Abstract: In order to study dynamic fracture properties and failure mechanism of HTPB propellant under impact loading conditions，a dynamic fracture experiment was carried out by using the cracked straight-through Brazilian disc （CSTBD） specimen on the split Hopkinson pressure bar（SHPB），and the mode Ⅰ dynamic initiation fracture toughness of HTPB propellant under high strain rate were obtained. The fracture surface microscopic pattern was observed by SEM，and by means of fractal geometry method，the fractal box dimension of the fracture surface was calculated. Experimental results indicate that proposed dynamic fracture testing for HTPB propellant is effective. The dynamic initiation fracture toughness is obviously sensitive to strain rate，and its value increases linearly with the loading rate increasing in the strain rate range of 400～1100s-1. The propellant presents brittle fracture property of a particle breakage and transgranular fracture mode under high strain rate，and the higher the strain rate，the greater the fractal box dimension is greater，and the degree of particle breakage is more serious. The stain rate sensitivity of the dynamic fracture toughness of solid propellant is validated in microscopic view.

Key words: Propellant；Brazilian disc；Dynamic fracture；Strain；Dynamic test

摘要： 为研究HTPB推进剂在冲击载荷作用下的动态断裂特性与破坏机理，使用中心直裂纹圆盘试件，在分离式Hopkinson压杆实验系统上开展了推进剂动态断裂实验，得到了高应变率下HTPB推进剂的Ⅰ型动态起裂韧性值，利用扫描电镜观察了推进剂的断面形貌，并使用分形几何方法计算了断面分形盒维数。结果表明:本文的实验方法是有效的，推进剂的动态起裂韧性具有明显的应变率敏感性，在应变率400～1100s-1范围内，其值随着加载速率的增加呈现线性增长的关系；推进剂在高应变率条件下呈现颗粒破碎、穿晶断裂等脆性断裂特性，应变率越高，推进剂断面的分形盒维数越大，推进剂的颗粒破碎程度越严重，从微观层面验证了推进剂断裂韧性的应变率敏感性。

关键词: 推进剂；圆盘；动态断裂；应变；动态实验