多重双尺度法在含界面层纳米碳管增强复合材料力学性能分析中的应用

The application of multiple two-scale method on the analysis of mechanical properties of nano-composites with interface layer

运用多重双尺度法分析了含界面层纳米碳管增强复合材料的力学性质。首先利用分子结构力学导出纳米框架结构的有效力学性质,取纳米分子结构中的框架结构为特征单元体,用一次均质化理论得到纳米碳管的有效弹性模量,将该纳米碳管等效为连续空心圆筒,与损伤界面组成新的特征单元体再进行第二次均匀化得到新的增强体,计算过程中在界面与基体交界处引入过渡的粘接单元描述可能出现的界面脱粘过程,最后将新增强体和基体组成的特征体积单元进行第三次均匀化得到纳米碳管增强复合材料的有效力学性质,分析了界面特性对宏观有效力学性能的影响。数值结果表明,界面层长厚比及界面层杨氏模量的变化对碳纳米管增强复合材料的弹性模量影响较大,界面相的存在不容忽视。所得结果与经典的Mori-Tanaka法和Halpin-Tsai法进行比较,取得了较好的一致性,验证了多重双尺度法的有效性。

The multiple two-scale homogenization method is applied to calculate the effective mechanical properties of nano-tube-composites with interface in this paper.First,the effective mechanical properties of nano-frame are obtained by the molecular structure mechanics,and the two-scale homogenization method is applied to get the effective elastic modulus of nano-tube,which is equivalent as a continuum hollow fiber.Then the new homogenized reinforcement phase is obtained by homogenizing the equivalent fiber and damaged interface,and the cohesive zone element is applied to model the debonding interface.Finally,the effective elastic properties of nano-composites are obtained by homogenizing the obtained reinforcement phase and matrix.The effects of interface on macroscopic mechanical properties are analyzed.The results show that the ratio of length-thickness and Young＇s modulus of interface have a significant influence on the mechanical properties of nano-tube composites,and the effect of the interface can not be neglected.The obtained results are compared well with those from Mori-Tanaka and Halpin-Tsai,showing the proposed method is practicable.