Abstract: When the modern aircraft flies, the thin-walled structure of the engine will be exposed to an extremely high-temperature environment, leading to the dynamic response of large deflection and fatigue damage. In order to obtain the structural dynamic responses of the structure in the high speed heat flux and the time of fatigue damage, which are generally difficult to measure, this paper adopts the method of coupled FEM/BEM for numerically simulate analysis and thermo-acoustic fatigue test. A numerical simulation model that is exactly of the same size as the test piece is constructed according to the load effect, and the thin wall structure under the thermo-acoustic load is simulated and calculated. The Power Spectral Density (PSD) method is used to analyze the peak frequency response to acoustic load variation, and the improved rain-flow counting method is used to analyze statistically the vibro-acoustic response data. The fatigue life time of the structure is then obtained. A comparison of the simulation results of acoustic response with the experimental results shows that the error is less than 2%, which verifies the reliability of the numerical simulation. A numerical simulation analysis of the thin-walled structure under the impact of high speed heat flux is carried out. The variation rules of stress response and life of the structure with temperature and flow velocity are summarized, and the reasons for the variation are expounded. The work completed in this paper can provide an important basis for response analysis and life prediction of thin-walled structures in high speed heat flux environment.

Key words: high speed heat flux, thin-walled structure, thermoacoustic fatigue, fatigue life prediction, improved rain-flow counting method