Based on the aircraft structure fatigue theory , the article discussed the theoretical basis of methods that are usually used for aircraft structure fatigue crack - forming life estimation , i . e . the stress severity factor approach ( normal stress approach ) , the local stress & strain approach , detail fatigue rating approach ( dfr ) . also the processes of life estimation of these approaches are studied in the article 文章在简要介绍飞机结构疲劳强度理论的基础上，对目前飞机结构劳疲劳裂纹形成寿命估算常用的应力严重系数法(名义应力法) ，局部应力应变法，细节疲劳额定值dfr法的理论依据作了较详细的论述，同时对这些估算方法进行寿命估算的过程与步骤也作了详尽的阐述。
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