HTPB推进剂装药蠕变行为及影响因素

Creep Behavior and Influence Factors of HTPB Propellant Grain

为研究HTPB固体推进剂装药长期自重载荷下的蠕变规律,获取影响立式贮存装药应力、应变及位移变化的主要参数,开展了低应力水平推进剂试件蠕变试验,获取蠕变过程应变—时间曲线;考虑推进剂材料和装药载荷等参数的不确定性,开展老化不同时间的固体推进剂装药在固化降温、不同时长重力和内压载荷联合作用下的蒙特卡洛随机有限元分析,获取各参数对蠕变结果的重要度变化规律。结果表明,Norton本构方程与试验结果在低应力水平下一致性较高,平均相对误差小于5%;装药在长期自重下会产生蠕变,随立式贮存次数的增加,装药应力逐渐减小,位移和应变逐渐增大;卧式贮存10年时,应变与固化降温初始结果相差不足2%,位移仅增加16.3%,同等条件下,立式贮存发动机应变和位移分别增加了75%和110%,考虑老化因素时,应变进一步增加;影响蠕变结果的各因素重要度与老化时间和立式贮存次数密切相关,发动机立贮20次时,质量m、模量E、泊松比v平均重要度分别为0.58、0.16和0.1。

To study the creep rules of HTPB propellant grain during long-time self weight load,and acquire the main parameters influencing the stress,strain and displacement of motor under vertical storage,the propellant specimen creep tests at low stress level were carried out,and the strain—time curves during creep process were obtained.Considering the uncertainty of propellant materials and grain loadings,the stochastic finite element analysis of propellant grain after different aging times under the combined action of solidification cooling,different storage time of weight load and inner pressure load was conducted based on the Monte Carlo method,and the variation of the importance of all parameters to the creep results were obtained.The results illustrate that Norton constitutive equation possesses highly consistency with creep test results at low stress level,the average relative error is less than 5%;the grain produces creep behavior with long-time self weight load,and the stress of grain decreases gradually with vertical storage times,while the strain and displacement increase;the difference between the strain and initial results of solidification cooling is less than 2%under horizontal storage for 10 years,the displacement only increases by 16.3%,while the strain and displacement of vertical storage increase by 75%and 110%,respectively under the same condition,the strain further increases when considering aging.Meanwhile,the degree of importance of all parameters on creep results change with aging time and vertical storage times,the average importance of mass(m),modulus(E),Poisson′s ratio(v)are 0.58,0.16,and 0.1 when the motor is vertical stored for 20 times.