Simplification of Low-Cycle Creep–Fatigue Load Spectrum of Combustion Chamber and Life Assessment for Feature Simulation Specimens

Based on the damage equivalence principle, simplification of the low-cycle creep-fatigue original load spectrum of a combustion chamber under multi-stage flight conditions, such as low speed, takeoff, climb, and cruise states, and experimental verification were carried out in this study. The low-cycle creep-fatigue life of the combustion chamber feature simulation specimens was predicted. The results showed that compared with the original load spectrum, the simplified load spectrum had an average life error of 6.13% in the low-cycle creep-fatigue tests of flat-plate specimens with a single hole. The simplified load spectrum test results and the original load spectrum test results were both within the double dispersion band of their average values. The low-cycle creep-fatigue test results of the flat specimens with single or multiple holes were both within the double dispersion band of the predicted results, while the test results of circular tube specimens with multiple holes were basically within the fourfold dispersion band of the predicted results. In addition, after passing cooling gas inside the circular tube test specimens with multiple holes, the temperature near the gas film holes was reduced, thereby improving their low-cycle creep-fatigue test life.