A generalized model of mistuning for bladed disks

Abstract

Bladed disks always have variations between blades, known as mistuning, which is a large focus of research within the turbomachinery industry. When mistuning is present, the forced response shows localized amplification of blade responses. Due to the random nature of these variations, statistical analyses are conducted to understand sensitivity to mistuning. For high-dimensional models this is an intractable problem unless the model is reduced. To this end, reduced order models have been developed that enabled projection of mistuning to reduce computational expenses. These methods include techniques for reducing systems with many types of mistuning including modulus and geometric variations.

This work creates a generalized model of mistuning (GMM) that incorporates mistuning into the blade or disk. The GMM method has many of the benefits of previous mistuning models by being compact and only requiring sector level models. GMM utilizes an augmented Craig-Bampton component mode synthesis to decouple the blade and disk. These models are then projected onto a reduced modal space with mistuning applied. The combination of the blade and disk reduction occurs through the projection of the interface onto special disk-blade interface modes. Validation is performed for a few types of mistuning (e.g. stiffness, damping, geometric) to demonstrate the effectiveness of GMM.