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: The strength of real solids depends essentially on the defect of the structure. In real materials, there is always a large number of various micro defects, the development of which under the influence of loading leads to the appearance of cracks and their growth in the form of local or complete destruction. In this paper, based on the method of singular integral equations, we present a unified approach to the solution of thermal elasticity problems for bodies weakened by inhomogeneities. The purpose of the work is to take into account the heterogeneities in the materials of the elements of the rocket structures on their functionally-gradient properties, including strength. The choice of the method of investigation of strength and destruction of structural elements depends on the size of the object under study. Micro-research is related to the heterogeneities that are formed in the surface layer at the stage of preparation, the technology of manufacturing structural elements. Defectiveness allows you to adequately consider the mechanism of destruction of objects as a process of development of cracks. In studying the limit state of real elements, weakened by defects and constructing on this basis the theory of their strength and destruction in addition to the deterministic one must consider the probabilistic – statistical approach. In the case of thermal action on structural elements in which there are uniformly scattered, non-interacting randomly distributed defects of the type of cracks, the laws of joint distribution of the length and angle of orientation of which are known, the limiting value of the heat flux for the balanced state of the crack having the length of the “weakest link” is determined. The influence of heterogeneities of technological origin (from the workpiece to the finished product) that occur in the surface layer in the technology of manufacturing structural elements on its destruction is taken into account by the developed model. The strength of real solids depends essentially on the defect of the structure. In real materials, there are always many various micro defects, the development of which under the influence of loading leads to the appearance of cracks and their growth in the form of local or complete destruction. In this paper, based on the method of singular integral equations, we present a unified approach to the solution of thermal elasticity problems for bodies weakened by inhomogeneities. The purpose of the work is to take into account the heterogeneities in the materials of the elements of the rocket structures on their functionally gradient properties, including strength. The choice of the method of investigation of strength and destruction of structural elements depends on the size of the object under study. Micro-research is related to the heterogeneities that are formed in the surface layer at the stage of preparation, the technology of manufacturing structural elements. Defectiveness allows you to adequately consider the mechanism of destruction of objects as a process of development of cracks. In studying the limit state of real elements, weakened by defects and constructing on this basis the theory of their strength and destruction besides the deterministic one must consider the probabilistic – statistical approach. With thermal action on structural elements in which there are uniformly scattered, non-interacting randomly distributed defects of the cracks, the laws of joint distribution of the length and angle of orientation of which are known, the limiting value of the heat flux for the balanced state of the crack having the length of the “weakest link” is determined. The influence of heterogeneities of technological origin (from the workpiece to the finished product) that occur in the surface layer in the technology of manufacturing structural elements on its destruction is taken into account by the developed model. The solution of the singular integral equation with the Cauchy kernel allows one to determine the intensity of stresses around the vertexes of defects of the cracks, and by comparing it with the criterion of fracture toughness for the material of a structural element, one can determine its state. If this criterion is violated, the weak link defect develops into a trunk crack. Also, a criterion correlation of the condition of the equilibrium defect condition with a length of 2l was got, depending on the magnitude of the contact temperature. When the weld is cooled, it develops “hot cracks” that lead to a lack of welding elements of the structures. The results of the simulation using singular integral equations open the possibility to evaluate the influence of thirdparty fillers on the loss of functional properties of inhomogeneous systems. The exact determination of the order and nature of the singularity near the vertices of the acute-angled imperfection in the inhomogeneous medium, presented in the analytical form, is necessary to plan and record the corresponding criterion relations to determine the functional properties of inhomogeneous systems.

Annotation: The shell structures widely used in space rocket hardware feature, along with decided advantage in the form of optimal combination of mass and strength, inhomogeneities of different nature: structural (different thicknesses, availability of reinforcements, cuts-holes et al.) and technological (presence of defects arising in manufacturing process or during storage, transportation and unforseen thermomechanical effects). The above factors are concentrators of stress and strain state and can lead to early destruction of structural elements. Their different parts are deformed according to their program and are characterized by different levels of stress and strain state. Taking into consideration plasticity and creeping of material, to determine stress and strain state, the approach is effective where the calculation is divided into phases; in each phase the parameters are entered that characterize the deformations of plasticity and creeping: additional loads in the equations of equilibrium or in boundary conditions, additional deformations or variable parameters of elasticity (elasticity modulus and Poisson ratio). Then the schemes of successive approximations are constructed: in each phase, the problem of elasticity theory is solved with entering of the above parameters. The problems of determining the lifetime of space launch vehicles and launching facilities should be noted separately, as it is connected with damages that arise at alternating-sign thermomechanical loads of high intensity. The main approach in lifetime determination is one that is based on the theory of low-cycle and high-cycle fatigue. Plasticity and creeping of material are the fundamental factors in lifetime substantiation. The article deals with various aspects of solving the problem of strength and stability of space rocket objects with consideration for the impact of plasticity and creeping deformations.

Annotation: The article deals with the peculiarities of creation of technological crimping device for assembling the spacecraft separation system clamp band. The crimping device is intended to ensure uniform distribution of tension forces in the clamp band belts during assembling of the attachment clamp band, which allows minimizing the load on pyrolocks-pushers and thereby ensuring their operation reliability. The device consists of pressing mechanisms located along circumference symmetrically to the clamp band belts interface plane and fixed on a rest with adjustable supports. The pressing mechanism is a structure with driving kinematic scheme, which allows compensating for mounting errors, unfavorable combination of tolerances, avoiding occurrence of radial load on the thrust screw. However, during testing of the clamp band assembling technology, jamming of threaded connection as a result of thrust screw turn crush in the area of first turn of insert, gap in the thread after multiple use, scratches and minor scores on the conical surface of pressing mechanism, hardship of work with two wrenches were detected. To remove these defects, the sleeve with insert was replaced by the sleeve with protruding part, which allowed distributing the load in all turns more uniformly. The material of nut and screw was replaced based on relation between the strength limits: σв of rod > 1.3 σв and nut. The design of pressing mechanism was changed in respect of connection of thrust screw with hold-down, which allowed decreasing the load on screw pair as a consequence of axial force transfer from screw’s spherical surface to flat surface of hold-down, decreasing the tightening moment to ensure design force of clamp band belts fixation and making the process of pressing mechanisms assembling and disassembling easier. As a result of the updates, the manufacturable and ergonomic structure of crimping device was obtained, the use of which during assembling of the clamp band allows uniformly distributing the crimping forces in clamp band belts, which ensures reliability of spacecraft separation system operation.