小变形条件下聚合物本构关系研究

The constitutive relation of polymer research in the range of infinitesimal strain

通过两种工程塑料不同温度条件下的准静态和动态压缩试验,研究这两种工程塑料的应力应变特性。同时,为描述所研究聚合物在高温、高应变率下的应力-应变特性,基于Johnson-Cook本构模型,建立一种形式简洁、便于参数拟合的聚合物本构模型。分别利用聚甲醛和密胺树脂在准静态下和高应变率条件下的真应力-真应变曲线,对模型进行参数拟合和标定,结果表明:在高温、高应变率条件下,模型可以预测到5%应变以前的应力-应变关系,与聚合物力学性质符合率良好。

The stress-strain characteristics of poly formaldehyde and melamine resin are investigated by quasi-static and dynamic compression experiments. In the meantime, in order to describe the dynamic compression mechanical properties of the polymer, a type of polymer constitutive model which is simple in form and easy for parameter fitting, was proposed based on Johnson-Cook constitutive model. The true stress-true strain curves of poly formaldehyde and melamine resin under the condition of quasi-static and high strain rate were used for parameter fitting and to calibrate the new model. The results show that under the condition of high temperature as well as high strain rate, the new model can predict the stress-strain relationship before strain reaches 5%. The coincidence rate of the model and the polymer mechanical properties are good.