Experimental study on fatigue curve law of turbine blade under combined high and low cycle loading

The effect of the high cycle vibration load on the high-temperature fatigue properties of the turbine blade were addressed. Combined high and low cycle fatigue tests were carried out on several blade specimens. The results show that the superposition of high-frequency vibration on low-cycle load can significantly reduce the fatigue life of the blade. It is noteworthy that combined high and low cycle fatigue has two features: great dispersion and no fatigue limit. The former is exhibited by much broader life range than the low cycle fatigue (LCF) test, and the latter indicated by fracture of the blades over 10⁷ high cycles (which is considered as the life limit of the metal materials for the invariable-amplitude fatigue). In addition, the fatigue data suggest a double logarithmic linear relationship between vibration stress level and the combined fatigue life. Further research has found that the law for superalloys operates universally.