Application of homogenization method on the analysis of micro-stress distributionin non-continuous carbon nanotube reinforced composites
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摘要: 利用具有精确周期性边界条件的均质化理论, 用宏微观有限元法分析了非连续碳纳米管呈规则和交错2 种排列情况下, 纳米管沿管长方向的应力分布规律。为保证传统的连续力学理论的适用性, 本文中的碳纳米管采用了用分子动力学方法简化的等效纤维模型。规则排列所得结果与应用Cox 剪滞理论及Lauke、Fu 等经典理论得出的结果比较发现: 除了经典理论中指出的碳纳米管长径比及纳米管体积含量2 个因素外, 纳米管形状及在基体中的排列方式对材料的力学性质也有较大影响。交错排列的纳米管在复合材料中有较高效率的应力转化和传递能力, 碳纳米管的端部间距(2 Tf ) 对应力的分布有较大的影响。结果显示出碳纳米管作为材料增强相的特殊性, 证明了均质化理论分析碳纳米管增强复合材料应力分布规律的可行性。
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关键词:
- 碳纳米管增强复合材料 /
- 均质化理论 /
- 应力分布 /
- 规则排列与交错排列
Abstract: The st ress dist ribution of non-continuous carbon nanotubes (CNTs) / polymer composites was analyzedusing the homogenization method with exact periodic boundary conditions , and the numerical calculations for regularand stagger array models were performed by the macro-microscopic finite element method ( FEM) . In order to utilizethe t raditional continuous mechanics approaches to determine the mechanical properties of CNTs composites , thecarbon nanotubes here were simplified as the effective fiber models which were obtained f rom the molecular dynamicssimulation. The result s obtained f rom regular array model were compared with those f rom Coxp shear-lag model ,Lauke and Fu theories , which show that the st resses t ransfer in CNTs composites are not only related to the aspectratio and volume f raction of CNTs as described in the above theories , but also sensitive to CNTs arrays and CNTspgeomet rical configuration within the selected representative volume element (RVE) . A better st ress t ransfer efficiency is obtained f rom stagger array , and the distance between two CNTs (2Tf ) has a great influence on the stressdist ribution. The result s show that there are some special characteristics for CNTs as the reinforcement phase ofcomposites , and they also prove that the homogenization method with multi-CNTs is efficient to analyze the st resst ransfer in CNTs composites. -
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