Resonant Response and Random Response Analysis of Mistuned Bladed Disk Consisting of Directionally Solidified Blade

Recently, DS (Directionally Solidified) and SC (Single Crystal) alloys have been widely applied for gas turbine blades instead of CC (Conventional Casting) alloys, in order to improve the creep rupture strength. The DS blade consists of several columnar grains of SC, where the growing direction of the columnar crystal is set to the direction of the centrifugal force. Because the elastic constants of the DS blade are anisotropic, the mistuning characteristics of the bladed disk consisting of the DS blades seem to be different from those of the CC blade. In this study, the resonant response and random response analysis of mistuned bladed disks consisting of the DS blades are carried out, considering the deviations of the elastic constants and the crystal angle of the DS blade. The FMM (Fundamental Mistuning Model) and the conventional modal analysis method are used to analyze the vibration response of the mistuned bladed disk. The maximum resonant response and random response of the mistuned bladed disk consisting of the DS blades are estimated by the Monte Carlo simulation combining with the response surface method. These calculated results for the DS blades are compared with those of the CC blades. From these results, it is concluded that the maximum response of the mistuned bladed disk consisting of the DS blades is the nearly same as that of the CC blades. However, in the design of the tuned blade, where the blade resonance should be avoided, it is necessary to consider that the range of the resonant frequency of the DS blade becomes wider than that of the CC blade.