Energy Technology Data Exchange (ETDEWEB)
Staat, M.; Heitzer, M. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Sicherheitsforschung und Reaktortechnik
1998-11-01
Detailed, inelastic FEM analyses yield accurate information about the stresses and deformations in passive components. The local loading conditions, however, cannot be directly compared with a limit load in terms of structural mechanics. Concentration on the load carrying capacity is an approach simplifying the analysis. Based on the plasticity theory, limit and shakedown analyses calculate the load carrying capacities directly and exactly. The paper explains the implementation of the limit and shakedown data sets in a general FEM program and the direct calculation of the load carrying capacities of passive components. The concepts used are explained with respect to common structural analysis. Examples assuming high local stresses illustrate the application of FEM-based limit and shakedown analyses. The calculated interaction diagrams present a good insight into the applicable operational loads of individual passive components. The load carrying analysis also opens up a structure mechanics-based approach to assessing the load-to-collapse of cracked components made of highly ductile fracture-resistant material. (orig./CB) [Deutsch] Genaue Kenntnis der Spannungen und Verformungen in passiven Komponenten gewinnt man mit detailierten inelastischen FEM Analysen. Die lokale Beanspruchung laesst sich aber nicht direkt mit einer Beanspruchbarkeit im strukturmechanischen Sinne vergleichen. Konzentriert man sich auf die Frage nach der Tragfaehigkeit, dann vereinfacht sich die Analyse. Im Rahmen der Plastizitaetstheorie berechnen Traglast- und Einspielanalyse die tragbaren Lasten direkt und exakt. In diesem Beitrag wird eine Implementierung der Traglast- und Einspielsaetze in ein allgemeines FEM Programm vorgestellt, mit der die Tragfaehigkeit passiver Komponenten direkt berechnet wird. Die benutzten Konzepte werden in Bezug auf die uebliche Strukturanalyse erlaeutert. Beispiele mit lokal hoher Beanspruchung verdeutlichen die Anwendung der FEM basierten Traglast- und
Accelerated FEM Analysis for Critical Engine Components
Directory of Open Access Journals (Sweden)
Leonardo FRIZZIERO
2014-10-01
Full Text Available This paper introduces a method to simplify a nonlinear problem in order to use linear finite element analysis. This approach improves calculation time by 2 orders of magnitude. It is then possible to optimize the geometry of the components even without supercomputers. In this paper the method is applied to a very critical component: the aluminium alloy piston of a modern common rail diesel engine. The method consists in the subdivision of the component, in this case the piston, in several volumes, that have approximately a constant temperature. These volumes are then assembled through congruence constraints. To each volume a proper material is then assigned. It is assumed that material behaviour depends on average temperature, load magnitude and load gradient. This assumption is valid since temperatures vary slowly when compared to pressure (load. In fact pressures propagate with the speed of sound. The method is validated by direct comparison with nonlinear simulation of the same component, the piston, taken as an example. In general, experimental tests have confirmed the cost-effectiveness of this approach.
Structural Weight Optimization of Aircraft Wing Component Using FEM Approach.
Arockia Ruban M,; Kaveti Aruna
2015-01-01
One of the main challenges for the civil aviation industry is the reduction of its environmental impact by better fuel efficiency by virtue of Structural optimization. Over the past years, improvements in performance and fuel efficiency have been achieved by simplifying the design of the structural components and usage of composite materials to reduce the overall weight of the structure. This paper deals with the weight optimization of transport aircraft with low wing configuratio...
Structural Weight Optimization of Aircraft Wing Component Using FEM Approach.
Directory of Open Access Journals (Sweden)
Arockia Ruban M,
2015-06-01
Full Text Available One of the main challenges for the civil aviation industry is the reduction of its environmental impact by better fuel efficiency by virtue of Structural optimization. Over the past years, improvements in performance and fuel efficiency have been achieved by simplifying the design of the structural components and usage of composite materials to reduce the overall weight of the structure. This paper deals with the weight optimization of transport aircraft with low wing configuration. The Linear static and Normal Mode analysis were carried out using MSc Nastran & Msc Patran under different pressure conditions and the results were verified with the help of classical approach. The Stress and displacement results were found and verified and hence arrived to the conclusion about the optimization of the wing structure.
Investigation of difficult component effects on FEM vibration prediction for the AH-1G helicopter
Dompka, Robert V.
1988-01-01
Under the NASA-sponsored Design Analysis Methods for Vibrations program, a series of ground vibration tests and NASTRAN finite element model correlations were conducted on the Bell AH-1G helicopter gunship to investigate the effects of difficult components on the vibration response of the airframe. Secondary structure and damping were found to have significant effects on the frequency response of the airframe above 15 Hz. The nonlinear effects of thrust stiffening and elastomeric mounts on the low-frequency pylon modes below the main rotor were also significant.
FEM modelling of shoes insoles components for standing and walking simulation
Directory of Open Access Journals (Sweden)
Braun Barbu
2017-01-01
Full Text Available The paper presents a research stage in which a new method applied for foot insoles components rapid prototyping was successfully tested in case of two young persons with small orthopaedic diseases. The research in this stage is focused on the FEA model analysis before and after prototyping, the model consisting in two sets of specific items to be inserted into the plantar supporters, with orthopaedic correction role. The simulation and testing was performed in condition of wearing shoes containing such of plantar supporters, when standing and walking, these situations being the most common. The main studied problem was to verify if the CAD modelled orthotic items to be prototyped should resist in case of static and dynamic loads, similar to those found in case of standing and walking. It was demonstrated a good correlation in terms of testing results before and after items prototyping, especially for the second person. Besides, it was demonstrated that the FEA analysis applied method could be successfully used to verify the prototyped orthotic items endurance and resistance.
Direkte krav i de senere års retspraksis
DEFF Research Database (Denmark)
Edlund, Hans Henrik
2006-01-01
Emnet for artiklen er, hvorledes adgangen til at gøre direkte krav gældende er blevet begrundet i dansk retspraksis i de senere år. Retspraksis kan relativt klart opdeles efter fire forskellige typer af retlige begrundelser for resultatet. Det konkluderes, at især reglerne om erstatningsansvar uden...
FEMS activities and FEMS Grants possibilities
Taleski, Vaso
2013-01-01
Abstract FEMS je federacija evropskih mikrobioloških društava ujedinjuje 50 udruženja iz 36 zemalja Evrope, sa preko 30.000 mikrobiologa. Nažalost, Udruženje mikrobiologa Bosne i Hercegovine do sada nikada nije apliciralo za clanstvo zbog cega nije clan FEMS-a. Jos samo tri udruzenja iz Evrope nisu clanovi FEMS-a ali se radi da postanu clanovi u najskorije vreme. Clanstvo u FEMS-u daje velike mogucnosti posebno za mlade mikrobiologe koji sun a pocetku naucne karijere. Misija FEMS-...
Solares Recyceln von Aluminium in einem direkt bestrahlten Drehrohrofen
Neises-von Puttkamer, Martina; Roeb, Martin; Beyer, T.; Reinhold, Jan Philipp; Willsch, Christian; Thelen, Martin; Raeder, Christian; Oliveira,Lamark de; TESCARI, Stefania; Breuer, Stefan; Sattler, Christian
2016-01-01
Das Aufschmelzen von Metallen ist ein energieintensiver Prozess, da hier hohe Temperaturen benötigt werden. Konventionell wird diese Energie mit fossilen Energieträgern zur Verfügung gestellt. Mit einem solaren Schmelzverfahren von Metallen können der Ausstoß von CO2 und die Energiekosten der Gießereien erheblich gesenkt werden. Insbesondere Länder mit hoher direkter Solarstrahlung wie Südafrika, können ein solches Verfahren zum Schmelzen und Wiederverwerten von Metallschrott einsetzten. ...
Most influential FEMS publications.
Prosser, James I; Cole, Jeff A; Nielsen, Jens; Bavoil, Patrik M; Häggblom, Max M
2014-05-01
A selection of influential FEMS publications to celebrate the 40th anniversary of FEMS. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.
DEFF Research Database (Denmark)
2013-01-01
En præsentation af de fem gymnasiale uddannelser i Danmark og en grundigere præsentation af stx......En præsentation af de fem gymnasiale uddannelser i Danmark og en grundigere præsentation af stx...
DEFF Research Database (Denmark)
Lindholst, Andrej Christian; Jensen, Thomas Haase; Kjems, Troels Høgfeldt
Denne case-rapport med i alt fem danske casestudier er en del af en serie af casestudier i INOPS-projektet, der afdækker erfaringer med udlicitering af driftsopgaver på det kommunale park- og vejområde i Danmark, Norge, Sverige og Storbritannien. Udover de fem danske casestudier har projektet i...
National Aeronautics and Space Administration — This contains attempts to create BEAM FEM model. I have started a Blog to discuss this... please put your comments there and I will attempt to keep everything...
Directory of Open Access Journals (Sweden)
Ebbe Lavendt
2015-12-01
Full Text Available Den britiske tænketank NEF (New Economics Foundation har efter en gennemgang af den mest opdaterede forskning udarbejdet anbefalinger til fem aktiviteter, du kan inkorporere i din hverdag, og som er vigtige for trivsel.
Energy Technology Data Exchange (ETDEWEB)
Leal, Walter; Schulte, Veronika; Gottwald, Julia
2010-07-01
Full text: It is widely acknowledged that the use of renewable energy may assist developing countries as a whole and Small Island States in particular, in addressing their energy needs and at the same time reducing their dependence on fossil fuels. In order to support these efforts, the project Small Developing Island Renewable Energy Knowledge and Technology Transfer Network (DIREKT) is being undertaken. DIREKT is a cooperation scheme involving universities from Germany, Fiji, Mauritius and Trinidad et Tobago with the aim of strengthening their science and technology capacity in the field of renewable energy, by means of technology transfer, information exchange and networking. Developing countries are especially vulnerable to problems associated with climate change and much can be gained by raising their capacity in the field of renewable energy, which is a key area. This paper introduces the project DIREKT, its aims and the partnership. It will also show how sustainable cooperation between the science and technology communities of ACP and EU institutions in the key area of Renewable Energy may be achieved, which is of great relevance for the socio-economic development of small island developing states. One of features of the project, namely the establishment of Research and Technology Transfer Centres within each of the partner countries, will be presented. (Author)
Eecen, P. J.; Tulupov, A. V.; Schep, T. J.
1995-01-01
The FOM Fusion FEM project involves the construction and operation of a 1-MW, 100 ms pulse, rapidly tunable FEM in the 130-250 GHz range for fusion applications. The undulator is a novel step-tapered undulator, consisting of two sections with different strengths and lengths and equal periodicities,
Institute of Scientific and Technical Information of China (English)
Moslem Namjoo; Hossein Golbakhshi
2015-01-01
It is noted that any variation in operating conditions has a considerable effect on the tire/road interaction. Furthermore, choosing a range of proper values for carcass stiffness is very essential for both tire safety and effective driving action. In this work, an elaborated 3D model fully compliant with the geometrical size of radial tire 185/60 R15 is worked up, for evaluating the effects of components properties and working conditions on deformation and stress/strain fields created inside the tire. For the simulation, the tire structure is assumed to be composed of tread, carcass ply, and bead. The mechanical behavior of rubber as main component of tire is described by Mooney−Rivlin material model. The comparison of the obtained results and laboratory tests demonstrates the validity and high accuracy of analysis.
Om direktørers fuldmagt på baggrund af UfR 2012.2533 H
DEFF Research Database (Denmark)
Andersen, Lennart Lynge; Schaumburg-Muller, Peer
2012-01-01
Den bemyndigelse, en adm. direktør - og den øvrige direktion - har til (bl.a.) at fastsætte løn- og ansættelsesvilkår for selskabets medarbejdere har hverken i den arbejdsretlige, selskabsretlige eller den aftaleretlige teori og praksis påkaldt sig megen opmærksomhed gennem årene. Højesterets dom...... af 2. maj 2012 (UfR 2012.2533 H) omhandler netop dette forhold, og afgørelsen må af flere grunde anses for principiel....
