The paper presents a method to simplify the calculus of the eigenmodes of a mechanical system with bars in order to obtain more information concerning the deformations and the loads in the elements of the system using a semi-analytical model. Finite element method, currently used in engineering applications offers a set of standard results and sometime is necessary to process the dataset to obtain useful results. The method is applied to a symmetrical structure, this kind of system being discussed in previous papers. In this paper we aim to study a symmetrical system of beams that presents vibrations perpendicular on the plane of the system. The determination of properties of such systems would decrease the computational time and effort and offers more information about system.

Key words: vibrations, symmetrical beams, finite element method, eigenmodes

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