Functional graded materials are based on two materials, with very different properties, which vary continuously, according to a material law, on their thickness (a beam or a plate). The concept of equivalent plate involves the replacement of the given plate, a plate made of FGM, with a homogeneous and isotropic plate, with the same geometric characteristics (shape and dimensions), with the same load, which is attributed material properties that lead to the same behavior with the given plate. The aim of the paper is to provide a way to solve a complex problem (mathematical and structural), as in the case of FGM plates, with available means, with known professional calculation programs, with common finite elements, without intervention in the structure of its program. of finite element matrices, in other words without dedicated calculation programs. The finite element method is applied using the Ansys program and one of the best known finite elements, the 3D Solid185 element, both in the common version (structural) and in the multilayer finite element version.