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IEEE OPEN JOURNAL OF INDUSTRY APPLICATIONS 2023年 4卷 87-98页

作者： Almozayen, Mohamed A. Knight, Andrew M. Tanta Univ Fac Engn Dept Elect Power Syst & Machines Engn Tanta 6632110 Egypt Univ Calgary Dept Elect & Software Engn Calgary AB T2N 1N4 Canada

Cosimulation studies of electric power systems and electric machines have always been a challenge. In order to reduce the simulation time to a reasonable value, lumped-parameter electric machine models are commonly used in electric power system modeling software packages to avoid the heavy computational burden of more accurate modeling methods especially finite-element method (FEM) on the expense of less accuracy. The proposed technique in this article combines the dynamic phasor modeling technique for power system simulations with the FEM to accurately model the doubly fed induction generator while connected to the grid. The utilization of dynamic phasors enables adopting large simulation time steps resulting in a significant reduction in the simulation time compared to the conventional time-domain FEM modeling. The mathematical foundation of the proposed modeling method is presented including the generator's core saturation. Custom-written C++ codes have been developed by the authors to execute the new dynamic phasor FEM algorithm and the conventional time-domain FEM in order to fairly compare their accuracy and numerical performances. As the proposed method combines time and frequency domains, a unique capability of modeling the rotor movement can be achieved. The rotation can be represented by physically incrementing the rotor and airgap mesh as in regular time-domain solvers, by mathematically representing the rotation using the virtual blocked rotor method as in frequency-domain solvers, and the proposed method of combining the two aforementioned approaches. The three methods of modeling rotor rotation are discussed, and their simulation results are compared to give a guide to choose the proper method for the different modeling targets. The results show that the proposed dynamic phasor FEM is capable of producing comparable results to the traditional time-domain solver at a substantially reduced simulation time.

关键词： Doubly fed induction generator (DFIG) dynamic phasor modeling finite-element modeling power system modeling wind energy

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An Efficient SQUID NDE Defect Detection Approach by Using an Adaptive finite-element modeling

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JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM 2011年第1-2期24卷 1077-1081页

作者： Sarreshtedari, Farrokh Razmkhah, Sasan Hosseini, Nahid Schubert, Jurgen Banzet, Marko Fardmanesh, Mehdi Sharif Univ Technol Dept Elect Engn Tehran Iran Forschungszentrum Julich Inst Bio & Nanosyst D-52425 Julich Germany

Incorporating the finite-element method for the modeling of the SQUID NDE response to a predefined defect pattern, an adaptive algorithm has been developed for the reconstruction of unknown defects using an optimization algorithm for updating of the forward problem. The defect reconstruction algorithm starts with an initial estimation for the defect pattern. Then the forward problem is solved and the obtained field pattern is compared with the measured signal from the SQUID NDE system. The result is used by an optimization algorithm to update the defect structure to be incorporated in the FEM forward problem for the next iteration. Since the mentioned model based inverse algorithm normally consumes a lot of computational resources, the number of iterations plays an important role in the determination of the total response convergence time. Consequently, different optimization algorithms have been applied and their performances are compared. In this work by incorporating an efficient forward model and using the stochastic and deterministic optimization algorithms for defect updating we have investigated their performance on the inversion of the SQUID NDE signal and also their ability to defect reconstruction in the noisy environment.

