Structural Dynamic Modifications Using Damped Updated Finite Element Model Updating

Abstract

An accurate finite element model of a structure is essential for predicting reliably its dynamic characteristics. Such a model can be used to predict the effects of structural modifications for dynamic design of the structure. These structural modifications may be imposed by design alterations for operating reasons. Most of the model updating techniques neglect damping and so these updated models can’t be used for accurate prediction of vibration amplitudes. This paper deals with the basic formulation of finite element model updating method having identified structural damping matrix, and its use for structural dynamic modifications. A case involving actual measured data for the case of F-shaped test structure, which resembles the skeleton of a drilling machine is used to evaluate the effectiveness of FE model updating method incorporating identified structural damping matrix for accurate prediction of the vibration levels and thus its use for structural dynamic modifications. Design modifications in terms of mass and stiffener modifications are introduced to evaluate the effectiveness updated model incorporating damping matrices for structural dynamic modifications. It has been concluded that the FE model updating incorporating identified structural damping matrix can be used for structural dynamic modifications with confidence.