纳米纤维增强闭孔泡沫材料的力学性能

为研究纳米纤维增强闭孔泡沫材料的力学性能,采用Voronoi随机泡沫模型对闭孔泡沫材料的细观几何结构进行模拟,并将纳米纤维随机分布在泡沫材料的胞壁中,利用改进的自动搜索耦合(ASC)技术将纤维单元与基体单元进行耦合,建立了能够反映纳米纤维增强闭孔泡沫材料细观结构的数值模型。在此基础上,进一步研究了泡沫模型随机度、相对密度以及纳米纤维长径比和质量分数对纳米纤维增强闭孔泡沫材料弹性模量与屈服强度的影响规律。结果表明:由所建立的数值模型得到的纳米纤维增强闭孔泡沫材料的弹性模量和屈服强度与实验值吻合较好;提高泡沫模型的随机度会使复合泡沫材料的弹性模量和屈服强度增加,而当随机度达到0.450以后,材料的弹性模量和屈服强度几乎不再发生变化;当相对密度在0.05~0.30范围内变化时,复合泡沫材料的弹性模量与屈服强度几乎随相对密度的增加呈线性增长;提高纳米纤维长径比和质量分数也会使材料的弹性模量和屈服强度得到提高,但当纤维长径比达到500以后,纤维长径比的增强作用逐渐减弱。所得结论对纳米纤维增强闭孔泡沫材料的制备具有重要意义。

Mechanical properties of nanofiber-reinforced closed-cell foams

In order to investigate the mechanical properties of nanofiber-reinforced closed-cell foams, the micro-geometry structures of closed-cell foams were simulated by Voronoi random foam model, and nanofiber was distributed in cell walls of foams randomly, fiber nodes and matrix nodes were coupled by the improved automatic search coupling (ASC) technology, thus the numerical model which can reflect the micro-structures of nanofiber-reinforced closed-cell foams was established. On the basis, the influence rules of random level of foam model, relative density as well as aspect ratio and mass fraction of nanofiber on elastic modulus and yield strength of nanofiber-reinforced closed-cell foams were investigated further. The results show that the elastic modulus and yield strength of nanofiber-reinforced closed-cell foams obtained by the numerical model established agree well with the experimental values. The increase for random degree of foam model will enhance the elastic modulus and yield strength of composite foams, while after the random degree reaches 0.450, the elastic modulus and yield strength of the materials change little. When the relative density changing in the range of 0.05-0.30, the elastic modulus and yield strength of composite foams almost increase linearly with the increase of relative density. The elastic modulus and yield strength of the materials can also be enhanced by increase the aspect ratio and mass fraction of nanofiber, while the strengthening effect of fiber aspect ratio gradually weakens after fiber aspect ratio achieves 500. The conclusions obtained have significance for the preparation of nanofiber-reinforced closed-cell foams.