高应变率下航空透明聚氨酯的动态本构模型

采用低阻抗分离式霍普金森压杆对航空透明聚氨酯进行了高应变率下的动态力学性能测试，得到的应力应变曲线表现出了显著的非线性黏弹性特征。基于本构理论和实验数据，构建了航空透明聚氨酯的松弛时间应变相关的超黏弹性本构形式。该本构模型由2部分组成:一部分表征准静态下的超弹性行为，另一部分描述非线性应变率的相关特性。利用超黏弹性本构模型对不同应变率下航空透明聚氨酯的动态应力应变曲线进行拟合，拟合曲线与实验曲线一致性良好。

Constitutive model of transparent aviation polyurethane at high strain rates

The uniaxial compressive properties of aviation polyurethane were investigated experimentally by using a modified aluminum split Hopkinson pressure bar apparatus. The obtained stress-strain curves presented distinct non-linear viscoelastic characteristic.Based on the constitutive theory and the experimental data, a hyper-viscoelastic constitutive model that incorporated a strain-dependent relaxation time was proposed to describe the large compressive deformation response of incompressible aviation polyurethane at high strain rates. The proposed model was made up of two parallel mechanical elements-one component to characterize quasi-static hyperelastic behavior, and the other to define rate-sensitivity and strain history dependence. The predictions of the mechanical behavior using a hyper-viscoelastic constitutive model based on strain energy functions and hereditary approach had a good agreement with experimental results.