Optimization-based vibration suppression method of deterministic blisks by nonlinear coatings with mistuning identification

Abstract

Vibration problems of rotor blisks have been investigated in the past several years. To suppress the vibration level, hard coatings have been employed on blisks in several works. The best way to improve the damping performance of coatings is optimization. However, previous optimization works only focus on tuned simplified blisks and optimized the mechanical parameters and thickness of coatings, which may be not applicable to complicated blisks with inevitable mistuning. In this work, an optimization-based vibration suppression method to optimize the coated pattern incorporating the coating material nonlinearity and substrate mistuning is presented with consideration of the possible application on deterministic complicated blisks, which contains mistuning identification of uncoated blisks and vibration suppression optimization of deterministic mistuned blisks. To improve the computational efficiency, an improved nonlinear reduced order model is presented to obtain the forced responses with consideration of the coating material nonlinearity. The mistuning pattern of uncoated blisks is identified by a particle swarm algorithm based on experimental and numerical results. To avoid large damping mistuning, the optimization model to minimize the forced responses of the deterministic mistuned blisk with the identified mistuning pattern is presented to optimize the coated pattern with an assumption that the coating volume of each blade is exactly the same, which is solved by a modified particle swarm algorithm. Several validations and vibration suppression optimization analyses are performed. The results indicate that the present reduced order model can improve the computational efficiency. The forced responses are reduced significantly by using the presented optimization-based vibration suppression method, but the coating material nonlinearity and different excitations have important effects on the optimum coated pattern.