A justified assessment of the work of constructions and their elements should take into account physical and mechanical characteristics of construction materials. Although taking physical nonlinearity and anisotropic features into consideration will make the design more complicated, it is strongly needed to develop tools and methods that cover all the specific features of the material more precisely. Mathematical methods of construction design that take physical nonlinearity into account are quite well investigated. They are: Newton Raphson method; modified Newton Raphson method which differs from the original version by the fact that the stiffness matrix has to be calculated only once at the first iteration and remains the same for several further iterations and steps of load; the method of growing stiffness which is quite efficient in dealing with problems of physical nonlinearity, and so on. But certain difficulties appear as we consider these problems from the point of view of physics: the majority of strength and plastic-yield criteria are not implemented in design process yet. That is caused by complicated mathematics and a need for more experiment in order to determine the constants in use.

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The paper describes usage of moder computing complex ANSYS in calculating constructions made of physically nonlinear materials.

Abstract. The article deals with the analysis of structures made from anisotropic nonlinear elastic materials. A variation of the deformation theory of plasticity by G.A. Geniev was chosen as theoretical basis for the analysis. The article introduces the method of finding the limit load of a structure made of an anisotropic nonlinear elastic material in the state of plane stress. The analysis was carried out with the help of ANSYS software package. A special subroutine UserMat developed by the authors enables the user to specify a model in accordance with the basic theory of material behavior.

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