Overview
Designed to achieve reduction in fuel consumption, the Ultra-High Bypass and High Propulsive Efficiency Geared Turbofan engine incorporates evolutions likely to produce high frequency (HF) vibration excitations which propagate through the structure. Numerical simulation is an efficient tool to control vibrations hence supporting the mechanical design. Where Finite Element (FE) based approaches show limitations due to computational hardware performances and HF dispersion management, Statistical Energy Analysis (SEA) stand as proven and effective method for this frequency range to predict the vibrational energy transfers across partitions – subsystems – of a structure.
Challenges of SEA modelling consist of the structure partitioning which usually requires expertise and the accuracy loss at lower frequencies where the high stiffness of parts or complexity of junctions counter the method initial assumptions. Those statements depend strongly on the studied structure, therefore the objective of the proposed project is to develop and demonstrate a SEA modelling process to predict the vibration propagated in a typical complex engine frame.
In this scope, best modelling practices from detailed numerical analysis are engaged to both support an extensive test campaign preparation including test vehicle design and manufacture, and produce models covering the target frequency range: from 400Hz to 10kHz. A crucial phase consists in the validation and update of these models from tests post-processing techniques and known methods such as Experimental SEA, Decay Rate damping estimation or input conductance as well as innovative inverse approaches relying on optimization loops. From the comprehensive comparison of these different methods with tests results, a best methods and associated modelling practices are delivered to the topic leader. CETIM and ESI join their complementary competences to develop the modelling and experimental know how applied to the HF vibrations assessment.