改性双基推进剂黏弹-黏塑性本构模型

Viscoelastic-viscoplastic constitutive model for modified double base propellant

为了表征改性双基推进剂的力学行为,推导出改性双基推进剂黏弹-黏塑性本构模型。利用一系列蠕变-回复试验,将材料的总应变分离为黏弹性应变和黏塑性应变,使用最小二乘法获得了黏弹性参数,使用Nelder-Mead单纯形优化算法,结合后向Euler数值方法获得了黏塑性参数。通过不同应力水平和不同加载时间的蠕变-回复试验对模型进行了验证,结果表明,在应力水平较低或加载时间较短的情况下,模型预测与试验值变化趋势基本一致,模型获得的黏弹性应变与黏塑性应变在总应变中所占的比例与试验吻合。改性双基推进剂黏弹-黏塑性本构模型能够在一定范围内描述材料的力学性能。

In order to characterize mechanical properties of modified double base propellant,a viscoelastic-viscoplastic constitutive model for modified double base propellant is developed.A series of creep-recovery tests is done to separate the total strain of material into viscoelastic strain and viscoplastic strain.The least square method is used to get viscoelastic parameters,and Nelder-Mead simplex optimization algorithm is combined with backward Euler method to get viscoplastic parameters.Creep-recovery tests under different stress levels and different loading times are conducted to verify the model.The results show that with lower stress levels or shorter loading time,the variation trend of model prediction is consistent with that of the test value,and the percentage of viscoelastic strain and viscoplastic strain in total strain obtained from model agree with that by test.It is concluded that the mechanical properties of the modified double base propellant can be described to some extent by the viscoelastic-viscoplastic constitutive model.