A.Ilgamov performed series of investigations:
Free oscillations of a thin ring were considered as a model of a fuel
collector of afterburner of turbo jet engine. Forced oscillations of a
ring in acoustic field were studied theoretically and experimentally.
A model of liquid outflow from a cantilever tube was constucted,
allowing one to describe dynamic behaviour of the tube in the case of
its breaking. Nonlinear oscillations of a pipe under the action of the
internal pressure waves were studied. The oscillations were shown to
be able to vary from periodic to chaotic, depending on the problem
parameters. A model of large bend of a high-temperature
superconducting cable, a system of concentric tubes, was proposed.
Equations of dynamics of three-layer plates and shells with structure
nonsymmetric in thickness were derived, analysis of static and dynamic
stability, forced and parametric oscillations including those with
allowing for hysteresis losses in filler was conducted. Nonstationary
thermoconductivity and thermal stability of three-layer plates were
considered. Influence of the pressure in the middle layer on the bend
was shown. Stability of a cantilever cylindrical shell under the
action of the transverse end force, the internal pressure and the
axial stretching force was investigated experimentally.
A large series of investigations was performed on oscillations of
cylindrical shells with a gas and a compressible fluid. That was the
simplest model of a combustion chamber of a liquid-propellant engine
with unstable operation (acoustic instability, vibrational burning)
and pipe-line systems. This problem was considered in various
approximations. The results obtained were generalized in the
monograph/1/.
Dynamic interaction of the cylindrical and spherical shells, the
continuous elastic filler and the gas in the space was studied. Such a
system was a model to study a solid-propellant engine. Static bend and
stability of a shell under the action of the own weight (overloading)
of the system were considered. Results of investigations of the system
shell-solid elastic filler became parts of
monographs /2,3/. The first
of them was translated into English in the USA.
A series of investigations was devoted to experimental and theoretical
study of longitudinal air oscilations in a pipe at one end of which a
plane piston moved with a prescribed law, the other end being closed,
open or equipped with some device. On resonances of the gas column and
near them, periodic shock waves arose. The existence of periodic shock
waves at excitation frequences near the half the first resonant
frequency was found experimentally. The corresponding theory was
proposed. Experimental set ups were made, allowing one to excite gas
oscillations of large amplitude. Axisymmetrical shapes of oscillations
of thin-walled cylindrical part of a tube were studied, generation of
waves in the circular direction and catastrophic failure were found.
Nonlinear static problems of bend and stability of plates and panels
contacting incompressible and compressible liquid, problems of static
and dynamic stability of a plate between liquids of equal density were
stated and solved. Those results were included in
monographs /6,7/.
Behaviour of plates, shallow panels and shells in a flow of
incompressible ideal liquid was studied. Issues of statement of
nonreflecting and absorbing conditions for artificial boundary of
computational domain, important for numerical simulations, were
investigated (monography /9/). A method of artificial boundaries near the elastic body
in a flow was developed, allowing one to essentially simplify
computations. Experiments with cylindrical shell and shallow panel
were performed. Ways of describing interaction of permeable and
impermeable thin shells with fluids were systematically presented. The
latter results were included in monographs /4,5/.
Large group of researchers headed by M.A.Ilgamov conducted
investigations of static and dynamic behaviour of membrane shells in a
fluid flow including simulation of inflation of a parachute. Methods
of numerical and physical experiments and qualitative analysis were
used. Oscillating and mean motion of a fluid about surfaces moving
with the mode of travelling wave were studied. Experimental models of
wave propellers were created, their mean velocities and mean thrust
were determined. Numerical simulation of peristaltics of a bioshells
was given.
The classical theory of bending of plates and panels under the influence of excess pressure on the lower and upper surfaces has been supplemented. A refined expression for the distributed shear force is used, which depends not only on the pressure difference on the surface, but also on the interaction of the average excess pressure and the curvature of the middle surface. The influence of surface effects on the bending, vibrations and stability of micronanoplates, films, and nanowires has been studied.
Significant attention was placed on practical use and propagation of
results of investigations, matters of organizing science (Look the monography /8/).
M.A.Ilgamov:
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