关键词： SQUID NDE Defect detection algorithm finite-element modeling

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Three-dimensional finite-element modeling of a thin-skinned fold-thrust belt wedge: Provo salient, Sevier belt, Utah

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GEOLOGY 2004年第7期32卷 561-564页

作者： Kwon, S Mitra, G Univ Rochester Dept Earth & Environm Sci Rochester NY 14627 USA

Three-dimensional finite-element (FE) analysis of a fold-thrust belt wedge model provides graphical and quantitative information for the strain geometry, kinematics, and mechanics of salient formation in three-dimensional space. A nonlinear, elastic-plastic FE model, using the initial basin configuration of the restored Provo salient, Utah, develops realistic deformation features (e.g., salient) in the deformed sedimentary prism. The three-dimensional fold-thrust, belt wedge model shows different deformation characteristics (based on S-1, gamma(max), and sigma(1) orientations and material-displacement directions) in. different parts of the salient, and its behavior is closely related to the preexisting template of the predeformational basin shape. The model results indicate plane-strain deformation with symmetric finite-strain geometry,in the middle of the salient and nonplane-strain deformation with nonsymmetric finite-strain geometry at the lateral boundaries. Thus, conventional two-dimensional plane-strain assumptions in fold-thrust belt analysis (e.g., in balancing cross sections) are reasonable only in the middle of the salient;however, at the lateral boundaries, the results indicate fully three dimensional deformation and suggest that restorations need to be more carefully constrained in three dimensions on the basis of detailed geologic data.

关键词： finite-element modeling fold-thrust belt wedge plane strain nonplane strain threedimensional deformation Provo salient

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Prediction and control of cavity growth during superplastic sheet forming with finite-element modeling

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JOURNAL OF MATERIALS PROCESSING TECHNOLOGY 1998年第1-3期75卷 87-93页

作者： Xing, HL Wang, ZR RIKEN Inst Phys & Chem Res Mat Fabricat Lab Wako Saitama 35101 Japan Harbin Inst Technol Sch Mat Sci & Engn Harbin 15001 Peoples R China

Superplastic forming is used widely in the aviation and aerospace industry, but the microstructure variation, especially the cavity growth, has a negative influence on the service properties of the parts. Therefore, the microstructure variation, and especially the cavity growth, and its influences on the flow stress have been studied, the superplastic constitutive equation with the cavity growth and the grain growth then being deduced and applied to the finite-element formulation. In addition, a three dimensional viscoplastic finite-element program using a constant triangular membrane has been developed and applied to predict the cavity growth and its distribution and to calculate the optimum back pressure-time cycle to control the cavity growth. At the same time the experiments with and without the calculated back pressure have been carried out, the results of which agree well with the calculated results. (C) 1998 Elsevier Science S.A.

关键词： cavity growth back pressure finite-element modeling superplastic forming

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Geometry-based finite-element modeling of the electrical contact between a cultured neuron and a microelectrode

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IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING 2003年第4期50卷 501-509页

作者： Buitenweg, J Rutten, WLC Marani, E Univ Twente Inst Biomed Technol Fac Elect Engn Signals & Syst Grp NL-7500 AE Enschede Netherlands Leiden Univ Med Ctr Dept Neurosurg Neuroregulat Grp NL-2300 RC Leiden Netherlands

The electrical contact between a substrate embedded microelectrode and a cultured neuron depends on the geometry of the neuron-electrode interface. Interpretation and improvement of these contacts requires proper modeling of all coupling mechanisms. In literature, it is common practice to model the neuron-electrode contact using lumped circuits in which large simplifications are made in the representation of the interface geometry. In this paper, the finite-element method is, used to model the neuron-electrode interface, which permits numerical. solutions for a variety of interface geometries. The simulation results offer detailed spatial and temporal information about the combined electrical behavior of extracellular volume, electrode-electrolyte interface and neuronal membrane.

关键词： ccultured neurons finite-element modeling multielectrode arrays neuron-electrode contact

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Development of finite-element modeling Approach for Lateral Load Analysis of Dry-Glazed Curtain Walls

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JOURNAL OF ARCHITECTURAL ENGINEERING 2011年第1期17卷 24-33页

作者： Memari, Ali M. Shirazi, Ali Kremer, Paul A. Behr, Richard A. Penn State Univ Dept Architectural Engn University Pk PA 16802 USA

