A thermodynamically consistent finite strain phase field approach to ductile fracture considering multi-axial stress states
A thermodynamically consistent finite strain phase field approach to ductile fracture considering multi-axial stress states
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DOI：
10.1016/j.cma.2022.115467
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发表时间：
2022-10
影响因子：
7.2
通讯作者：
Sina Abrari Vajari;M. Neuner;P. K. Arunachala;A. Ziccarelli;G. Deierlein;C. Linder
中科院分区：
文献类型：
--
作者：
Sina Abrari Vajari;M. Neuner;P. K. Arunachala;A. Ziccarelli;G. Deierlein;C. Linder
相场模型在近二十年来得到了广泛的关注，这是由于相场模型能够隐式地跟踪裂纹的成核和扩展。然而，大多数弹塑性固体的裂纹相场公式只关注塑性变形的影响，而不考虑实际设计中可能出现的不同的多轴应力状态。本文提出了一种考虑多轴应力状态的有限应变塑性相场方法。为了考虑塑性和应力状态之间的耦合，使用应力加权韧性断裂模型（SWDFM）。SWDFM代表了一个标准，用于预测延性裂纹萌生的基础上的历史的内部塑性变量，应力三轴，和矿脉角参数的单调和循环载荷。的SWDFM预测延性裂纹萌生的优异性能的动机，其纳入相场的方法预测裂纹萌生和扩展，通过断裂韧性的退化。此外，根据热力学第二定律，对断裂韧性的演变速率提出了严格的要求。提出了一种新的损伤演化过程中塑性屈服面退化函数。这个功能，在实验观察，导致累积的塑性变形在损坏的区域的固体，并避免了数值不稳定性所产生的浓度大的塑性变形在严重损坏的区域。为了验证所提出的模型，计算模拟的结果进行比较，从选定的测试考虑不同的多轴应力状态的数据。数值计算结果与实验室实验数据的比较表明，所提出的框架的能力。
Phase field models for ductile fracture have gained significant attention in the last two decades due to their ability in implicitly tracking the nucleation and propagation of cracks. However, most crack phase field formulations for elastoplastic solids focus only on the effects of plastic deformation, and do not consider the different multi-axial stress states that may arise in practical designs. In this work, a thermodynamically consistent phase field approach coupled with finite strain plasticity, considering multi-axial stress states is presented. In order to account for the coupling between plasticity and stress states, the Stress-Weighted Ductile Fracture Model (SWDFM) is utilized. The SWDFM represents a criterion for predicting ductile crack initiation under both monotonic and cyclic loadings based on histories of an internal plastic variable, stress triaxiality, and the Lode angle parameter. The excellent performance of the SWDFM for predicting ductile crack initiation motivates for its incorporation into a phase field approach for predicting both crack initiation and propagation through degradation of the fracture toughness. Moreover, based on the second law of thermodynamics, exact requirements are imposed on the rate at which the fracture toughness can evolve. A novel function for degrading the plastic yield surface during the evolution of damage is introduced. This function, in line with experimental observations, leads to an accumulation of plastic deformation in damaged regions of a solid, and avoids numerical instabilities arising from concentrations of large plastic deformations in severely damaged regions. For validating the proposed model, results of computational simulations are compared to data from selected tests considering different multi-axial stress states. Comparisons of the numerical results with data from laboratory experiments demonstrate the capabilities of the proposed framework.