Granfeldt, Jonas; Ågren, Malin
2014-01-01
One core area of research in Second Language Acquisition is the identification and definition of developmental stages in different L2s. For L2 French, Bartning and Schlyter (2004) presented a model of six morphosyntactic stages of development in the shape of grammatical profiles. The model formed the basis for the computer program Direkt Profil…
The analysis of the OECD/NEA/NSC PBMR-400 benchmark problem using PARCS-DIREKT
Energy Technology Data Exchange (ETDEWEB)
Seker, V.; Downar, T. J. [Purdue Univ., 400 Central Drive, West Lafayette, IN 47907 (United States)
2006-07-01
The OECD/NEA/NSC PBMR-400 benchmark problem was developed to support the validation and verification efforts for the PBMR design. This paper describes the analysis of this problem using the PARCS-DIREKT coupled code system. The benchmark problem involved the use of two different cross-section libraries, one which was generated from a VSOP equilibrium core calculation and has no dependence on core conditions. The second library provides for dependence on five state parameters and was designed for transient analysis. The paper here reports the steady-state cases using the VSOP set of cross-sections. The results are shown to be in good agreement with those of VSOP. Also reported here are the results of the steady-state thermal-hydraulic DIRECKT solution with a given power profile obtained from VSOP equilibrium core calculation. This analysis provides some insight as to the most important parameters in the design of PBMR-400. (authors)
Mellem tiderne - Fem dialektiske teologer
DEFF Research Database (Denmark)
I denne bog præsenteres Karl Barth, Friedrich Gogarten, Eduard Thurneysen, Emil Brunner og Rudolf Bultmann. Fem bidrag belyser deres teologiske anliggender, opgør og afgørelser, samt virkningshistorie og perspektiver for en nutidig teologi.......I denne bog præsenteres Karl Barth, Friedrich Gogarten, Eduard Thurneysen, Emil Brunner og Rudolf Bultmann. Fem bidrag belyser deres teologiske anliggender, opgør og afgørelser, samt virkningshistorie og perspektiver for en nutidig teologi....
Fem typer strategi i organisationer
DEFF Research Database (Denmark)
Steensen, Elmer Fly
2009-01-01
neret i den strategiske ledelseslitteratur fra 1970'erne frem til i dag præsenteres i denne artikel en samlingsmodel indeholdende fem forskellige strategi-typer: fælles strategi, skjult strategi, falsk strategi, ikke-overvejet strategisk potentiale og realiseret strategi. Det diskuteres, hvilke...
Investigation of Multifrequency Generation in the Fem
Eecen, P. J.; Tulupov, A. V.; Schep, T. J.
1994-01-01
The FOM Fusion FEM project involves the construction and operation of a 1-MW, 100 ms pulse, rapid tunable FEM in the 130-250 GHz range for fusion applications. The undulator of the FEM consists of two sections with different strengths and different lengths separated by a gap without undulator field.
Iepakojuma direktīvas reforma: plastmasas iepirkumu maisiņu regulējums
Tukiša, Liene
2014-01-01
Plastmasas iepirkumu maisiņi un to izturība pret noārdīšanos rada vides ilgtspējas problēmas, atstāj ietekmi uz sabiedrības veselību un valstu ekonomiku. Eiropas Savienības līmenī nav tiesību akta, kas īpaši attiektos uz plastmasas iepirkumu maisiņiem, taču šis ir būtisks jautājums vides aizsardzības jomā, kam nepieciešams regulējums. Pētījuma mērķis ir analizēt pašreizējo tiesisko regulējumu un Iepakojuma direktīvas grozījumu projektu, kā arī izvērtēt iespējamos variantus plastmasas iepirkum...
Fem balancepunkter i ledelse anno 2010
DEFF Research Database (Denmark)
Holt Larsen, Henrik
2010-01-01
Personlighed, omstilling, motivation, generalist og sammenhængskraft er fem nøgleord for en moderne leder og hans eller hendes medarbejdere......Personlighed, omstilling, motivation, generalist og sammenhængskraft er fem nøgleord for en moderne leder og hans eller hendes medarbejdere...
FEM electrode refinement for electrical impedance tomography.
Grychtol, Bartlomiej; Adler, Andy
2013-01-01
Electrical Impedance Tomography (EIT) reconstructs images of electrical tissue properties within a body from electrical transfer impedance measurements at surface electrodes. Reconstruction of EIT images requires the solution of an inverse problem in soft field tomography, where a sensitivity matrix, J, of the relationship between internal changes and measurements is calculated, and then a pseudo-inverse of J is used to update the image estimate. It is therefore clear that a precise calculation of J is required for solution accuracy. Since it is generally not possible to use analytic solutions, the finite element method (FEM) is typically used. It has generally been recommended in the EIT literature that FEMs be refined near electrodes, since the electric field and sensitivity is largest there. In this paper we analyze the accuracy requirement for FEM refinement near electrodes in EIT and describe a technique to refine arbitrary FEMs.
National Aeronautics and Space Administration — The finite element model being used by the AePW is based on the model provided at HIRENASD website The NASTRAN FEM's using HEXA solid elements and identified as...
Coupled FEM-DBEM method to assess crack growth in magnet system of Wendelstein 7-X
Directory of Open Access Journals (Sweden)
R. Citarella
2013-10-01
Full Text Available The fivefold symmetric modular stellarator Wendelstein 7-X (W7-X is currently under construction in Greifswald, Germany. The superconducting coils of the magnet system are bolted onto a central support ring and interconnected with five so-called lateral support elements (LSEs per half module. After welding of the LSE hollow boxes to the coil cases, cracks were found in the vicinity of the welds that could potentially limit the allowed number N of electromagnetic (EM load cycles of the machine. In response to the appearance of first cracks during assembly, the Stress Intensity Factors (SIFs were calculated and corresponding crack growth rates of theoretical semi-circular cracks of measured sizes in potentially critical position and orientation were predicted using Paris’ law, whose parameters were calibrated in fatigue tests at cryogenic temperature. In this paper the Dual Boundary Element Method (DBEM is applied in a coupled FEM-DBEM approach to analyze the propagation of multiple cracks with different shapes. For this purpose, the crack path is assessed with the Minimum Strain Energy density criterion and SIFs are calculated by the J-integral approach. The Finite Element Method (FEM is adopted to model, using the commercial codes Ansys or Abaqus;, the overall component whereas the submodel analysis, in the volume surrounding the cracked area, is performed by FEM (“FEM-FEM approach” or alternatively by DBEM (“FEM-DBEM approach”. The “FEM-FEM approach” considers a FEM submodel, that is extracted from the FEM global model; the latter provide the boundary conditions for the submodel. Such approach is affected by some restrictions in the crack propagation phase, whereas, with the “FEM-DBEM approach”, the crack propagation simulation is straightforward. In this case the submodel is created in a DBEM environment with boundary conditions provided by the global FEM analysis; then the crack is introduced and a crack propagation analysis
Traffic Flow Density Distribution Based on FEM
Ma, Jing; Cui, Jianming
In analysis of normal traffic flow, it usually uses the static or dynamic model to numerical analyze based on fluid mechanics. However, in such handling process, the problem of massive modeling and data handling exist, and the accuracy is not high. Finite Element Method (FEM) is a production which is developed from the combination of a modern mathematics, mathematics and computer technology, and it has been widely applied in various domain such as engineering. Based on existing theory of traffic flow, ITS and the development of FEM, a simulation theory of the FEM that solves the problems existing in traffic flow is put forward. Based on this theory, using the existing Finite Element Analysis (FEA) software, the traffic flow is simulated analyzed with fluid mechanics and the dynamics. Massive data processing problem of manually modeling and numerical analysis is solved, and the authenticity of simulation is enhanced.
FEM growth and yield data monocultures - Sycamore
Oldenburger, J.F.; Jansen, J.J.; Oosterbaan, A.; Mohren, G.M.J.; Ouden, den J.
2016-01-01
The current database is part of the FEM growth and yield database, a collection of growth and yield data from even-aged monocultures (douglas fir, common oak, poplar, Japanese Larch, Norway spruce, Scots pine, Corsican pine, Austrian pine, red oak and several other species, with only a few plots, ev
Oplevelsesmiljøernes fem ansigter
DEFF Research Database (Denmark)
Jensen, Thessa
2008-01-01
Oplevelsesøkonomi, sundhedsturisme, wellnessområder og meget mere er i dag bud på, hvordan turismeindustrien kan tiltrække flere og mere pengestærke forbrugere. Men hvordan kan man markedsføre sig over for disse oplevelseshungrende mennesker, der ifølge Gerhard Schulze udgøres af fem miljøer? Disse...... miljøer er en ramme for oplevelsen. De kunne kaldes oplevelsesøkonomiens fem ansigter. Kender man disse miljøer, kan man bedre finde ud af, hvad man kan og skal prøve at sælge i oplevelsesøkonomien hvordan. Ved hjælp af samfundsteoretikeren Schulzes bud på oplevelsesmiljøer skal der derfor her forsøges...
Directory of Open Access Journals (Sweden)
Tibor Tot
2011-01-01
Full Text Available A unique case of metaplastic breast carcinoma with an epithelial component showing tumoral necrosis and neuroectodermal stromal component is described. The tumor grew rapidly and measured 9 cm at the time of diagnosis. No lymph node metastases were present. The disease progressed rapidly and the patient died two years after the diagnosis from a hemorrhage caused by brain metastases. The morphology and phenotype of the tumor are described in detail and the differential diagnostic options are discussed.
Midtvejsstatus for fem kvarterløft
DEFF Research Database (Denmark)
Andersen, Hans Skifter; Bjørn, Sille; Nielsen, Hanne
I 2001 blev der igangsat fem nye kvarterløftprojekter i Vollsmose Odense, Vestbyen i Horsens, Brøndby Strand samt Nørrebro Park og Nordvest Kvarteret i København. Denne rapport har som formål at give et overblik over kvarterløftenes status og retning på et tidspunkt, hvor de er ca. midtvejs i...
Approximation of pressure perturbations by FEM
Bichir, Cătălin - Liviu
2011-01-01
In the mathematical problem of linear hydrodynamic stability for shear flows against Tollmien-Schlichting perturbations, the continuity equation for the perturbation of the velocity is replaced by a Poisson equation for the pressure perturbation. The resulting eigenvalue problem, an alternative form for the two - point eigenvalue problem for the Orr - Sommerfeld equation, is formulated in a variational form and this one is approximated by finite element method (FEM). Possible applications to concrete cases are revealed.
FEM1 proteins are ancient regulators of SLBP degradation.
Dankert, John F; Pagan, Julia K; Starostina, Natalia G; Kipreos, Edward T; Pagano, Michele
2017-03-19
FEM1A, FEM1B, and FEM1C are evolutionarily-conserved VHL-box proteins, the substrate recognition subunits of CUL2-RING E3 ubiquitin ligase complexes. Here, we report that FEM1 proteins are ancient regulators of Stem-Loop Binding Protein (SLBP), a conserved protein that interacts with the stem loop structure located in the 3' end of canonical histone mRNAs and functions in mRNA cleavage, translation and degradation. SLBP levels are highest during S-phase coinciding with histone synthesis. The ubiquitin ligase complex SCF(cyclin F) targets SLBP for degradation in G2 phase; however, the regulation of SLBP during other stages of the cell cycle is poorly understood. We provide evidence that FEM1A, FEM1B, and FEM1C interact with and mediate the degradation of SLBP. Cyclin F, FEM1A, FEM1B and FEM1C all interact with a region in SLBP's N-terminus using distinct degrons. An SLBP mutant that is unable to interact with all 4 ligases is expressed at higher levels than wild type SLBP and does not oscillate during the cell cycle. We demonstrate that orthologues of SLBP and FEM1 proteins interact in C. elegans and D. melanogaster, suggesting that the pathway is evolutionarily conserved. Furthermore, we show that FEM1 depletion in C. elegans results in the upregulation of SLBP ortholog CDL-1 in oocytes. Notably, cyclin F is absent in flies and worms, suggesting that FEM1 proteins play an important role in SLBP targeting in lower eukaryotes.
Analysis of Roll Gap Pressure in Sendzimir Mill by FEM
Institute of Scientific and Technical Information of China (English)
YU Hai-liang; LIU Xiang-hua; WANG Chao; Park Hae-doo
2008-01-01
The acting force on the roll system of Sendzimir mill was analyzed using 3D FEM. The roll gap pressure distribution and the acting force between rolls S and O, rolls O and I, rolls O and J, rolls I and A, rolls I and B, as well as rolls J and B were analyzed. The results showed that the roll gap pressure mainly affected the roll surface layer, 50 mm for backup roll; the roll gap pressure distribution is of double peaks among the work roll, the 1st intermediate roll (IMR), and the 2nd IMR; the maximum value of the roll gap pressure between the backup roll and the second IMR appears on the edge of the barrel of rolls; the component force presents the in-para-curve distribution. These are important for reducing the wear of rolls and the break of the backup roll and guiding for production.
