Effect of surface impulsive thermal loads on fatigue behavior of constant volume propulsion engine combustor materials

The development of advanced high-performance constant-volume–combustion-cycle engines (CVCCE) requires robust design of the engine components that are capable of enduring harsh combustion environments under high-frequency thermal and mechanical fatigue conditions. In this study, a simulated engine test rig has been established to evaluate thermal fatigue behavior of a candidate engine combustor material, Haynes 188, under superimposed CO2 laser surface impulsive thermal loads (30–100 Hz) in conjunction with the mechanical fatigue loads (10 Hz). The mechanical high-cycle fatigue (HCF) testing of some laser preexposed specimens has also been conducted at 100 Hz to determine the laser surface damage effect. The test results have indicated that material surface oxidation- and creep-enhanced fatigue is an important mechanism for the surface crack initiation and propagation under the simulated CVCCE engine conditions.