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Numerical evaluation of group-pile foundation subjected to cyclic horizontal load

Youngji JIN, Xiaohua BAO, Yoshimitsu KONDO, Feng ZHANG,

《结构与土木工程前沿(英文)》 2010年 第4卷 第2期   页码 196-207 doi: 10.1007/s11709-010-0021-6

摘要: In this paper, three-dimensional (3D) finite element analyses of a real-scale group-pile foundation subjected to horizontal cyclic loading are conducted using a program named DBLEAVES. In the simulations, nonlinear behaviors of ground and piles are described by subloading model and the axial-force dependent model (AFD model) which considered the axial-force dependency in the nonlinear moment-curvature relations. In order to consider the influence of an effective stress path on the prediction of the group-pile foundation, the analyses are conducted within the framework of the soil-water coupling method with finite-difference and finite-element regime. The material parameters of soils are determined based on conventional triaxial drained compression tests on undisturbed and remolded specimens. The applicability of the proposed numerical method is encouraging, and therefore, it is quite confident to say that the method can be used to predict the mechanical behaviors of group-pile foundation to a satisfactory accuracy, particularly with the effective stress analysis.

关键词: group-pile foundation     real-scale cyclic loading test     three-dimensional finite element method (3D-FEM)     soil-water coupling analysis     undisturbed and remolded specimens    

3D finite element method (FEM) simulation of groundwater flow during backward erosion piping

Kristine VANDENBOER,Vera van BEEK,Adam BEZUIJEN

《结构与土木工程前沿(英文)》 2014年 第8卷 第2期   页码 160-166 doi: 10.1007/s11709-014-0257-7

摘要: Backward erosion piping is an important failure mechanism for cohesive water retaining structures which are founded on a sandy aquifer. At present, the prediction models for safety assessment are often based on 2D assumptions. In this work, a 3D numerical approach of the groundwater flow leading to the erosion mechanism of backward erosion piping is presented and discussed. Comparison of the 2D and 3D numerical results explicitly demonstrates the inherent 3D nature of the piping phenomenon. In addition, the influence of the seepage length is investigated and discussed for both piping initiation and piping progression. The results clearly indicate the superiority of the presented 3D numerical model compared to the established 2D approach. Moreover, the 3D numerical results enable a better understanding of the complex physical mechanism involved in backward erosion piping and thus can lead to a significant improvement in the safety assessment of water retaining structures.

关键词: backward erosion piping     groundwater flow     3D finite element method (FEM)    

Ribbed strip rolling by three-dimensional finite element method combining extremely thin array of elements

Zhengyi JIANG,

《机械工程前沿(英文)》 2010年 第5卷 第1期   页码 52-60 doi: 10.1007/s11465-009-0087-9

摘要: In this paper, a three-dimensional finite element modelling of the ribbed strip rolling is carried out, coupling the use of an extremely thin array of elements that is equivalent to the calculation of the additional shear deformation work rate occurred by the velocity discontinuity in the roll bite. The formulation of the finite element modelling by adding a rib inclined contact surface boundary condition is derived, and the performance of the proposed method is conducted. The simulated rib height, forward slip, and the pulling down of rib height have been compared with the measured values and are in good agreement. The equivalent strain rate of the rib was obtained in the simulation. The effect of the rib inclined angle on pulling down of rib height has also been discussed, which is helpful in optimizing the design of the rib inclined angle.

关键词: rib inclined contact boundary condition     ribbed strip     extremely thin elements     pulling down of rib height     finite element modelling    

Three-dimensional seismic response analysis of a concrete-faced rockfill dam on overburden layers

Dakuo FENG, Ga ZHANG, Jianmin ZHANG,

《结构与土木工程前沿(英文)》 2010年 第4卷 第2期   页码 258-266 doi: 10.1007/s11709-010-0031-4

摘要: Reasonable seismic response analysis of a high rockfill dam is of great engineering significance in guiding its design and ensuring its seismic safety during operation, especially of a concrete-faced rockfill dam (CFRD) on overburden layers. The three-dimensional seismic behavior of the Miaojiaba CFRD is simulated and analyzed by the finite element method (FEM). The results indicate that: 1) the amplification coefficient along the dam axis gradually increases with the altitude, and reaches maximum at the dam crest; 2) the vertical residual deformation mainly exhibits downwards and reaches maximum near the dam crest; 3) the earthquake significantly aggravates the deformation of peripheral joints; 4) the impounding condition and overburden characteristics have great effects on the dam’s seismic response.