Analysis of airborne antenna using a FEM-UID hybrid method
Institute of Scientific and Technical Information of China (English)
WANG Meng; ZHANG Yu; LIANG Chang-hong
2006-01-01
In this paper,the near-field vector components were used to combine the FEM method and the uniform-geometrical theory of diffraction (UTD) method for analyzing phased array antenna mounted on an airborne platform.First,HFSS,a set of software based on finite element method (FEM),was utilized to find the near-field vector components of the phased army antennas,and then these vector components were used as the source of the UTD method to get the disturbed radiation pattern.Numerical results show that the hybrid of the two methods not only extends the use of the UTD program,but also effectively solves this type of challenging problems.
Application of FEM Analysis to Braced Excavation
Institute of Scientific and Technical Information of China (English)
LI Mingfei; Atsushi Nakamura; CAI Fei; Keizo Ugai
2008-01-01
It is becoming possible to do detailed numerical analyses for the various mechanical behavior of braced excavation by researching and developing the numerical analysis technique such as the finite ele-ment method (FEM).However,the mechanical behavior of braced excavation has not been clanfied fully both in theory and in expedence.Therefore,improving the prediction accuracy during the prior design is very important for making the observational method of braced excavation more effective.In this paper,FEM analyses were performed for a model of braced excavation by using Geotechnical Finite Element Elasto-plastic Analysis Software,GeoFEAS (2D).As the constitutive law of ground,MC-DP model, and Dun-can-Chang model were applied.The results were compared and discussed with that of a site measurement,and the effects of the constitutive law of ground on the analyzed result were verified.For the difference be-tween the results,the reason was investigated by the analyses adjusting the elastic modulus of ground,and the appropriate application of the constitutive law was researched.
Living with an imperfect cell wall : compensation of femAB inactivation in Staphylococcus aureus
Hübscher, Judith; Jansen, Andrea; Kotte, Oliver; Schäfer, Juliane; Majcherczyk, Paul A.; Harris, Llinos G.; Bierbaum, Gabriele; Heinemann, Matthias; Berger-Bächi, Brigitte
2007-01-01
Background: Synthesis of the Staphylococcus aureus peptidoglycan pentaglycine interpeptide bridge is catalyzed by the nonribosomal peptidyl transferases FemX, FemA and FemB. Inactivation of the femAB operon reduces the interpeptide to a monoglycine, leading to a poorly crosslinked peptidoglycan. fem
FEM Optimisation of Spark Plasma Sintering Furnace
Kellari, Demetrios Vasili
2013-01-01
Coupled electro-thermal FEM analysis has been carried out on a sintering furnace used to produce new materials for LHC collimators. The analysis showed there exist margins for improvement of the current process and equipment through minor changes. To optimise the design of the furnace several design changes have been proposed including: optimization of material selection using copper cooling plates, control of convection in cooling plates by lowering the water flow rate, modifying the electrode shape using unsymmetrical electrodes and upgrading the thermal shielding to make use of multilayer graphite shields. The results show that we have a significant improvement in temperature gradient on the plate, from 453 to 258 °C and a reduction in power requirement from 62 to 44 kW.
Financial security for women -- Fem Consult congress.
1996-01-01
The nongovernmental organization "Fem Consult," which seeks to strengthen the socioeconomic position of women by applying a gender perspective to programs and projects in developing countries, celebrated its 10th anniversary in 1996 by holding a conference in the Netherlands on financial security for women in the developing world. During the conference, the President of the WWF (Working Women's Forum) described her agency's 17 years of experience in lending to impoverished rural and urban women in India. By extending microcredit assistance through a network of cooperatives, the WWF has been the catalyst for lasting improvements in the economic and social status of impoverished women. Representatives of the Grameen Bank, Women's World Banking, the Ecumenical Development Cooperative Society, and other organizations also addressed the conference.
Energy Technology Data Exchange (ETDEWEB)
Klein, B. [Kassel Univ. (Germany). Leichbau, CAD und Entwicklungsmethodik
2007-07-01
Virtual product development at the workstation has become reality, creating a link between 3D-CAD, MKS, FEM, STRUOPT and Rapid Prototyping. Engineers must have good knowledge of computer-assisted techniques. The key element of CAE is the finite element method (FEM) which is a universal analytical tool providing deep insight into the elastic, dynamic, cinematic/kinetic, thermal, and fluid-mechanical characteristics of components and systems. On the basis of these simulations, reliable predictions are possible that will shorten innovation and trial periods and result in very short amortisation periods of FEM investments. This is shown by the textbook in a very clear and illustrative manner. Case studies are presented to enable the reader to deepen her knowledge by herself. (orig.)
Generalization of FEM Using Node-Based Shape Functions
Directory of Open Access Journals (Sweden)
Kanok-Nukulchai W.
2015-12-01
Full Text Available In standard FEM, the stiffness of an element is exclusively influenced by nodes associated with the element via its element-based shape functions. In this paper, the authors present a method that can be viewed as a generalization of FEM for which the influence of a node is not limited by a hat function around the node. Shape functions over an element can be interpolated over a predefined set of nodes around the element. These node-based shape functions employ Kriging Interpolations commonly found in geostatistical technique. In this study, a set of influencing nodes are covered by surrounding layers of elements defined as its domain of influence (DOI. Thus, the element stiffness is influenced by not only the element nodes, but also satellite nodes outside the element. In a special case with zero satellite nodes, the method is specialized to the conventional FEM. This method is referred to as Node-Based Kriging FEM or K-FEM. The K-FEM has been tested on 2D elastostatic, Reissner-Mindlin’s plate and shell problems. In all cases, exceptionally accurate displacement and stress fields can be achieved with relatively coarse meshes. In addition, the same set of Kringing shape functions can be used to interpolate the mesh geometry. This property is very useful for representing the curved geometry of shells. The distinctive advantage of the K-FEM is its inheritance of the computational procedure of FEM. Any existing FE code can be easily extended to K-FEM; thus, it has a higher chance to be accepted in practice.
FreeFem++, a tool to solve PDEs numerically
Sadaka, Georges
2012-01-01
FreeFem++ is an open source platform to solve partial differential equations numerically, based on finite element methods. It was developed at the Laboratoire Jacques-Louis Lions, Universit ́e Pierre et Marie Curie, Paris by Fr ́ed ́eric Hecht in collaboration with Olivier Pironneau, Jacques Morice, Antoine Le Hyaric and Kohji Ohtsuka. The FreeFem++ platform has been developed to facilitate teaching and basic research through prototyping. FreeFem++ has an advanced automatic mesh generator, ca...
Liu, Yang; Li, Yan; Wang, Dejun; Zhang, Shaoyi
2014-01-01
Updating the structural model of complex structures is time-consuming due to the large size of the finite element model (FEM). Using conventional methods for these cases is computationally expensive or even impossible. A two-level method, which combined the Kriging predictor and the component mode synthesis (CMS) technique, was proposed to ensure the successful implementing of FEM updating of large-scale structures. In the first level, the CMS was applied to build a reasonable condensed FEM of complex structures. In the second level, the Kriging predictor that was deemed as a surrogate FEM in structural dynamics was generated based on the condensed FEM. Some key issues of the application of the metamodel (surrogate FEM) to FEM updating were also discussed. Finally, the effectiveness of the proposed method was demonstrated by updating the FEM of a real arch bridge with the measured modal parameters.
Directory of Open Access Journals (Sweden)
Yang Liu
2014-01-01
Full Text Available Updating the structural model of complex structures is time-consuming due to the large size of the finite element model (FEM. Using conventional methods for these cases is computationally expensive or even impossible. A two-level method, which combined the Kriging predictor and the component mode synthesis (CMS technique, was proposed to ensure the successful implementing of FEM updating of large-scale structures. In the first level, the CMS was applied to build a reasonable condensed FEM of complex structures. In the second level, the Kriging predictor that was deemed as a surrogate FEM in structural dynamics was generated based on the condensed FEM. Some key issues of the application of the metamodel (surrogate FEM to FEM updating were also discussed. Finally, the effectiveness of the proposed method was demonstrated by updating the FEM of a real arch bridge with the measured modal parameters.
Uncertainty assessment of a dike with an anchored sheet pile wall using FEM
Directory of Open Access Journals (Sweden)
Rippi Aikaterini
2016-01-01
Full Text Available The Dutch design codes for the dikes with retaining walls rely on Finite Element Analysis (FEM in combination with partial safety factors. However, this can lead to conservative designs. For this reason, in this study, a reliability analysis is carried out with FEM calculations aiming to demonstrate the feasibility of reliability analysis for a dike with an anchored sheet pile wall modelled in the 2D FEM, Plaxis. Sensitivity and reliability analyses were carried out and enabled by coupling the uncertainty package, OpenTURNS and Plaxis. The most relevant (ultimate limit states concern the anchor, the sheet pile wall, the soil body failure (global instability and finally the system. The case was used to investigate the applicability of the First Order Reliability Method (FORM and Directional Sampling (DS to analysing these limit states. The final goal is to estimate the probability of failure and identify the most important soil properties that affect the behaviour of each component and the system as a whole. The results of this research can be used to assess and optimize the current design procedure for dikes with retaining walls.
In vitro toxicity of FemOn, FemOn-SiO2 composite, and SiO2-FemOn core-shell magnetic nanoparticles.
Toropova, Yana G; Golovkin, Alexey S; Malashicheva, Anna B; Korolev, Dmitry V; Gorshkov, Andrey N; Gareev, Kamil G; Afonin, Michael V; Galagudza, Michael M
2017-01-01
Over the last decade, magnetic iron oxide nanoparticles (IONPs) have drawn much attention for their potential biomedical applications. However, serious in vitro and in vivo safety concerns continue to exist. In this study, the effects of uncoated, FemOn-SiO2 composite flake-like, and SiO2-FemOn core-shell IONPs on cell viability, function, and morphology were tested 48 h postincubation in human umbilical vein endothelial cell culture. Cell viability and apoptosis/necrosis rate were determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and annexin V-phycoerythrin kit, respectively. Cell morphology was evaluated using bright-field microscopy and forward and lateral light scattering profiles obtained with flow cytometry analysis. All tested IONP types were used at three different doses, that is, 0.7, 7.0, and 70.0 μg. Dose-dependent changes in cell morphology, viability, and apoptosis rate were shown. At higher doses, all types of IONPs caused formation of binucleated cells suggesting impaired cytokinesis. FemOn-SiO2 composite flake-like and SiO2-FemOn core-shell IONPs were characterized by similar profile of cytotoxicity, whereas bare IONPs were shown to be less toxic. The presence of either silica core or silica nanoflakes in composite IONPs can promote cytotoxic effects.
In vitro toxicity of FemOn, FemOn-SiO2 composite, and SiO2-FemOn core-shell magnetic nanoparticles
Toropova, Yana G; Golovkin, Alexey S; Malashicheva, Anna B; Korolev, Dmitry V; Gorshkov, Andrey N; Gareev, Kamil G; Afonin, Michael V; Galagudza, Michael M
2017-01-01
Over the last decade, magnetic iron oxide nanoparticles (IONPs) have drawn much attention for their potential biomedical applications. However, serious in vitro and in vivo safety concerns continue to exist. In this study, the effects of uncoated, FemOn-SiO2 composite flake-like, and SiO2-FemOn core-shell IONPs on cell viability, function, and morphology were tested 48 h postincubation in human umbilical vein endothelial cell culture. Cell viability and apoptosis/necrosis rate were determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and annexin V-phycoerythrin kit, respectively. Cell morphology was evaluated using bright-field microscopy and forward and lateral light scattering profiles obtained with flow cytometry analysis. All tested IONP types were used at three different doses, that is, 0.7, 7.0, and 70.0 μg. Dose-dependent changes in cell morphology, viability, and apoptosis rate were shown. At higher doses, all types of IONPs caused formation of binucleated cells suggesting impaired cytokinesis. FemOn-SiO2 composite flake-like and SiO2-FemOn core-shell IONPs were characterized by similar profile of cytotoxicity, whereas bare IONPs were shown to be less toxic. The presence of either silica core or silica nanoflakes in composite IONPs can promote cytotoxic effects. PMID:28144141
Modeling structural dynamic behavior of SSME components
Kiefling, Larry A.; Saxon, J. B.; Prickett, T. L.
1991-01-01
FEM studies are presented of the nozzle and the low-pressure fuel-pump inducer designs for the Space Shuttle Main Engine (SSME) to analyze the effects of structural vibrations. FEM preprocessing software based on a CAD system is employed to develop a model of the component's sophisticated geometry. The nozzle geometry is also defined by means of the preprocessing technique and subsequently analyzed with respect to time-transient loading. The analysis is conducted with a Cray supercomputer using the SPAR/EAL FEM program. The investigation of the nozzle demonstrates the advantageous use of symmetry in the determination of nozzle response to SSME start-up transients. Plots of time vs strain are developed for gages on the nozzle wall and steerhorn tubing. The results of the inducer modeling are found to be adequate for investigating the component's principle modes, and the nozzle results indicate the suitability of the FEM techniques for optimizing the design of engine components.
