Experimental validation of the Asymptotic Mistuning Model for studying the forced response of bladed disks

Abstract

This paper presents a comprehensive experimental validation of a reduced order model based on the Asymptotic Mistuning Model (AMM) method for computing the response of mistuned bladed disks. Bladed disks are important components in aircraft propulsion systems, and their dynamic response is strongly affected by the presence of small differences between sectors. Classically, each sector contains a blade and an associated angular domain of the disk. Under cyclic symmetry assumption, only one sector needs calculation, but this assumption fails to describe mistuned disks correctly. Since detailed simulations of mistuned systems are computationally expensive, reduced order models appear as valuable tools for providing an efficient approach to investigate mistuning effects. In this work, the AMM is validated with a dedicated experiment performed on a compressor monobloc bladed disk (blisk) under rotating conditions in a vacuum environment. An intentional mistuning pattern is designed using the model and added to the physical blisk. The response of the mistuned system is measured using strain gauges located at the blade roots, while it is subjected to different engine order excitations and rotational speeds. The experimental results are compared against the model predictions. Key parameters, such as resonance frequencies, amplitudes, and mode components of the response, are analyzed to assess the accuracy and efficiency of the AMM to capture mistuning induced effects.