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Crystal Plasticity Phase-Field Model with Crack Tip Enhancement Through a Concurrent Atomistic-Continuum Model
Journal of the Mechanics and Physics of Solids ( IF 5.3 ) Pub Date : 2021-07-15 , DOI: 10.1016/j.jmps.2021.104563
Subhendu Chakraborty 1 , Somnath Ghosh 2
Affiliation  

This paper develops a method for physics-based augmentation of the Helmholtz free energy density functionals, used in coupled crystal plasticity phase-field finite element (CP-PF FE) models of fracture in crystalline metallic materials. Specifically, the defect and crack surface energy components are enhanced with terms that mechanistically account for the presence of atomic-scale, crack-tip nucleated dislocations. The additional terms in the free energy representation are motivated and calibrated by energy equivalence between a concurrent atomistic–continuum scale model and the CP-PF FE model. The atomistic domain of the concurrent model incorporates a time-accelerated, molecular dynamics (MD) LAMMPS code, while the continuum domain is modeled by a dislocation-density crystal plasticity FE model. The concurrent model transfers and transforms discrete dislocations in the atomistic domain to dislocation densities in the crystal plasticity domain. Dislocation densities are transported in the continuum domain by solving the advection equation using a particle-based reproducing kernel particle method with collocation. A new form of the defect energy density is proposed by considering the effect of crack-tip nucleated dislocations. Parameters in the augmented defect and surface energies are evaluated by comparing with the concurrent model results. A comparison of crack propagation with and without contributions from the nucleated dislocations demonstrates a significant effect of nucleated dislocations on the evolution of the crack.



中文翻译:

通过并发原子连续模型增强裂纹尖端的晶体塑性相场模型

本文开发了一种基于物理学的亥姆霍兹自由能密度泛函增强方法,用于晶体金属材料断裂的耦合晶体塑性相场有限元 (CP-PF FE) 模型。具体而言,缺陷和裂纹表面能分量通过机械上解释存在原子级裂纹尖端成核位错的项得到增强。自由能表示中的附加项是由并发原子连续尺度模型和 CP-PF FE 模型之间的能量等价激发和校准的。并发模型的原子域包含时间加速的分子动力学 (MD) LAMMPS 代码,而连续域由位错密度晶体塑性有限元模型建模。并发模型将原子域中的离散位错转移并转换为晶体可塑性域中的位错密度。通过使用基于粒子的再生核粒子方法和搭配求解对流方程,位错密度在连续域中传输。通过考虑裂纹尖端成核位错的影响,提出了一种新形式的缺陷能量密度。通过与并发模型结果进行比较来评估增强缺陷和表面能中的参数。有核位错贡献和没有成核位错贡献的裂纹扩展的比较表明,成核位错对裂纹演化有显着影响。通过使用基于粒子的再生核粒子方法和搭配求解对流方程,位错密度在连续域中传输。通过考虑裂纹尖端成核位错的影响,提出了一种新形式的缺陷能量密度。通过与并发模型结果进行比较来评估增强缺陷和表面能中的参数。有核位错贡献和没有成核位错贡献的裂纹扩展的比较表明,成核位错对裂纹演化有显着影响。通过使用基于粒子的再生核粒子方法和搭配求解对流方程,位错密度在连续域中传输。通过考虑裂纹尖端成核位错的影响,提出了一种新形式的缺陷能量密度。通过与并发模型结果进行比较来评估增强缺陷和表面能中的参数。有核位错贡献和没有成核位错贡献的裂纹扩展的比较表明,成核位错对裂纹演化有显着影响。通过考虑裂纹尖端成核位错的影响,提出了一种新形式的缺陷能量密度。通过与并发模型结果进行比较来评估增强缺陷和表面能中的参数。有核位错贡献和没有成核位错贡献的裂纹扩展的比较表明,成核位错对裂纹演化有显着影响。通过考虑裂纹尖端成核位错的影响,提出了一种新形式的缺陷能量密度。通过与并发模型结果进行比较来评估增强缺陷和表面能中的参数。有核位错贡献和没有成核位错贡献的裂纹扩展的比较表明,成核位错对裂纹演化有显着影响。

更新日期:2021-07-20
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