FEM analysis of impact of external objects to pipelines
Energy Technology Data Exchange (ETDEWEB)
Gracie, Robert; Konuk, Ibrahim [Geological Survey of Canada, Ottawa, ON (Canada)]. E-mail: ikonuk@NRCan.gc.ca; Fredj, Abdelfettah [BMT Fleet Technology Limited, Ottawa, ON (Canada)
2003-07-01
One of the most common hazards to pipelines is impact of external objects. Earth moving machinery, farm equipment or bullets can dent or fail land pipelines. External objects such as anchors, fishing gear, ice can damage offshore pipelines. This paper develops an FEM model to simulate the impact process and presents investigations using the FEM model to determine the influence of the geometry and velocity of the impacting object and also will study the influence of the pipe diameter, wall thickness, and concrete thickness along with internal pressure. The FEM model is developed by using LS-DYNA explicit FEM software utilizing shell and solid elements. The model allows damage and removal of the concrete and corrosion coating elements during impact. Parametric studies will be presented relating the dent size to pipe diameter, wall thickness and concrete thickness, internal pipe pressure, and impacting object geometry. The primary objective of this paper is to develop and present the FEM model. The model can be applied to both offshore and land pipeline problems. Some examples are used to illustrate how the model can be applied to real life problems. A future paper will present more detailed parametric studies. (author)
Energy Technology Data Exchange (ETDEWEB)
Bouzakis, K.D. [Aristoteles Univ., Thessaloniki (Greece). Dept. of Mech. Eng.; Vidakis, N. [Aristoteles Univ., Thessaloniki (Greece). Dept. of Mech. Eng.; Leyendecker, T. [CemeCon, 52068 Aachen (Germany); Lemmer, O. [CemeCon, 52068 Aachen (Germany); Fuss, H.G. [CemeCon, 52068 Aachen (Germany); Erkens, G. [CemeCon, 52068 Aachen (Germany)
1996-12-15
The impact test, in combination with a finite element method (FEM) simulation, is used to determine stress values that characterise the fatigue behaviour of thin hard coatings, such as TiAlN, TiAlCN, CrN, MoN, etc. The successive impacts of a cemented carbide ball onto a coated probe induce high contact loads, which can vary in amplitude and cause plastic deformation in the substrate. In the present paper FEM calculations are used in order to determine the critical stress values, which lead to coating fatigue failure. The parametric FEM simulation developed considers elastic behaviour for the coating and elastic plastic behaviour for the substrate. The results of the FEM calculations are correlated to experimental data, as well as to SEM observations of the imprints and to microspectrum analyses within the contact region. Herewith, critical values for various stress components, which are responsible for distinctive fatigue failure modes of the coating-substrate compounds can be obtained. (orig.)
FEM and FVM compound numerical simulation of aluminum extrusion processes
Institute of Scientific and Technical Information of China (English)
周飞; 苏丹; 彭颖红; 阮雪榆
2003-01-01
The finite element method (FEM) and the finite volume method (FVM) numerical simulation methods have been widely used in forging industries to improve the quality of products and reduce the costs. Because of very concentrative large deformation during the aluminum extrusion processes, it is very difficult to simulate the whole forming process only by using either FEM or FVM. In order to solve this problem, an FEM and FVM compound simulation method was proposed. The theoretical equations of the compound simulation method were given and the key techniques were studied. Then, the configuration of the compound simulation system was established. The tube extrusion process was simulated successfully so as to prove the validity of this approach for aluminum extrusion processes.
Novel Techniques using FEM for Material Production and Processing
Al-Shammaa, A I; Shaw, A; Stuart, R A; Wright, C C; Houghton, M
2005-01-01
The objectives of this European project are to use high frequency microwave technology to develop focussed energy sources for industrial applications. The microwaves, generated in the 10GHz to 20GHz frequency range by using a table top FEM has been used to investigate novel solutions for material processing and material production, including microwave heating of substrates, microwave chemistry for increasing the speed of thermal reactions, microwave plasma chemistry for aiding gaseous reactions in the reduction of combustion pollutants and the production of UV/ozone for germicidal activities. In this paper we report unique results and analysis in using tuneable FEM system compared with the conventional magnetron 2.45 GHz system.
FEM growth and yield data monocultures - other species
Goudzwaard, L.; Jansen, J.J.; Oosterbaan, A.; Oldenburger, J.F.; Mohren, G.M.J.; Ouden, den J.
2016-01-01
The current database is part of the FEM growth and yield database, a collection of growth and yield data from even-aged monocultures (douglas fir, common oak, poplar, Japanese Larch, Norway spruce, Scots pine, Corsican pine, Austrian pine, red oak and several other species, with only a few plots,
FEM simulation of static loading test of the Omega beam
Bílý, Petr; Kohoutková, Alena; Jedlinský, Petr
2017-09-01
The paper deals with a FEM simulation of static loading test of the Omega beam. Omega beam is a precast prestressed high-performance concrete element with the shape of Greek letter omega. Omega beam was designed as a self-supporting permanent formwork member for construction of girder bridges. FEM program ATENA Science was exploited for simulation of load-bearing test of the beam. The numerical model was calibrated using the data from both static loading test and tests of material properties. Comparison of load-displacement diagrams obtained from the experiment and the model was conducted. Development of cracks and crack patterns were compared. Very good agreement of experimental data and the FEM model was reached. The calibrated model can be used for design of optimized Omega beams in the future without the need of expensive loading tests. The calibrated material model can be also exploited in other types of FEM analyses of bridges constructed with the use of Omega beams, such as limit state analysis, optimization of shear connectors, prediction of long-term deflections or prediction of crack development.
Extended FEM modeling of crack paths near inclusions
DEFF Research Database (Denmark)
Nielsen, Chris Valentin; Legarth, Brian Nyvang; Niordson, Christian Frithiof
2012-01-01
The extended FEM is applied to model crack growth near inclusions. A procedure to handle different propagation rates at different crack tips is presented. The examples considered investigate uniform tension as well as equibiaxial tension under plane strain conditions. A parameter study analyzes...
Stress Field Analyses of Functionally Gradient Ceramic Tool by FEM
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The cutting properties of the functionally gradient ceramic cutting tools relate closely to the gradient distribution. A cutting model of the functionally gradient ceramic tool is firstly designed in the present paper. The optimum of gradient distribution is obtained by way of the FEM analyses.
Research on acoustic-structure sensitivity using FEM and BEM
Institute of Scientific and Technical Information of China (English)
ZHANG Jun; ZHAO Wenzhong; ZHANG Weiying
2007-01-01
Acoustic-structure sensitivity is used to predict the change of acoustic pressure when a structure design variable is changed. The sensitivity is significant for reducing noise of structure. Using FEM (finite element method) and BEM (boundary element method) acoustic-structure sensitiv- ity was formulated and presented. The dynamic response and response velocity sensitivity with respect to structure design variable were carried out by using structural FEM, the acous- tic response and acoustic pressure sensitivity with respect to structure velocity were carded out by using acoustic BEM. Then, acoustic-structure sensitivity was computed by linking velocity sensitivity in FEM and acoustic sensitivity in BEM. This method was applied to an empty box as an example. Acoustic pressure sensitivity with respect to structure thick- ness achieved in frequency ranges 1-100 Hz, and its change role along with stimulating frequency and design variable were analyzed. Results show that acoustic-structure sensi- tivity method linked with FEM and BEM is effective and correct.
FreeFem++, a tool to solve PDEs numerically
Sadaka, Georges
2012-01-01
FreeFem++ is an open source platform to solve partial differential equations numerically, based on finite element methods. It was developed at the Laboratoire Jacques-Louis Lions, Universit\\'e Pierre et Marie Curie, Paris by Fr\\'ed\\'eric Hecht in collaboration with Olivier Pironneau, Jacques Morice, Antoine Le Hyaric and Kohji Ohtsuka. The FreeFem++ platform has been developed to facilitate teaching and basic research through prototyping. FreeFem++ has an advanced automatic mesh generator, capable of a posteriori mesh adaptation; it has a general purpose elliptic solver interfaced with fast algorithms such as the multi-frontal method UMFPACK, SuperLU . Hyperbolic and parabolic problems are solved by iterative algorithms prescribed by the user with the high level language of FreeFem++. It has several triangular finite elements, including discontinuous elements. For the moment this platform is restricted to the numerical simulations of problems which admit a variational formulation. We will give in the sequel a...
Performance of the Undulator for the Fom-Fem Project
Varfolomeev, A. A.; Ivanchenkov, S. N.; Khlebnikov, A. S.; Osmanov, N. S.; van der Wiel, M. J.; Urbanus, W. H.; Pavluchenkov, V. F.
1994-01-01
A high-quality hybrid undulator (KIAE-4) has been designed for the FOM-FEM project. It provides a strong magnetic field of 2.0 kG for a relatively large gap with a nominal value of 26 mm at a period of 4 cm. Two magnet side arrays provide enhancement of the magnetic field as well as the transverse
FEM growth and yield data mixed species forest
Bartelink, H.H.; Jansen, J.J.; Goudzwaard, L.; Lu, Huicui; Oldenburger, J.F.; Mohren, G.M.J.; Ouden, den J.
2016-01-01
The current database is part of the FEM growth and yield database, a collection of growth and yield data from even-aged monocultures (douglas fir, common oak, poplar, Japanese Larch, Norway spruce, Scots pine, Corsican pine, Austrian pine, red oak and several other species with only a few plots like
Evaluating DEM results with FEM perspectives of load : soil interaction
Tadesse, D.
2004-01-01
Keywords: Load - soil interaction, soil structure, soil mechanical properties, FEM (Finite Element Method), Plaxis (Finite Element Code), granular particles, shear stress, DEM (Distinct Element Method), mic
LNG Safety Research: FEM3A Model Development
Energy Technology Data Exchange (ETDEWEB)
Liese Dallbauman
2004-06-30
During this reporting period, kickoff and planning meetings were held. Subcontracted experimental and modeling tasks were defined. Efforts to address the numerical stability problems that hamper FEM3A's applicability to low wind speed, stable atmospheric conditions were initiated. A detailed review of FEM3A code and its execution, required for development of an accessible user interface, was also begun. A one-day workshop on LNG safety models has been scheduled for September 2004. The goals of this project are to develop a national focal point for LNG safety research and technical dissemination and to develop the FEM3A dispersion model for application to general scenarios involving dispersion problems with obstacle and terrain features of realistic complexity. During this reporting period, the objectives and scope of the project and its constituent tasks were discussed at a project kickoff meeting in Morgantown. Details of the subcontracted experimental and modeling tasks were further defined at a separate meeting at the University of Arkansas. Researchers at the university have begun to modify the turbulence closure model used in FEM3A to insure numerical stability during simulation of low-wind-speed, stable atmospheric conditions. The university's wind tunnel is being prepared for upcoming experimental studies. GTI has begun a detailed review of the FEM3A code and its execution that will provide guidance during development of an accessible user interface. Plans were made for a one day workshop on LNG safety models that will be held at the end of September and will provide an introduction to currently available and pending software tools.
Enhancement of FEM radiation by prebunching of the e-beam (stimulated super-radiance)
Arbel, M; Kleinman, H; Yakover, I M; Abramovich, A; Pinhasi, Y; Luria, Y; Tecimer, M; Gover, A
2001-01-01
An electron beam (e-beam) prebunched at the synchronous FEM frequency and traversing through a waveguide, located coaxially with a magnetic undulator, emits coherent radiation at the bunching frequency. Introduction of both a premodulated e-beam and a radio-frequency (r.f.) signal at the same frequency at the input of the waveguide can lead to more efficient interaction, and thus more power can be extracted from the electron beam. In order to achieve this, the density modulation of the electron beam should be at an appropriate phase with respect to the r.f. signal. We report a first experimental demonstration of the influence of the phase difference between the r.f. input signal and the fundamental component of the density modulation of the e-beam on the radiated power in a Free-Electron Maser (FEM). Our experimental system allows control of the current density modulation, of the r.f. input power level, in the undulator region and of the phase between that r.f. input and the modulation of the e-beam. A compar...
