单轴拉伸下PVDF/POSS纳米复合材料的损伤模拟

目的研究PVDF及其氟化POSS纳米复合材料在单轴拉伸载荷下的损伤行为。方法首先依据实验结果和细观力学均匀化方法,建立纯PVDF和三种不同POSS含量PVDF/POSS纳米复合材料的颗粒掺杂有限元模型,并通过在实体单元之间嵌入可破坏的内聚力单元来模拟损伤。结果模拟得到的应力-应变关系与实验结果相吻合,证明了模拟结果的可靠性。损伤破坏的初始时间表明在破坏的初期阶段,POSS对于损伤有抑制作用,并且其效果随着POSS含量的增加而增强。损伤速度和最终的损伤面积和则表明质量分数在5%以下的POSS掺杂对于PVDF的损伤有抑制作用,并且随着POSS质量分数的增加其效果不断增强。当质量分数达到8%时,POSS的掺杂反而加速了PVDF的损伤。结论 POSS掺杂影响PVDF的损伤破坏,掺杂量对PVDF损伤破坏有抑制/促进作用,这一结果有助于理解实验所得到的力学参数的变化规律。

Finite Element Simulations of Damage Behaviors of PVDF/POSS Nanocomposites under Uniaxial Tensile Loads

Objective To study the damage behaviors of PVDF and its fluorinated POSS nanocomposites under uniaxial tensile loads. Methods The particle-mixed finite element models of neat PVDF and three kinds of PVDF/ POSS nanocomposites with different POSS contents were firstly built according to the experimental results and the homogenization method in the mesoscopic mechanics. Then the damage behaviors were simulated after inserting the destructible cohesive elements into the solid elements. Results The simulated stress-strain relationships were in good agreement with the experimental results, which proved that the simulations in this article were reliable. The starting time of the damage revealed that at the initial stage the POSS was able to restrain the damage and the effect became obvious when the POSS content increased. And the final damage areas and the damage speed showed that the POSS would restrain the damage when its content was below 5%. In this case, the restraining effect was even stronger when the POSS content was increasing. However, the addition of POSS would accelerate the damage speed when the POSS content reached to 8% . Conclusion Doped POSS influences the damage of PVDF, the doping amount has the inhibition/ promotion effect on damage and failure of PVDF. These results are very helpful to understand the variation rules of the mechanical properties observed in the experiments.