MDYB-3有机玻璃在不同应变率下的一维屈服行为

对MDYB-3有机玻璃进行了多组不同应变率(10-3~3 000 s-1)下的压缩实验, 得到准静态下的屈服应力与动态下的峰值应力。沿其增强与面内2个方向进行准静态压缩实验, 以分析定向拉伸对屈服应力的影响, 修正了Ree-Eyring模型与Cooperative模型以描述定向有机玻璃的屈服行为。采用Johnson-Cook模型描述屈服后的黏塑性行为。结果表明Cooperative屈服模型比Ree-Eyring屈服模型更接近实验结果, 且能准确描述准静态屈服应力。动态压缩下的峰值应力为失效应力, 说明试样在1 500 s-1以上应变率下未达到屈服应力时已经发生破坏。Johnson-Cook模型对于单条曲线拟合良好, 但无法准确描述材料的应变率相关性。

One-dimensional yield behavior of MDYB-3 polymethyl methacrylate at different strain rates

Several groups of compression tests at different strain rates(10-3~3 000 s-1)are carried out for MDYB-3 polymethyl methacrylate.Yield stress in the quasi-static tests and peak stress in the dynamic tests are obtained.Compression tests are performed along normal direction and parallel directions of samples to analyze the effect of orientation stretching on yield stress.Ree-Eyring model and Cooperative model are revised to describe the yield behavior of directional PMMA.Viscoplastic behaviors after yield are attempted to be described using Johnson-Cook model.The results of Cooperative yield model are shown to be closer to the test results than those of Ree-Eyring yield model.Cooperative yield model can describe the yield stress of quasi-static tests accurately.Peak stress in dynamic compression test is failure stress, which means that samples fail before yield at the strain rate above 1 500 s-1.The fitting results reveal that Johnson-Cook model can describe a single stress-strain curve well, but it cannot predict the dependence of strain rate.