Temperature Control in Spark Plasma Sintering: An FEM Approach
Directory of Open Access Journals (Sweden)
G. Molénat
2010-01-01
Full Text Available Powder consolidation assisted by pulsed current and uniaxial pressure, namely, Spark Plasma Sintering (SPS, is increasingly popular. One limitation however lies in the difficulty of controlling the sample temperature during compaction. The aim of this work is to present a computational method for the assembly temperature based on the finite elements method (FEM. Computed temperatures have been compared with experimental data for three different dies filled with three materials with different electrical conductivities (TiAl, SiC, Al2O3. The results obtained are encouraging: the difference between computed and experimental values is less than 5%. This allows thinking about this FEM approach as a predictive tool for selecting the right control temperatures in the SPS machine.
Capabilities of Using Fem in Sheet-Metal Forming
Directory of Open Access Journals (Sweden)
Korga S.
2016-06-01
Full Text Available The aim of this study was to determine and select boundary conditions of modeling and FEM simulation for plastic processing on the example of sheet-metal forming. For sheet-metal deformation analysis, Deform 3D has been used. The study presents research methods for real and virtual conditions. There are also described common features and these differentiating obtained results. Research of conducted process of sheet-metal forming allows to determine the effectiveness of computer research methods. The finite-element method can be used as an effective tool for the study of plastic processing phenomena considering various operating conditions of individual elements provided the appropriate tools for FEM analysis.
Tool Wear Estimate in Milling Operation by FEM
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Many researches show that, in metal cutting process, tool wear rate depends on some cutting process parameters, such as temperature at tool face, contact pressure and relative sliding velocity at tool/chip and tool/workpiece interfaces. Finite element method(FEM) application enables the estimate of these parameters and the tool wear. A tool wear estimate program based on chip formation and heat transfer analysis is designed and compiled with Python to calculate the wear rate and volume, and update tool geometry according to the tool wear. The progressive flank and crater wears in milling operation are estimated by the program. The FEM code ABAQUS/Explicit and Standard are employed to analyze chip formation and heat transfer process.
Fiber Concrete under Temperature Drop Load with Stochastic FEM
Institute of Scientific and Technical Information of China (English)
QI Feng; ZHANG Wen-jin
2008-01-01
Plain concrete plate and fiber concrete plate subjected to temperature drop load were analyzed on stochastic finite element method (FEM). It is found that fibers can enhance concrete ability to resist temperature drop load for improving concrete's fracture energy and deferring the crack process. It is found for concrete not to improve apparently its tensile strength and fracture energy is recommended to be its appraisal parameter.
CORRECTING ACCOUNTING RESULTS OF TENSIONS USING FEM BY HSS METHOD
Directory of Open Access Journals (Sweden)
D. O. Bannikov
2011-05-01
Full Text Available The usage of the Hot Spot Stress (HSS method by means of linear surface extrapolation (LSE approach was analyzed for the correction of results of the Finite-Element Method (FEM in case of singularity of stresses. The given examples of structures and testing examples were computed on the base of design-and-computation software SCAD for Windows (version 11.3.
Mode splitting effect in FEMs with oversized Bragg resonators
Energy Technology Data Exchange (ETDEWEB)
Peskov, N. Yu.; Sergeev, A. S. [Institute of Applied Physics Russian Academy of Sciences, Nizhny Novgorod (Russian Federation); Kaminsky, A. K.; Perelstein, E. A.; Sedykh, S. N. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Kuzikov, S. V. [Institute of Applied Physics Russian Academy of Sciences, Nizhny Novgorod (Russian Federation); Nizhegorodsky State University, Nizhny Novgorod (Russian Federation)
2016-07-15
Splitting of the fundamental mode in an oversized Bragg resonator with a step of the corrugation phase, which operates over the feedback loop involving the waveguide waves of different transverse structures, was found to be the result of mutual influence of the neighboring zones of the Bragg scattering. Theoretical description of this effect was developed within the framework of the advanced (four-wave) coupled-wave approach. It is shown that mode splitting reduces the selective properties, restricts the output power, and decreases the stability of the narrow-band operating regime in the free-electron maser (FEM) oscillators based on such resonators. The results of the theoretical analysis were confirmed by 3D simulations and “cold” microwave tests. Experimental data on Bragg resonators with different parameters in a 30-GHz FEM are presented. The possibility of reducing the mode splitting by profiling the corrugation parameters is shown. The use of the mode splitting effect for the output power enhancement by passive compression of the double-frequency pulse generated in the FEM with such a resonator is discussed.
RF Wave Simulation Using the MFEM Open Source FEM Package
Stillerman, J.; Shiraiwa, S.; Bonoli, P. T.; Wright, J. C.; Green, D. L.; Kolev, T.
2016-10-01
A new plasma wave simulation environment based on the finite element method is presented. MFEM, a scalable open-source FEM library, is used as the basis for this capability. MFEM allows for assembling an FEM matrix of arbitrarily high order in a parallel computing environment. A 3D frequency domain RF physics layer was implemented using a python wrapper for MFEM and a cold collisional plasma model was ported. This physics layer allows for defining the plasma RF wave simulation model without user knowledge of the FEM weak-form formulation. A graphical user interface is built on πScope, a python-based scientific workbench, such that a user can build a model definition file interactively. Benchmark cases have been ported to this new environment, with results being consistent with those obtained using COMSOL multiphysics, GENRAY, and TORIC/TORLH spectral solvers. This work is a first step in bringing to bear the sophisticated computational tool suite that MFEM provides (e.g., adaptive mesh refinement, solver suite, element types) to the linear plasma-wave interaction problem, and within more complicated integrated workflows, such as coupling with core spectral solver, or incorporating additional physics such as an RF sheath potential model or kinetic effects. USDoE Awards DE-FC02-99ER54512, DE-FC02-01ER54648.
CFD and FEM Model of an Underwater Vehicle Propeller
Directory of Open Access Journals (Sweden)
Chruściel Tadeusz
2014-10-01
Full Text Available Within the framework of the project for design and optimization of the Remotely Operated Vehicle (ROV, research on its propulsion has been carried out. Te entire project was supported by CFD and FEM calculations taking into account the characteristics of the underwater vehicle. One of the tasks was to optimize the semi-open duct for horizontal propellers, which provided propulsion and controllability in horizontal plane. In order to create a measurable model of this task it was necessary to analyze numerical methodology of propeller design, along with the structure of a propellers with nozzles and contra-rotating propellers. It was confronted with theoretical solutions which included running of the analyzed propeller near an underwater vehicle. Also preliminary qualitative analyses of a simplified system with contra-rotating propellers and a semi-open duct were carried out. Te obtained results enabled to make a decision about the ROVs duct form. Te rapid prototyping SLS (Selective Laser Sintering method was used to fabricate a physical model of the propeller. As a consequence of this, it was necessary to verify the FEM model of the propeller, which based on the load obtained from the CFD model. Te article contains characteristics of the examined ROV, a theoretical basis of propeller design for the analyzed cases, and the results of CFD and FEM simulations.
Hybrid fundamental-solution-based FEM for piezoelectric materials
Cao, Changyong; Qin, Qing-Hua; Yu, Aibing
2012-10-01
In this paper, a new type of hybrid finite element method (FEM), hybrid fundamental-solution-based FEM (HFS-FEM), is developed for analyzing plane piezoelectric problems by employing fundamental solutions (Green's functions) as internal interpolation functions. A modified variational functional used in the proposed model is first constructed, and then the assumed intra-element displacement fields satisfying a priori the governing equations of the problem are constructed by using a linear combination of fundamental solutions at a number of source points located outside the element domain. To ensure continuity of fields over inter-element boundaries, conventional shape functions are employed to construct the independent element frame displacement fields defined over the element boundary. The proposed methodology is assessed by several examples with different boundary conditions and is also used to investigate the phenomenon of stress concentration in infinite piezoelectric medium containing a hole under remote loading. The numerical results show that the proposed algorithm has good performance in numerical accuracy and mesh distortion insensitivity compared with analytical solutions and those from ABAQUS. In addition, some new insights on the stress concentration have been clarified and presented in the paper.
Energy Technology Data Exchange (ETDEWEB)
Schonert, Morten
2008-07-01
. There was no effect of cathode water on the cell voltage. However, the influence of different catalysts could be clearly identified and is a major influencing factor of MEA performance. The stability of the cell voltage, on the other hand, is strongly dependent on the flow distribution structure. For example, with a single meander operation at the low air volume flows required for water autonomy is possible. Methanol permeation can be influenced and minimized via the methanol concentration on the anode as a function of current density. (orig.) [German] In der vorliegenden Arbeit wurden die Einflussgroessen auf den Wasser- und Methanoltransport einer groesseren Direkt-Methanol Brennstoffzelle (Pel > 1 kW) untersucht. Hintergrund ist ein angestrebter wasserautarker Betrieb eines Direkt-Methanol Brennstoffzellensystems. Da bei der elektrochemischen Reaktion auf der Anode Wasser verbraucht wird und auf der Kathode dabei mehr Wasser entsteht, muss diese Differenz ueber die Luft ausgetragen werden. Alles weiter auf der Kathode anfallende Wasser muss kondensiert und der Anode zurueckgefuehrt werden. Mit zunehmender Umgebungstemperatur muss dabei der Luftvolumenstrom reduziert werden, da ansonsten mehr Wasser als erlaubt ausgetragen wuerde. Des Weiteren fuehren niedrigere Luftvolumenstroeme auf der Kathode zu einer instabilen Zellspannung, was auch einem uebermaessigen Anfall von Wasser zugeschrieben wird. Es ist daher von der Seite der Systemtechnik gewollt, die Menge des auf der Kathode anfallenden Wassers zu reduzieren. Es zeigte sich, dass die Wasserpermeation durch die Membran-Elektroden-Einheit (MEA) bei den fuer das Erreichen der Wasserautarkie notwendigen geringen Luftvolumenstroemen vorrangig von der Aufnahmekapazitaet und der Verweilzeit der Luft ueber der Kathode abhaengig ist und weniger von der Art des auf der Kathode verwendeten Materials. Die Wasserpermeation kommt bei einem Ausgleich des Konzentrationsgradienten zum Stillstand. Neben der Wasserpermeation kommt
Fem1b promotes ubiquitylation and suppresses transcriptional activity of Gli1.
Gilder, Andrew S; Chen, Yong-Bin; Jackson, Ramon J; Jiang, Jin; Maher, Joseph F
2013-10-25
The mammalian Fem1b gene encodes a homolog of FEM-1, a protein in the sex-determination pathway of the nematode Caenorhabditis elegans. Fem1b and FEM-1 proteins each contain a VHL-box motif that mediates their interaction with certain E3 ubiquitin ligase complexes. In C. elegans, FEM-1 negatively regulates the transcription factor TRA-1, and functions as an E3 ubiquitin ligase substrate recognition subunit to target TRA-1 for ubiquitylation. TRA-1 is homologous to the mammalian Gli1 protein, a transcription factor that mediates Hedgehog signaling as well as having Hedgehog-independent functions. Whether the interaction between nematode FEM-1 and TRA-1 proteins is conserved, between corresponding mammalian homologs, has not been reported. Herein, we show that Fem1b interacts with Gli1 within cells, and directly binds Gli1. Fem1b also promotes ubiquitylation of Gli1, suppresses transcriptional activation by Gli1, and attenuates an oncogenic Gli1 autoregulatory loop in cancer cells, all dependent on the VHL-box of Fem1b. These findings have implications for understanding the cellular functions of Fem1b, and the regulation of Gli1 oncoprotein activity. Copyright © 2013 Elsevier Inc. All rights reserved.
A Neural-FEM tool for the 2-D magnetic hysteresis modeling
Energy Technology Data Exchange (ETDEWEB)
Cardelli, E. [University of Perugia, Department of Engineering, Via G. Duranti 93, 06125 Perugia (Italy); Faba, A., E-mail: antonio.faba@unipg.it [University of Perugia, Department of Engineering, Via G. Duranti 93, 06125 Perugia (Italy); Laudani, A.; Lozito, G.M.; Riganti Fulginei, F.; Salvini, A. [Department of Engineering, Roma Tre University, Via V. Volterra 62, 00146 Rome (Italy)
2016-04-01
The aim of this work is to present a new tool for the analysis of magnetic field problems considering 2-D magnetic hysteresis. In particular, this tool makes use of the Finite Element Method to solve the magnetic field problem in real device, and fruitfully exploits a neural network (NN) for the modeling of 2-D magnetic hysteresis of materials. The NS has as input the magnetic inductions components B at the k-th simulation step and returns as output the corresponding values of the magnetic field H corresponding to the input pattern. It is trained by vector measurements performed on the magnetic material to be modeled. This input/output scheme is directly implemented in a FEM code employing the magnetic potential vector A formulation. Validations through measurements on a real device have been performed.
