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A “Sequential Design of Simulations” approach for exploiting and calibrating discrete element simulations of cohesive powders

《化学科学与工程前沿(英文)》 2022年 第16卷 第6期   页码 874-885 doi: 10.1007/s11705-021-2131-1

摘要: The flow behaviours of cohesive particles in the ring shear test were simulated and examined using discrete element method guided by a design of experiments methodology. A full factorial design was used as a screening design to reveal the effects of material properties of partcles. An augmented design extending the screening design to a response surface design was constructed to establish the relations between macroscopic shear stresses and particle properties. It is found that the powder flow in the shear cell can be classified into four regimes. Shear stress is found to be sensitive to particle friction coefficient, surface energy and Young’s modulus. A considerable fluctuation of shear stress is observed in high friction and low cohesion regime. In high cohesion regime, Young’s modulus appears to have a more significant effect on the shear stress at the point of incipient flow than the shear stress during the pre-shear process. The predictions from response surface designs were validated and compared with shear stresses measured from the Schulze ring shear test. It is found that simulations and experiments showed excellent agreement under a variety of consolidation conditions, which verifies the advantages and feasibility of using the proposed “Sequential Design of Simulations” approach.

关键词: discrete element method     cohesive materials     parameter calibration     ring shear cell     design of experiments    

An extended cell-based smoothed discrete shear gap method (XCS-FEM-DSG3) for free vibration analysis

M. H. NGUYEN-THOI,L. Le-ANH,V. Ho-HUU,H. Dang-TRUNG,T. NGUYEN-THOI

《结构与土木工程前沿(英文)》 2015年 第9卷 第4期   页码 341-358 doi: 10.1007/s11709-015-0302-1

摘要: A cell-based smoothed discrete shear gap method (CS-FEM-DSG3) was recently proposed and proven to be robust for free vibration analyses of Reissner-Mindlin shell. The method improves significantly the accuracy of the solution due to softening effect of the cell-based strain smoothing technique. In addition, due to using only three-node triangular elements generated automatically, the CS-FEM-DSG3 can be applied flexibly for arbitrary complicated geometric domains. However so far, the CS-FEM-DSG3 has been only developed for analyzing intact structures without possessing internal cracks. The paper hence tries to extend the CS-FEM-DSG3 for free vibration analysis of cracked Reissner-Mindlin shells by integrating the original CS-FEM-DSG3 with discontinuous and crack−tip singular enrichment functions of the extended finite element method (XFEM) to give a so-called extended cell-based smoothed discrete shear gap method (XCS-FEM-DSG3). The accuracy and reliability of the novel XCS-FEM-DSG3 for free vibration analysis of cracked Reissner-Mindlin shells are investigated through solving three numerical examples and comparing with commercial software ANSYS.

关键词: cracked Reissner-Mindlin shell     free vibration analysis     cell-based smoothed discrete shear gap method (CS-FEM-DSG3)     extended cell-based smoothed discrete shear gap method (XCS-FEM-DSG3)     smoothed finite element methods (SFEM)    

Frequencies of circular plate with concentric ring and elastic edge support

null

《机械工程前沿(英文)》 2014年 第9卷 第2期   页码 168-176 doi: 10.1007/s11465-014-0299-5

摘要:

Exact solutions for the flexural vibrations of circular plates having elastic edge conditions along with rigid concentric ring support have been presented in this paper. Values of frequency parameter for the considered circular plate are computed for different sets of values of elastic rotational and translation restraints and the radius of internal rigid ring support. The results for the first three modes of plate vibrations are computed and are presented in tabular form. The effects of rotational and linear restraints and the radius of the rigid ring support on the vibration behavior of circular plates are studied over a wide range of non-dimensional parametric values. The values of the exact frequency parameter presented in this paper for varying values of restraint parameters and the radius of the rigid ring support can better serve in design and as benchmark solutions to validate the numerical methods obtained by using other methods of solution.

关键词: circular plate     frequency     elastic edge     rigid ring     mode switching    

发生于胃和结直肠的印戒细胞癌的临床特征以及不同部位的转移对预后的预测价值的研究 Article

吴静静, 方戴琼, 满达, 吴文瑞, 王清, 李雅婷, 叶建中, 李兰娟

《工程(英文)》 2020年 第6卷 第9期   页码 1028-1034 doi: 10.1016/j.eng.2020.06.007

摘要: 这项研究纳入了4055例在2010—2012年被诊断为胃印戒细胞癌(signet ring cell carcinoma, SRCC)、结直肠印戒细胞癌患者,其中胃印戒细胞癌2905例,结肠印戒细胞癌和直肠印戒细胞癌

关键词: SEER数据库,生存分析,印戒细胞癌,转移,结直肠癌,胃癌    

Fundamental buckling of circular plates with elastically restrained edges and resting on concentric rigid ring

