复合固体推进剂“脱湿”点的率相关特性研究

Study on Rate-Dependent Characteristics of“Dewetting”Point of Composite Solid Propellant

复合固体推进剂颗粒和基体之间的界面“脱湿”是推进剂在加载过程中一种重要的损伤形式,“脱湿”点的强度和伸长率均与载荷相关。本文通过某推进剂在低温、不同围压和应变率下加载时的应力-应变响应曲线特征,发现推进剂的“脱湿”点表现出明显的率相关和围压相关性,围压载荷会抑制推进剂的“脱湿”,尤其是对于高应变率下具有“脱湿”点峰值的应力-应变曲线影响最大。针对推进剂“脱湿”点的率相关特征,借助分子动力学思想创建复合推进剂的细观颗粒夹杂几何模型,建立推进剂有限元计算细观模型对推进剂界面在不同应变率下的“脱湿”损伤进行了仿真计算。计算结果揭示了推进剂在不同应变率下加载时的“脱湿”损伤机理,通过应变率对“脱湿”点的影响规律阐释了推进剂在低温、高应变率下伸长率骤降的主要原因,发现推进剂的破坏取决于损伤界面数量和界面损伤程度在损伤演化过程中的交互作用,是一个动态发展的过程。

“Dewetting”can happen between solid particles and matrix of solid propellant during loading process.The strength and elongation at“dewetting”point are directly related to loads.The study based on the stress-strain response curve characteristics of a propellant under low temperature,different superimposed pressures and strain rates,the“dewetting”point of the propellant has shown obvious rate and superimposed pressure correlation,and the superimposed pressure load would inhibit“dewetting”,especially can influence the stress-strain curve with peak value of“dewetting”point at high strain rate.In order to obtain the rate-related characteristics of the“dewetting”point of the propellant,the mesoscale geometric particle inclusion model of the composite propellant is obtained based on the idea of molecular dynamics method,the mesoscale finite element model is created to calculate the“dewetting”damage of solid propellant under different strain rates.Finally,the damage mechanism of propellant“dewetting”under different strain rates is revealed,and the main reason of abruptly decrease of elongation of propellant at low temperature and high strain rate is explained by the influence rule of strain rate on“dewetting”point.It is found that the propellant failure depends on the interaction of the number of damage interfaces and the degree of interface damage in the process of damage evolution,which is a dynamic process.