Locally enhanced Voronoi cell finite element model (LE‐VCFEM) for simulating evolving fracture in ductile microstructures containing inclusions
Locally enhanced Voronoi cell finite element model (LE‐VCFEM) for simulating evolving fracture in ductile microstructures containing inclusions
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DOI：
10.1002/nme.2400
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发表时间：
2008-12
影响因子：
2.9
通讯作者：
Chao Hu;Somnath Ghosh
中科院分区：
文献类型：
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作者：
Chao Hu;Somnath Ghosh
延性异质材料（例如铸造铝合金）会经历灾难性的失效，这种失效始于颗粒破碎，并随着空隙的增长和局部强烈塑性变形和应变软化带中的聚结而演变。基于假设的应力混合公式的 Voronoi 单元有限元模型 (VCFEM) 无法解释塑性应变引起的软化。为了克服塑性应变局部化导致材料软化的缺点，本研究引入了局部增强 VCFEM (LE-VCFEM)，用于模拟异质金属和合金中非常复杂的延性破坏现象。在 LE-VCFEM 中，有限变形位移元素自适应地添加到原本假设的基于应力的混合 Voronoi 单元有限元中的局部区域，以局部增强韧性断裂的建模能力。位移元素采用自适应 h 细化来提高精度。粒子破裂引起的损坏是由威布尔模型触发的。在 LE-VCFEM 中采用多孔塑性非局部 Gurson-Tvergaard-Needleman 模型来模拟基体开裂。位移元素采用迭代应变更新算法。通过与传统有限元代码和真实材料实验的结果进行比较，验证了 LE-VCFEM 代码。还研究了各种微观结构形态特征的影响。版权所有 © 2008 约翰·威利父子有限公司
Ductile heterogeneous materials such as cast aluminum alloys undergo catastrophic failure that initiates with particle fragmentation, which evolves with void growth and coalescence in localized bands of intense plastic deformation and strain softening. The Voronoi cell finite element model (VCFEM), based on the assumed stress hybrid formulation, is unable to account for plastic strain‐induced softening. To overcome this shortcoming of material softening due to plastic strain localization, this study introduces a locally enhanced VCFEM (LE‐VCFEM) for modeling the very complex phenomenon of ductile failure in heterogeneous metals and alloys. In LE‐VCFEM, finite deformation displacement elements are adaptively added to regions of localization in the otherwise assumed stress‐based hybrid Voronoi cell finite element to locally enhance modeling capabilities for ductile fracture. Adaptive h‐refinement is used for the displacement elements to improve accuracy. Damage initiation by particle cracking is triggered by a Weibull model. The nonlocal Gurson–Tvergaard–Needleman model of porous plasticity is implemented in LE‐VCFEM to model matrix cracking. An iterative strain update algorithm is used for the displacement elements. The LE‐VCFEM code is validated by comparing with results of conventional FE codes and experiments with real materials. The effect of various microstructural morphological characteristics is also investigated. Copyright © 2008 John Wiley & Sons, Ltd.