Concrete Micromechanics Validated with In-Situ Stress and Strain Measurements

通过现场应力和应变测量验证混凝土微观力学

• 批准号: 2125023
• 负责人: Ryan Hurley
• 金额: $ 35.16万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2125023&HistoricalAwards=false
• 关键词: Concrete; Micromechanics; Validated; Situ; Stress

This research will examine the mechanical response of concrete at micrometer to centimeter length scales to validate theories and computational models used to predict its behavior and failure. Concrete is the world’s most-common building material and extensive research efforts are on-going to improve its resiliency and environmental friendliness. Concrete is composed of particles and inclusions with varying properties and dimensions ranging from nanometers to centimeters that interact during mechanical loading. The results of these interactions are captured by theories and computational models in the field of micromechanics. While micromechanics-based theories accurately predict many mechanical properties of concrete, the assumptions underlying these theories have not been validated at small length scales. Furthermore, determining the resolution needed for accurate computational modeling of concrete is still challenging. This research project will employ new, advanced x-ray measurements to assess the response of concrete from micrometers to centimeters, to test the hypotheses underlying micromechanics theories, and to provide the research community with high-fidelity data for validating models. The results of this research are expected to improve predictions of concrete’s mechanical response and promote understanding of its properties. The research results will also be used to teach advanced concepts in a graduate engineering course and to provide research opportunities to under-represented high school students interested in STEM careers.This research consists of making in-situ x-ray tomography and diffraction measurements of stress and strain at micron to centimeter length scales during mechanical loading of concrete specimens at laboratory and synchrotron facilities. These measurements will be used to validate and extend micromechanics theories, such as Eshelby’s inclusion and Mori-Tanaka’s theories, and their underlying assumptions across length scales. For instance, the measurements will be used to examine whether average inclusion stresses used as intermediate variables in deriving homogenized material properties are accurate and to what degree individual inclusion stresses deviate from the average. The measurements will also be used to examine the accuracy of mesoscale modeling with varying levels of microstructural refinement, addressing open problems related to the length scales that must be captured in such models. The outcomes of the project will be a fundamental understanding of stress and strain variability across length scales in concrete, guidance for mesoscale modeling, and high-fidelity datasets for calibration and validation of theories and models used throughout the research community.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

这项研究将检查微米到厘米长度尺度上混凝土的机械响应，以验证用于预测其行为和失效的理论和计算模型。混凝土是世界上最常见的建筑材料，并且正在进行广泛的研究工作以提高其弹性。混凝土由具有不同性质和尺寸（从纳米到厘米）的颗粒和夹杂物组成，这些颗粒和夹杂物在机械载荷过程中相互作用，这些相互作用的结果可以通过理论和计算模型来捕获。虽然基于微观力学的理论准确地预测了混凝土的许多力学性能，但这些理论的假设尚未在小尺度上得到验证。此外，确定混凝土精确计算建模所需的分辨率仍然具有挑战性。新的、先进的 X 射线测量可评估从微米到厘米的混凝土响应，测试微观力学理论的假设，并为研究界提供用于验证模型的高保真数据。这项研究的结果预计将得到改进。预测研究结果还将用于在研究生工程课程中教授先进概念，并为对 STEM 职业感兴趣的高中生提供研究机会。这项研究包括- 在实验室和同步加速器设施中对混凝土样本进行机械加载期间，进行微米至厘米长度尺度的应力和应变原位 X 射线断层扫描和衍射测量。这些测量将用于验证和扩展微观力学理论，例如例如，Eshelby 的夹杂物和 Mori-Tanaka 的理论，以及它们在长度尺度上的基本假设，将用于检查用作推导均质材料特性的中间变量的平均夹杂物应力是否准确，以及单个夹杂物应力偏离的程度。测量结果还将用于检查具有不同微观结构水平的介观模型的准确性，解决与细化此类模型中必须捕获的长度尺度相关的开放问题。是对混凝土长度尺度上应力和应变变化的基本理解，介观建模的指导，以及用于校准和验证整个研究界使用的理论和模型的高保真数据集。该奖项反映了 NSF 的法定使命，并被认为是值得的通过使用基金会的智力优势和更广泛的影响审查标准进行评估来获得支持。

项目成果

Examining the micromechanics of cementitious composites using In-Situ X-ray measurements

• DOI: 10.1016/j.ijsolstr.2023.112162
• 发表时间: 2023-02
• 期刊: International Journal of Solids and Structures
• 影响因子: 3.6
• 作者: R. Hurley;D. Pagan;E. Herbold;C. Zhai

On mesoscale modeling of concrete: Role of heterogeneities on local stresses, strains, and representative volume element

混凝土的细观建模：异质性对局部应力、应变和代表性体积单元的作用

• DOI: 10.1016/j.cemconres.2022.107031
• 发表时间: 2023
• 期刊: Cement and Concrete Research
• 影响因子: 11.4
• 作者: Thakur, Mohmad M.;Henningsson, N. Axel;Engqvist, Jonas;Autran, Pierre-Olivier;Wright, Jonathan P.;Hurley, Ryan C.
• 通讯作者: Hurley, Ryan C.