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以土体应力状态计算边坡安全系数的方法

王国体

《中国工程科学》 2006年 第8卷 第12期   页码 80-84

摘要:

土坡的稳定分析一直是沿着条分法的思路发展的。由于对土体应力状态条件的忽视和条分法本身的缺陷,使得条分法得到的安全系数在工程中的应用面临激烈的挑战。土体不同条件下的应力状态表现为K0效应和变化,它对坡体的安全度影响不可忽视。笔者以考虑土体应力状态为条件,应用土的库伦强度定律和摩尔-库伦准则,推导出平面土坡的安全系数计算公式,与条分法的安全系数对比结果说明这种方法具有概念明确、计算简便、定性可靠的重要特点,可以直接提供于工程应用和参考。

关键词: 侧应力系数K0     初始应力状态     稳定安全系数公式    

土坡稳定分析应力状态新方法的过程解析

王国体,王婉娣

《中国工程科学》 2010年 第12卷 第1期   页码 52-55

摘要:

依据土体应力状态、计算边坡稳定安全系数的思想,结合对土体根本性质的认识,对基本假定、公式推导过程和工程应用进行了详细的说明。由于土坡稳定安全系数的计算公式在理论分析依据是严密的,推证得到的计算公式是正确的,所以在工程实用是可靠的。文章为该方法的工程应用和深入开展相关的研究奠定坚实的基础。

关键词: 土坡稳定分析方法     应力状态     稳定安全系数    

Development of a constitutive model for rockfills and similar granular materials based on the disturbed state

Mehdi VEISKARAMI, Ali GHORBANI, Mohammadreza ALAVIPOUR

《结构与土木工程前沿(英文)》 2012年 第6卷 第4期   页码 365-378 doi: 10.1007/s11709-012-0178-2

摘要: Behavior of rockfills was investigated experimentally and theoretically. A series of standard triaxial compression tests were carried out on a quarried rockfill material at different stress levels. It was found that both the stress level and the shear stress ratio, like most of granular materials, controls the behavior of rockfill materials. At lower shear stress ratios the behavior is much more similar to a nonlinear elastic solid. When the shear stress goes further, the stress-strain curve shows an elasto-plastic behavior which suggests using the disturbed state concept to develop a constitutive model to predict the stress-strain behavior. The presented constitutive model complies reasonably with the experimental data.

关键词: constitutive model     granular material     rockfill     plasticity     disturbed state concept     stress level    

Hot-dip galvanizing of cold-formed steel hollow sections: a state-of-the-art review

Min SUN, Jeffrey A. PACKER

《结构与土木工程前沿(英文)》 2019年 第13卷 第1期   页码 49-65 doi: 10.1007/s11709-017-0448-0

摘要: A good understanding of the effects of galvanizing on the short- and long-term behaviours of steel components is essential for structural design. This review paper is motivated by a series of recent reports on cracking in galvanized cold-formed tubular steel structures and the limitations of current steel product standards and steel design specifications in this field. The steel-related and galvanizing-related factors, different pre-galvanizing countermeasures for brittle cracking and the available technical documents are summarized. An extensive bibliography is provided as a basis for future research and development in this field.

关键词: cold-formed steel     hollow structural sections     hot-dip galvanizing     embrittlement     heat-treatment     residual stress     cracking    

Surficial stability analysis of soil slope under seepage based on a novel failure mode

《结构与土木工程前沿(英文)》 2021年 第15卷 第3期   页码 712-726 doi: 10.1007/s11709-021-0729-5

摘要: Normally, the edge effects of surficial landslides are not considered in the infinite slope method for surficial stability analysis of soil slopes. In this study, the limit stress state and discrimination equation of an infinite slope under saturated seepage flow were analyzed based on the Mohr-Coulomb strength criterion. Therefore, a novel failure mode involving three sliding zones (upper tension zone, middle shear sliding zone, and lower compression zone) was proposed. Accordingly, based on the limit equilibrium analysis, a semi-analytical framework considering the edge effect for the surficial stability of a soil slope under downslope seepage was established. Subsequently, the new failure mode was verified via a numerical finite element analysis based on the reduced strength theory with ABAQUS and some simplified methods using SLIDE software. The results obtained by the new failure mode agree well with those obtained by the numerical analysis and traditional simplified methods, and can be efficiently used to assess the surficial stability of soil slopes under rainwater seepage. Finally, an evaluation of the infinite slope method was performed using the semi-analytical method proposed in this study. The results show that the infinite slope tends to be conservative because the edge effect is neglected, particularly when the ratio of surficial slope length to depth is relatively small.

