循环加载下复合推进剂的非线性热粘弹性本构模型

A nonlinear thermo-viscoelastic constitutive model of composite solid propellant under cyclic loading

复合推进剂在动态加载下伴随着自热效应,即存在明显的温度升高现象。为了定量描述这种热力耦合特性,基于不可逆热力学理论建立了非线性热粘弹性本构模型和相应的数值算法,编写了基于Abaqus的用户子程序,并通过实验验证了数值算法的正确性。研究结果发现,非线性本构模型成功地描述了复合推进剂在不同加载模式下的非线性力学行为和自热效应,自热效应对复合推进剂的力学行为有着直接影响,与不考虑自热效应相比,循环加载下应力-应变滞回圈的斜率降低显著,表明力学性能已受到自身温度升高的影响。结果表明,考虑自热效应的热力耦合本构模型能更准确地描述复合推进剂的循环力学行为,滞回圈的形状与实验结果更为吻合,斜率误差在10%以内。

The composite propellant not only exhibits nonlinear mechanical properties under dynamic loading,but also has a self-heating effect,there exists obvious temperature rise phenomena.In order to quantitatively describe the thermo-mechanical coupling characteristics,a nonlinear thermo-viscoelastic constitutive model and corresponding numerical algorithm were established based on the irreversible thermodynamic theory.A user subroutine based on Abaqus was compiled,and the correctness of the numerical algorithm was verified by experiments.The results show that the nonlinear constitutive model successfully describes the nonlinear mechanical behavior and self-heating effect of the composite propellant under different loading modes.The self-heating effect has a direct impact on the mechanical behaviors of the composite propellant.Without considering the self-heating effect,the slope of the stress-strain hysteresis loop under cyclic loading is significantly reduced,indicating that the mechanical properties have been affected by temperature rise.The thermal-mechanical coupling constitutive model considering the self-heating effect can be more accurately describe the cyclic behaviors of composite propellant.The shape of the hysteresis loop is more consistent with the experimental results,and the slope error is within 10%.