[A 3D FEM model for calculation of electromagnetic fields in transmagnetic stimulation].
Seilwinder, J; Kammer, T; Andrä, W; Bellemann, M E
2002-01-01
We developed a realistic finite elements method (FEM) model of the brain for the calculation of electromagnetic fields in transcranial magnetic stimulation (TMS). A focal butterfly stimulation coil was X-rayed, parameterized, and modeled. The magnetic field components of the TMS coil were calculated and compared for validation to pointwise measurements of the magnetic fields with a Hall sensor. We found a mean deviation of 7.4% at an axial distance of 20 mm to the coil. A 3D brain model with the biological tissues of white and gray matter, bone, and cerebrospinal fluid was developed. At a current sweep of 1000 A in 120 microseconds, the maximum induced current density in gray matter was 177 mA/m2 and the strongest electric field gradient covered an area of 40 mm x 53 mm.
FEM Analysis of Tube Preforming and Hydroforming Process for an Automotive Part
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The tube hydroforming technology is used today in the mass production of lightweight components for the automotive industries due to its advantages over conventional stamping methods. A typical tube hydroforming process is usually a multiple forming operation process. The tube preforming and hydroforming process of an automobile subframe were analyzed by finite element method (FEM), and a parametric study was also carried out to obtain the effect of the forming parameters such as the die closing, the internal pressure and the axial feeding. The simulation results were also compared with industrial products in respect to the thickness distribution of some typical and key cross-sections. The study indicates that the internal pressure and the axial feeding should be set correctly and the multiple forming operations of tube hydroforming process can be simulated well by using the explicit code Ls-Dyna.
Object Oriented Approach to Consistent Implementation of Meshless and Classical FEM
Directory of Open Access Journals (Sweden)
Albert Seidl
2006-02-01
Full Text Available Numerical experiments show that the full potential of the Finite Element Method (FEM can be exploited by combination of classical with meshless FEM. A class structure for flexible consistent implementation of both methods is presented. Fully automatized 3D mesh-generation still constitutes a serious problem in software development concerning FEM. In the recent years various methods of meshless FEM have been developed as an alternative to overcome this problem. In this work meshless and classical FEM have been implemented. A further objective of this work is to implement different classical and meshless methods together with an appropriate mesh/point-set generation method. An appropriate class structure for realizing this in a consistent manner with classical FEM is developed and implemented in C++. The performance of the discussed methods was tested with problems relevant in electrical and civil engineering i.e. static electrical field calculations (Poison equation and elasticity problems.
X-ray crystal structure of Staphylococcus aureus FemA.
Benson, Timothy E; Prince, D Bryan; Mutchler, Veronica T; Curry, Kimberly A; Ho, Andrea M; Sarver, Ronald W; Hagadorn, Jeanne C; Choi, Gil H; Garlick, Robert L
2002-08-01
The latter stages of peptidoglycan biosynthesis in Staphylococci involve the synthesis of a pentaglycine bridge on the epsilon amino group of the pentapeptide lysine side chain. Genetic and biochemical evidence suggest that sequential addition of these glycines is catalyzed by three homologous enzymes, FemX (FmhB), FemA, and FemB. The first protein structure from this family, Staphylococcus aureus FemA, has been solved at 2.1 A resolution by X-ray crystallography. The FemA structure reveals a unique organization of several known protein folds involved in peptide and tRNA binding. The surface of the protein also reveals an L-shaped channel suitable for a peptidoglycan substrate. Analysis of the structural features of this enzyme provides clues to the mechanism of action of S. aureus FemA.
Simulation of ultrasonic and EMAT arrays using FEM and FDTD.
Xie, Yuedong; Yin, Wuliang; Liu, Zenghua; Peyton, Anthony
2016-03-01
This paper presents a method which combines electromagnetic simulation and ultrasonic simulation to build EMAT array models. For a specific sensor configuration, Lorentz forces are calculated using the finite element method (FEM), which then can feed through to ultrasonic simulations. The propagation of ultrasound waves is numerically simulated using finite-difference time-domain (FDTD) method to describe their propagation within homogenous medium and their scattering phenomenon by cracks. Radiation pattern obtained with Hilbert transform on time domain waveforms is proposed to characterise the sensor in terms of its beam directivity and field distribution along the steering angle.
FEM Simulations of Leaky Lamb Wave in Ultrasonic Waveguide Sensor
Energy Technology Data Exchange (ETDEWEB)
Bae, Jin Ho; Joo, Young Sang; Kim, Jong Bum [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2011-05-15
As the sodium coolant of a sodium-cooled fast reactor (SFR) is opaque to light, a conventional visual inspection cannot be used for carrying out an in-service inspection of the internal structures under a sodium level. An ultrasonic wave should be applied for an under-sodium viewing of the internal structures in a reactor vessel. Recently, a noble plate-type ultrasonic waveguide sensor has been developed for versatile applications in an under-sodium viewing application. The beam profile of a A{sub 0}-mode leaky Lamb wave of the waveguide sensor affects the resolution of visualization image in under-sodium viewing. In the design and manufacture of the waveguide sensor, the finite element method (FEM) modeling and simulation of the propagation of a leaky Lamb wave is required for the estimation and optimization of the waveguide sensor design parameters. In the previous research, the simple 2D modeling and simulation of the waveguide sensor had been carried out. In this work, FEM simulation of the propagation and radiation of the leaky Lamb wave in the waveguide sensor is performed for the vertical and lateral beam profile analysis using the pseudo 3D modeling including the wedge
A Hybrid FEM-ANN Approach for Slope Instability Prediction
Verma, A. K.; Singh, T. N.; Chauhan, Nikhil Kumar; Sarkar, K.
2016-08-01
Assessment of slope stability is one of the most critical aspects for the life of a slope. In any slope vulnerability appraisal, Factor Of Safety (FOS) is the widely accepted index to understand, how close or far a slope from the failure. In this work, an attempt has been made to simulate a road cut slope in a landslide prone area in Rudrapryag, Uttarakhand, India which lies near Himalayan geodynamic mountain belt. A combination of Finite Element Method (FEM) and Artificial Neural Network (ANN) has been adopted to predict FOS of the slope. In ANN, a three layer, feed- forward back-propagation neural network with one input layer and one hidden layer with three neurons and one output layer has been considered and trained using datasets generated from numerical analysis of the slope and validated with new set of field slope data. Mean absolute percentage error estimated as 1.04 with coefficient of correlation between the FOS of FEM and ANN as 0.973, which indicates that the system is very vigorous and fast to predict FOS for any slope.
A Hybrid FEM-ANN Approach for Slope Instability Prediction
Verma, A. K.; Singh, T. N.; Chauhan, Nikhil Kumar; Sarkar, K.
2016-09-01
Assessment of slope stability is one of the most critical aspects for the life of a slope. In any slope vulnerability appraisal, Factor Of Safety (FOS) is the widely accepted index to understand, how close or far a slope from the failure. In this work, an attempt has been made to simulate a road cut slope in a landslide prone area in Rudrapryag, Uttarakhand, India which lies near Himalayan geodynamic mountain belt. A combination of Finite Element Method (FEM) and Artificial Neural Network (ANN) has been adopted to predict FOS of the slope. In ANN, a three layer, feed- forward back-propagation neural network with one input layer and one hidden layer with three neurons and one output layer has been considered and trained using datasets generated from numerical analysis of the slope and validated with new set of field slope data. Mean absolute percentage error estimated as 1.04 with coefficient of correlation between the FOS of FEM and ANN as 0.973, which indicates that the system is very vigorous and fast to predict FOS for any slope.
Hartman, P. S.; Hlavacek, A.; Wilde, H.; Lewicki, D.; Schubert, W.; Kern, R. G.; Kazarians, G. A.; Benton, E. V.; Benton, E. R.; Nelson, G. A.
2001-01-01
The fem-3 gene of Caenorhabditis elegans was employed to determine the mutation frequency as well as the nature of mutations induced by low earth orbit space radiation ambient to Space Shuttle flight STS-76. Recovered mutations were compared to those induced by accelerated iron ions generated by the AGS synchrotron accelerator at Brookhaven National Laboratory. For logistical reasons, dauer larvae were prepared at TCU, transported to either Kennedy Space Center or Brookhaven National Laboratory, flown in space or irradiated, returned to TCU and screened for mutants. A total of 25 fem-3 mutants were recovered after the shuttle flight and yielded a mutation frequency of 2.1x10(-5), roughly 3.3-fold higher than the spontaneous rate of 6.3x10(-6). Four of the mutations were homozygous inviable, suggesting that they were large deletions encompassing fem-3 as well as neighboring, essential genes. Southern blot analyses revealed that one of the 25 contained a polymorphism in fem-3, further evidence that space radiation can induce deletions. While no polymorphisms were detected among the iron ion-induced mutations, three of the 15 mutants were homozygous inviable, which is in keeping with previous observations that high LET iron particles generate deficiencies. These data provide evidence, albeit indirect, that an important mutagenic component of ambient space radiation is high LET charged particles such as iron ions.
Gain-of-function mutations of fem-3, a sex-determination gene in Caenorhabditis elegans
Energy Technology Data Exchange (ETDEWEB)
Barton, M.K.; Schedl, T.B.; Kimble, J.
1987-01-01
The authors have isolated nine gain-of-function (gf) alleles of the sex-determination gene fem-3 as suppressors of feminizing mutations in fem-1 and fem-2. The wild type fem-3 gene is needed for spermatogenesis in XX self-fertilizing hermaphrodites and for male development in both soma and germ line of XO animals. Loss-of-function alleles of fem-3 transform XX and XO animals into females (spermless hermaphrodites). In contrast, fem-3 (gf) alleles masculinize only one tissue, the hermaphrodite germ line. Thus, XX fem-3 (gf) mutant animals have a normal hermaphrodite soma, but the germ line produces a vast excess of sperm and no oocytes. All nine fem-3 (gf) alleles are temperature sensitive. The temperature-sensitive period is from late L4 to early adult, a period just preceding the first signs of oogenesis. The finding of gain-of-function alleles which confer a phenotype opposite to that of loss-of-function alleles supports the idea that fem-3 plays a critical role in germ-line sex determination. Furthermore, the germ-line specificity of the fem-3 (gf) mutant phenotype and the late temperature-sensitive period suggest that, in the wild-type XX hermaphrodite, fem-3 is negatively regulated so that the hermaphrodite stops making sperm and starts making oocytes. Temperature shift experiments also show that, in the germ line, sexual commitment appears to be a continuing process. Spermatogenesis can resume even after oogenesis has begun, and oogenesis can be initiated much later than normal.
Solving optimisation problems in metal forming using FEM: A metamodel based optimisation algorithm
Bonte, M.H.A.
2005-01-01
During the last decades, Finite Element (FEM) simulations of metal forming processes have become important tools for designing feasible production processes. In more recent years, several authors recognised the potential of coupling FEM simulations to mathematical opti- misation algorithms to design
FEM Modelling of Lateral-Torsional Buckling Using Shell and Solid Elements
DEFF Research Database (Denmark)
Valeš, Jan; Stan, Tudor-Cristian
2017-01-01
The paper describes two methods of FEM modelling of I-section beams loaded by bending moments. Series of random realizations with initial imperfections following the first eigenmode of lateral-torsional buckling were created. Two independent FEM software products were used for analyses of resista...
Design and Fem Analysis of Car Alloy Wheel
Directory of Open Access Journals (Sweden)
Venkatesh. K
2016-12-01
Full Text Available The requirements for improved stiffness, reliability, fatigue life and increased efficiency involves challenges of developing innovative design solutions. The present work mainly focus on the design of car alloy wheel, where the analytical and FEM analysis approach was implemented to analyze baseline design. Initially static analysis was performed to obtain total deformation, strain and the stress of car alloy wheel. Three Dimensional model was created using CATIA and FE software ANSYS was used for discretization and analysis to obtain expected solution. The results were obtained through linear static analysis in terms of Total deformation while Minimum principal stress, Max Principal stress were found to be nearly equal for both 6 arms wheel and 4 arms wheel and 22.16 % of reduction in weight was observed and hence overall weight of the car alloy wheel was optimized.
FEM Techniques for High Stress Detection in Accelerated Fatigue Simulation
Veltri, M.
2016-09-01
This work presents the theory and a numerical validation study in support to a novel method for a priori identification of fatigue critical regions, with the aim to accelerate durability design in large FEM problems. The investigation is placed in the context of modern full-body structural durability analysis, where a computationally intensive dynamic solution could be required to identify areas with potential for fatigue damage initiation. The early detection of fatigue critical areas can drive a simplification of the problem size, leading to sensible improvement in solution time and model handling while allowing processing of the critical areas in higher detail. The proposed technique is applied to a real life industrial case in a comparative assessment with established practices. Synthetic damage prediction quantification and visualization techniques allow for a quick and efficient comparison between methods, outlining potential application benefits and boundaries.
