Through the calculation of amendatory stress intensity factors of the crack-tip under the condition of small scale yielding,the disadvantage of the method of equivalent crack length is found.

• 简要介绍了断裂力学的发展,通过在小范围屈服条件下裂纹尖端修正的应力强度因子的计算,发现用等效裂纹长度方法的不足。