固体推进剂黏弹性参数的确定及细观损伤演化

On the Determination of Viscoelastic Model Parameters and Microstructural Damage Evolution of Solid Propellants

固体推进剂力学模型参数的准确性对其宏观力学响应预测具有重要的意义,为解耦标定固体推进剂非线性黏弹性模型参数,提出一种基于台阶应力松弛试验的模型参数确定方法。通过台阶应力松弛平衡响应确定固体推进剂弹性部分参数,通过小变形下的应力松弛确定无量纲松弛模量,分析一种固体推进剂力学响应。研究结果表明:固体推进剂在台阶应力松弛及单轴拉伸条件下的力学性能预测结果与试验结果吻合,验证了所提方法的有效性;由于平衡响应包含损伤,采用该方法标定的参数可用于预测含损伤固体推进剂力学响应。在此基础上,提出一种基于推进剂模型参数标定等效黏合剂力学参数的方法,并通过引入基于黏弹性脱湿准则的相界面模型建立代表性体积单元计算模型,实现在宽应变(~100%)范围内推进剂脱湿损伤分析,为推进剂宏观力学性能预测及细观损伤演化分析提供了支撑。

Accurately determining the model parameters of solid propellant is of great importance for the prediction of its macroscopic mechanical response.A parameter determination method based on multi-step stress relaxation experiments is proposed to calibrate the nonlinear viscoelastic model parameters of solid propellants uncoupled.The proposed method determines the parameters for the elastic part by multi-step stress relaxation equilibrium response and the dimensionless relaxation modulus by stress relaxation in the case of small deformation.The proposed method is then used to analyze the mechanical response of solid propellants.The results show that the predicted results of multi-step stress relaxation and uniaxial tension under different strain rates of the material agree with the experimental results,which verifies the validity of the proposed method.Moreover,since the equilibrium response includes damage,the parameters calibrated by the proposed method can be used to predict the mechanical response of solid propellant with damage.Consequently,the parameters of the composite matrix are derived from the determined parameters of solid propellant,and a viscoelastic debonding criterion-based interface model is introduced to establish a representative volume element(RVE)model,thus achieving the interface debonding analysis in a wide range of strain(~100%),which provides an effective method supporting the prediction of mechanical response and microstructural damage evolution of solid propellants.