Nonlinear vibration analysis of coated blisks in the presence of stiffness mistuning identification

Abstract

Several papers have studied the modelling methods of coated blisks and proved the perfect damping performance of hard coatings. However, nonlinear strain dependence characteristics of the coatings have been rarely incorporated in opened studies of complicated coated blisks. In this paper, a linear reduced order model (ROM) of coated blisks is developed, where two reduction methods, Craig-Bampton (CB) method and the second modal analysis, are performed. By introducing the nonlinear strain dependence characteristics of the coatings in the linear ROM, a nonlinear ROM is presented and solved by an iteration method to obtain the forced responses of coated blisks with nonlinear strain dependence characteristics. Furthermore, the stiffness mistuning pattern and loss factor of uncoated blisks obtained by the developed experimental based identification process are introduced in the analysis model. The linear and nonlinear ROMs of coated blisks are validated by the experimental tests. Finally, the effect of nonlinear strain dependence characteristics on forced responses of coated blisks where the blisk substrate has different loss factors is analyzed.