关键词: concrete-faced rockfill dam (CFRD)     overburden layer     dynamic analysis     finite element method (FEM)    

Reliability assessment of three-dimensional bearing capacity of shallow foundation using fuzzy set theory

Rajarshi PRAMANIK, Dilip Kumar BAIDYA, Nirjhar DHANG

《结构与土木工程前沿(英文)》 2021年 第15卷 第2期   页码 478-489 doi: 10.1007/s11709-021-0698-8

摘要: The aim of this study is to investigate the applicability of reliability theory on surface square/rectangular footing against bearing capacity failure using fuzzy set theory in conjunction with the finite element method. Soil is modeled as a three-dimensional spatially varying medium, where its parameters (cohesion, friction angle, unit weight, etc.) are considered as fuzzy variables that maintain some membership functions. Soil is idealized as an elastic-perfectly plastic material obeying the Mohr–Coulomb failure criterion, where both associated and non-associated flow rules are considered in estimating the ultimate bearing capacity of the footing. The spatial variability of the soil is incorporated for both isotropic and anisotropic fields, which are determined by the values of scales of fluctuation in both the horizontal and vertical directions. A new parameter namely, limiting applied pressure at zero failure probability is proposed, and it indirectly predicts the failure probability of the footing. The effect of the coefficient of variation of the friction angle of the soil on the probability of failure is analyzed, and it is observed that the effect is significant. Furthermore, the effect of the scale of fluctuation on the probability of failure is investigated, and the necessity for considering spatial variability in the reliability analysis is well proven.

关键词: finite element method     square footing     reliability analysis     fuzzy set theory     coefficient of variation     spatial variability    

Stability of three-dimensional printable foam concrete as function of surfactant characteristics

《结构与土木工程前沿(英文)》   页码 935-947 doi: 10.1007/s11709-023-0964-z

摘要: Extrudability is one of the most critical factors when designing three-dimensional printable foam concrete. The extrusion process likely affects the foam stability which necessitates the investigation into surfactant properties particularly for concrete mixes with high foam contents. Although many studies have been conducted on traditional foam concrete in this context, studies on three-dimensional printed foam concrete are scarce. To address this research gap, the effects of surfactant characteristics on the stability, extrudability, and buildability of three-dimensional printed foam concrete mixes with two design densities (1000 and 1300 kg/m3) using two different surfactants and stabilizers (synthetic-based sodium lauryl sulfate stabilized with carboxymethyl cellulose sodium salt, and natural-based hingot surfactant stabilized with xanthan gum) were investigated in this study. Fresh density tests were conducted before and after the extrusion to determine stability of the foam concrete. The results were then correlated with surfactant qualities, such as viscosity and surface tension, to understand the importance of key parameters in three-dimensional printing of foam concrete. Based on the experimental results, surfactant solu1tion with viscosity exceeding 5 mPa·s and surface tension lower than 31 mN/m was recommended to yield stable three-dimensional printable foam concrete mixes. Nevertheless, the volume of foam in the mix significantly affected the printability characteristics. Unlike traditional foam concrete, the variation in the stabilizer concentration and density of concrete were found to have insignificant effect on the fresh-state-characteristics (slump, slump flow, and static yield stress) and air void microstructure of the stable mixes.

关键词: foam concrete     3D printable concrete     stability     rheology     air void microstructure    

Three-dimensional electromagnetic analysis and design of permanent magnet retarder

Lezhi YE, Desheng LI, Bingfeng JIAO

《机械工程前沿(英文)》 2010年 第5卷 第4期   页码 438-441 doi: 10.1007/s11465-010-0111-0

摘要: An eddy current retarder for vehicles generates much heat when it works continuously, which leads to serious decline in braking torque. This paper proposes a novel permanent magnet retarder (PMR) for vehicles, whose cooling system connects with engine cooling-water. A three-dimensional finite element model is developed to model the electromagnetic behavior of a permanent magnet retarder under a constant speed. The magnetic field and eddy current field in PMR are numerically solved by a finite element method. By accounting for the nonlinear permeability of the rotor and the weakened effect in the magnetic field that is generated by the eddy current magnetic field, the calculation accuracy of air-gap magnetic field is enhanced. Experiment shows that the temperature of the retarder is less than 150°C, and the braking torque keeps the hard characteristics curve. The calculated air-gap magnetic flux density is fairly good agreement with the measured one.