Lokavarapu Bhaskara Rao, Chellapilla Kameswara Rao

《机械工程前沿(英文)》 2013年 第8卷 第3期   页码 291-297 doi: 10.1007/s11465-013-0255-9

摘要:

This work presents the existence of buckling mode switching with respect to the radius of concentric rigid ring support. The buckling mode may not be axisymmetric as previously assumed. In general, the plate may buckle in an axisymmetric mode but when the radius of the ring support becomes small, the plate may buckle in an asymmetric mode. The optimum radius of the concentric rigid ring support for maximum buckling load is also determined. Introducing internal rigid ring support, when placed at an optimal position increases the elastic buckling load capacity by 149.39 percent. The numerical results obtained are in good agreement with the previously published data.

关键词: buckling     circular plate     elastically restrained edge     rigid ring support     mode switching    

Modeling of shear walls using finite shear connector elements based on continuum plasticity

Ulf Arne GIRHAMMAR, Per Johan GUSTAFSSON, Bo KÄLLSNER

《结构与土木工程前沿(英文)》 2017年 第11卷 第2期   页码 143-157 doi: 10.1007/s11709-016-0377-3

摘要: Light-frame timber buildings are often stabilized against lateral loads by using diaphragm action of roofs, floors and walls. The mechanical behavior of the sheathing-to-framing joints has a significant impact on the structural performance of shear walls. Most sheathing-to-framing joints show nonlinear load-displacement characteristics with plastic behavior. This paper is focused on the finite element modeling of shear walls. The purpose is to present a new shear connector element based on the theory of continuum plasticity. The incremental load-displacement relationship is derived based on the elastic-plastic stiffness tensor including the elastic stiffness tensor, the plastic modulus, a function representing the yield criterion and a hardening rule, and function representing the plastic potential. The plastic properties are determined from experimental results obtained from testing actual connections. Load-displacement curves for shear walls are calculated using the shear connector model and they are compared with experimental and other computational results. Also, the ultimate horizontal load-carrying capacity is compared to results obtained by an analytical plastic design method. Good agreements are found.

关键词: shear walls     wall diaphragms     finite element modelling     plastic shear connector     analytical modelling     experimental comparison    

Nonlinear numerical simulation of punching shear behavior of reinforced concrete flat slabs with shear-heads

Dan V. BOMPA, Ahmed Y. ELGHAZOULI

《结构与土木工程前沿(英文)》 2020年 第14卷 第2期   页码 331-356 doi: 10.1007/s11709-019-0596-5

摘要: This paper examines the structural response of reinforced concrete flat slabs, provided with fully-embedded shear-heads, through detailed three-dimensional nonlinear numerical simulations and parametric assessments using concrete damage plasticity models. Validations of the adopted nonlinear finite element procedures are carried out against experimental results from three test series. After gaining confidence in the ability of the numerical models to predict closely the full inelastic response and failure modes, numerical investigations are carried out in order to examine the influence of key material and geometric parameters. The results of these numerical assessments enable the identification of three modes of failure as a function of the interaction between the shear-head and surrounding concrete. Based on the findings, coupled with results from previous studies, analytical models are proposed for predicting the rotational response as well as the ultimate strength of such slab systems. Practical recommendations are also provided for the design of shear-heads in RC slabs, including the embedment length and section size. The analytical expressions proposed in this paper, based on a wide-ranging parametric assessment, are shown to offer a more reliable design approach in comparison with existing methods for all types of shear-heads, and are suitable for direct practical application.

关键词: non-linear numerical modelling     concrete damage plasticity     RC flat slabs     shear-heads     punching shear    

Behaviour of self-centring shear walls——A state of the art review

《结构与土木工程前沿(英文)》 2023年 第17卷 第1期   页码 53-77 doi: 10.1007/s11709-022-0850-0

摘要: The application of unbonded post-tensioning (PT) in structural walls has led to the development of advanced self-centring (rocking) shear wall systems that has significant advantages, including accelerated construction due to the incorporation of prefabricated elements and segmental construction for different materials (e.g., concrete, masonry, and timber), reduced residual drifts, and little damage upon extreme seismic and wind loads. Concrete, masonry, and timber are often used for the construction of unbonded PT structural wall systems. Despite extensive research since the 1980s, there are no well-established design guidelines available on the shear wall configuration with the required energy dissipation system, joint’s locations and acceptance criteria for shear sliding, confinement, seismic performance factors, PT loss, PT force range and residual drifts of shear walls subjected to lateral loads. In this research a comprehensive state-of-the-art literature review was performed on self-centring shear wall system. An extensive study was carried out to collect a database of 100 concrete, masonry, and self-centring shear wall tests from the literature. The established database was then used to review shear walls’ configurations, material, and components to benchmark requirements applicable for design purposes. The behaviour of concrete, masonry and timber shear walls were compared and critically analysed. The general behaviour, force-displacement performance of the walls, ductility, and seismic response factors, were critically reviewed and analysed for different self-centring wall systems to understand the effect of different parameters including configurations of the walls, material used for construction of the wall (concrete, masonry, timber) and axial stress ratio. The outcome of this research can be used to better understand the behaviour of self-centring wall system in order to develop design guidelines for such walls.

