纤维复合材料界面横向拉伸分析

Transverse tensile analysis of interface in fiber composites

以单纤维十字型横向拉伸试验为研究对象,对纤维/基体界面采用弹性-软化双线性内聚力模型,建立了纤维复合材料在横向拉伸作用下界面法向失效过程的解析模型。得到了沿纤维/基体圆周界面的法向应力分布,纤维/基体界面的状态与界面承载力和单纤维复合材料承载力的关系,以及内聚力参数和试件几何尺寸对它们的影响。结果表明:纤维/基体圆周界面在脱粘前经历全部弹性及弹性+软化两种状态;当界面为弹性状态时,界面法向应力随界面强度线性增加;当界面为弹性+软化状态时,界面软化范围随界面裂纹萌生位移的增加而增大;界面初始脱粘位置与拉伸荷载方向重合;界面初始脱粘时的界面承载力随界面强度及界面裂纹萌生位移的增加而增加,随界面裂纹生成位移的增加而降低;单纤维复合材料的脱粘荷载受基体截面尺寸的影响,当纤维体积含量相同时,沿荷载方向截面尺寸的增大对提高脱粘荷载更显著。

The single-fiber composite model for the cruciform specimen test under transverses tensile loading is studied analytically in the paper.A cohesive zone model governed by the elastic-softening bilinear law and described the fiber/matrix interface is used to simulate the interfacial normal behavior during the loading.The interfacial normal stresses distribution at fiber/matrix interface,the relationship between circular interfacial states and the transverse load,the bearing capacity of the single fiber composite under transverse tension,and the effects of cohesive zone parameters are determined.The results indicate that the interface along the circumference experiences both the all elastic state and the elastic+softening state before debonding;the interfacial normal stresses increase linearly with the interface normal strength at interfacial elastic state,the softening range of the circumference interface increases with the interface crack initiation displacement at interfacial elastic+softening state,the initial interfacial debonding location coincides with the direction of tensile load;the interface bearing capacity at initial interfacial debonding increases with the interface normal strength and interface crack initiation displacement,and decreases with the interface crack generation displacement;the debonding load on the cruciform specimen is influenced by the size of the matrix section,the increase of the section size along the load direction is more inclined to increase the debonding load when the volume content of the fiber is fixed.