This paper is devoted to the development of a continuum theory for materials having granular microstructure and accounting for some dissipative phenomena like damage and plasticity. The continuum description is constructed by means of purely mechanical concepts, assuming expressions of elastic and dissipation energies as well as postulating a hemi-variational principle, without incorporating any additional postulate like flow rules. Granular micromechanics is connected kinematically to the continuum scale through Piola’s ansatz. Mechanically meaningful objective kinematic descriptors aimed at accounting for grain–grain relative displacements in finite deformations are proposed. Karush–Kuhn–Tucker (KKT)-type conditions, providing evolution equations for damage and plastic variables associated with grain–grain interactions, are derived solely from the fundamental postulates. Numerical experiments have been performed to investigate the applicability of the model. Cyclic loading–unloading histories have been considered to elucidate the material hysteretic features of the continuum, which emerge from simple grain–grain interactions. We also assess the competition between damage and plasticity, each having an effect on the other. Further, the evolution of the load-free shape is shown not only to assess the plastic behavior, but also to make tangible the point that, in the proposed approach, plastic strain is found to be intrinsically compatible with the existence of a placement function.

本文致力于发展具有颗粒微结构并考虑到一些耗散现象（如损坏和可塑性）的材料的连续理论。连续描述是通过纯粹的机械概念构造的，假设弹性和耗散能量的表达式以及假定半变原理，而没有像流动规则那样包含任何其他假定。细微力学通过Piola的ansatz在运动学上与连续体尺度相连。提出了旨在说明有限变形中晶粒与晶粒之间的相对位移的具有机械意义的客观运动学描述子。Karush–Kuhn–Tucker（KKT）类型的条件，提供了与谷物-谷物相互作用相关的破坏和塑性变量的演化方程，仅来自基本假设。已经进行了数值实验以研究该模型的适用性。为了了解连续体的材料滞后特性，循环加载-卸载历史被认为是由简单的颗粒-晶粒相互作用产生的。我们还评估了损害与可塑性之间的竞争，两者之间相互影响。此外，无负载形状的演变不仅显示出评估塑性行为，而且还明确指出了在所提出的方法中，发现塑性应变与放置函数的存在本质上兼容的观点。为了了解连续体的材料滞后特性，循环加载-卸载历史被认为是由简单的颗粒-晶粒相互作用产生的。我们还评估了损害与可塑性之间的竞争，两者之间相互影响。此外，无负载形状的演变不仅显示出评估塑性行为，而且还明确指出了在所提出的方法中，发现塑性应变与放置函数的存在本质上兼容的观点。为了了解连续体的材料滞后特性，循环加载-卸载历史被认为是由简单的颗粒-晶粒相互作用产生的。我们还评估了损害与可塑性之间的竞争，两者之间相互影响。此外，无负载形状的演变不仅显示了评估塑性行为，而且还明确指出了在所提出的方法中，发现塑性应变与放置函数的存在本质上兼容的观点。