FINITE ELEMENT MODELING IN ANALYSIS OF LONG-TERM STRENGTH OF CYLINDRICAL HANGARS OF VARIOUS LENGTHS

Abstract

The goals and objectives of research on creep and long-term strength of protective building structures for aviation equipment made of aluminum alloy are considered, the relevance of such research is shown. The model of nonlinear deformation of thin-walled elements under short-term and long-term loading, the calculation method are described. What allows determining the bearing capacity and long-term strength of protective structures. The implementation of the proposed model under long-term deformation by the finite element method based on the proposed variational functional is presented. The accumulation of irreversible creep deformations and the related process of material degradation are considered. An example of calculations of the coating structure is given and recommendations are given for the rational outline of the cylindrical panel of the hangar. A large number of accumulated creep test materials allows evaluating existing and new deformation models, performing calibrations and selecting appropriate constants in the creep and fracture equations. The obtained data are used to structure the equations of state of mathematical models. The variational formulation of the problem is necessary for constructing finite element equations. The Lagrangetype principle is used, in which the variational functional is given on the displacements. In problems of creep theory, the variational equation includes additional forces and moments from irreversible creep deformations. At an arbitrary moment in time, the creep deformations are taken as known (their variations are zero), therefore, the shell displacement functions at a given moment in time correspond to the additional values of the force and moment and will be the solution of the variational equation. The method was used for the case of creep bending in conical shells. Given that a large number of protective building structures correspond to models of thin-walled bodies – plates and shells. Such structures must have the necessary strength and rigidity. Thus, improving the structures of elements of complex shape is one of the priority practical tasks in the design of protective structures.