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High cycle fatigue P-S-N curve of material are important for the design of aero-engine strength. Based on the data processing requirement of the high cycle fatigue of aero-engine materials, a novel data processing method has been developed by proposing the criterion of selecting fitting model and the method for determining the critical stress between the medium and high fatigue cycle regions. Furthermore, the testing data of two common Ti-alloy materials in aero-engine are used to validate the present batch processing method, and the P-S-N curves in various conditions have been obtained. And the comparison of the process time between the present method and the conventional method has been conducted finally. The results show that the present data processing method is suitable not only for the data processing of the traditional high cycle fatigue issues, but also for the data processing of very high cycle fatigue issues. And the efficiency of data processing is significantly improved.

This paper proposes an ultra high frequency fatigue experimental approach based on electrodynamic shaker. The ultra high frequency fatigue specimen of TA11 titanium alloy sheet was designed after FEM calculation. The actual testing frequency of the designed specimen could be reached as high as 1756 Hz. The fatigue tests of both the ultra high frequency specimen and standard vibration fatigue specimen were carried out under the same stress level, and the consistency of test results was statistically verified. The results show that under the same stress condition,the testing results of the high frequency fatigue specimen proposed in this study are in good agreement with the experimental results of standard vibration fatigue specimen. Furthermore, the comparison of the present experimental results with the axial-loading fatigue and rotating bending fatigue results for the same material is conducted,and also a good consistency is obtained.

Fatigue crack propagation behaviors at high temperature are important preconditions for damage tolerance design in aircraft and engine structures.Therefore, fatigue tests were carried out on titanium alloy Ti-6Al-4V/ELI subjected to constant amplitude loading at two temperatures of 25 ℃ and 250 ℃ and three stress radios of 0.06, 0.5, -1 to determine fatigue crack propagation behaviors. Fatigue crack propagation da/dN-ΔK curves and da/dN-ΔK-R surfaces were obtained from experimental data by secant method. Those behaviors at different temperatures were compared and analyzed, and the interaction mechanism between high-temperature and fatigue load was deduced from fractographical study by SEM analysis.The results show that the larger the stress ratio R, the faster the rate of crack propagation of Ti-6Al-4V/ELI under the same temperature and stress intensity factors rangeΔK. Oxidation products and large numbers of secondary cracks are found on the fatigue fracture surfaces at high temperature and the destruction mode of crack propagation is gradually changed form cleavage to quasi-cleavage. Acceleration effect of oxidation and deceleration effect of secondary cracks combine affecting the crack propagation rate; when R is 0.5 or 0.06, those two seem equal and the effect of temperature is not obvious, while R is -1, more and deeper secondary cracks caused by fully interaction of high temperature and fatigue load make crack propagation rate at high temperature lower than that at room temperature.