关键词: auxiliary brake     permanent magnet retarder     water-cooling     finite element method    

Structural characteristics of cement-stabilized soil bases with 3D finite element method

Yunfeng PENG, Yunlong HE,

《结构与土木工程前沿(英文)》 2009年 第3卷 第4期   页码 428-434 doi: 10.1007/s11709-009-0059-5

摘要: Cement-stabilized soil bases have been widely used in expressways due to its high strength, appropriate stiffness, good water resistance, and frost resistance. So far, the structural characteristics and mechanical behaviors of cement-stabilized soil bases were not investigated so much. In this paper, the 3D elastic-plastic finite element method (FEM) was used to analyze the mechanical behaviors and structural characteristics of cement-stabilized soil bases from construction to operation. The pavement filling and the traffic loading processes were simulated, and a contact model was used to simulate the contact behavior between each layer of the pavement. Considering the construction process, the structural characteristics and mechanical behaviors of cement-stabilized soil bases were studied under asphalt-concrete pavement conditions. Furthermore, the general rules of deformations and stresses in cement-stabilized soil bases under different conditions were discussed, and some suggestions were put forward for the design and construction of cement-stabilized soil bases.

关键词: different     strength     asphalt-concrete pavement     FEM     appropriate stiffness    

Fabrication of Si-based three-dimensional microbatteries: A review

Chuang YUE, Jing LI, Liwei LIN

《机械工程前沿(英文)》 2017年 第12卷 第4期   页码 459-476 doi: 10.1007/s11465-017-0462-x

摘要:

High-performance, Si-based three-dimensional (3D) microbattery systems for powering micro/nano-electromechanical systems and lab-on-chip smart electronic devices have attracted increasing research attention. These systems are characterized by compatible fabrication and integratibility resulting from the silicon-based technologies used in their production. The use of support substrates, electrodes or current collectors, electrolytes, and even batteries used in 3D layouts has become increasingly important in fabricating microbatteries with high energy, high power density, and wide-ranging applications. In this review, Si-based 3D microbatteries and related fabrication technologies, especially the production of micro-lithium ion batteries, are reviewed and discussed in detail in order to provide guidance for the design and fabrication.

关键词: three-dimensional (3D)     wafer-scale     Si-based anode     micro-LIBs     thin-film deposition    

Slope stability analysis based on a multigrid method using a nonlinear 3D finite element model

Yaoru LIU, Zhu HE, Bo LI, Qiang YANG

《结构与土木工程前沿(英文)》 2013年 第7卷 第1期   页码 24-31 doi: 10.1007/s11709-013-0190-1

摘要: The rigid-body limit equilibrium method cannot reflect the actual stress distribution in a rock mass, and the finite-element-based strength reduction method also has some problems with respect to convergence. To address these problems, a multi-grid method was adopted in this study to establish a structural grid for finite element computation and a slip surface grid for computing slope stability safety factors. This method can be used to determine the stability safety factor for any slip surface or slide block through a combination of nonlinear finite element analysis and limit equilibrium analysis. An ideal elastic–plastic incremental analysis method based on the Drucker–Prager yield criterion was adopted in the nonlinear finite element computation. Elasto-plastic computation achieves good convergence for both small load steps and large load steps and can increase computation precision to a certain extent. To increase the scale and accuracy of the computation, TFINE, a finite element parallel computation program, was used to analyze the influence of grid density on the accuracy of the computation results and was then applied to analysis of the stability of the Jinping high slope. A comparison of the results with results obtained using the rigid-body limit equilibrium method showed that the slope stability safety factors determined using finite element analysis were greater than those obtained using the rigid-body limit equilibrium method and were in better agreement with actual values because nonlinear stress adjustment was considered in the calculation.

