固体推进剂黏弹性本构模型及其有限元应用研究

Study on viscoelastic constitutive model of solid propellant and its implementation in finite element method

基于时温等效原理和WLF方程建立推进剂黏弹性泊松比主曲线方程,进而建立考虑时间温度相关泊松比的推进剂本构模型。基于增量有限元方法,采用完全显式积分算法推导增量形式的黏弹性本构方程。根据MSC. Marc用户子程序编程规则,确定本构模型对应的一致切线刚度矩阵从而实现本构模型的有限元应用。先后通过固化降温以及点火增压工况,分别采用黏弹性泊松比以及弹性泊松比对药柱结构进行应力应变力学响应分析,并对比不同类型泊松比对应力应变场的影响。研究方法和结果可为发动机药柱的精细结构完整性分析提供参考。

The viscoelastic Poisson′s ration master curve of solid propellant was established on the basis of the time-temperature equivalence principle and WLF equation,and then the viscoelastic constitutive model of solid propellant was proposed.The viscoelastic constitutive model in incremental form was deduced on the basis of the incremental finite element method and by adopting the fully explicit integration method.The constitutive model was realized in finite element software by using the consistent tangent stiffness acquired according to the programming rules of user subroutine in MSC.Marc.The stress-strain mechanical response of solid propellant grains was analyzed by using the viscoelastic and the elastic Poisson′s ration under solidification process and ignition pressurization process.Furthermore,the effects of different kind of Poisson′s rations on the stress-strain field were compared.The method and result can provide a reference for the structural integrity analysis of engine grain.