Structural design and LCF lifetime prediction of simulating specimen for the tenon tooth of nickel-based single crystal turbine blade

In this study, the structural design, low-cycle fatigue (LCF) experiments and lifetime prediction of simulating specimens for the tenon tooth chamfer of a nicked-based single crystal turbine blade were conducted. Firstly, a crystal plasticity constitutive analysis of the turbine blade was performed to identify hotspots under in-service operating conditions. Then, ensuring consistency in geometric structure and lifetime-related parameter, a simulating specimen was designed. Comparing the finite element simulation results of the stress concentration area of the simulating specimen and the tenon tooth chamfer of the turbine blade, the error in the lifetime-related parameter was less than 4.75%, demonstrating that the designed simulating specimen achieved lifetime equivalence for the tenon tooth chamfer. Moreover, a modified method for determining critical distance that considers the influence of notch size was established based on the theory of critical distance (TCD). By combining this method with the slip-based damage model, the LCF lifetime of notched specimens and simulating specimens was accurately predicted.