关于裂纹扩展速率测度中几个问题的分析

本文疲劳试验表明．在疲劳裂纹扩展过程中，试件表面和内部裂纹扩展情况不同，其 本质是扩展速率不等，不是滞后问题，由表面与内部裂纹长度的差别而引起的k误差不可 忽视。本文提出了对表面直读法的修正公式和修正方法．最后讨论了直三点弯曲试件在da／ dN测试中裂纹长度的合理取值范围。

About Analysis of Several Guestions in the Rate of Crackle Spread Tested

This paper pointed out that the time lag in not the reason but the different extending speed is the essential reason of different crack extending conditions of both surface and internal crack in certain samples while the different reasons of crack development in the surface or internal crack of samples were carefully analysce. It also concluded that the errors in K due to the differ-ent length of the surface orinternal crack were not negligible. Corrections must be made on direct reading method. Methods and formulae of corrections were tabulated. They are simple and easy to hand. Fi-nally the reasonable limits of the Crack length adopted in da/dN measuerment of a stright three points bending sample were discussed.