基于宏—细观模型的疲劳裂纹萌生数值模拟

为了研究材料微观特性对结构疲劳寿命的影响,提高结构疲劳寿命预估精度,根据Tanaka-Mura单一微裂纹及裂尖微裂纹萌生寿命预测模型,模拟疲劳载荷下某马氏体钢孔边疲劳裂纹萌生寿命。利用泰森多边形生成法,生成代表多晶结构的二维特征单元。考虑晶粒内相互垂直的多滑移特性以及已起裂裂纹对相邻晶粒裂纹萌生的影响,建立微裂纹起裂与扩展的改进模型。中心孔平板试件疲劳寿命的数值模拟结果与试验值吻合良好,说明给出的改进宏细观疲劳寿命预测模型的有效性。

NUMERICAL SIMULATION OF FATIGUE CRACK INITIATION BASED ON MACRO-MICRO MODELS

To study the influence of material microcosmic character to the structure fatigu e life,and improve the fatigue life estimation precision,the initiation life o f fatigue cracks in the edge of a martensitic steel hole under cycle fatigue loa ding,is simulated based on the Tanaka-Mura single micro-crack and micro-crac k from notches nucleation models.A two-dimensional representative element of po lycrystalline material is generated using a Voronoi tessellation process.Conside ring the vertical multiple slip bands and the influence of previous cracks to ne w cracks initiation in neighbouring grains,the improved micro-crack generation and propagation model is constructed.Compared with the testing data of center h ole flat specimens,the numerical simulation result agree well with the experime ntal one,which demonstrates the validity of the presented macro-micro fatigue crack initiation simulation model.