基于内聚裂纹模型的高聚物粘结炸药模拟材料动态巴西实验的数值模拟

高聚物粘结炸药(PBX)是战斗部的关键组成部分,其动态力学行为,特别是动态断裂特性关系到战斗部的安全性和使用可靠性。基于内聚裂纹模型,对PBX模拟材料(PBX-M)的动态巴西实验进行数值模拟,对比霍普金森杆实验中测得的拉伸应力曲线,以及高速摄像结合数字图像相关方法得到的试样表面位移场和应变场。对比结果发现,拉伸应力峰值的数值模拟结果比实验结果小约5%,拉应变集中带的数值模拟结果与实验结果的偏差小于15%,验证了内聚裂纹模型的有效性。根据数值模拟结果,探讨了PBX-M试样在动态巴西实验过程中的起裂和裂纹扩展规律,给出了裂纹宽度的定量化信息。

Numerical Simulation of Dynamic Brazilian Test of Polymer Bonded Explosive Simulant Based on Cohesive Crack Model

Polymer bonded explosive (PBX) is the key component of warhead. The dynamic behaviors of PBX, especially dynamic fracture behavior, are crucial issues on the safety and reliability of warhead. By introducing cohesive crack model (CCM), the dynamic explicit software LS-DYNA is used to simulate the dynamic Brazilian experiment on polymer bonded explosive simulant (PBX-M). By comparing with time history of tensile stress obtained by the strain gauge glued on the Hopkinson bar, the displacement fields and strain fields obtained by digital image correlation and high-speed camera, it is found that the tensile stress peak value obtained by numerical simulation is 5% smaller than the experimental result, and the deviation of the concentration zone of tensile strain from experimental data is less than 15%. Thus the validity of CCM is confirmed. The law of crack initiation and propagation of PBX-M sample during dynamic Brazilian experiment is studied from the results of numerical simulation. The quantitative information about crack width in sample is given.