碳纳米管增强Nb-Si基复合材料界面应力传递的研究

Study on interfacial stress transfer in Nb-Si matrix composites strengthened with carbon nanotubes

基于均匀化理论,建立了碳纳米管增强Nb-Si基复合材料的代表体积元模型,并采用剪切滞后模型对碳纳米管增强Nb-Si基复合材料界面上的应力分布和传递机制进行了研究,探讨了分子间作用力、杨氏模量比β、长径比α、体积分数?等对其应力分布和传递机制的影响。结果表明,复合材料界面应力分布的变化主要集中在碳纳米管的两端,最大的应力都是分布在加载端或拔出端,然后向另一端传递;分子间作用力、杨氏模量比、长径比、体积分数等参数对界面应力的传递均有一定的影响,其中长径比和体积分数的影响最明显,体积分数为0.02时拔出端的界面剪切应力值相对于体积分数为0.0025时增大幅度达到近7倍,而长径比从200减小到50时,其应力传递距离增大了近8倍。

Based on homogenization theory,the representative volume element(RVE)of carbon nanotubes reinforced Nb-Si matrix composites is established.The stress distribution and transfer properties between carbon nanotubes and matrix in the Nb-Si matrix composites are theoretically studied by shear-lag model.Effects of van der Waals force,Young’s modulus ratioβ,aspect ratioαand volume fraction?on the stress distribution are discussed.Results show that the change of interfacial stress distribution of the composites mainly is concentrated on the two ends of carbon nanotubes.The maximum stress at the interface between the nanotubes and matrix is distributed at the loading end or pullout end of carbon nanotubes,and then is transfered to the other end.The parameters of van der Waals forces,Young’s modulus ratio,aspect ratio and volume fraction have influences on interfacial stress transfer,and among them,effects of aspectratio and volume fraction are the most obvious.When the volume fraction is 2%,the interface shear stress increases nearly 7 times,and the stress transfer distance increases nearly 8 times when the aspect ratio decreases to 50.