聚氨酯泡沫塑料拉伸本构关系及其失效机理的研究

INVESTIGATION INTO THE TENSILE CONSTITUTIVE RELATION AND FAILURE MECHANISM OF PUR FOAMED PLASTICS

通过 3种密度硬质聚氨酯泡沫塑料的拉伸实验 ,研究了它们的应力 -应变特性及其应变率效应。同时 ,为确定泡沫塑料拉伸失效机理 ,对材料进行了扫描电镜下的细观拉伸实验 ,观察了试件表面胞体的变形与失效过程 ,再结合宏观拉伸试件断口的扫描电镜分析 ,进一步讨论了泡沫塑料在拉伸加载下的失效机理。基于泡沫塑料的拉伸应力 -应变曲线 ,用数值方法拟合了泡沫塑料的拉伸本构关系。

The stress strain characteristics and strain rate effect of PUR foamed plastics are investigated by tensile experiments for three kinds of densities. In the meantime, in order to determine the tensile failure mechanism of foamed plastics, microscopic tensile tests were conducted in the observing room of a scanning electronic microscopy. The tensile failure mechanism of foamed plastics is discussed on the basis of observing the deformation and failure course of cells on the surface of a tensile specimen and the SEM analysis of fracture surface of tensile specimens. Finally, the tensile constitutive relation is fitted by the numerical method according to the tensile stress strain curves of PUR foamed plastics, which agrees well with the experimental curves.