疲劳裂纹扩展行为的跨尺度分析方法  

MULTISCALING ANALYSIS APPROACH OF FATIGUE CRACK GROWTH BEHAVIOR

作　　者：唐雪松[1] 赵小鹏[1] 

机构地区：[1]长沙理工大学土木与建筑学院力学系,湖南长沙410114

出　　处：《工程力学》2012年第10期20-26,共7页Engineering Mechanics

基　　金：教育部博士点专项基金项目(200805360002)

摘　　要：该文以跨尺度应变能密度因子作为裂纹扩展的控制参量,建立了跨尺度疲劳裂纹扩展模型。疲劳破坏全过程可用该模型进行统一描述,而不必划分成疲劳裂纹形成与扩展两个不同阶段,采用不同的理论分别进行分析。以LY12铝合金板为例,采用上述模型,精确拟合出不同循环特征下的S-N试验曲线。当考虑材料微结构的影响时,疲劳试验数据的发散性也可拟合出来。研究表明:材料初始缺陷及微结构在疲劳过程中的演化特性,对于构件的疲劳寿命有显著影响,是疲劳试验数据发散的主要原因。By taking the dual-scale strain energy density factor as controlling quantity,a multiscaling fatigue crack growth model is developed in this work.Hence,the whole fatigue failure process can be depicted in a consistent way by applying the proposed model.It no longer needs dividing a fatigue process into two different stages of fatigue crack initiation and propagation described by different approaches as usual.Then,the experimental S-N curves for different cyclic stress ratios are exactly re-produced by the proposed model.When the effects of material micro-structure are taken into account,the discrete fatigue test data can be re-produced.The results indicate that the size of initial micro-defects as well as the different evolution modes of material micro-structure have a pronounced influence on the fatigue life of specimens.The microscopic effect is a main reason of the scatter of fatigue test data.

关 键 词：疲劳裂纹扩展 S-N曲线 铝合金板 跨尺度裂纹模型 约束应力区 材料微结构参数 

分 类 号：O346.1[理学—固体力学]