Abstract: In order to study and simulate the CMDB propellant fracture properties under quasi-static conditions， a three-dimensional model of a flatten disc with an embedded straight through crack was established based on the extended finite element(XEFM)technique. Based on linear visco-elastic theory， the maximum tensile stress 8.21MPa of the CMDB propellant through uniaxial tensile test was obtained directly， to be as the fracture strength of the cohesive zone.The crack propagation process of the solid propellant under static loading conditions was simulated. The crack propagated in mode-I firstly and then in mixed-mode in the solid propellant specimen that were found in both experimental and simulation results. The influence of the changing stress along crack path was analyzed. The numerical simulation results show a good agreement with the experiment results. The results suggest that the XFEM technique provides a new method to simulate the CMDB propellant fracture process.

Key words: Solid propellant；XFEM；Linear visco-elastic；Mixed-mode fracture

摘要： 为研究和模拟改性双基推进剂(CMDB)在准静态条件下的断裂特性，利用扩展有限元XFEM技术，建立了中心直裂缝含加载平台的圆盘形三维模型。基于线粘弹性理论，通过单轴拉伸实验直接获取改性双基推进剂的最大拉应力8.21MPa，作为仿真模型中裂纹粘聚区的断裂强度，模拟了固体推进剂在静态加载条件下裂纹实时扩展过程。结果表明实验和仿真过程中裂纹均首先呈I型扩展，最后以复合断裂形式扩展失效。讨论了推进剂在压缩断裂过程中裂纹扩展区的应力变化对裂纹扩展的影响，发现实验预期结果与仿真结果符合性良好，说明扩展有限元法能够为改性双基推进剂断裂过程的数值模拟提供新的方法。

关键词: 固体推进剂; 扩展有限元；线粘弹性；复合断裂