This paper presents a finite-element modeling option to provide an analytical approach for a seismic analysis of dry- glazed curtain-wall systems. In this modeling approach, Ansys finite-element software was used to model the glass panel, aluminum glazing frame, perimeter rubber gaskets, rubber setting and side blocks, glass-to-frame clearances, and glass-to-frame contact once the clearance was overcome by in-plane drift. The results of the finite-element modeling of the curtain-wall system were compared with full-scale laboratory test results. The effect of some of the parameters such as gasket friction and aspect ratio were evaluated. The study showed that finite-element modeling is a viable approach for analytical evaluation of curtain walls. The modeling can function to predict the drift associated with glass-panel cracking. Further refinement of the modeling approach developed can increase the accuracy of the prediction. (C) 2011 American Society of Civil Engineers.

关键词： Glazing Curtain wall finite-element modeling Seismic analysis Racking test

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Micro-Raman analysis and finite-element modeling of 3 C-SiC microstructures

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JOURNAL OF RAMAN SPECTROSCOPY 2013年第2期44卷 299-306页

作者： Piluso, N. Anzalone, R. Camarda, M. Severino, A. La Magna, A. D'Arrigo, G. La Via, F. IMM CNR Catania Italy

Micro- and nano-electromechanical systems (MEMS and NEMS) fabricated in 3?C-SiC are receiving particular attention thanks to the material physical properties: its wide band gap (2.3?eV), its ability to operate at high temperatures, its mechanical strength and its inertness to the exposure in corrosive environments. However, high residual stress (which is normally generated during the hetero-epitaxial growth process) makes the use of 3?C-SiC in Si-based MEMS fabrication techniques very limited leading to a failure of micro-machined/sensor structures. In this paper, micro-Raman characterizations and finite-element modeling (FEM) of microstructures realized on poly and single-crystal (100) 3?C-SiC/Si films are performed. Transverse optical (TO) Raman mode analysis reveals the stress relaxation on the free standing structure (796.5?cm-1) respect to the stressed unreleased region (795.7?cm-1). Also, microstructures as cantilever, bridge and planar rotating probe show an intense stress field located around the undercut region. Here, the TO Raman mode undergoes an intense shift, up to 2?cm-1, ascribed to the modification of the Raman stress tensor. Indeed, the generalized axial regime, described by diagonal components of the Raman stress tensor, cannot be applied in this region. Raman maps analysis and FEM simulations show the activation of the shear stress, i.e. non-diagonal components of the stress tensor. The stress-Raman modes shift correlation, in the case of fully non-diagonal stress tensors, has been investigated. The aim of future works will be to minimize the stress field generation and the defects density within the epitaxial layer. Copyright (C) 2012 John Wiley & Sons, Ltd.

关键词： 3?C-SiC finite-element modeling free standing microstructures cantilever stress field

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Numerical errors and uncertainties in finite-element modeling of trabecular bone

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JOURNAL OF BIOMECHANICS 1998年第10期31卷 941-945页

作者： Ladd, AJC Kinney, JH Univ Florida Dept Chem Engn Gainesville FL 32611 USA Lawrence Livermore Natl Lab Livermore CA 94550 USA

Although micromechanical finite-element models are being increasingly used to help interpret the results of bio-mechanical tests, there has not yet been a systematic study of the numerical errors and uncertainties that occur with these methods. In this work, finite-element models of human Ll vertebra have been used to analyze the sensitivity of the calculated elastic moduli to resolution, boundary conditions, and variations in the Poisson's ratio of the tissue material. Our results indicate that discretization of the bone architecture, inherent in the tomography process, leads to an underestimate in the calculated elastic moduli of about 20% at 20 mu m resolution;these errors vary roughly linearly with the size of the image voxels. However, it turns out that there is a cancellation of errors between the softening introduced by the discretization of the bone architecture and the excess bending resistance of eight-node hexahedral finite elements. Our empirical finding is that eight-node cubic elements of the same size as the image voxels lead to the most accurate calculation for a given number of elements, with errors of less than 5% at 20 mu m resolution. Comparisons with mechanical testing are also hindered by uncertainties in the grip conditions;our results show that these uncertainties are of comparable magnitude to the systematic differences in mechanical testing methods. Both discretization errors and uncertainties in grip conditions have a smaller effect on relative moduli, used when comparing between different specimens or different load directions, than on an absolute modulus. The effects of variations in the Poisson's ratio of the bone tissue were found to be negligible. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.

