摘要
基于材料低周疲劳临界损伤,采用应变幅和平均应力定义了一种新的局部疲劳损伤参量,以最大主应变方向的垂直方向作为疲劳裂纹的扩展方向,提出了一种预测材料与结构裂纹在高周疲劳下疲劳裂纹扩展速率的数值模拟新方法:LFF方法(LCF-Low Cycle Fatigue+FCP-Fatigue Crack Propagation+FEA-Finite Element Analysis)。借助有限元分析商业软件,开发了一套命令流程序实现了数值模拟算法,得到裂纹扩展方向上裂尖塑性区域各节点的应力-应变幅,获得每个节点的损伤参数,进而根据疲劳裂纹非连续扩展特性建立疲劳裂纹扩展模型。以大型汽轮机转子材料Cr2Ni2MoV钢为例,通过光滑单轴试样及紧凑拉伸试样试验分别得到了室温低周疲劳临界损伤模型和裂纹扩展模型,即Manson-Coffin模型和Paris模型,结果表明LFF方法对Cr2Ni2MoV材料复杂裂纹的疲劳裂纹扩展过程有较好模拟精度。
Based on low cycle fatigue critical damage behavior of materials, a numerical simulation method used to predict fatigue crack propagation behavior of materials and structures was presented, and this new method is named as LFF （LCF-Low Cycle Fatigue＋FCP-Fatigue Crack Propagation ＋FEA-Finite Element Analysis）. For LFF method, a set of ANSYS command streams for the numerical simulation algorithm were developed to determine the stress and strain amplitude of nodes located at the plastic zone in the direction of crack propagation and fatigue damage of these nodes can be obtained, furtherly, the fatigue crack propagation prediction can be realized by discontinuous crack propagation assumption. For steam turbine rotor material： Cr2Ni2MoV steel, Manson-Coffin critical damage model and Paris crack propagation model of Cr2Ni2MoV steel were obtained by tests on smooth uniaxial specimens and CT （compact tensile） specimens at room temperature respectively. Results show that LFF method has better accuracy to predict fatigue crack propagation behavior of complicated cracks of CT specimens.
出处
《工程力学》
EI
CSCD
北大核心
2011年第10期202-208,共7页
Engineering Mechanics
基金
西南交通大学中央高校基本科研业务费专项资金项目(SWJTU09ZT35)
