基于三维细观结构的PBX炸药的损伤机理

为了解细观结构差异和热力作用对高聚物黏结炸药(polymer bonded explosives, PBX)损伤的影响,采用Voronoi方法建立三维细观模型,并考虑颗粒的弹塑性和黏结剂的弹黏塑性以及界面内聚力本构关系,分析不同细观结构PBX在热力载荷下的损伤演化机理。结果表明升温不易造成界面的损伤,降温时收缩率较小的黏结剂对颗粒的收缩有阻碍,导致界面间法向拉应力增大,易造成界面损伤。提高黏结剂含量,有利于减小降温时界面的损伤程度。当黏结剂含量相近时,颗粒粒径越趋于一致,界面损伤程度越小。在低压作用下,损伤由法向应力导致转为由切向应力导致,损伤程度减小,但当压力过大时界面产生新的损伤。

Damage mechanism of PBX explosives based on three-dimensional meso-structure

In order to understand the influence of microstructure difference and thermal effect on the damage of PBX, a three-dimensional meso model is established using Voronoi method. The damage mechanism of PBX with different microstructure under thermal load is analyzed by considering the elasto-plastic properties of particles, the elasto-viscoplastic properties of binder and the interfacial cohesion constitutive relationship. The results show that the interface is not easy to be damaged when the temperature rises, but the binder with small shrinkage hinders the shrinkage of particles when the temperature decreases, resulting in the increase of the normal tensile stress between the interfaces, which is easy to cause interface damage. Increasing the content of binder is beneficial to reducing the damage of interface during cooling. When the binder content is similar, the more uniform the particle size is, the smaller the interfacial damage is. Under the action of low pressure, the damage changes from normal stress to tangential stress, and the damage decreases. However, when the pressure is too high, new damage occurs at the interface.