MODELLING THE MICROSLIP IN THE FLANGE JOINT AND ITS EFFECT ON THE DYNAMICS OF A MULTI-STAGE BLADED DISK ASSEMBLY

The complex architecture of aircraft engines requires demanding computational efforts to take into account the dynamic coupling of the many components constituting the whole assembly. For this reason numerically efficient Reduced Order Models (ROM) and techniques have been developed with the aim of reproducing the global dynamics of the system being computationally fast at the same time. In particular, ROMs have been presented to perform the modal analysis and the calculation of the forced response of rotating components like turbine bladed disks multi-stage assembly. In order to study the effect that joints may have in terms of nonlinearities due to friction in complex structures, in this paper the flange joint is studied as a source of damping due to microslip occurring at the contact interface between two turbine disks. An analytical contact model is proposed to calculate the local microslip based on the different deformations that the two flanges take during vibration. The model is first introduced using a simple geometry representing two flanges in contact and then it is applied to a reduced FE model in order to calculate the nonlinear forced response