Moscow University Mechanics Bulletin最新文献

The paper presents the current results of experimental studies of the creep properties of metallic materials and related processes. Uniaxial tension, the effect of aging and temperature on the strength of a welded joint, complex stress, and the effect of factors of chemical interaction of the environment on creep and creep rupture strength are considered. An equivalent stress is given that allows describing the difference in creep lifetimes under uniaxial tension and under equal multiaxial tension for the same value of the principal stress.

The known physical and phenomenological approaches and failure criteria for structural materials at long-term and variable loading are systematized and their classification are proposed. The modern state of the durability problem is associated with the formulation of multilevel probabilistic models at complex loading, based on the physical laws of processes of brittle and viscous failure.

Wind power generators of oscillatory type use the energy of flow induced vibrations of bodies to generate electricity. Numerous scientific publications are dedicated to development and analysis of various schemes and designs of such devices. The present paper contains a brief review of the literature on this issue.

The article is devoted to the review of scientific achievements of the staff of the Chair of Applied Mechanics and Control, the Laboratories of Control and Navigation and Mathematical Support of Simulation Dynamic Systems in the 21st century.

The presented review consists of two parts. The first one is devoted to research generalizing the classical Prandtl problem in the case of taking into account the inertia of the convergence of rigid plates and dynamic effects occurring in a thin perfect rigid plastic layer. The second part examines the work related to the formation and development of the neck in plastic materials under quasi-static and dynamic loading. In particular, attention is paid to thin solids with a perturbed boundary shape, which have technological significance. The presence of a small geometric parameter allows using the asymptotic methods.

The safety of space flights is one of the topical issues. It combines a large number of different tasks. The Chair of Gas and Wave Dynamics presents several areas of work in this field. A study of cracks is proposed, because their appearance in the spacecraft skin can lead to an accident. A large number of experiments are being conducted on the ISS to refine mathematical models of media and processes, as well as the physical constants included in them. So, in emergency situations, fires may occur on the ISS. For their modeling, the cases of the presence of both one and several independent gross reactions describing the chemical interaction of an oxidizer with a fuel are considered. The results were compared with FLEX experiments on the combustion of single droplets in zero gravity. In order to refine the filtration models, experiments conducted under microgravity conditions have been studied.

An overview of recent works in the field of gas dynamics and plasma dynamics, which were initiated by Academician L.I. Sedov and his descendants, is given. An analytical study of the equations was carried out, exact solutions were constructed, and the problem of energy-momentum concentration was solved. Higher invariants of characteristics for a system of equations of one-dimensional gas dynamics in Eulerian and Lagrangian variables for special adiabatic exponents are found. Based on the use of higher invariants of characteristics, the solution of the Cauchy problem is reduced to a system of ordinary differential equations. Two Cauchy problems are presented, the solutions of which exist indefinitely without a gradient catastrophe.

Problems related to cosmic gasdynamic studies at the Chair of Aeromechanics and Gasdynamics of Lomonosov Moscow State University are discussed. We give main directions and methods of the space studies at our chair. Results of the developed theoretical models describing and predicting physical phenomena in space are presented in details. The models include the interaction of the solar wind with the local interstellar medium and comet atmospheres, motions of the interstellar medium under nonequilibrium ionization.

In the paper, scientific and pedagogical activities of the Chair of Theoretical Mechanics and Mechatronics of the Faculty of Mechanics and Mathematics of Lomonosov Moscow State University have been described. Some scientific results obtained in recent years by current employees and the most significant scientific results of former employees of the chair have been presented.

The article shows an experimental (part 2) improvement in thestabilization of the gaze under galvanic vestibular stimulation.