不确定条件下贮箱区间凸模型可靠性评估

Reliability evaluation of tank under uncertain conditions based on interval convex model

针对不确定条件下液体推进剂贮箱的可靠性评估问题,基于贮箱应力强度与区间凸模型理论,确立了贮箱应力强度可靠性评估方法。首先,在液体推进剂贮箱数学模型的基础上,分析推导了贮箱的应力分布,结合应力强度理论,确定了贮箱的等效应力。其次,结合应力强度干涉理论及正则化区间面积比方法,定义了贮箱的应力强度区间凸模型可靠性指标。最后,结合某型火箭推进剂贮箱的实际参数,将贮箱等效应力与临界应力的不确定性转化为区间凸集形式进行了实例验证,并与椭球凸模型可靠性指标结果进行了对比。结果表明:应力强度区间凸模型可靠性指标可准确评估贮箱的完全可靠状态,并可将贮箱非完全可靠状态下的可靠度量化到[0,1]区间。

Aimed at the reliability evaluation problem of liquid propellant tank under uncertain condi- tions,the reliabiXity evaluation method of tank stress strength is established based on tank stress strength and interval convex model theory.Firstly,the stress distribution of propellant tank is analyzed and derived based on the liquid propellant tank mathematical model,and the equivalent stress is confirmed through combining with the stress strength theory.Secondly,based on the stress strength interference theory and the area ratio of regularized interval theory,the interval convex model reliability index of tank stress strength is defined.Final- ly,combined with the actual parameters of a certain type rocket propellant tank,the method is verified through transforming the equivalent stress and critical stress into interval convex set form,and then it is compared with the reliability index results of ellipsoid convex model.The results show that the stress intensity interval convex model reliability index can evaluate the tank's entirely reliable states accurately,and can quantize the relia- bility degree of tank's non-entirely reliable states into the interval of [0,1].