The set of operations on diagnosing the changes in the properties of materials due to aging includes accelerated climate tests (ACTs) and pre- and post-ACT performance tests. Along with the use of various methods for diagnosing defects that arise and develop during aging, it is also important to determine changes in the thermophysical, hydrophysical, and other properties of materials subject to long-term operation that are associated with changes in the material structure. In this paper, we present a method for synchronous calculation of changes in thermophysical and hydrophysical properties of materials due to material aging and respective changes to the hygrothermal modes of products under long-term storage and operation. An experimental setup and a method for experimental-analytical determination of the thermophysical properties of materials at variable heating rates, as well as a method of synchronous calculation, are presented. The experimental-analytical determination method was developed using the results of thermal testing of specimens both subjected to ACT and without ACT. The analysis of the test results makes use of the approximation-superposition method to solve the inverse heat conduction problem.

The paper provides a designed under the supervision and with the participation of authors of the paper complex of methods of accounting for structural inhomogeneities of elements of a Thermal Protection System (TPS) made of C-C composites used to estimate ablated shapes of high-speed Flight Vehicles (FVs) and corresponding methods of measuring and processing of the needed structural parameters of C-C composites. During the mass ablation along a flight trajectory reinforcing elements and a graphitized matrix ablate differently, and there appears primary large-scale roughness on the surface. Moreover, pores, shells, and other fine-grained inhomogeneities outcrop forming the secondary finely divided roughness. Roughness impacts heat exchange, and summary equivalent roughness parameters are used to estimate FVs ablated shapes. A C-C composite graphitation degree that is defined with the X-ray diffraction study also influences an ablation rate. The density of materials is linearly related to their porosity, and for a number of currently in use and promising materials the density distributions were studied using computer tomography as well as the distribution of pores, shells, and other fine-grained inhomogeneities over volume of TPS elements was examined with electron microscopes. X-ray diffraction studies of the C-C composites were also carried out. Comparative computations of ablated shapes and aerodynamic characteristics of a model cylindrical FV with applied TPS elements of the examined C-C composites were performed with the use of obtained results of tomography, electron microscopic and X-ray diffraction studies.

The paper provides a complex of experimental investigations of structural non-unifonnities of carbon composites for FV IPS and a methodology used to process and apply the obtained experimental results when analyzing heat exchange, changes in FV shapes and aerodynamic characteristics during mass ablation in flight.

The paper is devoted to one of acute issues of determining aerodynamic properties of high-speed reentry vehicles (HSRV) of the rotary-body shape with small irregular surface distortions of a composite thermal protection coating, i. e. an issue of assessment of a scale of variance D{m(x)(alpha alpha)}, D{m(x)(beta beta)}, D{m(x)(alpha beta)} of second-order derivatives of aerodynamic disturbance rolling moment coefficient m(x) with respect to attack and yaw angles alpha and beta, respectively, at a zero spatial angle of attack. An approximate analytical integral solution of the posed problem for a rotary body with a given autocorrelated function of irregular distortions of its surface is obtained on the basis of Fourier expansion of the surface distortion and a method of differential locality hypothesis used to evaluate pressure variations. The obtained solution is qualitatively analyzed. A curve of practically ultimate values of m(x)(alpha alpha), m(x)(alpha beta), m(x)(beta beta) at 3 sigma{m(x)(alpha alpha)} versus a degree of correlation dependence for the modeled autocorrelated function of irregular surface distortions of a sharp 10 degrees- cone is provided.

Model specimens in the form of rings made of high-strength corrosion resistance steel (09Kh16N4B-Sh) are tested for corrosion under voltage in order to produce artificial defects in the form of corrosion pits and surface cracks.The specimens served to test the effectiveness of the magnetic particle, ferroprobe and eddy current testing techniques for detecting discontinuities in high-duty products made of the steel under study.The study has shown that magnetic particle testing by the applied field method, the ferroprobe and eddy current techniques offer a reliable detection of defects in the form of regions of pit corrosion and surface cracks on products made of the 09Kh16N4B steel.All the three techniques enable one to locate defects and estimate their sizes.

The paper presents results of comparative studies of the mechanical properties and adhesive strength of a hard anodic oxide coating and a coating applied on the surface of the AMg6 aluminum-magnesium alloy by chromating, widely used in the construction of rocket and space equipment.It is established that, among all the investigated protective coatings on the AMg6 aluminummagnesium alloy, an anodic oxide coating additionally impregnated with the Anakrol-204 anaerobic adhesive sealant has the best combination of mechanical properties and resistance to adhesive fracture under local effects.

The paper considers problems of analyzing aerodynamic properties (ADP) of reenetry vehicles (RV) as blunted rotary bodies with small random surface distortions. The interactions of math simulation of surface distortions, selection of tools for predicting ADPs of shaped bodies, evaluation of different-type ADP variations and their adaptation for dynamic problems are analyzed. The possibilities of deterministic and probabilistic approaches to evaluation of ADP variations are considered. The practical value of the probabilistic approach is demonstrated. The examples of extremal deterministic evaluations of ADP variations for a sphere and a sharp cone are given.

The material of a shell structure subjected to 20-year use under ambient conditions has been studied. The structure and mechanical characteristics of a strain-hardened AMg6 alloy, as well as the effect of subsequent holdings of this alloy for 10–3000 h at temperatures of 50, 70, 80, 100, 130, 150, 180, and 220°C, on changes in its dislocation structure and mechanical characteristics have been investigated. It has been shown that, in the structures under study, the AMg6 alloy has a cellular structure with a high density of dislocations and the ultimate strength σu = 445.5 ± 2.5 MPa, the proof stress σ0.2 = 326.5 ± 3.5 MPa, and the relative elongation δ = 11.7 ± 0.5%. Polygonization in the alloy occurs at a temperature of 220°C and the initial stage of the recovery process corresponds to a temperature range of 50–100°С in which the softening process can be divided into two stages, i.e., stage (1) of active softening due to the interaction of point defects with each other and stage (2) of the stabilization of the characteristics of the alloy.

We study the possibility of accounting for the influence of residual stress in structural elements of a high-duty item on the strain–stress state and predicting the residual life of cyclical strength throughout the entire part for an extension of the safety period. Checking calculation of the static strength checking by computer simulation reveals that the influence of residual stress on the stress field from the external load is more difficult to determine than by simple algebraic addition. It is shown that the part under the action of external cyclical stresses with the maximum peak intensity of external stresses should be considered as a structure under multicycle fatigue conditions, since the intensity of total (external and residual) stresses is higher than the endurance limit.

An ionized flow around the RAM C-II space vehicle is studied by the direct simulation Monte Carlo method in the range of altitudes of 73 to 81 km. It is shown that the predicted value of the plasma density in the shock layer essentially depends on the approach to simulation of high-temperature nonequilibrium dissociation. Good agreement of the results of numerical simulation with flight experiment data is obtained.