基于梯度有限元法的HTPB推进剂药柱结构完整性分析

Structural integrity analysis of HTPB propellant grainbased on gradient finite element method

为研究端羟基聚丁二烯(HTPB)推进剂力学性能非均匀性对药柱结构完整性的影响,针对HTPB推进剂在定应变载荷作用下的两类典型本构响应特性构建药柱力学性能非均匀场,采用梯度有限元法开展药柱在点火增压载荷作用下的结构完整性评估。结果表明,HTPB推进剂力学性能的非均匀性引起的药柱等效应变响应的变化,以及定应变引起的药柱最大延伸率的非均匀分布是影响药柱结构完整性的两个直接因素;药柱中模量的不均匀分布是影响其在点火增压载荷下应变响应的主要因素;药柱力学性能的非均匀分布对其在点火增压载荷下的安全系数有较大的影响。考虑药柱力学性能非均匀性时,Ⅰ型推进剂药柱安全系数由2.32上升到3.14,上升幅度约为35.34%;Ⅱ型推进剂药柱安全系数由2.13下降到1.48,下降幅度为30.52%,其中药柱等效应变响应的变化对两型推进剂药柱安全系数的影响度分别为-10.15%与31.63%,最大延伸率的变化对两型推进剂药柱安全系数的影响度分别为110.15%与68.37%。药柱安全系数变化主要由推进剂最大延伸率变化决定。

In order to study the influence of mechanical heterogeneity of hydroxyl-terminated polybutadiene(HTPB)propellant on the structural integrity of grain,the heterogeneous field of mechanical properties of propellant grain was constructed for two typical constitutive response characteristics of HTPB propellant under constant strain load,and the structural integrity of grain under ignition pressurization load was evaluated by gradient finite element method.The results show that the variation of equivalent strain response caused by the heterogeneous of mechanical properties of HTPB propellant grain and the heterogeneous distribution of maximum elongation caused by constant strain are two direct factors affecting the structural integrity of propellant grain.The heterogeneous distribution of modulus in grain is the main factor affecting its strain response under ignition pressurization load.The heterogeneous distribution of the mechanical properties of the propellant grain has a great influence on its safety factor under the ignition pressurization load.When considering the heterogeneous of the mechanical properties of the propellant grain,the safety factor of the type Ⅰ propellant grain increases from 2.32 to 3.14,with an increase of about 35.34%;the safety factor of the type Ⅱpropellant grain decreased from 2.13 to 1.48,with a decrease of 30.52%.The influence of the variation of the equivalent strain response of the grain on the safety factor of the type Ⅱpropellant grain is-10.15%and 31.63%,respectively.The influence of the variation of the maximum elongation on the safety factor of the type II propellant grain is 110.15%and 68.37%,respectively.The variation of safety factor is mainly determined by the variation of maximum elongation of propellant.