考虑界面过渡层的编织CMC裂尖混合度的研究

FRACTURE MODE MIXING AT THE TIP OF CRACKS OF 3D BRAIDED CMC ON THE INTERPHASE

对于界面断裂的三维编织CMC,其断裂混合度Ψ对材料的断裂韧性影响显著。尽管由于一个不确定的参量——断裂特征长度,界面断裂混合度几乎难以确定,但是与界面断裂混合度相关的裂纹尖端断裂混合度Ψtip可以唯一确定。这样,就可以用裂纹尖端断裂混合度Ψtip研究三维编织CMC的断裂韧性。本文通过数值方法分析了倾斜角度、界面层厚度与混合度的关系,进一步研究了三维编织CMC的裂纹扩展路径对于裂尖混合度的影响,为材料断裂韧性的优化设计提供了依据。

For 3D braided CMC owing to interfacial fracture, it is remarkable that interfacial fracture mode mixing Ψ works on the material fracture toughness. Although the interfacial fracture mode mixing can hardly be determined because its expression involves an uncertain parameterfracture length eigenvalue, the fracture mode mixing at the tip of crack Ψtip, which correlates with Ψ, can be decided uniquely. So the fracture toughness of 3D braided CMC material can be researched on interfacial cracks with Ψtip. By numerical simulation, this paper analyses the relation of the mixing Ψtip with the declining angle and interfacial thickness, further researches the influence of the 3D braided CMC's cracks path on the mixing Ψtip, and finds a way of fracture design of 3D braided CMC. 