Zastosowanie dyskretnego modelu odkształcalnego samolotu do badania drgań własnych

In this paper a method of numerical analysis of frequencies and modes of natural vibrations of a deformable aeroplane is presented. The method constitutes a generalization of that employed in Refs. [4-7]. A one – dimensional discretisation of deformable structural units is applied by making use of the displacement finite element technique. A dynamic model composed of deformable beams and rigid bodies has been proposed. The equations of dynamic equilibrium for deformable and rigid parts of the aeroplane have been derived together with the conditions of the coupling between those equations. The program is prepared in the FORTRAN IV language for calculations on the ODRA 1305 computer. The calculations were performed for a hypothetical aircraft with constant distributions of parameters over the length of deformable units, and by using the data of a training jet-aircraft. Making use of the results obtained it can be stated that the method suggested constitutes an effective instrument for calculating frequencies and forms of the aircraft natural vibrations.