Abstract: In order to describe the viscoelastic mechanical behavior of NEPE (Nitrate Ester Plasticized Polyether) propellant，the damage due to dewetting was introduced into linear viscoelastic constitutive model by the reduced time based on viscoelastic dewetting criteria and proposed time-damage superposition principle to establish the proposed nonlinear constitutive model that can reflect the effect of meso-structure change on macro mechanical behavior. Then，the necessary model parameters were obtained by combining numerical inversion technology with uniaxial tensile tests and relaxation tests of customized NEPE propellant under different temperatures (-50， -35， -20， 0， 20， 35 and 50°C) and strain levels (5%， 10%， 15%， 20%， 25% and 30%). Finally，the proposed nonlinear constitutive model was programmed through Matlab software and evaluated with constant rate tests. The predicted results well matched the measured ones. The difference between predicted values and experimental data is within the limits of 15%，which shows that the proposed nonlinear constitutive model is capable of describing the viscoelastic mechanical behavior of NEPE propellant within a certain range of strain rate(3.333×10-4～0.1s-1) and provides a simple means to predict the macroscopic mechanical behavior of solid propellant with complicated mesostructure.

Key words: NEPE composite propellant；Viscoelasticity；Particle dewetting；Time-damage superposition principle；Nonlinear viscoelastic constitutive model

摘要： 为了描述NEPE(Nitrate Ester Plasticized Polyether Propellant)复合固体推进剂的非线性粘弹性力学行为，基于粘弹性脱湿准则及所建立的粘弹性时间-损伤等效原理，将颗粒脱湿所造成的材料损伤以折算时间的形式引入至线性粘弹性本构关系中，从而建立起可考虑细观颗粒脱湿影响的NEPE复合固体推进剂非线性粘弹性本构模型。通过定制配方NEPE材料在不同温度(-50， -35， -20， 0， 20， 35及50°C)、不同应变水平(5%， 10%， 15%， 20%， 25%以及30%)的应力松弛试验及单轴拉伸试验，结合反演技术，获取了本构模型参数。最后利用Matlab软件平台实现了本构模型对于NEPE单轴拉伸力学行为的数值预测，数值计算结果与试验曲线较为吻合，预测数值与试验值差值在15%以内，说明所建本构模型能够较好地描述NEPE推进剂在一定应变率范围内(3.333×10-4～0.1s-1)的粘弹性力学行为，为预测具有复杂细观结构的复合固体推进剂的宏观力学行为提供了一条较为简单便利的实现方式。

关键词: NEPE复合固体推进剂；粘弹性；颗粒脱湿；时间-损伤等效原理；非线性粘弹性本构模型