An approach for the 3D dynamic mathematical modelization of big structures with special respect to ARIANE 5

Abstract

With special respect to ARIANE 5, solutions are outlined that allow an improvement of the mathematical modelization and calculation in structural dynamics. Substructuring and the application of modern component mode synthesis methods (e.g. Craig-Chang) are necessary. However, most of the methods result in modal degrees of freedom (DOF) of the interfaces and demand a high effort to couple the substructures. In this paper, a general method is described that allows to overcome the disadvantages of the modal interface DOFs. As a result, the coupling of substructures is reduced to a simple addition of matrices. The methods of Craig-Chang and Hurty resp. Craig-Bampton are special applications of this method. All reduced matrices of the substructures are real and symmetric. In a second section, special aspects of modelization are discussed. Structural aspects that are taken into accout are the viscoelastic material behaviour of the propellant of the solid rocket booster, the idealization of fluids and shells and the fluid-structure-interaction including the stiffening effect of the tank pressure. Finally, the coupling between axial, lateral and circumferential wave modes of the launcher ARIANE 5 is no longer neglectable. The mathematical representation of the interfaces between adjacent substructures is of some importance. A hybrid description of the DOFs of the complete launcher by grid point displacements and Fourier series is possible and offers an additional way to reduce the number of DOFs.