A thermo-mechanical fatigue life assessment method for single crystal turbine blades

A thermo-mechanical fatigue (TMF) life assessment method of single crystal turbine blades was developed based on TMF experiments of single crystal turbine blades combined with deformation and damage theory of single crystal as well as numerical simulation for thermo-mechanical fatigue problem of single crystal turbine blades. Firstly, the cyclic stresses and temperatures generated on the critical section in the single crystal turbines during service were simulated with the TMF experimental system of hollow air-cooled turbine blades, and the position of crack initiation and the TMF life were determined. Then, the Walker viscoplastic constitutive model based on slip systems and cyclic damage accumulation (CDA) model based on critical plane were proposed considering the features of deformation and damage behavior of single crystal turbine blades. Finally, the numerical simulation of TMF of single crystal turbine blades under the experimental conditions was performed with the above-proposed constitutive model and life model. Results show that the theoretical dangerous point is consistent with the experimental results, and the calculated life is basically within three times scatter band of the experimental life.