论文部分内容阅读
一、前言复合材料不仅在刚度和强度方面具有强烈的各向异性,而且其断裂韧度也具有明显的各向异性。就是说,材料对不同方向上的裂纹扩展具有不同的抵抗阻力。裂纹倾向于顺纤维方向扩展,而不易在垂直纤维方向上扩展。很多作者对单向复合材料中的裂纹扩展问题进行了研究。Ashby和Maiti对平行纤维与垂直纤维的两种不同裂纹方向的Ⅰ型断裂韧度进行了分析,对这两种断裂韧度大小作了比较。这对认识复合材料断裂韧度的各向异性性质是很有意义的。但是,在他们的分析与给出的表达式中存在明显的问题。本研究报告针对这个问题给出简单的分析与推导,得到了不同的表达式。由本文公式进行的预测结果与实验结果符合较好。
I. Introduction Composite materials not only have strong anisotropy in stiffness and strength, but also have obvious anisotropy in fracture toughness. That is, the material has different resistance to crack propagation in different directions. Cracks tend to propagate in the direction of the fiber, rather than in the direction of the vertical fiber. Many authors have studied the crack propagation in unidirectional composites. Ashby and Maiti analyzed the type I fracture toughness in two different crack orientations of parallel and perpendicular fibers and compared their fracture toughness. This is of great significance for understanding the anisotropic nature of composite fracture toughness. However, there are obvious problems in their analysis and given expressions. This research report gives a simple analysis and derivation of this problem and obtains different expressions. The results predicted by this paper are in good agreement with the experimental results.