关键词: soil slope     seepage     surficial failure mode     stress state     edge effects    

Stress induced polarization switching and coupled hysteretic dynamics in ferroelectric materials

Linxiang WANG, Roderick MELNIK, Fuzai LV

《机械工程前沿(英文)》 2011年 第6卷 第3期   页码 287-291 doi: 10.1007/s11465-011-0230-2

摘要:

The dynamic responses of ferroelectric materials upon external mechanical and electrical stimulations are inherently nonlinear and coupled. In the current paper, a macroscopic differential model is constructed for the coupled hysteretic dynamics via modeling the orientation switching induced in the materials. A non-convex potential energy is constructed with both mechanic and electric field contributions. The governing equations are formulated as nonlinear ordinary differential equations by employing the Euler-Lagrange equation, and can be easily recast into a state space form. Hysteresis loops associated with stress induced polarization switching and butterfly-shaped behavior in ferroelectric materials are also successfully captured. The effects of mechanical loadings on the electrically induced switching are numerically investigated, as well as the mechanically-induced switching with various bias electric fields.

关键词: differential model     state space     electromechanical switching     butterfly effects     hysteresis    

强度理论与实验现象

刘大斌,韩文坝,蔡冰清,韩晓东

《中国工程科学》 2007年 第9卷 第12期   页码 44-52

摘要: 用四大经典理论、莫尔强度理论和质点平衡强度理论的准则和强度条件,对单向拉压、二向拉压、纯扭转等已被认定的实验现象进行对比,对低、中碳钢重新做了纯扭转求最大屈服剪应力实验。发现质点平衡强度理论的符合率较高,13个实验中的有12个符合。尤其是拉伸—剪切使剪切破坏试验变得容易,压缩—剪切使剪切破坏试验变得困难的实验现象与质点平衡强度理论完全符合;莫尔强度理论也只有当拉伸和压缩极限强度不同时才能符合;其他强度理论都与此实验不符合。特别是当三向等应力拉伸(或压缩)时第三强度理论出现相当应力为零;三向等应力拉伸(或压

关键词: 强度理论     实验现象     屈服现象     应力状态    

三向应力状态下混凝土强度和变形特性研究

闫东明,林皋

《中国工程科学》 2007年 第9卷 第6期   页码 64-70

摘要:

对设计强度为10MPa的混凝土立方体试件进行三轴压缩试验,系统研究了等围压条件下混凝土的强 度和变形特性,围压分别为0,4,8,12,16MPa5个量级;同时研究了不等围压条件下混凝土强度变化特性, 试验表明,随着围压增加,混凝土的极限抗压强度有明显增强的趋势;随着小主应力的增加,中主应力的影响 有减弱的趋势;峰值应力处应变随围压增加幅度显著。得出了在不同恒定围压下混凝土的应力应变全过程曲线; 通过与当前文献资料的对比分析,指出了在混凝土结构计算中适用的强度及变形表达式,为工程实践提供了 依据。

关键词: 三向受力状态     不等围压     极限强度     变形     混凝土    

复杂曲面薄壁构件流体压力成形理论与技术研究进展 Review

苑世剑

《工程(英文)》 2021年 第7卷 第3期   页码 358-366 doi: 10.1016/j.eng.2020.08.014

摘要:

 面向航空航天、汽车和高速列车等工业领域迫切需求的管、板和壳三类典型结构以及难变形材料构件,新一代流体压力成形技术得到迅速发展。本文系统介绍了管类构件低载荷液压成形、板类构件双向加压成形、椭球壳体无模液压成形和难变形材料双调热介质成形理论与工艺的最新研究进展,重点阐述了变形行为、应力调控、缺陷控制和典型应用。此外,本文还展望了流体压力成形技术的未来发展方向,包括超大尺度非均质构件超低载荷成形、金属间化合物和高熵合金构件精密成形、智能化流体压力成形工艺与装备,以及非均质强各向异性薄壳的精确有限元仿真。

