An open-source Abaqus implementation of the phase-field method to study the effect of plasticity on the instantaneous fracture toughness in dynamic crack propagation
An open-source Abaqus implementation of the phase-field method to study the effect of plasticity on the instantaneous fracture toughness in dynamic crack propagation
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DOI：
10.1016/j.cma.2020.113004
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发表时间：
2020-06
影响因子：
7.2
通讯作者：
G. Molnár;A. Gravouil;R. Seghir;J. Réthoré
中科院分区：
文献类型：
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作者：
G. Molnár;A. Gravouil;R. Seghir;J. Réthoré
固体中的脆韧性动态断裂是一种复杂的力学现象，由于其技术上的重要性而引起了工程师和科学家的广泛关注。基于不连续描述的动态情况下的裂纹建模是困难的，因为它需要额外的分支和扩大的标准。由于动力学问题的时间尺度很短，空间复杂性很大，其实验分析仍然很困难。因此，研究人员仍然不得不依靠数值模拟来为许多观察到的现象找到更深层次的解释。本研究旨在探讨塑性对动态断裂扩展的影响。另一方面，扩散相场公式使得在满足热力学基本原理的情况下有可能引发、扩展、阻止甚至产生分支裂纹。通过UEL选项，在商业有限元程序Abaqus中实现了相场法的隐式交错弹塑性版本。通过简单的例子，我们表明，局部韧性变形首先增加电阻和韧性。然后，在最大值之后，电阻开始随着能量耗散的显著增加而减小。通过有利于剪切变形超过拉伸破坏，断裂模式改变。首先，分支消失，然后裂纹扩展角改变，成为剪切带。最后，我们观察到的增量的瞬时动态应力强度因子在加速阶段的裂纹，而不引入率依赖的临界断裂能。我们用断裂面粗糙度的增加解释了这一现象。
Brittle and ductile dynamic fracture in solids is a complex mechanical phenomenon which attracted much attention from both engineers and scientists due to its technological interests. Modeling cracks in dynamic cases based on a discontinuous description is difficult because it needs additional criteria for branching and widening. Due to the very short time scales and the spatial complexity of the dynamic problem, its experimental analysis is still very difficult. Therefore, researchers still have to rely on numerical simulations to find a deeper explanation for many observed phenomena. This study is set out to investigate the effect of plasticity on dynamic fracture propagation. On the other hand, the diffuse phase-field formulation makes it possible to initiate, propagate, arrest or even branch cracks while satisfying the basic principles of thermodynamics. An implicit, staggered elastoplastic version of the phase-field approach was implemented in the commercial finite element code Abaqus through the UEL option. By means of simple examples we show that localized ductile deformations first increase both resistance and toughness. Then, after a maximum value, the resistance starts to decrease with a significant increment in energy dissipation. By favoring shear deformation over tensile failure the fracture pattern changes. First the branching disappears, then the crack propagation angle changes and becomes a shear band. Finally, we observed the increment of the instantaneous dynamic stress intensity factor during the acceleration stage of the crack without introducing a rate dependent critical fracture energy. We explained this phenomenon with the increasing roughness of the fracture surface.