Abstract: In order to investigate the dynamic fracture characteristics of the composite modified double-base propellant (CMDB) under impact loading，impact fracture experiments were performed on the split Hopkinson pressure bar (SHPB) device，and the reliability of the experimental data was verified. Moreover，a numerical analysis was conducted to verify the experimental data，and the dynamic fracture toughness of CMDB propellant was obtained. The fractured CMDB specimens were investigated by using Scanning Electron Microscope (SEM). It is found that the CMDB propellant is a significant loading rate sensitivity material within the range of normalized loading rates from 58906MPa·m1/2·s-1 to 100056 MPa·m1/2·s-1. However，as the loading rate increase to 105000 MPa·m1/2·s-1，the dynamic fracture toughness of CMDB propellant does not continue to increase，but decrease. SEM?analysis?shows that the loading rate sensitivity of CMDB propellant is directly related to the microstructure failure mechanism of ammonium perchlorate (AP) particles.

Key words: Composite modified double-base propellant；SHPB；Loading rate sensitivity；SEM

摘要： 为研究改性双基推进剂(CMDB)的动态断裂特性，利用霍普金森实验技术(SHPB)对CMDB推进剂进行了冲击实验，并对实验数据的可靠性进行了校验；通过数值仿真的方法进一步验证了实验数据的有效性，获得了CMDB推进剂的动态断裂韧性；利用电镜扫描技术对试件断面进行了微观表征和分析。结果表明:CMDB推进剂在加载率58906～ 100056MPa·m1/2·s-1范围内，表现出明显的加载率敏感性；加载率达到105000 MPa·m1/2·s-1左右时，断裂韧性不再继续增大，反而出现下降趋势；电镜分析结果表明，CMDB推进剂加载率敏感性与其内部高氯酸铵(AP)颗粒的微观破坏机理直接相关。

关键词: 改性双基推进剂; 霍普金森实验；加载率敏感性；电镜扫描