摘要
断裂韧度 K_(IC)值是工程结构材料的重要性能指标。而对于 K_(IC)<25MN·m^(-3/2)的材料,很难按照常规方法预制疲劳裂纹。其原因是,疲劳载荷较小时裂纹不能引发,而载荷稍大则容易导致失稳扩展,使试样报废。另外,对这些较脆的材料如采用常规方法,即使勉强预制出疲劳裂纹,其裂纹前缘线也很不清晰,甚至根本看不见,这给随后的数据处理带来困难。为此。
This paper describes a new method of fatigue precracking for brittle mate-rials and the corresponding Ioading device.Using this method,it is realizedthat the stress in tensity factor K_f_(mar)at crack tip decreases automaticalywith the increase of crack length.The unstability of crack can be controlled and the crack length preset can beobtained by properly selecting loading parameters.There are some advantagesfor the method that the shape of sample is simple,ending length of fatigueprecracking can be chosen and can be limited automatically,unstable crackingcan not be generated and finishing line of crack is quite clear.The loadingdevice is easy to operate and reliable.This new method opens up a new wayfor fatigue precracking for brittle materials.
关键词
脆性材料
疲劳
裂纹
预制
Fatigue precracking
brittle material
stress intensity factor
