高温低周疲劳短裂纹萌生的数值模拟  

Numerical Simulation of Low-Cycle Short Fatigue Crack Initiation at High Temperature

作　　者：王正[1] 谭伟同[1] 王璐[1] 陈楠[1] 

机构地区：[1]大连理工大学能源与动力学院,大连116023

出　　处：《机械工程材料》2014年第3期90-95,共6页Materials For Mechanical Engineering

基　　金：国家自然科学基金资助项目(50771024)

摘　　要：基于大量的高温低周疲劳试验,编写Matlab程序修正voronoi多边形模拟了20钢表面的显微组织;用有限元软件计算得到了不同试验条件下试样表面的应力、应变状态;以基础能量表征晶界及滑移带抵抗裂纹萌生的能力,改进位错累积理论并计算获得了裂纹的萌生寿命,实现了对低碳钢高温低周疲劳短裂纹萌生的数值模拟。结果表明:在高温下,疲劳短裂纹主要萌生于应力集中处的驻留滑移带及不稳定晶界上,受表面显微组织的影响,既有沿晶萌生又有穿晶萌生;修正的voronoi多边形很好地反映了表面显微组织,数值模拟能够准确再现不同循环次数下疲劳短裂纹的群体萌生行为。Based on lots of low-cycle fatigue experiments of 20 steel at high temperature, surfacial microstructure of the steel was simulated by voronoi-polygen modified by writing Matlah program, and then, the stress and strain state on sample surface under different test conditions were calculated using ANSYS software. The numerical simulation for shor fatigue crack of low carbon steel at high temperature was achieved by the following： using basic energy to characteristic grain boudaries and the ability of slip band resisting crack initiation, and modifying dislocation pile-up theory and then obtain initiation life of crack by calculation. The results show that shor fatigue cracks mainly initiated from persistent slip band and unstable grain boudaries, the cracks exhibited both intergranular and transgranular initiation affected by surfacial microstructure. The modified voronoi-polugen could reflect surfacial microstructure well, and the numerical simulation could accurately reproduce the group initiation behavior of shor fatigue cracks at different cycles

关 键 词：高温 低周疲劳 短裂纹 萌生寿命 数值模拟 

分 类 号：TK05[动力工程及工程热物理] TG115[金属学及工艺—物理冶金]