A systematical investigation on the impact of coupling crystal orientations on vibration characteristics of a single crystal superalloy cooling turbine blade

Revealing the dispersion mechanism of vibration characteristic is significant for turbine blade that is one of the most important hot components of aero-engine. Thus, the aim of this article is to systematically address the influence of primary and secondary orientation deviations on the dynamic responses of a single crystal blade by theoretical analysis in combination with finite element numerical calculation. Besides, the relationship between the crystal orientation in engineering and material science is clarified by a mathematical approach. Primary orientations characterized by two deviation angles, each having 16 directions and secondary orientations with 11 deviation angles are defined by three angles measured by the Laue method. Good agreement on variation of structural eigenfrequency for the first bending or torsional mode is attained between theory analysis and numerical calculation. Numerical results show that the primary orientation deviation direction could cause significant dispersion of the natural frequencies for low and high order modes. The increasing deviation angle widens the dispersion, with the maximum variation ratio of 5.62% for the torsional mode. Importantly, the conjunction with the secondary orientation could further changes the dispersion of the natural frequencies, and the maximum variation of 6.5% is achieved for the torsional mode. This research may provide new perspectives for substantially improving the resonance margin of single crystal turbine blades, with potential applications in preventing high cycle fatigue failure, which is very meaningful to guide the design of the aero-engine.