碳化硅与聚脲纳米复合材料拉伸力学性能和本构模型

Polyurea, as a coating or sandwich material, can be used to improve the protective performance of target structure in the fields of blast and impact. In order to study the tensile mechanical properties and constitutive model of SiC/polyurea nanocomposites, an universal testing machine and split Hopkinson tensile bar (SHTB) apparatus were used in quasi-static and dynamic tests, respectively. The true stress-true strain curves of specimens were obtained in the range of low strain rates (0.001-0.1 s^-1) and high strain rates (1 260-4 500 s^-1). The effects of strain rate hardening and nano SiC on the mechanical properties of the specimens were discussed. A constitutive model with strain rate effect was constructed based on the hyperelastic theory. The experimental results show that the higher the strain rate is, the greater the flow stress of specimen is, the test specimens show obvious strain rate effects under dynamic loading, and the mechanical characters are enhanced by adding nano SiC into pure polyurea. The relation between the flow stress and the logarithm of relative strain rate is basically linear. The simulation on the dynamic tensile mechanical properties of polyurea shows that the simulated results are in good agreement with the test results, which verifies the accuracy of the stress-strain results in tensile test. Finally, the fitting results of constitutive model are in good agreement with the test results. This indicates that the constitutive model can better describe the tensile mechanical behavior.