Analysis of Multistage Structures using Cyclic Symmetry

In the last decades, the Aeronautical industry had to face with important challenges towards improving sustainability and reducing environmental impact on climate changes. In this overview, great emphasis is placed on producing engines more efficient and with excellent performance and reliability. These improvements also come from new and innovative analysis techniques applied to the key engine’s components; among them, Low Pressure Turbine (LPT) which plays a crucial role. This thesis deals with the modal and forced response analysis (in which synchronous of engine order type excitations are considered) of a multi-stage assembly of cyclic structures such as, for example, turbine engine bladed disks. Such assemblies are traditionally modeled stage by stage but, in this way, the inter-stage coupling effect can sometime be erroneously neglected. As an answer to this issue, a new method which combines a cyclic modeling of each stage with a realistic inter-stage coupling is here proposed. Study cases and confronts with single stage models and 360 full models are presented in order to evaluate the efficiency of the method first on a simple case study and, then, on a more realistic industrial example.