Collaborative Research Strain-rate Dependent Properties of Cement-Based Materials: A Multi-Scale Experimental and Modeling Effort

该提案概述了一个联合实验和计算程序，旨在开发框架的水泥基材料，这将提供其异质结构的定量描述和能力的进步，以预测从正常强度混凝土的材料失效的加载速率的影响，以纤维增强混凝土的多尺度模型。具体而言，拟议的活动分为四个任务：1）定量表征多尺度结构和细观尺度波动的结构描述符，2）发展细观力学模型预测应变率相关的行为的混凝土/水泥基材料，3）随机模拟为基础的建模在细观尺度的混凝土/水泥基材料的本构性质的变化，以及，4）在不同应变率下单轴/双轴压缩下的样品的全尺寸有限元模型，沿着使用Kolsky杆设备的实验验证。通过拟议的活动进行的研究将解决混凝土材料上的冲击载荷的重要问题，通过提供新的建模范例和实验技术，以解决水泥基材料的应变率相关的故障。这些协议可以为提高材料的抗爆性和更有效的结构设计奠定基础。此外，该技术也有望适用于更广泛的家庭的脆性材料在高应变率下，如模拟破坏的岩石下采矿爆炸或陶瓷装甲下的弹道载荷。拟议的活动代表了一个多机构的合作，这将为学生提供指导的PI曝光不仅是专业知识的PI，而且在每个参与机构的教育研究环境。每个PI将指导一个博士。学生和本科研究人员都将被鼓励定期前往其他机构分享研究结果。

This proposal outlines a joint experimental and computational program aimed at developing the framework for a multi-scale model of cement-based materials, which will provide for advances in quantitative descriptions of their heterogenous structure and an ability to predict the effect of loading rate on failure in materials ranging from normal strength concrete to fiber-reinforced ultrahigh performance concrete. Specifically, the proposed activities are divided into four tasks: 1) quantitative characterization of multi-scale structure and meso-scale fluctuations in structural descriptors; 2) development of micromechanical models for predicting strain-rate dependent behavior of concrete/cementitious materials; 3) stochastic simulation-based modeling of variations in meso-scale constitutive properties of concrete/cementitious materials; and, 4) full-scale finite element model of samples under uniaxial/biaxial compression at varying strain rates, along with experimental validation using Kolsky bar equipment. The research conducted through the proposed activities will address the important problem of impact loading on concrete materials, by providing new modeling paradigms and experimental techniques to address the strain-rate-dependent failure of cement-based materials. These protocols can form the basis for improved blast-resistance of materials and more effective structural design. In addition, the techniques are also expected to be applicable to the broader family of brittle materials under high strain rates, such as modeling failure of rocks under mining blasts or ceramic armors under ballistic loading. The proposed activities represent a multi-institutional collaboration, which will provide students mentored by the PIs exposure not only to the expertise of both PIs, but also to the educational research environments at each of the involved institutions. Each PI will mentor one Ph.D. student and undergraduate researchers who will all be encouraged to travel to the other institution on a regular basis to share findings.