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: Substantiation of the research tools has been performed as a part of methodology development for the air and missile defense system. The problem under consideration is very complex due to the multifactorial nature of the research object, its qualitative variety and manifold structure, incomplete definition of the problem statement. Furthermore, the ability of modern technologies to produce different arms systems, which are capable of carrying out same class tasks, considerably increases the risk of making not the best decisions. Based on this, as well as taking into account the sharp increase in the cost of weaponry, the considered problem is classified as an optimization one that should be solved through the theory of operations research. In this theory, such task is viewed as a mathematical problem, and mathematical simulation is the basic method of research. The main types of mathematical models, their areas of application have been considered as a part of the analysis. The classification of mathematical models has been indicated according to the scale of reproduced operations, purpose, and goal orientation. Quantitative and qualitative correlation of forces has been accepted as the efficiency criterion, which determines a goal orientation of the model. The problems related to this have been shown. In particular, searching for the compromise between simplicity of the mathematical model and its adequacy to the research object is among these problems. Two of the basic approaches to principles of the military operation model construction and its assessment have been considered. The first is implemented through modeling of the combat operations. The second approach is based on the assumption that different armament types can be compared based on their contribution to the outcome of the operation, and on the possibility to assign «a weighting coefficient» named as a combat potential to each of these types. The modern level of problem solving related to this method has been shown. The reasonability of its application in the considered task, including the definition of forces correlation of the opposing parties, has been substantiated. The basic regulations of the construction concept of the required mathematical model and tools for its research have been formulated based on the analysis results: the assigned problem should be solved by analytical methods through the theory of operations research; the analytical model is the most acceptable conception of the analyzed level of the military operation; the synthesis of the model should be based on the idea of a combat potential. At the same time, it should be taken into account that the known approach to the definition of forces correlation, which uses the combat potential method, has a number of essential limitations, including the methodological ones. Therefore, within the bounds of further research, this approach requires the development both in terms of improving the reliability of the single assessment and in terms of giving the system qualities to the synthesized mathematical model.