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Analysis of cement-treated clay behavior by micromechanical approach

Dong-Mei ZHANG, Zhen-Yu YIN, Pierre-Yves HICHER, Hong-Wei HUANG

《结构与土木工程前沿（英文）》 2013年第7卷第2期页码 137-153 doi: 10.1007/s11709-013-0204-z

摘要： Experimental results show the significant influence of cement content on the mechanical properties of cement-treated clays. Cementation is produced by mixing a certain amount of cement with the saturated clay. The purpose of this paper is to model the cementation effect on the mechanical behavior of cement-treated clay. A micromechanical stress-strain model is developed considering explicitly the cementation at inter-cluster contacts. The inter-cluster bonding and debonding during mechanical loading are introduced in two ways: an additional cohesion in the shear sliding and a higher yield stress in normal compression. The model is used to simulate isotropic compression and undrained triaxial tests under various confining stresses on cement-treated Ariake clay and Singapore clay with various cement contents. The applicability of the present model is evaluated through comparisons between numerical and experimental results. The evolution of local stresses and local strains in inter-cluster planes are discussed in order to explain the induced anisotropy due to debonding at contact level under the applied loads. The numerical simulations demonstrate that the proposed micromechanical approach is well adapted for taking into account the main physical properties of cement-treated clay, including damage and induced anisotropy under mechanical loading.

关键词： microstructure cementation clay micromechanics anisotropy debonding

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Computational modeling of fracture in concrete: A review

Luthﬁ Muhammad Mauludin, Chahmi Oucif

《结构与土木工程前沿（英文）》 2020年第14卷第3期页码 586-598 doi: 10.1007/s11709-020-0573-z

摘要： This paper presents a review of fracture modeling of concrete. The complex material, such as concrete, has been widely used in construction industries and become trending issue in the last decades. Based on comprehensive literature review, there are two main approaches considered to-date of concrete fracture modeling, such as macroscopic and micromechanical models. The purpose of this review is to provide insight comparison from different techniques in modeling of fracture in concrete which are available. In the first section, an overview of fracture modeling in general is highlighted. Two different approaches both of macroscopic and micromechanical models will be reviewed. As heterogeneity of concrete material is major concern in micromechanical-based concrete modeling, one section will discuss this approach. Finally, the summary from all of reviewed techniques will be pointed out before the future perspective is given.

关键词： concrete fracture macroscopic micromechanical heterogeneity

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硅微z轴谐振陀螺仪负电刚度效应分析及实验验证

夏敦柱,周百令,王寿荣

《中国工程科学》 2007年第9卷第8期页码 66-68

摘要：

介绍了在开环工作状态下硅微z轴谐振陀螺仪由于加工工艺缺陷所导致的误差机理。为减小陀螺仪初始电容差和抑制正交耦合误差，提出了一种闭环控制检测策略。重点分析了其力矩反馈器的电刚度效应并给出其线性数学模型表示式。通过对硅微z轴陀螺仪敏感模态的反馈力与谐振频率的关系分析，间接得出了在敏感方向上电负刚度与力矩器所施电压的内在联系，并在实验上进一步验证电刚度效应。这将为下一步闭环控制方案的设计奠定重要基础。

关键词：硅微z轴陀螺仪负电刚度力矩反馈器微机电系统

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Application and evaluation of optical distance measurements in geometrical quality testing of microgears

Albert ALBERS, Duotai PAN, Leif MARXEN, Claudia BECKE,

《机械工程前沿（英文）》 2010年第5卷第3期页码 261-269 doi: 10.1007/s11465-010-0100-3

摘要： Microgears are increasingly important in industry. Compared to normal gears, the quality assurance of microgears needs more accurately measured data and simple but feasible measurement methods because of their dimension particula

关键词： microgear optical distance measurement profile deviation CWL sensor micromechanical technology (MMT)

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纳米工程混凝土界面过渡区的纳米力学特征 Article

王欣悦, 董素芬, 李镇明, 韩宝国, 欧进萍

《工程（英文）》 2022年第17卷第10期页码 99-109 doi: 10.1016/j.eng.2020.08.025

摘要：

本研究利用纳米压痕试验和统计学方法研究了纳米填料对水泥石与骨料间界面过渡区（interfacial transition zone, ITZ）的影响，并通过微观力学分析揭示了影响机制。纳米压痕试验结果表明，水泥石复合纳米填料可提高水泥石-骨料ITZ 内部水化程度，减少微孔隙和低密度水化硅酸钙（low-density calcium silicate hydrate, LD C-S-H）的含量，增加高密度水化硅酸钙（high-density calcium silicate hydrate, HD C-SH）和超高密度水化硅酸钙（ultra-high-density calcium silicate hydrate, UHD C-S-H）的含量。此外，本研究表征了一种新的由于纳米中心效应诱导产生的低密度水化硅酸钙（nano-core induced low-density calcium silicate hydrate, NCILD C-S-H），其压痕模量与HD C-S-H 和UHD C-S-H 相似，但硬度高达2.50 GPa。微观力学分析结果表明，ITZ水泥石复合纳米填料后产生的纳米中心-壳单元会增加LD C-S-H的堆积密度，并显著增强水化硅酸钙（calcium silicate hydrate, C-S-H）基本粒子之间的相互作用（包括黏聚力和摩擦力），从而诱导产生NCILD C-S-H，进而改善ITZ。本研究为在纳米尺度上理解纳米填料对混凝土ITZ 的影响提供了理论基础。

关键词：混凝土纳米填料界面过渡区纳米压痕微观力学分析纳米中心效应