LOAD SPECTRUM DAMAGE ANALYSIS OF TURBINE BLADE BASED ON CREEP DEFORMATION SIMULATION

Based on the three-stage normalized parametric creep model, the creep simulation of turbine blade under typical test load spectrum with multi-working conditions is realized by USERCREEP subroutine. The load spectrum of single cycle and multiple cycles are simulated under variable load, the results show that the stress relaxation occurs in the stress concentration region with the increase of the creep strain, the obvious creep strain growth and stress relaxation occur under high working conditions. The creep curves and stress relaxation curves of typical characteristic parts of turbine blades are described, and the life of turbine blades can be predicted by the stress relaxation. Under the test load spectrum, creep and fatigue are the main factors that cause the blade failure. Based on Miner's rule of linear damage accumulation, the damage analysis of turbine blade is carried out on the basis of life prediction. In practical applications, the test load is much higher than the actual operating strength, so in order to better fit the actual evaluation of the blade mean time between failures time, it is necessary to use the equivalent damage coefficient to evaluate the equivalent running time of the blade and establish the estimation process.