An extended 3D discrete-continuous model and its application on single- and bi-crystal micropillars
An extended 3D discrete-continuous model and its application on single- and bi-crystal micropillars
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扩展的 3D 离散连续模型及其在单双晶微柱上的应用
DOI：
10.1088/1361-651x/aa5aac
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发表时间：
2017-02
期刊：
影响因子：
--
通讯作者：
Zhenhuan Li
中科院分区：
文献类型：
--
作者：
Minsheng Huang;Shuang Liang;Zhenhuan Li
将三维离散位错动力学(3D DDD)和有限元方法(FEM)相结合，建立了一种三维离散-连续模型(3D DCM)。提出了DDD与有限元之间两种关键信息传递的新方案，即从DDD到有限元的塑性应变分布和从有限元到DDD的应力传递。由位错段运动引起的塑性应变通过特定的新分布函数分布到基本球体(椭球体或球体)上。特别考虑了各种界面(如自由面和晶界)对塑性应变分布的影响。通过这些处理，即使在严重倾斜于有限元网格的滑移面上的位错，也可以精确地求解出变形场，而不会产生虚假的应力集中点。此外，还引入了截断球内奇异性和非奇异性理论解的应力修正，以精确计算位错上的应力。通过这些格式，DCM对有限元网格的敏感度降低，数值计算效率提高，即使相邻位错处于同一有限元网格中，也能适当地考虑它们之间的相互作用。此外，本文还用DCM模拟了单晶和双晶微柱与刚性和位错吸收的微柱的压缩。为了更好地理解这些重要的微塑性问题，详细研究了内部边界层对跳跃应力-应变响应和变形模式的影响。
A 3D discrete-continuous model (3D DCM), which couples the 3D discrete dislocation dynamics (3D DDD) and finite element method (FEM), is extended in this study. New schemes for two key information transfers between DDD and FEM, i.e. plastic-strain distribution from DDD to FEM and stress transfer from FEM to DDD, are suggested. The plastic strain induced by moving dislocation segments is distributed to an elementary spheroid (ellipsoid or sphere) via a specific new distribution function. The influence of various interfaces (such as free surfaces and grain boundaries (GBs)) on the plastic-strain distribution is specially considered. By these treatments, the deformation fields can be solved accurately even for dislocations on slip planes severely inclined to the FE mesh, with no spurious stress concentration points produced. In addition, a stress correction by singular and non-singular theoretical solutions within a cut-off sphere is introduced to calculate the stress on the dislocations accurately. By these schemes, the present DCM becomes less sensitive to the FE mesh and more numerically efficient, which can also consider the interaction between neighboring dislocations appropriately even though they reside in the same FE mesh. Furthermore, the present DCM has been employed to model the compression of single-crystal and bi-crystal micropillars with rigid and dislocation-absorbed GBs. The influence of internal GB on the jerky stress-strain response and deformation mode is studied in detail to shed more light on these important micro-plastic problems.
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DOI：
10.1016/j.actamat.2012.03.013
发表时间：
2012-02
期刊：
--
影响因子：
--
作者：
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发表时间：
1999-09
影响因子：
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DOI：
10.1088/0965-0393/14/7/003
发表时间：
2006-10
影响因子：
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作者：
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