关键词： finite-element modeling trabecular bone

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finite-element modeling for Static Bending Analysis of Rotating Two-Layer FGM Beams with Shear Connectors Resting on Imperfect Elastic Foundations

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JOURNAL OF AEROSPACE ENGINEERING 2023年第3期36卷 04023013-04023013页

作者： Thai, Le Minh Luat, Doan Trac Ke, Tran Van Van, Minh Phung Le Quy Don Tech Univ Fac Special Equipment Dept Special Equipment 236 Hoang Quoc Viet St Hanoi 100000 Vietnam Quy Don Tech Univ Fac Mech Engn Dept Solid Mech 236 Hoang QuocViet St Hanoi 100000 Vietnam

The static bending of rotating two-layer functionally graded material (FGM) beams with shear connectors resting on imperfect elastic foundations was performed for the first time in this study. Timoshenko beam theory and the finite-element method are used to derive finite-element formulations. The precision of the current approach and mechanical model is shown by comparing the calculated findings of this study to those of previous precise papers. A wide variety of parameter studies are carried out to capture the impact of geometric and material characteristics on the structure's static bending behaviors, such as the distance d, rotational speed, volume fraction index, elastic foundation parameters, and boundary conditions. This paper's theory and mechanical models are fascinating since mechanical systems involving rotational motion are pretty standard in engineering practice. Therefore, the computed results of this work aim to contribute to our understanding of structures of this kind.

关键词： finite-element modeling Rotating beam Two-layer functionally graded material (FGM) beam Shear connectors Imperfect elastic foundation

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finite-element modeling and Experimental Verification of Two-Way Sandwich Panels Made of Natural Fiber Composites

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JOURNAL OF COMPOSITES FOR CONSTRUCTION 2023年第1期27卷 04022101-04022101页

作者： Betts, Dillon Sadeghian, Pedram Fam, Amir Dalhousie Univ Dept Civil & Resource Engn 5268 DaCosta Row Halifax NS B3H 4R2 Canada Dalhousie Univ Canada Res Chair Sustainable Infrastruct Dept Civil & Resource Engn 5268 DaCosta Row Halifax NS B3H 4R2 Canada Queens Univ Chair Prof Engn & Appl Sci Dept Civil Engn Kingston ON K7L 3N6 Canada

finite-element (FE) modeling of sandwich panels with bidirectional flax fiber-reinforced polymer (FFRP) faces and polyisocyanurate foam cores in two-way bending under concentrated loads was performed. In addition, three large-scale (1,200 x 1,200 mm) sandwich panels with FFRP faces of various thicknesses (one, two, or three layers of flax fabric) and 75-mm-thick foam cores were tested under a concentrated load. The modeling was completed using commercially available software. The material nonlinearity of both the FFRPs and the foam cores was considered as well as the geometric nonlinearity due to localized deformation. Four failure modes were considered: FFRP compression crushing, FFRP tensile rupture, core shear, and compression-face wrinkling. Using the verified model, a parametric study investigated the effect of foam core density, face thickness, core thickness, and size of the loading area. It was found that panels with low-density cores were more susceptible to face-wrinkling failure, while panels with high-density cores were susceptible to both tensile rupture and core-punching shear failure. It was also shown that an increase in the diameter of the loading area decreased the effect of localized deformation for panels with high-density (96 kg/m(3)) cores.

关键词： Sandwich structures Flax fibers Bio-resins Experimental testing finite-element modeling

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