Reliability analysis of high-temperature structure with multiple failure models base on time-varying response surface method

Aircraft structures such as leading edge and engine inlet can reach high temperature during high-speed flight due to the aerodynamic heating effect. High temperature will produce thermal stress in structure and change the material property parameters, thus cause multiple failure models such as thermal strength failure and thermal vibration failure. Because all the failure models of high-temperature structure are caused by the common load and related to the common material property parameters. The correlations among different failure models must be took into consideration in the structural reliability analysis. The mutual physical correlation among different failure modes are analyzed based on the physical mechanism. The approximate explicit functions of all the structure response values are built based on time-varying response surface method. The time-varying models of the structural response threshold values are established by using temperature as intermediate variable. Thus the time-varying limit state function of each failure model is built and it is a normal process when the basic invariables follow normal distribution. The multidimensional Gaussian probability density function is derived by its first-order and second-order. The time-varying structural system reliability is calculated by numerical integration of the joint probability density function. A study case is given to demonstrate the applicability and accuracy of this method.