HTPB推进剂蠕变本构方程研究

Investigation on constitutive equations of HTPB-based solid propellant grain creeping

固体火箭发动机立式贮存时,药柱在长期的自重载荷作用下,产生蠕变变形,结构上表现为药柱向尾部下沉,从而影响发动机结构完整性甚至内弹道性能。利用某HTPB推进剂试件在0.4、0.5、0.6、0.7 MPa应力水平条件下的蠕变试验数据,针对幂律模型、指数模型、有理式模型等12种蠕变模型开展研究,确定了适用于该配方HTPB推进剂的蠕变本构方程。结果表明,HTPB推进剂的蠕变过程符合蠕变一般规律;幂律类蠕变本构方程、复合时间硬化蠕变本构方程和广义时间硬化蠕变本构方程均可整体描述HTPB推进剂的蠕变过程,其中复合时间硬化蠕变本构方程的拟合结果与试验数据间误差最小;幂律类蠕变本构方程的拟合曲线与试验曲线在各应力水平都具有较好的一致性,且形式简单、处理方便,可在初步分析或特定应力水平下使用。

During vertical storage of solid rocket motor,creep deformation of the grain resulting from long-term gravity load lead to the grain sinking to the tail structurally,and disturbing the structural integrity and the interior ballistic performance of SRM.Creep test data of HTPB propellant specimen under stress levels such as 0.4 MPa,0.5 MPa,0.6 MPa and 0.7 MPa was used to analyze 12 creep models such as power law model,exponential model and rational model,and the creep constitutive equation applicable to HTPB propellant was determined.The results show that the creep process of HTPB propellant conforms to the general creep law and is described by the power law creep constitutive equation,the combined time hardening creep constitutive equation and the generalized time hardening creep constitutive equation.The fitting results of the combined time hardening creep constitutive equation have the least error with the test data.The fitting curves of power law creep constitutive equations have good consistency with the test curves at all stress levels,which can be used in preliminary analysis or under specific stress levels.