Ductile crack propagation by plastic collapse of the intervoid ligaments
Ductile crack propagation by plastic collapse of the intervoid ligaments
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DOI：
10.1007/s10704-012-9728-9
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发表时间：
2012-06
影响因子：
2.5
通讯作者：
G. Hütter;L. Zybell;Uwe Mühlich;M. Kuna
中科院分区：
文献类型：
--
作者：
G. Hütter;L. Zybell;Uwe Mühlich;M. Kuna
在本研究中，韧性裂纹的萌生和扩展的小规模屈服条件下的微观力学模型的装置进行了研究。空隙离散地解决在断裂过程区，其中陡峭的梯度发生在加载历史期间，并考虑到考虑由均匀化的多孔塑性定律在其他地方。离散空隙区域的尺寸不是先验设定的，而是一致地确定的。结果表明，有效的裂纹扩展发生的塑性崩溃，即纯粹的几何软化的间隙韧带没有纳入材料分离。由于这种机制，存在与最大断裂韧性一致的极限载荷。此外，事实证明，屏蔽由于周围的裂缝平面的空隙的增长有相当大的影响，计算的R-曲线相比，模型忽略这种效果。根据空隙的排列，观察到扩散软化区或甚至裂纹分支。与文献中的实验数据比较表明，塑性破坏和空洞扩展扩散区的形成是延性裂纹扩展的现实机制。
In the present study ductile crack initiation and propagation is investigated by means of a micro-mechanical model under small-scale yielding conditions. Voids are resolved discretely in the fracture process zone where steep gradients occur during the loading history and are taken into accounted by a homogenized porous plasticity law elsewhere. The size of the region of discrete voids is not set a priori but is determined consistently. The results show that effective crack growth occurs by plastic collapse, i.e. purely geometric softening of the intervoid ligaments without incorporating material separation. Due to this mechanism a limit load exists coinciding with the maximum fracture toughness. In addition, it turns out that the shielding due to the growth of voids around the crack plane has a considerable influence on the computed R-curves compared to models neglecting this effect. Depending on the void arrangement a diffuse softening zone or even crack branching is observed. A comparison with experimental data from literature indicates that plastic collapse and the formation of diffuse zones of void growth are realistic mechanisms of ductile crack propagation.