中文摘要：

向日葵髓芯是一种天然的高分子泡沫材料。文中通过扫描电子显微镜（SEM）和光学显微镜,研究了一种具有复合结构的向日葵髓芯的胞体形态结构,并结合胞体可能的堆砌模式,得出这种天然泡沫体的单元胞体的立体形状基本上是十四面体。探讨了胞体形状对泡沫材料的压缩变形机制,以及压缩杨氏模量和压缩屈服强度的影响,并对其原因作了进一步的分析。研究结果表明,胞体形状的变化,即由比较规则的十四面体逐渐变为伸长的十四面体,是引起泡沫材料在拉长方向的压缩杨氏模量比其它大3-4倍,压缩屈服强度大2倍以上的主要原因。

英文摘要：

The pith of sunflowers is a kind of natural cellular material. In this paper, through scanning electron microscope （SEM） and optical microscope, a sunflower＇s pith with compound structure and morphology was studied. The single cell shape deduced is a tetrakaidehedron. The compressive yield stress and modulus of the pith of the sunflower were tested. The effects of the cell shapes and structures of the pith on their mechanics properties and deformation mechanisms on compress have been studied and discussions about their reasons are made on the basis of the different models The results show that the change of cell shape, from a normal tetrakaidehedron to the elongated one, is the main reason why the compressive modulus in the elongated direction increases 3 to 4 times than others, and the compressive yield stress over 2 times.