Model Updating of Nonlinear Structures

There are always certain discrepancies between modal data of a structure obtained from its mathematical model and experimentally measured ones. Therefore it is a general practice to update the theoretical model by using experimental measurements in order to have a more accurate model. Since in several real life engineering problems there exist structural nonlinearities, model updating of nonlinear structures come into prominence. To be able to apply one of the well-established model updating methods, the linear FRFs of a nonlinear structure are to be measured. Although it may be possible to obtain linear FRFs of a nonlinear structure experimentally with a certain approximation by using low level forcing in FRF measurement, when there is frictional type of nonlinearity, this is not possible. In this study a model updating method for nonlinear structures is proposed. A noble method developed recently by the authors to obtain linear FRFs of nonlinear structures having multiple nonlinearities including friction type of nonlinearity is used in the nonlinear model updating approach proposed. The method is validated by applying the method developed to a nonlinear test system.