关键词: self-centring shear walls     rocking walls     energy dissipation     seismic performance factors     PT loss     residual drift    

Prediction of the shear wave velocity

Amoroso SARA

《结构与土木工程前沿(英文)》 2014年 第8卷 第1期   页码 83-92 doi: 10.1007/s11709-013-0234-6

摘要: The paper examines the correlations to obtain rough estimates of the shear wave velocity from non-seismic dilatometer tests (DMT) and cone penetration tests (CPT). While the direct measurement of is obviously preferable, these correlations may turn out useful in various circumstances. The experimental results at six international research sites suggest that the DMT predictions of from the parameters (material index), (horizontal stress index), (constrained modulus) are more reliable and consistent than the CPT predictions from (cone resistance), presumably because of the availability, by DMT, of the stress history index .

关键词: horizontal stress index     shear wave velocity     flat dilatometer test     cone penetration test    

On braced trapezoidal corrugated steel shear panels: An experimental and numerical study

《结构与土木工程前沿(英文)》 2023年 第17卷 第3期   页码 396-410 doi: 10.1007/s11709-023-0934-5

摘要: In this study, a new system consisting of a combination of braces and steel infill panels called the braced corrugated steel shear panel (BCSSP) is presented. To obtain the hysteretic behavior of the proposed system, the quasi-static cyclic performances of two experimental specimens were first evaluated. The finite element modeling method was then verified based on the obtained experimental results. Additional numerical evaluations were carried out to investigate the effects of different parameters on the system. Subsequently, a relationship was established to estimate the buckling shear strength of the system without considering residual stresses. The results obtained from the parametric study indicate that the corrugated steel shear panel (CSSP) with the specifications of a = 30 mm, t = 2 mm, and θ = 90° had the highest energy dissipation capacity and ultimate strength while the CSSP with the specifications of a = 30 mm, t = 2 mm, and θ = 30° had the highest initial stiffness. It can thus be concluded that the latter CSSP has the best structural performance and that increasing the number of corrugations, corrugation angle, and plate thickness and decreasing the sub-panel width generally enhance the performance of CSSPs in terms of the stability of their hysteretic behaviors.

关键词: trapezoidal corrugated plate     steel shear panel     braced steel shear panel     experimental study     buckling resistance.    

A novel algorithm for frequency dependent modeling of ferrite ring and its optimum design to study VFTO

Mehrdad MAJIDI, Hamid JAVADI, Moein MANBACHI

《能源前沿(英文)》 2014年 第8卷 第1期   页码 90-100 doi: 10.1007/s11708-013-0286-2

摘要: One of the fundamental issues in gas insulated substations (GIS) which has destructive effects on GIS equipment is the very fast transient over-voltages (VFTOs). This paper models a 400/230 kV substation in order to study the effects of VFTO extensively implemented on EMTP-RV. In addition, the application of ferrite rings for suppressing VFTOs is assessed thoroughly. The main advantage of this paper is its new proposed algorithm according to the ferrite ring frequency dependent modeling that is validated with experimental results. This paper examines the effects of three compositions of the ferrite ring on VFTO suppression. Moreover, it estimates the dimension of the ferrite ring based on the SF6 gas insulation withstand and the maximum effect of ferrite rings on VFTO suppression constraint with the COMSOL multiphysics software. Furthermore, it gains VFTO attenuated percentages due to the installation of the ferrite ring in different GIS nodes. Finally, it analyzes the offered VFTO amendment technique in various GIS switching scenarios.

关键词: comsol multiphysics     EMTP-RV     ferrite ring     gas insulated substations (GIS)     transient over-voltage     insulation coordination    

单向离合器外环应力计算的有限元方法研究

罗一新,吴波

《中国工程科学》 2004年 第6卷 第9期   页码 56-59

摘要:

单向离合器是一种常见的机械传动部件,其外环应力计算尚无理想的方法。文章以五滚柱式单向离合器为研究对象,根据外环的特点,采用有限元分析方法,分析了影响其计算精度的各种因素,计算出其外环的应力,并且将计算结果与曲梁计算法进行了比较。研究表明,有限元分析方法对于外环类零件的应力计算确是一种理想的方法。

关键词: 离合器     外环     应力     有限元    

Experimental study on shear behavior of reinforced concrete beams with web horizontal reinforcement

