Thermal fatigue is the typical failure mode of high-temperature combustion chamber components used in power plants and in the aerospace and transportation industries.With growing demand for good performance and high reliability,thermal fatigue is becoming a serious problem.The thermal working conditions of combustion chamber components include start-stop cycles and routine working cycles simultaneously.The former refer to large temperature changes,with the amplitude of 200°C-500°C and time period of several hundred seconds that are responsible for low-cycle fatigue(LCF)damage.The latter correspond to low temperature amplitudes of 20°C-60°C,with time period of milliseconds,and are responsible for high-cycle fatigue(HCF)damages.The LCF or HCF tests belong to constantamplitude cyclic loading.In contrast,the loading combination of LCF and HCF leads to combined-cycle fatigue(CCF)because of the variable amplitude cyclic loading.Considering the interaction of thermal loadings under different amplitudes,the thermal fatigue of CCF tests is expected to differ from that of LCF or HCF tests.