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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。
In order to study the dynamic fracture behavior and failure mechanism of HTPB propellants under impact loading, a dynamic crack test of propellant was carried out on a split Hopkinson pressure bar experimental system using a centrally-cracked disk specimen. The experimental results show that under high strain rate Type Ⅰ dynamic fracture toughness of HTPB propellants. The cross section morphology of the propellants was observed by scanning electron microscopy. Fractal geometry fractal dimension was calculated by fractal geometry method. The results show that the experimental method in this paper is effective. The dynamic fracture toughness of propellants has obvious strain rate sensitivity. The linear increase of the value of the propellants shows a linear increase with the loading rate in the range of strain rate of 400 ~ 1100s-1 . The propellants showed brittle fracture characteristics such as grain breakage and transgranular fracture under the condition of high strain rate. The higher the strain rate, the larger the fractal box dimension of the propellant section and the more serious the particle breakage of the propellant. From the microscopic level Strain rate sensitivity of propellants to fracture toughness.