Abstract: To get lower limitation of modified double-base propellant’s fracture energy，a series of uniaxial tensile experiments under different tensile rates were conducted with standard dumbbell specimen(SDS)，compact tension specimen(CTS) and double edge notched specimen (DENS). The experiment results show that the relationship between force and displacement reflects different failure modes of three kinds of specimens，and the failure modes determine the way to get lower limitation of modified double-base propellant’s fracture energy. Fracture energy density rises sharply at first and then rises slowly and tends to a stable value along with the increase of tensile rates. The fracture energy density of CTS and DENS is lower than that of SDS significantly. When the tensile rate is less than 200 mm/min，CTS’s fracture energy density is lower than that of DENS，and the gap reduces with the increase of tensile rates，thus，the fracture energy density of CTS can be used as the lower limitation of modified double-base propellant’s fracture energy. When the tensile rate is greater than 200 mm/min，CTS and DENS have almost equal fracture energy density，so the fracture energy density of anyone of these two specimens can be regard as the lower limitation of modified double-base propellant’s fracture energy.

Key words: Modified double-base propellant；Fracture energy density；Lower limitation of fracture energy；Acquisition method

摘要： 为获得改性双基推进剂断裂能下限值，使用标准哑铃型试件、紧密拉伸试件和双边切口试件进行了不同拉伸速率下的单轴拉伸实验。实验结果表明:力与位移之间的关系可以反映三种试件失效形式的不同，失效形式决定了推进剂断裂能下限的获取方法。断裂能密度随拉伸速率的增大呈现出先急速上升后缓慢上升最终趋于稳定的过程。紧密拉伸试件和双边切口试件的断裂能密度明显低于标准哑铃型试件；当拉伸速率<200mm/min时，紧密拉伸试件的断裂能密度小于双边切口试件，随着拉伸速率的增大，两者的差距越来越小，可将紧密拉伸试件的断裂能密度作为改性双基推进剂断裂能下限；当拉伸速率>200mm/min时，紧密拉伸试件和双边切口试件的断裂能密度几乎相等，两种试件获得的断裂能密度均可作为改性双基推进剂断裂能下限。

关键词: 改性双基推进剂；断裂能密度；断裂能下限；获取方法