升温和降温引起TATB基PBX炸药脱黏的数值分析

Numerical Analysis on Debonding of Crystal⁃Binder Interface in TATB⁃Based Polymer⁃Bonded Explosive Caused by Heating and Cooling Processes

高聚物黏结炸药(polymer⁃bonded explosive,PBX)是含能颗粒与黏结剂组成的、具有微结构的非均质材料.热力环境下,PBX出现损伤是由晶粒与黏结剂及其界面的力学性能导致的.基于Voronoi理论与Monte Carlo的级配思想,建立了五种晶粒体积分数的PBX二维几何模型.考虑温度变化对晶粒和黏结剂热力学特性的影响,引入双线性本构模型描述晶粒⁃黏结剂界面的力学性质.数值研究了升温和降温过程PBX界面损伤机理.结果表明,升温时主要由较大的界面切向应力使得界面出现脱黏,降温时界面上的法向拉应力是界面脱黏的主要因素.相较升温阶段,降温过程更易产生界面脱黏,符合实验观察的结果.随着炸药晶粒体积分数的增加,降温后界面的残余刚度更大,表明提高PBX晶粒体积分数有助于降低界面脱黏.当晶粒体积分数越相近时,各晶粒粒径越趋于一致,则在界面上的损伤程度就越小.

Polymer⁃bonded explosive(PBX)is a kind of heterogeneous material composed of energetic crystals and binder as a microstructure.The mechanical properties of crystals,binder layers and the crystal⁃binder interface under thermomechanical environment are the main fac⁃tors on PBX damages.Based on the Voronoi theory and the Monte Carlo gradation thought,a 2D geometric model for PBX was established with 5 different crystal volume fractions.With the influence of temperature change on the thermodynamic properties of the crystals and binder,a bilinear cohesive contact relationship model was introduced to describe the mechanical proper⁃ties of the crystal⁃binder interface,and the damage mechanism of PBX interface during the heating and cooling processes was analyzed numerically.The results show that,the interface tangential stress increases with the temperature,which leads to debonding of the interface.The debonding of the crystal⁃binder interface mainly depends on the interface normal stress at a de⁃creased temperature.Compared with the heating process,the cooling process makes interface debonding easier to occur,in agreement with experimental observations.With the increase of the crystal volume fraction,the residual stiffness of interface after the cooling process goes higher,which means that the increase of the PBX crystal volume fraction is helpful to control interfacial debonding.With the same crystal volume fraction,the more uniform the crystal sizes are,the smaller the interfacial damage degree will be.