钛合金晶界变形损伤有限元仿真研究

Finite Element Simulation on Deformation and Damage of Grain Boundary in Titanium Alloy

为研究晶界的变形损伤过程,通过偏移钛合金真实组织中初生α相(αp)和转变β基体(βt)的界面,实现晶界的几何建模,建立包含晶界内聚力单元的真实组织有限元模型,模型预测与实验获得的TA15钛合金应力-应变曲线吻合良好。研究结果表明,晶界高应力单元的数量随变形量的增加而增加,晶界单元平均损伤特征值在宏观应变小于2%时迅速增加,在应变大于2%时增速趋于平缓。与理想αp相和βt基体界面结合相比,当宏观应变较小时,晶界内聚力单元应力不影响αp相和βt基体中应力分布;随宏观应变的增加,晶界高应力单元的损伤退化会导致αp相和βt基体中应力降低。

In order to analyze the deformation and damage of grain boundary,the real microstructure based finite element model including cohesive interface element was established by offsetting the boundary between primary αphase(αp) and transformed β matrix(βt) in the microstructure of titanium alloy.The simulated stress-strain curve is in good agreement with the experimental result.The results show that the amount of interface element with high stress increases with macroscopic deformation.The damage characteristic value of interface element increases rapidly when macroscopic strain is less than 2% and increase slowly when macroscopic strain is larger than 2%.Compare with the result of model with ideal grain boundary,the interface elements have no effect on the stress in αp and βt when macroscopic strain is small.However,damage of interface elements leads to stress decrease in αp and βt as macroscopic strain increases.