The purpose of the study is to develop a software – oriented algorithm for calculating flat rod systems with variable length modulus of elasticity. The object of study – a flat rod system, located in a single load, the elements of which are interfaced at the nodes rigidly or pivotally; the shape of the axes and the conditions of the support are set. A special finite element is developed on the basis of the finite element method in the form of a mixed method. To calculate the elements of the response matrix and the vector of freight coefficients, a numerical integration procedure is used. Examples of calculation of cantilever rods in two variants are given: with a variable length modulus of elasticity; and a rod having three, five and seven sections along the length made of different materials. The comparison with the results of other authors is given. A flat frame of four finite elements with variable modulus of elasticity is calculated. The results of solving the examples indicate the correct operation of the proposed algorithm. It is shown that the parameters of the stress-strain state of the structure can be adjusted by changing the properties of the material.

Keywords: mixed method, finite element, variable modulus of elasticity, response matrix