一种新的Ⅰ型分层裂纹桥联模型

An Improved Fiber-Bridged Model of Mode I Crack in the Fiber Direction of Fiber-Reinforced Composites

以往针对复合材料层间 I型裂纹的桥联模型 ,假设裂纹面上下平行。这与真实情况是不相符的。在考虑裂纹面不平行这一因素后 ,给出了一种新的桥联模型。还通过对桥联纤维附着力与桥联纤维轴向力大小的比较分析 ,将前者合理地舍去 ,使模型的表达得到简化。由计算结果的对比可以看出 。

When the mode I interlamina fracture occurs in fiber reinforced composites, a lot of bridging fibers between upper and lower crack faces may appear which make composites′ fracture toughness high. In studying this phenomenon, it is very important to establish the relation between the fiber bridging force f d and the crack opening displacement u . In the old model mentioned in Ref., it is supposed that the upper and lower crack faces are parallel to each other, which is not in agreement with the true situation. In this paper, we give an improved model (Eq.(18)). Compared with the old one, the new model includes two amendments: (1) the unparallel of crack faces is considered; (2) bridging fibers′ adhesive force P b is omitted, for it is too small compared with bridging fibers′ axial tension force P t (P b/P t≈10 -8 ). The new model is simple in mathematic form, and calculations (see Fig.4, Fig.5) indicate that the amendments are very necessary especially when the crack opening angle α increases.