Probabilistic design and reliability assessment methods for ablative thermal protection systems
In order to reduce the weight on the premise of ensuring the reliability of a thermal protection system,a probabilistic design and reliability evaluation method for an ablative thermal protection system considering multi-source uncertainties is established in this paper.The finite element method is used to calculate the thermal response of the system,and the validity of the method is verified by comparing the experimental test with the numerical model.A surrogate model for the uncertain input parameters and target output of the thermal protection system is constructed,and the probability characteristics of the target variables of the thermal protection system are analyzed based on the surrogate model and the Monte Carlo method.The sensitivity analysis of uncertainty parameters is carried out by using Sobol index,and the probability design is carried out by taking system reliability as an index.In this method,the probabilistic design and reliability evaluation of thermal protection systems are carried out for multi-source uncertainties such as flow,geometry and material properties.Taking the two-dimensional plate model as an example,the probability characteristics of the maximum back temperature of the thermal protection system and the sensitivity of the uncertainty parameters are calculated,and the reliability of the system under different coating thicknesses is obtained.The results show that,compared with the design with safety factor n=1.5,the probabilistic design achieves 24％weight reduction.
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