应变率与相对密度对聚氨酯泡沫压缩力学行为的影响

The Effect of Strain Rate and Relative Density in the Compressive Behavior of Polyurethane Foams

采用三种加载设备（万能材料实验机、冲击落锤和霍普金森压杆）对三种相对密度的聚氨酯泡沫进行了广泛应变率条件下（10-3～103 s-1）的单轴压缩实验.实验结果表明：相对密度是影响聚氨酯泡沫等效力学行为（弹性模量、初始屈服强度、塑性坍塌强度）的主导因素;且聚氨酯泡沫的力学行为具有明显的应变率效应.同时,基于实验结果分析了应变率效应产生的原因.此外,结合实验结果和一个考虑了相对密度和应变率对塑性坍塌强度复合效应的理论模型,量化了上述两个重要参数对塑性坍塌强度的影响.

The compressive behavior of polyurethane foams with three different relative densities had been inves- tigated experimentally over a wide range of the strain rates by using three loading methods, i.e. universal material testing machine, drop weight, Split Hopkinson Pressure Bars. The experimental results show that the elastic modu- lus, the initial yield stress and the plateau stress are remarkable dependent on strain rate and relative density. Base on the experimental results, the mechanism of strain rate effect is analysed systematically. A theoretical model was proposed to predict the material＇s plateau stress as a function of the strain rate and relative density. The capability of the theoretical model was examined bY simulating the compressive behavior of polyurethane foams over a wide range of the strain rates.