A comparison of nonlinear forced responses of LPT blades using different model strategies

Nowadays, the aerospace industry is actively working to reduce its environmental impact and improve the sustainability. A particular focus is placed on engines, which obviously play a crucial role in achieving these goals. The overall engine's improvement, in terms of both efficiency and weight, is achievable through the optimization of each of its components, including the Low Pressure Turbine (LPT). However, the optimization process requires a significant effort in terms of computational cost associated to aerodynamic and structural analyses. In particular, the dynamic analyses have become one of the priorities, since that lighter structures are more susceptible to high cycle fatigue failures due to vibrations. This thesis, developed in collaboration with Avio Aero – a GE Aerospace Company, aims to analyze the dynamic behavior of an LPT bladed disk in the presence of friction contacts. The nonlinear dynamic analyses were performed using the in-house software Policontact, developed at the AerMec laboratory of Politecnico di Torino in collaboration with Avio Aero. Specifically, the state-of-the-art approach of modeling bladed disk dynamics based on cyclic symmetry constraints was used as a benchmark to evaluate the effectiveness of an approximate method utilizing a suitably defined sector consisting of a few blades. The comparison between the two methods is presented in terms of qualitative diagrams reporting normalized data.