Annotation: Amid acute problems that arise in the field of rocket and space technology, mechanical engineering, and other fields and require a workable engineering solution, the problem of prediction and prevention of the unpredicted collapse of the structural members of the structures subjected to loading is considered. Prediction of the load-carrying capacity and residual life of the space frames during the long-term operation is based on the analysis of the stress and strain state, using readings from the strain and displacement pickups installed in the most loaded zones. In this case the yield strength of the structural material or the fatigue strength of the material may be considered as the criterion of the maximum load. At the same time the loss of stability of the compressed structural members used in the load-carrying thin-walled structures are among the potentially dangerous failure modes. In these cases such failure occurs unexpectedly without any visible signs of change in the initial geometry. Application of the adequate diagnostic techniques and methods of prediction of the maximum loads under compression conditions will make it possible to avoid the structural failures. In this case an assembly under test may be used for other purposes. To perform static strength testing, the rocket and space companies use costly compartments of as-built dimension. Therefore, keeping compartments safe solves an important problem of saving financial costs for hardware production. Nowadays this problem is particularly acute when ground testing the new technology prototypes.

Annotation: The article dwells on the problem of enhancement of durability for the mechanical rubber articles, which is directly related to the enhance of rubber resistance to various types of heat aging. Heat resistance during compression is most important for rubbers used for seals of various types: rings, collars, armored collars, gaskets for aviation and rocket technology hardware. Stress relaxation and the accumulation of relative residual deformation of rubbers, caused by the kinetic rearrangement of chemical bonds, are extremely sensitive to the influence of high temperatures. The main cause of the defects is the loss of elastic properties of the seals because of the accelerated heat aging of the nitrile group under conditions of long-term exposure to elevated temperatures in conditions of hot climate. The results of accelerated climatic testing of specimens of mechanical rubber articles, as well as the results of climatic endurance testing of the units for the period simulating 20-year service life are specified, and the main types of defects which result in the loss of performance properties of the mechanical rubber articles are as follows: great (up to 100%) residual deformation of intersections, cracking, loss of elasticity. The warranty life of fuel system units, made of ИРП-1078 nitrile rubber, does not exceed 12 years. Replacing the existing rubbers with rubbers created on the basis of more heat-bearing rubbers is the most promising way to improve the performance properties of the mechanical rubber articles under the high temperatures. The new D2301 rubber is based on fluorosiloxane rubber. It provides high thermal stability and, especially, the ability to maintain high performance properties for a long time under the simultaneous impact of hostile environment and high temperatures. The results of climatic endurance testing of fuel system units, equipped with rubber articles made of D2301 rubber, fully justify the increase of the specified service life of the specified units from 12 to 16 years. It is recommended to introduce D2301 rubber into the effective normative documentation and continue studies in order to extend the nomenclature of mechanical rubber articles made of D2301 rubber to provide the reliable sealing of units during the service life of 16 years or longer.

Annotation: Presented is the theoretical justification of the phenomenon of the inertia initiation under accelerated motion of the body, and gravity origin in the circumterrestrial space. There is no description of the physical nature of the inertia and gravity in the scientific publications. In the phenomenological approach under study, allowing for reflection properties of the space, earlier unknown interdependent information-physical link of the body and its mechanical particles with space under the accelerated motion was determined in the state of rest of the gravitation field as well as in the state of weightlessness. Alongside with the environment, eigenspace, i.e. configuration space of the body and corresponding metric lines of the space are considered. Idea of metric lines agrees with the concept of F. Wilczek, the American physicist, Nobel-Prize laureate, on the existence of the unobservable metric field in the real space. Solution of the problem rests on the example of the cantilever beam and mathematical model of the information reflection process, which for the first time takes into consideration previously unknown property of space reflection. Under the accelerated motion of the body reflection gains the acceleration vector dt d а     . In this case reflection manifests itself in the initiation of the beam of polarization vector under study   ~ in every point of the configuration space and is expressed as     ~ а . Value of the polarization vector equals the value of acceleration vector with negative sign. As a result metric lines of the configuration space under conditions of beam acceleration become polarized lines, generating vector information inertia field. Interaction of mechanical particles with the information inertia field in the configuration space generates physical inertia field of force, providing the real inertia under accelerated motion of the beam. (Relatively slow motion of bodies is studied as compared to the speed of light). According to the set forth unconventional approach the nature of the earth gravity is conditioned by the polarization of the radial metric lines of the circumterrestrial space. And polarization vector is directed to the center of the Earth and equals acceleration vector of the free fall with the same sign. Interaction of the body with specific mass with the vector information field of the Earth generates the physical force field of gravity. Article deals with the fundamental issues of theoretical physics and other fields of natural science. Materials of the conducted research are regarded as a potential scientific discovery.

Annotation: The experimental and theoretical justification is presented for the phenomenon of sudden buckling with dynamic effect at stability loss of a rectilinear rod with real existing imperfections. The interdependent connection is established between the initial imperfections and buckling intensity in the effect of zero rigidity of an utmost compressed rod at stability loss in the large.

Annotation: This work deals with the problem of cylindrical shell stability within Donnel-Vlasov linear theory based on updated equilibrium equations and dynamic approach to their solution. The new theoretical results of critical stress determination that are well agreed with experimental data are presented here. The plot of critical stress as a function of dynamic behavior of specific shell is shown here. The wave generation parameters for the moment of equilibrium loss for each specific case are also presented in this work.

Annotation: New theoretical results were obtained in definition of the stability longitudinal stress of the stiffened cylindrical shells both with internal and external arrangement of the stiffened stacks. They were obtained due to application of the dynamic approach to the solution of the refined equilibrium equations, introduction of the Qfactor of the structural elements into the system of equations, definition and application of the forces and moments in the calculation, that act in the sections of the joint bending of the shell and elements of stiffening. Expressions are given, which define the process of stability loss, including parameters of wave generation and amplitude of shell oscillation from the moment of application of the axial compressive force P0 up to the moment of snap action. With dynamic approach to the solution of the problem of the shell’s longitudinal stability the achievement of the first zero frequency by one of the higher modes of bending oscillations of the shell will indicate the loss of stability under the impact of the axial compressive force P0. This process is most obvious during testing of the absolutely flexible shells, which permit multiple loading. In the initial step of shell loading with axial compressive force P0, high-frequency bending oscillations with m, n ˃˃ 1 modes and low amplitudes occur. With a rise in force P0 oscillation frequency begins to drop, and amplitude to increase, with oscillatory mode remaining unchanged. There is a snap action when zero frequency is achieved for the first time by one of the oscillatory modes. This fact allowed formulation of the basic principles of nondestructive method for estimation of the critical stability stress of the flight-ready shell, main point of which is in the comparison of the theoretical curve of the frequency drop due to force P0 action on the structure versus the actual curve of the frequency drop of the flight-ready structure under the impact of the same values of P0 in the elastic range.