三维编织CMC断裂韧性表征形式的试验研究

Experimental Investigation on Token Method of Fracture Toughness for 3D Braided CMC

在试验的基础上 ,发现三维编织陶瓷基复合材料断裂试件的裂纹扩展沿着编织角方向进行 ,表现出一种非自相似的裂纹扩展模式 ,表明三维编织CMC的断裂是复合型断裂。利用材料的载荷 -位移曲线和声发射技术 ,分析了三维编织CMC在外载荷作用下的损伤行为和断裂机理 ,并且根据不同的外载荷类型 ,将三维编织CMC的断裂韧性表征分别界定在线弹性和弹塑性的两个领域里 。

In this paper, an experimental investigation to discuss the problem of token method of fracture toughness is presented. It is found that cracks come into being on a direction of the material braided angle, and extends along the angle. Obviously , it is a type of mixed fracture mode no matter what modes of exterior load. Based on the load displacement curves and with the help of acoustic emission technology (AE), the mechanical character of 3D braided CMC on the condition of bending load and tensile load, including fracture mechanism and damage behaviors, can be understood. Then the token method of fracture toughness is divided into two fields by mode of load: elasticity and plasticity. So, the macro mechanics expressions of the mixed fracture toughness for 3D braided CMC can be given. And energy release rate G of material also can be determined by flexibility method in test.