复合固体推进剂细观结构建模及脱黏过程数值模拟

为研究复合固体推进剂损伤演化规律,基于分子动力学颗粒填充算法构建了HTPB(hydroxyl terminated polybutadiene)推进剂细观结构模型,通过在AP(ammonium perchlorate)颗粒/HTPB基体界面处引入黏接接触替代传统的黏接单元,并基于Hooke Jeeves的参数优化算法反演得到颗粒/基体界面处内聚力模型参数,利用双线性和自定义指数型损伤内聚力模型模拟了AP颗粒和HTPB基体黏接界面处损伤的萌生、发展、聚合直至宏观裂纹破坏的过程。通过数值仿真与实验结果对比发现,指数型损伤内聚力模型比双线性模型能更准确描述推进剂单轴拉伸过程中颗粒与HTPB基体界面间脱黏过程。最后对比了多阶段加载实验结果与仿真结果曲线,发现两者变化趋势基本一致,最大偏差仅为10%,验证了所建细观模型的可靠性及反演所得界面参数的准确性。 

Mesoscopic structure modeling and numerical simulation of debonding process of composite solid propellants

To study the damage evolution law of composite solid propellants, the mesoscopic structure model for HTPB(hydroxyl terminated polybutadiene) propellants was established based on the molecular dynamics particle filled algorithm. The adhesive contact method was employed for the adhesion interface between AP(ammonium perchlorate) particle and HTPB matrix, instead of the traditional cohesive element method, and the Hooke Jeeves optimization algorithm was used to identify the parameters of cohesive zone model of the particles/matrix interface. Then both bilinear cohesive zone model and the self defined exponential cohesive zone model were employed to simulate the damage evolution process for the interface of AP particle and HTPB matrix, including the initiation, development, gathering and macroscopic crack. The numerical simulation curves and experimental curves were compared, showing that the exponential cohesive zone model can better describe the debonding process between the AP particles and HTPB matrix under the uniaxial tension loading. Finally, the multi stage loading experiment was compared with the simulation curve. It was found that the change trend was consistent and the tolerance was less than 10%, demonstrating the high reliability of mesoscopic model and the interface parameters accuracy.