Fatigue Life Prediction Of Thin-Wall Structures Under Thermal-Acoustic-Flux-Solid Interaction

With the rapid development of aerospace technology,the engine is now working for a long time under the extremely severe heat flux impact environment during the flight of the supersonic aircraft.The thin-walled structure is prone to large deflection dynamic response and fatigue damage.In order to obtain the structural dynamic response law and fatigue life under the impact of heat flux,it is especially important to carry out the numerical simulation calculation of the dynamic response law and life estimation under the coupling of multi-physics load of aeronautical metal thin-wall structure.1.The multiphysics coupled dynamic response and fatigue life calculation problem of thin-walled structure,according to the theory of fluid-structure interaction dynamics,the theory of thin-walled structural dynamic response is used to support the construction of dynamic response theory system;The theory is to construct a numerical simulation analysis method for support;the fatigue life calculation of thin-wall structure is carried out according to the theory of fatigue life prediction.2.Acoustic vibration response and fatigue life problem for high-temperature heat flux of thin-walled structures.The coupled FEM/BEM is used to construct the numerical simulation model of the thin-walled structure and the acoustic response of the thin-walled structure.The fatigue life is calculated by the improved rainflow counting method.The reliability of the simulation method was verified by comparing the thermoacoustic fatigue test with the numerical simulation results.On this basis,the acoustic vibration response and fatigue life calculation of thin-walled alloy plates under different high-speed heat flux environments are completed,and the acoustic vibration response and fatigue life variation of structures at different flux rates are obtained,and the reasons for this change are explained.3.The problem of random vibration response and fatigue life calculation for thin-wall structure heat flux environment.The axial dynamic stress response of the dangerous point of the thin-walled structures under different temperature and vibration levels is studied by numerical simulation.And the structural fatigue life is calculated.The availability and accuracy of the simulation method are verified by comparing the simulation calculation with the high temperature random vibration fatigue test results.The calculation of the random vibration stress response of thin-walled structures under high-speed heat flux environment is completed.The stress response and fatigue life time of thin-walled structures under different airflow temperatures,flow rates and random vibration magnitudes were obtained.The variation of structural thermal random vibration stress response and fatigue life under various working conditions is analyzed.4.Based on the theory of acoustic vibration response calculation of high-speed heat flux,a simplified model of aero-engine short circular flame tube structure is established by numerical simulation method.The wall temperature distribution and aerodynamic pressure distribution of the flame tube under different heat flux environments are obtained,and the flame tube is completed.Structural thermal modality and structural dynamics response results were calculated.The influence of the coupling of temperature load,aerodynamic load and noise load on the dynamic response of short circular flame tube structure is analyzed.Based on the basic theory,this paper studies the dynamic response analysis and fatigue life estimation of aeronautical metal thin-walled structures and short circular flame tube structures under multi-field coupling.It provides a reference for the reliability design of aerospace metal thin-wall structure and aero-engine short circular flame tube structure.