Automatic updating of large aircraft models using experimental data from ground vibration testing

The aeroelastic stability certification of todayʹs civil aircraft structures requires validated analytical models which have to meet high flutter calculation, fan-blade-off and windmilling certification calculation standards. The dynamic model of the aircraft must be validated in such a way that the dynamic behaviour of the aircraft is reproduced nearly exactly in order to reflect real scenarios when infuriate extreme or flight loads on the model. In addition, the dynamic model must be an accurate representation in order to predict the behaviour of the structure with regard to different boundary conditions. In view of shorter testing times or large-scale civil aircraft this topic will increase in importance in the future since correct free-free boundary conditions are very severe to realize during ground vibration testing (GVT). The above mentioned application fields illustrate the all-important role of the validated analytical model within the scope of civil aeronautics. The aim of this study was to find a new way of updating analytical models of large aircraft by using modal data obtained by GVT in order to save time during model validation. A strategy is presented in this article for validating the finite element (FE) model of a civil four-engine aircraft using a computational model updating (CMU) method.