关键词: slope     stability     multi-grid method     nonlinear     finite element method    

The smoothed finite element method (S-FEM): A framework for the design of numerical models for desired

Gui-Rong Liu

《结构与土木工程前沿(英文)》 2019年 第13卷 第2期   页码 456-477 doi: 10.1007/s11709-019-0519-5

摘要:

The smoothed finite element method (S-FEM) was originated by G R Liu by combining some meshfree techniques with the well-established standard finite element method (FEM). It has a family of models carefully designed with innovative types of smoothing domains. These models are found having a number of important and theoretically profound properties. This article first provides a concise and easy-to-follow presentation of key formulations used in the S-FEM. A number of important properties and unique features of S-FEM models are discussed in detail, including 1) theoretically proven softening effects; 2) upper-bound solutions; 3) accurate solutions and higher convergence rates; 4) insensitivity to mesh distortion; 5) Jacobian-free; 6) volumetric-locking-free; and most importantly 7) working well with triangular and tetrahedral meshes that can be automatically generated. The S-FEM is thus ideal for automation in computations and adaptive analyses, and hence has profound impact on AI-assisted modeling and simulation. Most importantly, one can now purposely design an S-FEM model to obtain solutions with special properties as wish, meaning that S-FEM offers a framework for design numerical models with desired properties. This novel concept of numerical model on-demand may drastically change the landscape of modeling and simulation. Future directions of research are also provided.

关键词: computational method     finite element method     smoothed finite element method     strain smoothing technique     smoothing domain     weakened weak form     solid mechanics     softening effect     upper bound solution    

Three-dimensional composite Li metal anode by simple mechanical modification for high-energy batteries

《能源前沿(英文)》 2023年 第17卷 第5期   页码 569-584 doi: 10.1007/s11708-023-0875-7

摘要: Lithium (Li) metal is believed to be the “Holy Grail” among all anode materials for next-generation Li-based batteries due to its high theoretical specific capacity (3860 mAh/g) and lowest redox potential (−3.04 V). Disappointingly, uncontrolled dendrite formation and “hostless” deposition impede its further development. It is well accepted that the construction of three-dimensional (3D) composite Li metal anode could tackle the above problems to some extent by reducing local current density and maintaining electrode volume during cycling. However, most strategies to build 3D composite Li metal anode require either electrodeposition or melt-infusion process. In spite of their effectiveness, these procedures bring multiple complex processing steps, high temperature, and harsh experimental conditions which cannot meet the actual production demand in consideration of cost and safety. Under this condition, a novel method to construct 3D composite anode via simple mechanical modification has been recently proposed which does not involve harsh conditions, fussy procedures, or fancy equipment. In this mini review, a systematic and in-depth investigation of this mechanical deformation technique to build 3D composite Li metal anode is provided. First, by summarizing a number of recent studies, different mechanical modification approaches are classified clearly according to their specific procedures. Then, the effect of each individual mechanical modification approach and its working mechanisms is reviewed. Afterwards, the merits and limits of different approaches are compared. Finally, a general summary and perspective on construction strategies for next-generation 3D composite Li anode are presented.

关键词: lithium (Li)-ion battery (LIB)     Li metal battery     three-dimensional (3D) composite Li metal anode     mechanical modification     reducing local current density    

liquid bridge forces on rheological properties, and resulting extrudability and constructability of three-dimensional

《结构与土木工程前沿(英文)》   页码 1295-1309 doi: 10.1007/s11709-023-0999-1

摘要: Extrudability and constructability are two important, yet contradictory issues pertaining to the construction of three-dimensional (3D) printing concrete. Extrudability is easily achieved when 3D printing cement mortar has a high water content and low cohesion, but the printed structure is easily collapsible. However, a 3D printing cement mortar with a low water content and high cohesion has a relatively stable printed structure although the cement mortar might not be extrudable. This study proposes a particle-based method to simulate 3D printing mortar extrusion and construction as an overall planning tool for building design. First, a discrete element model with time-varying liquid bridge forces is developed to investigate the microscopic effects of these forces on global rheological properties. Next, a series of numerical simulations relevant to 3D printable mortar extrudability and constructability are carried out. The study demonstrates that the effects of time-varying liquid bridge forces on rheological properties and the resulting extrudability and constructability of 3D printing mortar are considerable. Furthermore, an optimized region that satisfies both the extrusion and construction requirements is provided for 3D printing industry as a reference.