关键词: 流体压力成形     液压成形     热介质压力成形     薄壁构件     应力状态    

EFFECTS OF TRANSPORT STRESS ON THE INTESTINES INVOLVING NEURONAL NITRIC OXIDE SYNTHASE

《农业科学与工程前沿(英文)》   页码 285-295 doi: 10.15302/J-FASE-2022469

摘要:

● Transport stress declined the level of leukocytes including lymphocytes in rat serum.

关键词: intestine     nNOS     nNOS-positive neurons     transport stress    

Advances in tissue state recognition in spinal surgery: a review

Hao Qu, Yu Zhao

《医学前沿(英文)》 2021年 第15卷 第4期   页码 575-584 doi: 10.1007/s11684-020-0816-3

摘要: Spinal disease is an important cause of cervical discomfort, low back pain, radiating pain in the limbs, and neurogenic intermittent claudication, and its incidence is increasing annually. From the etiological viewpoint, these symptoms are directly caused by the compression of the spinal cord, nerve roots, and blood vessels and are most effectively treated with surgery. Spinal surgeries are primarily performed using two different techniques: spinal canal decompression and internal fixation. In the past, tactile sensation was the primary method used by surgeons to understand the state of the tissue within the operating area. However, this method has several disadvantages because of its subjectivity. Therefore, it has become the focus of spinal surgery research so as to strengthen the objectivity of tissue state recognition, improve the accuracy of safe area location, and avoid surgical injury to tissues. Aside from traditional imaging methods, surgical sensing techniques based on force, bioelectrical impedance, and other methods have been gradually developed and tested in the clinical setting. This article reviews the progress of different tissue state recognition methods in spinal surgery and summarizes their advantages and disadvantages.

关键词: spinal surgery     tissue state recognition     image     force sensing     bioelectrical impedance    

Effectiveness of state incentives for promoting wind energy: A panel data examination

Deepak SANGROYA,Jogendra NAYAK

《能源前沿(英文)》 2015年 第9卷 第3期   页码 247-258 doi: 10.1007/s11708-015-0364-8

摘要: Over the last decade, India has started to concentrate earnestly on renewable energy. The Indian government, as well as different state governments, are adopting policy instruments such as feed in tariff, captive consumption, renewable purchase obligation and generation based incentive etc. aimed at renewable energy development. This paper evaluates the effectiveness of state level incentives for the development of wind energy in India. Fixed effect panel data modelling technique of econometric analysis is used to analyse the data of 26 Indian states in 11 years. The results show that feed in tariff and captive consumption are the significant predictors of wind energy development. However, renewable purchase obligation does not affect wind energy significantly.

关键词: India     wind energy development     state incentives     econometric analysis     panel data    

Analysis on annealing-induced stress of blind-via TSV using FEM

Jie SHAO, Tielin SHI, Li DU, Lei SU, Xiangning LU, Guanglan LIAO

《机械工程前沿(英文)》 2018年 第13卷 第3期   页码 401-410 doi: 10.1007/s11465-017-0457-7

摘要:

Copper-filled through silicon via (TSV) is a promising material owing to its application in high-density three-dimensional (3D) packaging. However, in TSV manufacturing, thermo-mechanical stress is induced during the annealing process, often causing reliability issues. In this paper, the finite element method is employed to investigate the impacts of via shape and SiO2 liner uniformity on the thermo-mechanical properties of copper-filled blind-via TSV after annealing. Top interface stress analysis on the TSV structure shows that the curvature of via openings releases stress concentration that leads to ~60 MPa decrease of normal stresses, sxx and syy, in copper and ~70 MPa decrease sxx of in silicon. Meanwhile, the vertical interface analysis shows that annealing-induced stress at the SiO2/Si interface depends heavily on SiO2 uniformity. By increasing the thickness of SiO2 linear, the stress at the vertical interface can be significantly reduced. Thus, process optimization to reduce the annealing-induced stress becomes feasible. The results of this study help us gain a better understanding of the thermo-mechanical behavior of the annealed TSV in 3D packaging.