Preparation of Electrode Array by Electrochemical Etching Based on FEM
Institute of Scientific and Technical Information of China (English)
Minghuan WANG; Di ZHU; Lei WANG
2008-01-01
Process technology of multiple cylindrical micro-pins by wire-electrical discharge machining (wire-EDM) and electrochemical etching was presented.A row of rectangular micro-columns were machined by wire-EDM and then machined into cylindrical shape by electrochemical etching.However,the shape of the multiple electrodes and the consistent sizes of the electrodes row are not easy to be controlled.In the electrochemical process,the shape of the cathode electrode determines the current density distribution on the anode and so the forming of multiple electrodes.This paper proposes a finite element method (FEM) to accurately optimize the electrode profile.The microelectrodes row with uniformity diameters with size from hundreds micrometers to several decades could be fabricated,and mathematical model controlling the shape and diameter of multiple microelectrodes was provided.Furthermore,a good agreement between experimental and theoretical results was confirmed.
Friction Model for FEM Simulation of Sheet Metal Forming Operations
Keum, Y. T.; Wagoner, R. H.; Lee, J. K.
2004-06-01
In order to find the effect of frictional characteristics, lubricant viscosity, tool geometry, and forming speed on the sheet metal forming, a friction tester was designed and manufactured. Friction tests were performed using drawing oils, various tool radii and forming speeds for aluminum alloy sheets, galvanized steels sheets and cold rolled steel sheets. From the experimental observation, the mathematical friction model considering lubricant viscosity, sheet surface roughness and hardness, punch corner radii, and punch speed is developed. By comparing the punch load found by FEM using the proposed friction model with that of experimental measurement when the steel sheets are formed in 2-D geometry in dry and lubricating conditions, the validity and accuracy of the mathematical friction model are demonstrated.
Broaching Performance of Superalloy GH4169 Based on FEM
Institute of Scientific and Technical Information of China (English)
Xiangwei Kong; Bin Li; Zhibo Jin; Wenran Geng
2011-01-01
The nickel-based superalloy GH4169 is an important material for high temperature applications in the aerospace industry. However, due to its poor machinability, GH4169 is hard to be cut and generates saw-tooth chips during high speed machining, which could significantly affect the dynamic cutting force, cutting temperature fluctuation, tool life, and the surface integrity of the parts. In this paper, the saw-tooth chip formation mechanism of superalloy GH4169 was investigated by the elasto-viscoplastic finite element method (FEM). Using the finite element software of ABAQUS/Explicit, the deformation of the part during high speed machining was simulated. The effective plastic strain, the temperature field, the stress distribution, and the cutting force were analyzed to determine the influence of the cutting parameters on the saw-tooth chip formation. The study on broaching performance has great effect on selecting suitable machining parameters and improving tool life.
Report on first masing and single mode locking in a prebunched beam FEM oscillator
Energy Technology Data Exchange (ETDEWEB)
Cohen, M.; Eichenbaum, A.; Kleinman, H. [Tel-Aviv Univ., Ramat-Aviv (Israel)] [and others
1995-12-31
Radiation characteristics of a table-top free electron maser (FEM) are described in this paper. The FEM employs a prebunched electron beam and is operated as an oscillator in the low-gain collective (Raman) regime. Using electron beam prebunching single mode locking at any one of the possible oscillation modes was obtained. The electron beam is prebunched by a microwave tube section before it is injected into the wiggler. By tuning the electron beam bunching frequency, the FEM oscillation frequency can be locked to any eigen frequency of the resonant waveguide cavity which is within the frequency band of net gain of the FEM. The oscillation build up process is sped up, when the FEM operates with a prebunched electron beam, and the build-up time of radiation is shortened significantly. First measurements of masing with and without prebunching and characterization of the emitted radiation are reported.
Generalized multiscale finite element methods (GMsFEM)
Efendiev, Yalchin R.
2013-10-01
In this paper, we propose a general approach called Generalized Multiscale Finite Element Method (GMsFEM) for performing multiscale simulations for problems without scale separation over a complex input space. As in multiscale finite element methods (MsFEMs), the main idea of the proposed approach is to construct a small dimensional local solution space that can be used to generate an efficient and accurate approximation to the multiscale solution with a potentially high dimensional input parameter space. In the proposed approach, we present a general procedure to construct the offline space that is used for a systematic enrichment of the coarse solution space in the online stage. The enrichment in the online stage is performed based on a spectral decomposition of the offline space. In the online stage, for any input parameter, a multiscale space is constructed to solve the global problem on a coarse grid. The online space is constructed via a spectral decomposition of the offline space and by choosing the eigenvectors corresponding to the largest eigenvalues. The computational saving is due to the fact that the construction of the online multiscale space for any input parameter is fast and this space can be re-used for solving the forward problem with any forcing and boundary condition. Compared with the other approaches where global snapshots are used, the local approach that we present in this paper allows us to eliminate unnecessary degrees of freedom on a coarse-grid level. We present various examples in the paper and some numerical results to demonstrate the effectiveness of our method. © 2013 Elsevier Inc.
CT image segmentation using FEM with optimized boundary condition.
Directory of Open Access Journals (Sweden)
Hiroyuki Hishida
Full Text Available The authors propose a CT image segmentation method using structural analysis that is useful for objects with structural dynamic characteristics. Motivation of our research is from the area of genetic activity. In order to reveal the roles of genes, it is necessary to create mutant mice and measure differences among them by scanning their skeletons with an X-ray CT scanner. The CT image needs to be manually segmented into pieces of the bones. It is a very time consuming to manually segment many mutant mouse models in order to reveal the roles of genes. It is desirable to make this segmentation procedure automatic. Although numerous papers in the past have proposed segmentation techniques, no general segmentation method for skeletons of living creatures has been established. Against this background, the authors propose a segmentation method based on the concept of destruction analogy. To realize this concept, structural analysis is performed using the finite element method (FEM, as structurally weak areas can be expected to break under conditions of stress. The contribution of the method is its novelty, as no studies have so far used structural analysis for image segmentation. The method's implementation involves three steps. First, finite elements are created directly from the pixels of a CT image, and then candidates are also selected in areas where segmentation is thought to be appropriate. The second step involves destruction analogy to find a single candidate with high strain chosen as the segmentation target. The boundary conditions for FEM are also set automatically. Then, destruction analogy is implemented by replacing pixels with high strain as background ones, and this process is iterated until object is decomposed into two parts. Here, CT image segmentation is demonstrated using various types of CT imagery.
Koch, Vasco; Nissen, Inga; Schmitt, Björn D; Beye, Martin
2014-01-01
The primary signal of sex determination in the honeybee, the complementary sex determiner (csd) gene, evolved from a gene duplication event from an ancestral copy of the fem gene. Recently, other paralogs of the fem gene have been identified in several ant and bumblebee genomes. This discovery and the close phylogenetic relationship of the paralogous gene sequences led to the hypothesis of a single ancestry of the csd genetic system of complementary sex determination in the Hymenopteran insects, in which the fem and csd gene copies evolved as a unit in concert with the mutual transfers of sequences (concerted evolution). Here, we show that the paralogous gene copies evolved repeatedly through independent gene duplication events in the honeybee, bumblebee, and ant lineage. We detected no sequence tracts that would indicate a DNA transfer between the fem and the fem1/csd genes between different ant and bee species. Instead, we found tracts of duplication events in other genomic locations, suggesting that gene duplication was a frequent event in the evolution of these genes. These and other evidences suggest that the fem1/csd gene originated repeatedly through gene duplications in the bumblebee, honeybee, and ant lineages in the last 100 million years. Signatures of concerted evolution were not detectable, implicating that the gene tree based on neutral synonymous sites represents the phylogenetic relationships and origins of the fem and fem1/csd genes. Our results further imply that the fem1 and csd gene in bumblebees, honeybees, and ants are not orthologs, because they originated independently from the fem gene. Hence, the widely shared and conserved complementary sex determination mechanism in Hymenopteran insects is controlled by different genes and molecular processes. These findings highlight the limits of comparative genomics and emphasize the requirement to study gene functions in different species and major hymenopteran lineages.
Living with an imperfect cell wall: compensation of femAB inactivation in Staphylococcus aureus
Directory of Open Access Journals (Sweden)
Bierbaum Gabriele
2007-09-01
Full Text Available Abstract Background Synthesis of the Staphylococcus aureus peptidoglycan pentaglycine interpeptide bridge is catalyzed by the nonribosomal peptidyl transferases FemX, FemA and FemB. Inactivation of the femAB operon reduces the interpeptide to a monoglycine, leading to a poorly crosslinked peptidoglycan. femAB mutants show a reduced growth rate and are hypersusceptible to virtually all antibiotics, including methicillin, making FemAB a potential target to restore β-lactam susceptibility in methicillin-resistant S. aureus (MRSA. Cis-complementation with wild type femAB only restores synthesis of the pentaglycine interpeptide and methicillin resistance, but the growth rate remains low. This study characterizes the adaptations that ensured survival of the cells after femAB inactivation. Results In addition to slow growth, the cis-complemented femAB mutant showed temperature sensitivity and a higher methicillin resistance than the wild type. Transcriptional profiling paired with reporter metabolite analysis revealed multiple changes in the global transcriptome. A number of transporters for sugars, glycerol, and glycine betaine, some of which could serve as osmoprotectants, were upregulated. Striking differences were found in the transcription of several genes involved in nitrogen metabolism and the arginine-deiminase pathway, an alternative for ATP production. In addition, microarray data indicated enhanced expression of virulence factors that correlated with premature expression of the global regulators sae, sarA, and agr. Conclusion Survival under conditions preventing normal cell wall formation triggered complex adaptations that incurred a fitness cost, showing the remarkable flexibility of S. aureus to circumvent cell wall damage. Potential FemAB inhibitors would have to be used in combination with other antibiotics to prevent selection of resistant survivors.
Design and Implementation of FEM Parallel Program%有限元并行程序设计与实现
Institute of Scientific and Technical Information of China (English)
余天堂; 姜弘道
2000-01-01
Parallel computation of FEM under systolic distributednetwork is a important direction of FEM parallel computation. A programdesigning method and its implementation for FEM parallel analysis undernetwork based on PVM is presented. Substructure parallel analysismethod with multi-front parallel processing is adopted in FEM parallelcomputation, the interface equations are solved with PreconditionedConjugate Gradient (PCG) method. The implementation of this designingmethod is easy. Example shows the designing method can obtain higherspeedup ratio.
An Analysis of Flow in a Centrifugal Impeller by FEM with k-ε Model
Institute of Scientific and Technical Information of China (English)
Satoshi Matsumoto; Hideki Ohba; Hiroyuki Miyamoto
2001-01-01
In this study, we attempt the analysis of the passage flow in the centrifugal impeller using FEM with/without the turbulence model, and compare this result with the experimental result. The turbulence model is the low Reynolds k- ε model proposed by Chien. We use the GSMAC method for the Reynolds averaged Navier-Stokes equations,the Euler explicit method for the transport equations of the turbulent kinetic energy and the dissipation rate. All equations are discretized by the Galerkin's method.At the midpassage of the centrifugal impeller, the passagewise velocity component tends to increase in the pressure-to-suction direction, and the other component toward the pressure surface tends to be large in the region of the middle blade-to-blade to the hub side. The tip leakages appear around the region of the middle blade-to-blade near the casing together with the secondary flow toward the suction surface. These phenomena correspond with the experimental result, qualitatively.
A mass-redistributed finite element method (MR-FEM) for acoustic problems using triangular mesh
He, Z. C.; Li, Eric; Liu, G. R.; Li, G. Y.; Cheng, A. G.
2016-10-01
The accuracy of numerical results using standard finite element method (FEM) in acoustic problems will deteriorate with increasing frequency due to the "dispersion error". Such dispersion error depends on the balance between the "stiffness" and "mass" of discretization equation systems. This paper reports an improved finite element method (FEM) for solving acoustic problems by re-distributing the mass in the mass matrix to "tune" the balance, aiming to minimize the dispersion errors. This is done by shifting the integration point locations when computing the entries of the mass matrix, while ensuring the mass conservation. The new method is verified through the detailed numerical error analysis, and a strategy is also proposed for the best mass redistribution in terms of minimizing dispersion error. The relative dispersion error of present mass-redistributed finite element method (MR-FEM) is found to be much smaller than the FEM solution, in both theoretical prediction and numerical examination. The present MR-FEM works well by using the linear triangular elements that can be generated automatically, which enables automation in computation and saving computational cost in mesh generation. Numerical examples demonstrate the advantages of MR-FEM, in comparison with the standard FEM using the same triangular meshes and quadrilateral meshes.
