Non-linearities in an aero-engine structure: From test to design

There are several features in an aero-engine structure, including the bolted scalloped flange, the rotor attachment to bearings, amongst others, which may give rise to non-linear behaviour at large amplitudes of vibration. Currently in industry, linear finite element models have been used to predict the behaviour of the structure at various force patterns experienced in the operating conditions of the structure. However, these predictions may become invalid if the non-linearities in the structure considerably affect the structure's dynamic behaviour. In this paper, a testing technique is presented for identifying and characterising the non-linear behaviour of an aero-engine. Furthermore, this technique is used to obtain test data from a real engine structure and the results from the test are discussed with respect to correcting the non-linear elements of the analytical model of the aero-engine structure.