关键词: particle-based simulation     liquid bridge force     rheological property     3D printing mortar     extrudability     constructability    

Three-dimensional reconstruction of light microscopy image sections: present and future

null

《医学前沿(英文)》 2015年 第9卷 第1期   页码 30-45 doi: 10.1007/s11684-014-0337-z

摘要:

Three-dimensional (3D) image reconstruction technologies can reveal previously hidden microstructures in human tissue. However, the lack of ideal, non-destructive cross-sectional imaging techniques is still a problem. Despite some drawbacks, histological sectioning remains one of the most powerful methods for accurate high-resolution representation of tissue structures. Computer technologies can produce 3D representations of interesting human tissue and organs that have been serial-sectioned, dyed or stained, imaged, and segmented for 3D visualization. 3D reconstruction also has great potential in the fields of tissue engineering and 3D printing. This article outlines the most common methods for 3D tissue section reconstruction. We describe the most important academic concepts in this field, and provide critical explanations and comparisons. We also note key steps in the reconstruction procedures, and highlight recent progress in the development of new reconstruction methods.

关键词: microtomy     3D imaging     computer-assisted image processing     3D printing     tissue scaffold    

Non linear modeling of three-dimensional reinforced and fiber concrete structures

Fatiha IGUETOULENE, Youcef BOUAFIA, Mohand Said KACHI

《结构与土木工程前沿(英文)》 2018年 第12卷 第4期   页码 439-453 doi: 10.1007/s11709-017-0433-7

摘要: Under the effect of the ascending loading, the behavior of reinforced concrete structures is rather non linear. Research in industry and science aims to extend forward the use of non-linear calculation of fiber concrete for structural parts such as columns, veils and pious, as the fiber concrete is more ductile behavior then the classical concrete behavior. The formulation of the element has been established for modeling the nonlinear behavior of elastic structures in three dimensions, based on the displacement method. For the behavior of concrete and fiber concrete compressive and tensile strength (stress-strain) the uniaxial formulation is used. For steel bi-linear relationship is used. The approach is based on the discretization of the cross section trapezoidal tables. Forming the stiffness matrix of the section, the integral of the surface is calculated as the sum of the integrals on each of the cutting trapezoids. To integrate on the trapeze we have adopted the type of Simpson integration scheme.

关键词: numerical modeling     column and beam     nonlinear analysis     fibers     pious     reinforcement     3D formulation     response load-deflection    

标题 作者 时间 类型 操作

Numerical evaluation of group-pile foundation subjected to cyclic horizontal load

Youngji JIN, Xiaohua BAO, Yoshimitsu KONDO, Feng ZHANG,

期刊论文

3D finite element method (FEM) simulation of groundwater flow during backward erosion piping

Kristine VANDENBOER,Vera van BEEK,Adam BEZUIJEN

期刊论文

Ribbed strip rolling by three-dimensional finite element method combining extremely thin array of elements

Zhengyi JIANG,

期刊论文

Three-dimensional seismic response analysis of a concrete-faced rockfill dam on overburden layers

Dakuo FENG, Ga ZHANG, Jianmin ZHANG,

期刊论文

Reliability assessment of three-dimensional bearing capacity of shallow foundation using fuzzy set theory

Rajarshi PRAMANIK, Dilip Kumar BAIDYA, Nirjhar DHANG

期刊论文

Stability of three-dimensional printable foam concrete as function of surfactant characteristics

期刊论文

Three-dimensional electromagnetic analysis and design of permanent magnet retarder

Lezhi YE, Desheng LI, Bingfeng JIAO

期刊论文

Structural characteristics of cement-stabilized soil bases with 3D finite element method

Yunfeng PENG, Yunlong HE,

期刊论文

Fabrication of Si-based three-dimensional microbatteries: A review

Chuang YUE, Jing LI, Liwei LIN

期刊论文

Slope stability analysis based on a multigrid method using a nonlinear 3D finite element model

Yaoru LIU, Zhu HE, Bo LI, Qiang YANG

期刊论文

The smoothed finite element method (S-FEM): A framework for the design of numerical models for desired

Gui-Rong Liu

期刊论文

Three-dimensional composite Li metal anode by simple mechanical modification for high-energy batteries

期刊论文

liquid bridge forces on rheological properties, and resulting extrudability and constructability of three-dimensional

期刊论文

Three-dimensional reconstruction of light microscopy image sections: present and future

null

期刊论文

Non linear modeling of three-dimensional reinforced and fiber concrete structures

Fatiha IGUETOULENE, Youcef BOUAFIA, Mohand Said KACHI

期刊论文