Numerical Analysis of Stress-Strain State of Fuel Tanks of Launch Vehicles in 3D Formulation

To model the kinetics of the thermal stress state in 3D structural elements with complex material properties, with account taken of plastic deformations, design features, and real loading conditions based on the finite-element method, a special calculation technique and software package have been developed. In this paper, the main relations of the developed calculation technique are presented and the main features of this technique are described. To study the stress-strain state of fuel tanks of launch vehicles, the software has been improved and upgraded. During the construction of different, in the degree of complexity and level of discretization, computational fine-element schemes, both the design and loading features of fuel tanks were taken into account. Calculation studies were performed based on data on the physical and mechanical properties of aluminum alloys and the corresponding strain diagrams. Calculations were performed with account taken of the internal and water pressures, the latter varying with the water level in the tank. The solution of elastic-plastic problems was carried out by the method of time steps with a given number of iterations in each of them. For different calculation models, values of plastic strains were obtained at fixed points of the tank. It was established that the results obtained by different calculation schemes are in good agreement with each other.