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.

这项研究将检验混凝土在微米到厘米长尺度下的力学响应，以验证用于预测其行为和破坏的理论和计算模型。混凝土是世界上最常见的建筑材料，目前正在进行广泛的研究工作，以提高其弹性和环境友好性。混凝土是由不同性质和尺寸的颗粒和夹杂物组成的，这些颗粒和夹杂物在机械加载期间相互作用，范围从纳米到厘米。这些相互作用的结果被细观力学领域的理论和计算模型捕捉到。虽然基于细观力学的理论准确地预测了混凝土的许多力学性能，但这些理论所依据的假设尚未在小范围内得到验证。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。这项研究项目将使用新的、先进的x射线测量来评估混凝土从微米到厘米的响应，测试微观力学理论背后的假设，并为研究界提供高保真的数据来验证模型。这项研究的结果有望改善对混凝土力学响应的预测，并促进对其性质的了解。研究成果还将被用来教授工程学研究生课程中的先进概念，并为对STEM职业感兴趣的未被充分代表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试件在机械加载过程中进行微米到厘米长尺度的应力和应变的原位x射线层析和衍射测量。这些测量将被用来验证和扩展微观力学理论，如EShelby的包含体和Mori-Tanaka的理论，以及它们在长度尺度上的基本假设。例如，这些测量将用于检查作为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平均值的程度。这些测量还将用于检查具有不同微观结构改进水平的中尺度建模的准确性，解决与必须在此类模型中捕获的长度尺度相关的公开问题。该项目的成果将是对混凝土长度尺度上的应力和应变变异性的基本了解，对中尺度建模的指导，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，被认为值得支持。

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.