运载火箭结构动力学响应分析存在诸多不确定性,基于有限元的标准蒙特卡罗不确定性分析方法计算代价过高,为解决该问题,引入多层蒙特卡罗方法。针对模型不确定性建立不同网格尺度运载火箭有限元模型,使用多层蒙特卡罗方法对发动机点火工况进行结构动力学响应不确定性分析,并与标准蒙特卡罗方法对比。结果表明在相同精度的情况下,多层蒙特卡罗方法能显著提高效率,所得结果对运载火箭初步设计阶段结构分析与设计有一定指导意义。

There are many uncertainties in the dynamic response analysis of launch vehicle structure. The computational cost of standard Monte Carlo uncertainty analysis method based on finite element model is too high. In order to solve this problem, Multilevel Monte Carlo (MLMC) method is introduced in this paper. To consider the model uncertainty, different mesh-scale finite element models are established. Based on these models, MLMC method is used to conduct the dynamic uncertainty analysis under engine ignition conditions. The results are compared with the standard Monte Carlo method and comparative results show that the MLMC method can significantly reduce the computational cost while obtain the same accuracy, which provides a guideline to strength analysis and structure design on initial design stage of launch vehicles.