关键词: through silicon via (TSV)     annealing-induced stress     interface stress     plastic deformation     finite element method    

An investigation on stress distribution effect on multi- piezoelectric energy harvesters

Hailu YANG, Dongwei CAO

《结构与土木工程前沿(英文)》 2017年 第11卷 第3期   页码 301-307 doi: 10.1007/s11709-017-0404-z

摘要: With the fast development of piezoelectric materials and due to its green and renewable characteristics, the piezoelectric energy harvesting technology has been paid more and more attention by pavement engineers. The stress distribution will significantly affect the piezoelectric material performance. In this paper, the effects of multiple piezoelectric elements on the generation of electrical energy and output power are studied. In the case of constant external load, the number of the piezoelectric units does not necessarily produce more energy. When the same multi piezoelectric units work together, if the stress state of the piezoelectric units is different, the total output energy affected by the connection mode. For uneven stress distribution, the optimal output mode is that each of the piezoelectric units rectified before connected in parallel.

关键词: piezoelectric transducer     uneven stress     impedance matching     optimal energy output    

The formation mechanism and the influence factor of residual stress in machining

null

《机械工程前沿(英文)》 2014年 第9卷 第3期   页码 265-269 doi: 10.1007/s11465-014-0311-0

摘要:

Residual stresses generated in cutting process have important influences on workpiece performance. The paper presents a method of theoretical analysis in order to explicate the formation mechanism of residual stresses in cutting. An important conclusion is drawn that the accumulated plastic strain is the main factor which determines the nature and the magnitude of surface residual stresses in the workpiece. On the basis of the analytical model for residual stress, a series of simulations for residual stress prediction during cutting AISI 1045 steel are implemented in order to obtain the influences of cutting speed, depth of cut and tool edge radius on surface residual stress in the workpiece. And these influences are explained from the perspective of formation mechanism of residual stress in cutting. The conclusions have good applicability and can be used to guide the parameters selection in actual production.

关键词: residual stress     analytical model     strain     plastic     cutting parameter    

标题 作者 时间 类型 操作

以土体应力状态计算边坡安全系数的方法

王国体

期刊论文

土坡稳定分析应力状态新方法的过程解析

王国体,王婉娣

期刊论文

Development of a constitutive model for rockfills and similar granular materials based on the disturbed state

Mehdi VEISKARAMI, Ali GHORBANI, Mohammadreza ALAVIPOUR

期刊论文

Hot-dip galvanizing of cold-formed steel hollow sections: a state-of-the-art review

Min SUN, Jeffrey A. PACKER

期刊论文

Surficial stability analysis of soil slope under seepage based on a novel failure mode

期刊论文

Stress induced polarization switching and coupled hysteretic dynamics in ferroelectric materials

Linxiang WANG, Roderick MELNIK, Fuzai LV

期刊论文

强度理论与实验现象

刘大斌,韩文坝,蔡冰清,韩晓东

期刊论文

三向应力状态下混凝土强度和变形特性研究

闫东明,林皋

期刊论文

复杂曲面薄壁构件流体压力成形理论与技术研究进展

苑世剑

期刊论文

EFFECTS OF TRANSPORT STRESS ON THE INTESTINES INVOLVING NEURONAL NITRIC OXIDE SYNTHASE

期刊论文

Advances in tissue state recognition in spinal surgery: a review

Hao Qu, Yu Zhao

期刊论文

Effectiveness of state incentives for promoting wind energy: A panel data examination

Deepak SANGROYA,Jogendra NAYAK

期刊论文

Analysis on annealing-induced stress of blind-via TSV using FEM

Jie SHAO, Tielin SHI, Li DU, Lei SU, Xiangning LU, Guanglan LIAO

期刊论文

An investigation on stress distribution effect on multi- piezoelectric energy harvesters

Hailu YANG, Dongwei CAO

期刊论文

The formation mechanism and the influence factor of residual stress in machining

null

期刊论文