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Incorporation of tension-compression asymmetry into plastic damage phase-field modeling of quasi brittle geomaterials
International Journal of Plasticity ( IF 9.8 ) Pub Date : 2020-01-01 , DOI: 10.1016/j.ijplas.2019.08.003 Tao You , Qi-Zhi Zhu , Peng-Fei Li , Jian-Fu Shao
International Journal of Plasticity ( IF 9.8 ) Pub Date : 2020-01-01 , DOI: 10.1016/j.ijplas.2019.08.003 Tao You , Qi-Zhi Zhu , Peng-Fei Li , Jian-Fu Shao
Abstract Both experiments and theoretical investigations have evidenced the existence of compressive-shear fracture mode in geomaterials like concrete, rocks and gypsum. Proper description and modeling of intricate fracturing pattern with consideration of strong tension-compression asymmetry in mechanical response remain an open issue in phase-field modeling and simulation. In this work, a new phase field model with plasticity-damage coupling is formulated in the framework of irreversible thermodynamics. Two essential features, tension-compression asymmetry in mechanical response as well as two distinct fracture modes, are taken into account by incorporating two scalar-valued damage variables into the classical modeling framework. By defining a specific free energy density function, the coupling between damage and plasticity is achieved by involving a phase field variable into the yield function. The proposed model is validated at two levels. In the homogeneous cases, the mechanical behaviors of typical geomaterials are investigated in the plane stress condition. Meanwhile, a stress-based crack onset criterion is utilized to capture the distinct failure behavior both in tension and in compression. In numerical simulations, a local numerical integration with implicit return mapping algorithm and plasticity-damage decoupling treatment are developed. Three numerical examples are performed to demonstrate respectively the mode I, mixed-mode and model II fracture in geomaterials. Comparisons between numerical simulations and experimental data make it possible to evaluate the predictive performance of the proposed bi-dissipative phase field damage model. In addition, the local stress analysis is carried out to explain a changing mode of fracture propagation and to demonstrate the existence of tensile-shear (hybrid) fracture mode.
中文翻译:
将拉压不对称性纳入准脆性岩土材料塑性损伤相场建模
摘要 实验和理论研究都证明了混凝土、岩石、石膏等岩土材料中存在压剪断裂模式。考虑到机械响应中强烈的拉压不对称性,对复杂的压裂模式进行正确描述和建模仍然是相场建模和模拟中的一个悬而未决的问题。在这项工作中,在不可逆热力学的框架内建立了具有塑性-损伤耦合的新相场模型。通过将两个标量值损伤变量合并到经典建模框架中,考虑了两个基本特征,机械响应中的拉压不对称性以及两种不同的断裂模式。通过定义特定的自由能密度函数,损伤和塑性之间的耦合是通过将相场变量引入屈服函数来实现的。所提出的模型在两个层次上得到验证。在均质情况下,研究了典型岩土材料在平面应力条件下的力学行为。同时,基于应力的裂纹起始准则用于捕获拉伸和压缩中的不同破坏行为。在数值模拟中,开发了具有隐式返回映射算法和塑性损伤解耦处理的局部数值积分。通过三个数值算例分别演示了岩土材料中的I型、混合型和II型断裂。数值模拟和实验数据之间的比较使得评估所提出的双耗散相场损伤模型的预测性能成为可能。此外,还进行了局部应力分析,以解释裂缝扩展的变化模式并证明拉剪(混合)断裂模式的存在。
更新日期:2020-01-01
中文翻译:
将拉压不对称性纳入准脆性岩土材料塑性损伤相场建模
摘要 实验和理论研究都证明了混凝土、岩石、石膏等岩土材料中存在压剪断裂模式。考虑到机械响应中强烈的拉压不对称性,对复杂的压裂模式进行正确描述和建模仍然是相场建模和模拟中的一个悬而未决的问题。在这项工作中,在不可逆热力学的框架内建立了具有塑性-损伤耦合的新相场模型。通过将两个标量值损伤变量合并到经典建模框架中,考虑了两个基本特征,机械响应中的拉压不对称性以及两种不同的断裂模式。通过定义特定的自由能密度函数,损伤和塑性之间的耦合是通过将相场变量引入屈服函数来实现的。所提出的模型在两个层次上得到验证。在均质情况下,研究了典型岩土材料在平面应力条件下的力学行为。同时,基于应力的裂纹起始准则用于捕获拉伸和压缩中的不同破坏行为。在数值模拟中,开发了具有隐式返回映射算法和塑性损伤解耦处理的局部数值积分。通过三个数值算例分别演示了岩土材料中的I型、混合型和II型断裂。数值模拟和实验数据之间的比较使得评估所提出的双耗散相场损伤模型的预测性能成为可能。此外,还进行了局部应力分析,以解释裂缝扩展的变化模式并证明拉剪(混合)断裂模式的存在。