表面裂纹在不同控制模式下的扩展特性

Propagation characteristics of surface crack controlled by different modes

在应变、载荷和位移三种控制模式下,采用Gross板状试样,研究了10CrNi5Mo高强钢在悬臂弯曲加载方式下低周疲劳表面裂纹扩展特性,研究结果表明:表面裂纹扩展速率d(2c)/dN在位移和载荷控制模式下差别不大,且都高于应变控制模式;三种控制模式都可以用裂纹前缘名义总应变范围ΔεT作为统一参量来描述表面裂纹疲劳扩展速率,且表达式与Paris公式类似,均满足幂函数规律;试验中通过不断调整载荷或位移的大小来保证应变恒定,会增加试验的操作难度和工作强度。

The propagation characteristics of low cycle fatigue surface crack of high strength steel 10CrNiSMo was studied using Gross plate specimen under three control modes, strain, loading and displacement, at cantilever bend. The results indicated that the surface crack growth rate d（2c）/dN under displacement and loading control modes had no obvious difference and beth of them were faster than that of strain control mode. The results also indicated that the nominal total strain range of the surface crack lip △εT could be used as a uniform parameter to describe the fatigue propagation of surface crack in these three control modes, and the expression is similar as Paris power function law. However, it would increase operational difficulty and work intensity if using the method of adjusting load or displacement to maintain strain constant.