This paper presents a novel three-phase damage model for the prediction of the post-peak responses of composite materials, such as recycled aggregate concrete (RAC). The proposed damage model is based on composite damage mechanics and is composed of three phases: cement paste, interface transition zone (ITZ), and aggregate. All phases are assumed to be linearly elastic and isotropic materials. The aggregate is supposed to be the undamaged material, while the cement paste and ITZ are considered the damaged materials. Three different composite damage models, namely Voigt (parallel), Reuss (serial), and the proposed generalized self-consistent (spherical), represent the damage growth in the composite materials. The Voigt parallel model is employed to address the upper bound of post-peak stiffness and stress, while the Reuss serial model represents the lower bound. To investigate the softening phenomenon after the post-peak state, both linear and exponential functions are used to describe the stress-strain curve in this state. Two numerical simulations are provided to examine the stress degradation in the softening state. Both simulations reveal that the post-peak stress degrades with increasing damage parameters and ITZ thickness. Therefore, both damage and ITZ’s thickness are significant factors for analyzing the post-peak responses of RAC.

中文翻译：

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基于复合力学的三相损伤模型用于再生骨料混凝土峰后分析


本文提出了一种新的三相损伤模型，用于预测复合材料（如再生骨料混凝土 （RAC））的峰后响应。所提出的损伤模型基于复合损伤力学，由水泥浆、界面过渡区 （ITZ） 和骨料三个阶段组成。假设所有相都是线弹性和各向同性材料。骨料应该是未损坏的材料，而水泥浆和 ITZ 被认为是损坏的材料。三种不同的复合材料损伤模型，即 Voigt （平行）、Reuss （串联）和提出的广义自洽 （球形） ，代表了复合材料中的损伤增长。Voigt 平行模型用于解决峰后刚度和应力的上限，而 Reuss 级数模型表示下限。为了研究峰后状态后的软化现象，使用线性函数和指数函数来描述此状态下的应力-应变曲线。提供了两个数值模拟来检查软化状态下的应力退化。两种仿真都表明，峰后应力随着损伤参数和 ITZ 厚度的增加而退化。因此，损伤和 ITZ 厚度都是分析 RAC 峰后响应的重要因素。