Periporomechanmics is a strong nonlocal framework for modeling the mechanics and physics of variably saturated porous media with evolving discontinuities. In periporomechanics, the horizon serves as a mathematical nonlocal parameter that lacks a precise physical meaning. In this article, as a new contribution we formulate a Cosserat periporomechanics paradigm for modeling dynamic shear banding and crack branching in dry porous media incorporating a micro-structure based length scale. In this micro-periporomechanics framework, each material point has both translational and rotational degrees of freedom in line with the Cosserat continuum theory. We formulate a stabilized Cosserat constitutive correspondence principle via the energy method through which classical viscous material models for porous media can be used in the proposed Cosserat periporomechanics. We have numerically implemented the micro-periporomechanics model through an explicit Lagrangian meshfree algorithm for dynamic problems. Two benchmark numerical examples are presented to test the computational micro-periporomechanics paradigm in modeling shear bands and mode-I cracks. We then present two numerical examples to show the efficacy of the proposed micro-periporomechanics for modeling the characteristics of shear banding bifurcation and dynamic crack branching in dry porous media.

翻译：近场孔隙力学是一个强非局部框架，用于模拟含演化不连续性的可变饱和多孔介质的力学与物理行为。在近场孔隙力学中，近场作用范围作为一个数学非局部参数，缺乏精确的物理含义。本文作为一项新贡献，我们提出了一个Cosserat近场孔隙力学范式，用于模拟干燥多孔介质中的动态剪切带形成和裂纹分叉，该范式基于微结构引入特征长度尺度。在这一微观近场孔隙力学框架中，每个材料点根据Cosserat连续介质理论同时具有平动和转动自由度。我们通过能量方法建立了稳定的Cosserat本构对应原理，使得经典的粘性多孔介质材料模型可用于所提出的Cosserat近场孔隙力学。我们通过显式拉格朗日无网格算法对该微观近场孔隙力学模型进行了数值实现，以处理动态问题。通过两个基准数值算例来测试该计算微观近场孔隙力学范式在模拟剪切带和I型裂纹中的表现。随后，我们展示两个数值算例，以证明所提出的微观近场孔隙力学在模拟干燥多孔介质中剪切带分叉特性和动态裂纹分叉方面的有效性。