Discrete dislocation modeling on interaction between type-I blunt crack and cylindrical void in single crystals
Discrete dislocation modeling on interaction between type-I blunt crack and cylindrical void in single crystals
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DOI：
10.1016/j.ijsolstr.2014.11.012
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发表时间：
2015-03
影响因子：
3.6
通讯作者：
S. Liang;Minsheng Huang;Zhenhua Li
中科院分区：
文献类型：
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作者：
S. Liang;Minsheng Huang;Zhenhua Li
采用二维离散位错动力学（2-DDDD）方法模拟了I型钝裂纹与近端空洞的相互作用，重点研究了空洞的扩展、裂纹尖端的变形及其尺寸效应。与经典的基于晶体塑性的有限元模拟不同，本文的二维DDD模拟清楚地表明，即使对于I型张开裂纹，也容易形成连接裂纹尖端和空洞表面的水平滑移带，特别是当裂纹尖端和空洞表面之间的韧带不太长时。除了水平滑移带外，还可以形成与水平轴成斜角的非对称滑移带，并与微孔洞相交。在两个耦合的平行滑移带上，一些相反符号的位错，这可以被视为等效的棱柱位错环，滑向空洞/裂纹尖端表面，从而驱动空洞的增长和裂纹尖端进一步钝化。此外，还研究了韧带长度和孔洞半径对孔洞扩展和裂纹-孔洞相互作用的尺寸效应。结果表明，尺寸效应与水平剪切滑移带的形成密切相关。存在一个临界空穴半径，在此半径下，近端空穴趋于扁平，其面积随着应力强度因子K的增大而逐渐减小。这些结果可能有助于更好地理解裂纹尖端过程区的断裂和损伤机制。
The interaction between a type-I blunt crack and a near-tip void were modeled by the two-dimensional discrete dislocation dynamics (2-D DDD), with special emphasis on the void growth, crack-tip deformation and their size effect. Different from the classical crystal plasticity-based FE modeling, the present 2-D DDD modeling clearly indicates that, even for the type-I opening crack, the horizontal slip bands connecting the crack tip and the void surface are easily formed, especially when the ligament between the crack-tip and void surface is not too long. Besides the horizontal slip bands, some asymmetric slip bands which are at an oblique angle to the horizontalx-axis can also be formed and intersect with the micro-void. On two coupled parallel slip bands, some oppositely signed dislocations, which can be regarded as equivalent prismatic dislocation loops, glide toward the void/crack-tip surface and thus drive the void growth and the crack tip further blunting. In addition, the size effect by ligament length and void radius on void growth and crack-void interaction has also been investigated carefully. It was found that the size effect is closely related to the formation of horizontal shear slip bands. There exists a critical void radius, under which the near-tip void tends to change into a flat shape and its area decreases gradually with increasing the applied stress intensity factor (SIF)K. These results might be helpful for a better understanding of the fracture and damage mechanisms in the crack-tip process zone.