Studies in dynamic design using updated models

Abstract

Model updating techniques are used to update a finite element model of a structure so that an updated model predicts more accurately the dynamics of a structure. The application of such an updated model in dynamic design demands that it also predict the effects of structural modifications with a reasonable accuracy. This paper presents studies that deal with updating of a finite element model of a structure and its subsequent use for predicting the effects of structural modifications. Updated models have been obtained by a recently proposed method of model updating based on constrained optimization and by an iterative method of model updating based on the modal data. The suitability of updated models for predicting the effect of structural modifications is evaluated by some computer and laboratory experiments. First, a study is performed using a simulated fixed-fixed beam. Cases of complete, incomplete and noisy data are considered. The simulated study is followed by a study involving actual measured data for the case of an F-shape test structure. Structural modifications in terms of mass and beam modifications are then introduced to evaluate the updated models obtained in the simulated and the experimental studies for their usefulness in dynamic design. The prediction results obtained on the basis of an updated model based on the proposed method for the simulated and the experimental studies are found to be comparatively better than those obtained on the basis of an updated model based on the iterative method.