基于原位拉伸的HTPB推进剂多尺度损伤演化分析

Multi⁃scale Damage Evolution Analysis of HTPB Propellant Based on In⁃situ Stretching

作为由填料和基体混合而成的复合材料,端羟基聚丁二烯(HTPB)推进剂的损伤主要涉及颗粒的破碎、基体的断裂以及粘结界面层的脱粘,为进一步探究其在外载作用下结构损伤和力学性能的演变,通过微CT、高速CCD相机,以及全原子分子动力学模拟,实现原位加载下推进剂多尺度损伤分析。结果表明,推进剂典型损伤过程起始于粘结界面层破坏,扩展于脱粘孔隙的增长,演化于孔隙的合并,加速于局部大变形的汇集,终止于基体的断裂;界面结合能和应力集中程度使得大粒径高氯酸铵(AP)颗粒最先脱粘,且孔隙率与应变呈现类指数函数关系;微观界面层牵引⁃分离曲线符合指数型内聚力模型,微观空隙的萌生与扩展破坏了其内聚性,而分子间距则影响了应力的演变。

As a composite material composed of fillers and matrix,the damage of hydroxylated polybutadiene(HTPB)propellant mainly involves particle breakage,matrix fracture,and debonding of the bonding interface layer.To further explore its structural damage and mechanical performance evolution under external loading,a combination of micro CT,high⁃speed CCD camera,and all atom molecular dynamics simulation was used to analyze the multi⁃scale damage of the propellant under in⁃situ loading.The results indicate that the typical damage process of the propellant begins with the failure of the bonding interface layer,ex⁃tends to the growth of debonding pores,evolves through the merging of pores,accelerates the collection of local large deforma⁃tions,and terminates at the fracture of the matrix.Meanwhile,the interface binding energy and stress concentration degree cause the large ammonium perchlorate(AP)particles to debond first,and the porosity and strain exhibit an exponential function relationship.Furthermore,the traction separation curve of the micro interface layer conforms to an exponential cohesive force model,where the initiation and expansion of micro voids disrupt their cohesion,while the molecular spacing affects the evolu⁃tion of stress.