Direct update of dynamic mathematical models from modal test data

Abstract

Two methods for the direct updating of mathematical models based on modal test data are described. A set of minimum required constraints derived from eigendynamic and force equilibrium conditions are presented. Both methods generate mass and stiffness matrices fitted exactly to the given modal test data. One method changes all coefficients of the mass respective to the stiffness matrix and lessens the solution effort by the algebraical elimination of the Lagrangian multipliers. The other method changes only those selected matrix coefficients requiring additional solutions for the numerical calculation of the Lagrangian multipliers. Examples and comments on the applicability of the methods are given.