考虑粘弹性泊松比的固体推进剂蠕变型本构模型

Creep constitutive model of the solid propellants considering the viscoelastic Poisson’s ratio

在粘弹性材料中,泊松比是时间和温度相关的函数。提出了一种新的考虑时间和温度相关泊松比的推进剂蠕变型本构模型。为了建立合适的本构模型,采用拉普拉斯变换方法对经典蠕变型本构模型进行了改进,将时间无关的弹性泊松比变换成时间相关的粘弹性泊松比。基于时温等效原理,将泊松比的时间和温度相关特性利用WLF方程进行建立联系。基于蠕变型本构模型的增量形式将该模型开发到有限元程序MSC.MARC中。针对星孔发动机点火增压工况进行了结构完整性分析。仿真结果表明,粘弹性泊松比对结构的应力应变影响介于初始和平衡泊松比对结构分析的影响之间。并且该蠕变型本构模型与松弛型本构模型的分析结果一致。

Poisson’s ratio is the function of the time and temperature in the viscoelastic materials.In this paper,a new creep constitutive model has been proposed considering the time- and temperature-dependent Poisson’s ratio.The traditional creep constitutive equation is modified based on the Laplace transformation and the time-independent Poisson’s ratio has been replaced by the time-dependent one.WLF equation is utilized to connect the time and temperature dependence of the Poisson's ratio based on the time temperature equivalence principle.The incremental form of the model are used to the implementation in the FEM software MSC.MARC.The ignition pressurization loading case are conducted on the star grain solid rocket motor.The simulation results show that the effect of the viscoelastic Poisson's ratio on the stress and strain response fall in between the initial and equilibrium Poisson’s ratio.In addition,the response results from creep and relaxation constitutive models are consistent.