各向异性双晶和三晶体晶界附近应力场分析

采用率相关晶体滑移有限元程序对不同取向晶粒构成的双晶体和三晶体在晶界和三晶交点附近的应力集中特性进行了计算分析．双晶体的数值结果表明，不同取向晶粒的晶界附近应力场具有较大的应力梯度，存在应力集中现象；三晶体由于晶界之间的相互作用使得三晶交点可能造成应力集中地，也可能不造成应力集中，晶界附近的应力结构与双晶体晶界附近的应力结构亦不相同，这主要取决于三个晶粒的晶体取向．对双晶体和三晶体的分析说明，不同取向的晶粒具有不同的变形规律．因此研究金属材料的损伤、断裂问题至少需要采用晶体滑移理论从细观的角度分析不同晶粒之间的相互作用．

Stress Distribution Near Grain Boundary in Anisotropic Bicrystals and Tricrystals

The rate dependent crystallographic finite element program was implemented in ABAQUS as a UMAT for the analysis of the stress distributions near grain boundary in anisotropic bicrystals and tricrystals, talcing the different crystallographic orientations into consideration. The numerical results of bicrystals model with the different crystallographic orientations shows that there is a high stress gradient near the grain boundaries. The characteristics of stress structures are dependent on the crystallographic orientations of the two grains. The existing of triple junctions in the tricrystals may result in the stress concentrations, or may not, depending on the crystallographic orientations of the three grains. The conclusion shows that grain boundary with different crystallographic orientations can have different deformation, damage, and failure behaviors. So it is only on the detail study of the stress distribution can the metal fracture be understood deeply.