基于控制参数△K_q的短裂纹扩展特性研究

Analysis of the Behaviour of Short Crack Growth Based on △k_q Parameter

本文提出了一种新的短裂纹扩展控制参数，即修正后的△Ｋ＿ｑ值。在△Ｋ＿ｑ计算式中，考虑了塑性区尺寸大小以及表面边界质量、微观组织、裂纹长度等作用因素的影响，并认为在裂纹扩展过程中，这个影响值是变化的。△Ｋ＿ｑ值可以被用来描述裂纹形成后的整个裂纹扩展过程，并能利用此参数在长裂纹的扩展结果基础上预测短裂纹的扩展，较方便地计算出整个裂纹的扩展寿命。文中还用２Ｇ２５和Ｅ级钢的试验验证了该参数的合理性和实用性。

A new control parameter △Kq to short the crack growth is put forward,In the compute of △Kq value the various affected factors,e. g. plastic zone size,surface quality,micro structure,crack length, etc. ,are consldered. Tbe effects of factors on △Kq are thought changeable in the process of the crack propagation.The △Kq cau be used to descrlbe the whole crack growth after crack emergence and predict the growth rate and the fatig ue life of short crack depended on the result of large crack growth.Tbe short crack growth experiments of ZG25 and E steel show that the △Kq parameter is rational and praetical.