Dong XU,Yu ZHAO,Chao LIU

《结构与土木工程前沿(英文)》 2014年 第8卷 第4期   页码 325-336 doi: 10.1007/s11709-014-0080-1

摘要: In determining the shear capacity of reinforced concrete beams, current codes do not provide any calculation method to evaluate the influence of web horizontal reinforcement, although they exist as structural reinforcements (or skin reinforcement). The present paper comprises results of 11 reinforced concrete beams in an effort to investigate the influence of web horizontal reinforcement on the shear behavior of reinforced concrete beams. The primary design variables are the shear-span-depth ratio, different reinforcement ratio of stirrups and web horizontal reinforcement. Influence of web horizontal reinforcement on crack patterns and failure mode was studied. It was found that web horizontal reinforcement can increase the shear capacity of the beams and restrain growth of inclined cracks effectively. Test results are very valuable, as very few references of shear tests can be found focusing on the effect of web horizontal reinforcement on the shear capacity of the beams.

关键词: reinforced concrete beam     shear strength     web horizontal reinforcement     experiments    

Intelligent algorithm for optimal meter placement and bus voltage estimation in ring main distribution

L. RAMESH, N. CHAKRABORTY, S. P. CHOWDHURY

《能源前沿(英文)》 2012年 第6卷 第1期   页码 47-56 doi: 10.1007/s11708-011-0159-5

摘要: The advancement in power distribution system poses a great challenge to power engineering researchers on how to best monitor and estimate the state of the distribution network. This paper is executed in two stage processes. The first stage is to identify the optimal location for installation of monitoring instrument with minimal investment cost. The second stage is to estimate the bus voltage magnitude, where real time measurement is conducted and measured through identified meter location which is more essential for decision making in distribution supervisory control and data acquisition system (DSCADA). The hybrid intelligent technique is applied to execute the above two algorithms. The algorithms are tested with institute of electrical and electronics engineers (IEEE) and Tamil Nadu electricity board (TNEB) benchmark systems. The simulated results proves that the swarm tuned artificial neural network (ANN) estimator is best suited for accurate estimation of voltage with different noise levels.

关键词: artificial intelligence     power distribution control     state estimation    

Effect of loading rate on shear strength parameters of mechanically and biologically treated waste

《环境科学与工程前沿(英文)》 2022年 第16卷 第12期 doi: 10.1007/s11783-022-1595-7

摘要:

● Mechanical behavior of MBT waste affected by loading rate was investigated.

关键词: Mechanically and biologically treated waste     Landfill     Triaxial test     Loading rate     Axial strain     Shear strength parameter    

标题 作者 时间 类型 操作

A “Sequential Design of Simulations” approach for exploiting and calibrating discrete element simulations of cohesive powders

期刊论文

An extended cell-based smoothed discrete shear gap method (XCS-FEM-DSG3) for free vibration analysis

M. H. NGUYEN-THOI,L. Le-ANH,V. Ho-HUU,H. Dang-TRUNG,T. NGUYEN-THOI

期刊论文

Frequencies of circular plate with concentric ring and elastic edge support

null

期刊论文

发生于胃和结直肠的印戒细胞癌的临床特征以及不同部位的转移对预后的预测价值的研究

吴静静, 方戴琼, 满达, 吴文瑞, 王清, 李雅婷, 叶建中, 李兰娟

期刊论文

Fundamental buckling of circular plates with elastically restrained edges and resting on concentric rigid ring

Lokavarapu Bhaskara Rao, Chellapilla Kameswara Rao

期刊论文

Modeling of shear walls using finite shear connector elements based on continuum plasticity

Ulf Arne GIRHAMMAR, Per Johan GUSTAFSSON, Bo KÄLLSNER

期刊论文

Nonlinear numerical simulation of punching shear behavior of reinforced concrete flat slabs with shear-heads

Dan V. BOMPA, Ahmed Y. ELGHAZOULI

期刊论文

Behaviour of self-centring shear walls——A state of the art review

期刊论文

Prediction of the shear wave velocity

Amoroso SARA

期刊论文

On braced trapezoidal corrugated steel shear panels: An experimental and numerical study

期刊论文

A novel algorithm for frequency dependent modeling of ferrite ring and its optimum design to study VFTO

Mehrdad MAJIDI, Hamid JAVADI, Moein MANBACHI

期刊论文

单向离合器外环应力计算的有限元方法研究

罗一新,吴波

期刊论文

Experimental study on shear behavior of reinforced concrete beams with web horizontal reinforcement

Dong XU,Yu ZHAO,Chao LIU

期刊论文

Intelligent algorithm for optimal meter placement and bus voltage estimation in ring main distribution

L. RAMESH, N. CHAKRABORTY, S. P. CHOWDHURY

期刊论文

Effect of loading rate on shear strength parameters of mechanically and biologically treated waste

期刊论文