ANALYSIS OF COMPLEX ELASTIC STRUCTURES BY A RAYLEIGH-RITZ COMPONENT MODES METHOD USING LAGRANGE MULTIPLIERS

摘要

The free vibrations of elastic structures of arbitrary complexity arc analyzed in terms of their component modes. The method is based upon the use of the normal unconstrained modes of the components in a Rayleigh-Ritz analysis. The continuity conditions are enforced by means of Lagrange Multipliers. Examples of the structures considered are: beams with nonuniform properties, airplane structures with high or low aspect ratio lifting surface components, the oblique wing airplane as proposed by R.T. Jones, and plate structures.nThe method is also applied to the analysis of modal damping of linear elastic structures. Convergence of the method versus the number of modes per component and/or the number of components is discussed;the method is compared to more conventional approaches, to ad-hoc methods for some examples, and to experimental results.