IDENTIFICATION OF MAIN MODES OF A LOW ORDER MODEL FOR A FORCED VIBRATIONS ANALYSIS OF CYLINDRICAL SHELLS

Abstract

This work analyzes the contribution of each nonlinear vibration mode, present in the modal solution of the transverse field displacement, on nonlinear forced vibration of a simply supported cylindrical shell axially excited. The geometry of the cylindrical shell analyzed causes a scenario with modal interaction between two distinct modes of vibration that have the same natural frequency, which in turn creates a modal discretized solution to transverse displacements with a high number of degrees of freedom to ensure convergence of the order vibrations twice the thickness of the cylindrical shell. Then, the aim of this work is to identify by the application of Karhunen-Loève method the most important modes of modal solution that represents the nonlinear forced vibration of cylindrical shell and it is a dimension of reduced order model (few degrees of freedom). It was used a commercial finite element computational code to build the sample matrix necessary for the Karhunen-Loève method, and obtaining its orthogonal modes of the problem and the modal participation of each nonlinear vibration mode on the nonlinear of the cylindrical shell. The results indicate a reduction in the number of degrees of freedom of the problem. Keywords: Karhunen-Loève, modal interaction, cylindrical shell, reduced order model.