The Dynamic Influence of Crystal Orientation on a Second Generation Single Crystal Material for Turbine Buckets

Abstract

High cycle fatigue is a factor that influence gas turbine buckets lifetime and it’s due to high frequency vibrations during service. Rotation and fluid flow around the blades cause static and dynamic stresses on the buckets row. For this reason the natural frequencies and HCF resistance evaluation are fundamental in the design phase of gas turbine engines in order to avoid resonance problems during service. Single crystal and directionally solidified superalloys shows anisotropic material properties, in particular single crystal can be modeled as orthotropic material in lattice directions for FEM simulations purposes. In this paper the influence of the lattice growth orientation, identified by two angles, on the natural frequencies of first stage bucket has been investigated. Six-sigma analysis has been performed in order to obtain a transfer function between lattice orientation and bucket vibration. The Design of Experiment (DoE) has been performed using FEA modal results on ten different vibration modes. The results obtained by FEA are verified by an experimental test on the real Heavy Duty MS5002 buckets.

Uncertainty and global sensitivity analysis of bladed disk statics with material anisotropy and root geometry variations

“…There are few articles in the literature that investigate the effect of blade anisotropy orientation on blade deformation. Kaneko, Manetti et al, and Wen et al studied the effects of variation in crystal orientation on natural frequencies of blades. Savage investigated the effects of crystal orientation on elastic stresses in single‐crystal blades, whereas Arakere and Swanson studied the effects of crystal orientation on the fatigue life of a bladed disk.…”

Sensitivity and Forced Response Analysis of Anisotropy-Mistuned Bladed Disks With Nonlinear Contact Interfaces

“…This has been investigated e.g. in [8] for turbine buckets using computational and experimental means and in [9] for simple beam models. The study of the sensitivity of the natural frequencies and mode shapes with respect to the crystal orientation parameters of bladed disks has been presented in [10], which shows significant sensitivities for the blade dominated and localized mode shapes.…”

Vibration 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 (Conventionally Casting) alloys to meet the requirement of the high temperature operation and to improve the thermal efficiency [1,2]. The SC blade consists of one columnar grain, and therefore creep rupture and thermal fatigue resistance can be improved by eliminating the grain boundary.…”