复合固体推进剂脱湿过程细观建模与损伤定量表征

Meso-modeling and damage quantitative characterization of dewetting process in composite solid propellant

复合固体推进剂脱湿涉及导弹武器的贮存和使用情况。针对复合固体推进剂脱湿过程细观建模与损伤定量表征开展研究。首先为研究复合固体推进剂在外界载荷作用下的细观损伤演化规律,基于随机序列吸附法、热膨胀原理和分步填充的思想,实现了高体积分数颗粒填充,并通过几何合并的方式,加入粘合剂基体和颗粒/基体界面,建立了高体积分数固体推进剂三维细观结构模型。该细观几何模型将固体氧化剂(AP)颗粒与羟基封端的聚丁二烯(HTPB)粘合剂基体的连接界面处设定为内聚力单元,基于双线性损伤内聚力模型,考虑粘合剂基体与时间相关的粘弹特性,开展了不同应变率下固体推进剂的颗粒/基体界面脱湿数值模拟。提取内聚力界面单元高斯积分点的几何体积和刚度衰减率SDEG数据,定义固体推进剂材料内部脱湿面积,对其细观损伤进行了定量表征。结果表明,该三维细观结构模型能有效表征固体推进剂的细观结构。在外界载荷作用下,颗粒/基体界面脱湿容易出现在大颗粒及颗粒比较密集的区域,界面损伤导致颗粒承载能力下降,且应变率越高,推进剂内部越容易出现损伤。

Dewetting of composite solid propellant potentially appears in storage stage or use of missile weapons.In this paper,the main purpose was to study the meso-modeling damage evolution of interface dewetting in composite solid propellant based on meso-modeling and damage quantitative characterization.Firstly,in order to study the meso-damage evolution law of composite solid propellants under external loads,a particle filling model with high volume fraction was proposed by using the methods of the random sequence adsorption,the thermal expansion principle,and the idea of step-by-step filling.Next,the binder matrix and the particle/matrix interface were added by geometric merging to establish a three-dimensional meso-structure model of solid propellant.The interfaces between ammonium perchlorate(AP)particles and hydroxyl-terminated poly-butadiene(HTPB)matrix were set to cohesive element with meso-geometric model.Based on the bilinear damage cohesion model and considering the time-dependent viscoelastic properties of the matrix material,numerical simulations were carried out to investigate the interface dewetting in solid propellant under different strain rates.Based on the volume of interface cohesive element and the data of scalar stiffness degradation(SDEG),the internal dewetting area in meso-structure model of solid propellant was defined to character the meso-damage quantitatively.The results show that the three-dimensional meso-structure model can effectively character the meso-structure of solid propellants.Interface dewetting is more likely to occur in areas near large particles or with concentrated distribution of particles.Interface damage leads to a decrease of material carrying capacity.With a higher strain rate,the material is more likely to be damaged with a decrease of modulus.