基于疲劳裂纹形成曲线的裂纹扩展分析数值方法

通过损伤力学将裂纹形成与裂纹扩展两个过程有机结合在一起。根据裂纹形成阶段的疲劳曲线,获取损伤演化方程中的材质参量,通过损伤力学—有限元法,确定了裂纹扩展阶段中裂纹尺寸与载荷循环次数之间的关系,从而将裂纹萌生与扩展由当作两个独立过程纳入一个统一的理论体系。因此,在裂纹形成与裂纹扩展两阶段的任一试验数据已知的情况下,均可根据损伤力学—有限元法获取另一阶段数据,这就大大减少试验数量,并可弥补试验手册数据的不足。

NUMERICAL METHOD FOR CRACK EXTENSION ANALYSIS BASED ON FATIGUE CRACK FORMATION CURVE

Two phases, fatigue crack initiation and extension, are rightly associated by damage mechanics method. Based on material parameters in the damage evolution equation computed by means of fatigue curve in the crack initiation process, the relation between crack length and fatigue life in the crack ex-tension process may be obtained by the damage mechan-ics-finite element method. The above two phases being sepa-rately dealt in existing researches are brought into a uniform theoretical frame. By the damage mechanics-finite element method, if one of two sets of test data in crack initiation process and crack extension process is known, another one is acquired. Then, the work of test to obtain fatigue properties are reduced and the handbook of material behavior would be complemented by additional data computed by this method.