Iterative Techniques for Eigenvalue Solutions of Damped Structures Coupled with Fluids

Abstract

complex eigenvalue solver. The paper discusses energy norms which are used to evaluate convergence by estimating the size of residues, and how these residues are used to enrich the basis for the next iteration. The effectiveness of using standard modal approximations of the exact solutions to start the iterations is finally discussed. Evaluations in terms of speed and accuracy are shown for a 57,000 DOFs model of a PSA Peugeot Citroen oil pan, with a constrained viscoelastic layer, and for a model of the main cryogenic stage of Ariane 5 consisting of 88,000 DOFs. Computations are performed using the Structural Dynamics Toolbox for MATLAB taking the MSC/NASTRAN com- plex eigenvalue solver as reference for comparisons.