Applications of ATILA FEM software to smart materials case studies in designing devices
Uchino, Kenji
2013-01-01
ATILA Finite Element Method (FEM) software facilitates the modelling and analysis of applications using piezoelectric, magnetostrictor and shape memory materials. It allows entire designs to be constructed, refined and optimized before production begins. Through a range of instructive case studies, Applications of ATILA FEM software to smart materials provides an indispensable guide to the use of this software in the design of effective products.Part one provides an introduction to ATILA FEM software, beginning with an overview of the software code. New capabilities and loss integratio
Bolt-Grout Interactions in Elastoplastic Rock Mass Using Coupled FEM-FDM Techniques
Directory of Open Access Journals (Sweden)
Debasis Deb
2010-01-01
Full Text Available Numerical procedure based on finite element method (FEM and finite difference method (FDM for the analysis of bolt-grout interactions are introduced in this paper. The finite element procedure incorporates elasto-plastic concepts with Hoek and Brown yield criterion and has been applied for rock mass. Bolt-grout interactions are evaluated based on finite difference method and are embedded in the elasto-plastic procedures of FEM. The experimental validation of the proposed FEM-FDM procedures and numerical examples of a bolted tunnel are provided to demonstrate the efficacy of the proposed method for practical applications.
Solution of 2D Boussinesq systems with FreeFem++: The flat bottom case
Sadaka, Georges
2012-01-01
FreeFem++ is an open source platform to solve partial differential equations numerically, based on finite element methods. The FreeFem++ platform has been developed to facilitate teaching and basic research through prototyping. For the moment this platform is restricted to the numerical simulations of problems which admit a variational formulation. We will use FreeFem++ in this work to solve a three-parameter family of Boussinesq type systems in two space dimensions which approximate the three-dimensional Euler equations over an horizontal bottom.
FEM numerical model study of electrosurgical dispersive electrode design parameters.
Pearce, John A
2015-01-01
Electrosurgical dispersive electrodes must safely carry the surgical current in monopolar procedures, such as those used in cutting, coagulation and radio frequency ablation (RFA). Of these, RFA represents the most stringent design constraint since ablation currents are often more than 1 to 2 Arms (continuous) for several minutes depending on the size of the lesion desired and local heat transfer conditions at the applicator electrode. This stands in contrast to standard surgical activations, which are intermittent, and usually less than 1 Arms, but for several seconds at a time. Dispersive electrode temperature rise is also critically determined by the sub-surface skin anatomy, thicknesses of the subcutaneous and supra-muscular fat, etc. Currently, we lack fundamental engineering design criteria that provide an estimating framework for preliminary designs of these electrodes. The lack of a fundamental design framework means that a large number of experiments must be conducted in order to establish a reasonable design. Previously, an attempt to correlate maximum temperatures in experimental work with the average current density-time product failed to yield a good match. This paper develops and applies a new measure of an electrode stress parameter that correlates well with both the previous experimental data and with numerical models of other electrode shapes. The finite element method (FEM) model work was calibrated against experimental RF lesions in porcine skin to establish the fundamental principle underlying dispersive electrode performance. The results can be used in preliminary electrode design calculations, experiment series design and performance evaluation.
Adaptive stochastic Galerkin FEM with hierarchical tensor representations
Eigel, Martin
2016-01-08
PDE with stochastic data usually lead to very high-dimensional algebraic problems which easily become unfeasible for numerical computations because of the dense coupling structure of the discretised stochastic operator. Recently, an adaptive stochastic Galerkin FEM based on a residual a posteriori error estimator was presented and the convergence of the adaptive algorithm was shown. While this approach leads to a drastic reduction of the complexity of the problem due to the iterative discovery of the sparsity of the solution, the problem size and structure is still rather limited. To allow for larger and more general problems, we exploit the tensor structure of the parametric problem by representing operator and solution iterates in the tensor train (TT) format. The (successive) compression carried out with these representations can be seen as a generalisation of some other model reduction techniques, e.g. the reduced basis method. We show that this approach facilitates the efficient computation of different error indicators related to the computational mesh, the active polynomial chaos index set, and the TT rank. In particular, the curse of dimension is avoided.
Cicciu, Marco; Bramanti, Ennio; Matacena, Giada; Guglielmino, Eugenio; Risitano, Giacomo
2014-01-01
Prosthetic rehabilitation of partial or total edentulous patients is today a challenge for clinicians and dental practitioners. The application of dental implants in order to recover areas of missing teeth is going to be a predictable technique, however some important points about the implant angulation, the stress distribution over the bone tissue and prosthetic components should be well investigated for having final long term clinical results. Two different system of the prosthesis fixation are commonly used. The screw retained crown and the cemented retained one. All of the two restoration techniques give to the clinicians several advantages and some disadvantages. Aim of this work is to evaluate all the mechanical features of each system, through engineering systems of investigations like FEM and Von Mises analyses. The FEM is today a useful tool for the prediction of stress effect upon material and biomaterial under load or strengths. Specifically three different area has been evaluated through this study: the dental crown with the bone interface; the passant screw connection area; the occlusal surface of the two different type of crown. The elastic features of the materials used in the study have been taken from recent literature data. Results revealed an adequate response for both type of prostheses, although cemented retained one showed better results over the occlusal area.
Cicciu, Marco; Bramanti, Ennio; Matacena, Giada; Guglielmino, Eugenio; Risitano, Giacomo
2014-01-01
Prosthetic rehabilitation of partial or total edentulous patients is today a challenge for clinicians and dental practitioners. The application of dental implants in order to recover areas of missing teeth is going to be a predictable technique, however some important points about the implant angulation, the stress distribution over the bone tissue and prosthetic components should be well investigated for having final long term clinical results. Two different system of the prosthesis fixation are commonly used. The screw retained crown and the cemented retained one. All of the two restoration techniques give to the clinicians several advantages and some disadvantages. Aim of this work is to evaluate all the mechanical features of each system, through engineering systems of investigations like FEM and Von Mises analyses. The FEM is today a useful tool for the prediction of stress effect upon material and biomaterial under load or strengths. Specifically three different area has been evaluated through this study: the dental crown with the bone interface; the passant screw connection area; the occlusal surface of the two different type of crown. The elastic features of the materials used in the study have been taken from recent literature data. Results revealed an adequate response for both type of prostheses, although cemented retained one showed better results over the occlusal area. PMID:24955150
Smith, Andrew; LaVerde, Bruce; Waldon, James; Hunt, Ron
2014-01-01
Marshall Space Flight Center has conducted a series of ground acoustic tests with the dual goals of informing analytical judgment, and validating analytical methods when estimating vibroacoustic responses of launch vehicle subsystems. The process of repeatedly correlating finite element-simulated responses with test-measured responses has assisted in the development of best practices for modeling and post-processing. In recent work, force transducers were integrated to measure interface forces at the base of avionics box equipment. Other force data was indirectly measured using strain gauges. The combination of these direct and indirect force measurements has been used to support and illustrate the advantages of implementing the Force Limiting approach for equipment qualification tests. The comparison of force response from integrated system level tests to measurements at the same locations during component level vibration tests provides an excellent illustration. A second comparison of the measured response cases from the system level acoustic tests to finite element simulations has also produced some principles for assessing the suitability of Finite Element Models (FEMs) for making vibroacoustics estimates. The results indicate that when FEM models are employed to guide force limiting choices, they should include sufficient detail to represent the apparent mass of the system in the frequency range of interest.
Analysis of Temperature Field and Thermal Crown of Roll During Hot Rolling by Simplified FEM
Institute of Scientific and Technical Information of China (English)
GUO Zhong-feng; LI Chang-sheng; XU Jian-zhong; LIU Xiang-hua; WANG Guo-dong
2006-01-01
Thermal crown of roll is an important factor, which affects strip profile. It is necessary to analyze the temperature field and thermal crown of roll for hot strip mill. A new simplified finite element method (FEM) was used to analyze the temperature field and thermal crown of roll, and corresponding models were built according to the practical boundary conditions. Transient roll temperature field and thermal crown were simulated by ANSYS FEM software with considering transient thermal contact and complex boundary condition. Temperature and thermal crown variations on roll surface nodes were obtained. The thermal crown results of roll obtained by FEM simulation were in good agreement with the measured data, indicating that simplified FEM models and results were correct.
Effect of Modeling Range on Structural Analysis for Powerhouse of Hydroelectric Power Plant by FEM
Institute of Scientific and Technical Information of China (English)
ZHANG Qiling; WU Hegao; YANG Huaquan
2009-01-01
In this paper, three different modeling ranges were selected in the structural analysis for a hydropower house. The analysis was carried out using ABAQUS 6.6. The modeling range has a remarkable effect on finite ele-ment method(FEM)calculation result at the middle position of typical cross-sections where the concrete is rela-tively thin, and at the region close to turbine floor. If the ventilation barrel, floor slabs and columns above turbine floor are excluded from FEM model, the maximum rise difference of pedestal structure increases by about 24% compared with that of the whole model. It is indicated that different modeling ranges indeed affect FEM calculation result, and the structure above turbine floor in the FEM model should be included.
FEM and Von Mises analyses of different dental implant shapes for masticatory loading distribution
CICCIÙ, M.; BRAMANTI, E.; CECCHETTI, F.; SCAPPATICCI, L.; GUGLIELMINO, E.; RISITANO, G.
2014-01-01
SUMMARY The rehabilitation of edentulous patients is today a challenge for the clinicians. The healthy of the hard and soft issue may be considered a fundamental element for having long-term results. The dental implant progresses about the predictable and safe results made this technique chosen from a large group of practitioners. However some problems related intra-operative and postoperative conditions may create discomfort on the patients and consequently to the clinician. The unfavourable results are often related to the bone tissue quality but sometime the dental implant shape and the prosthesis framework may undergo to technical difficulties. The purpose of this work is, through the use of appropriate FEM models, to analyse the effect of all these parameters in the construction of a prosthesis type “Toronto”, evaluating all the surgical and prosthetic components in order to direct the choices made by the surgeon and to optimize the distribution of loads reducing the patient’s discomfort and having a long term clinical success. PMID:25694795
DG-FEM solution for nonlinear wave-structure interaction using Boussinesq-type equations
DEFF Research Database (Denmark)
Engsig-Karup, Allan Peter; Hesthaven, Jan; Bingham, Harry B.
2008-01-01
We present a high-order nodal Discontinuous Galerkin Finite Element Method (DG-FEM) solution based on a set of highly accurate Boussinesq-type equations for solving general water-wave problems in complex geometries. A nodal DG-FEM is used for the spatial discretization to solve the Boussinesq equ...... and absorbed in the interior of the computational domain using a flexible relaxation technique applied on the free surface variables....
FEM application for modelling of PVD coatings properties
Directory of Open Access Journals (Sweden)
A. Śliwa
2010-07-01
Full Text Available Purpose: The general topic of this paper is problem of determining the internal stresses of composite tool materials with the use of finite element method (FEM. The chemical composition of the investigated materials’ core is corresponding to the M2 high-speed steel and was reinforced with the WC and TiC type hard carbide phases with the growing portions of these phases in the outward direction from the core to the surface. Such composed material was sintered, heat treated and deposited appropriately with (Ti,AlN or Ti(C,N coatings.Design/methodology/approach: Modelling of stresses was performed with the help of finite element method in ANSYS environment, and the experimental values of stresses were determined basing on the X-ray diffraction patterns. The computer simulation results were compared with the experimental results.Findings: Computer aided numerical analysis gives the possibility to select the optimal parameters for coatings covering in PVD process determining the stresses in coatings, employing the finite element method using the ANSYS software.Research limitations/implications: It was confirmed that using of finite element method in stresses modelling occurring in advanced composite materials can be a way for reducing the investigation costs. In order to reach this purpose, it was used in the paper a simplified model of composite materials with division on zones with established physical and mechanical properties. Results reached in this way are satisfying and in slight degree differ from results reached by experimental method.Originality/value: Nowadays the computer simulation is very popular and it is based on the finite element method, which allows to better understand the interdependence between parameters of process and choosing optimal solution. The possibility of application faster and faster calculation machines and coming into being many software make possible the creation of more precise models and more adequate ones to
Combined analytical FEM approach for efficient simulation of Lamb wave damage detection.
Shen, Yanfeng; Giurgiutiu, Victor
2016-07-01
Lamb waves have been widely explored as a promising inspection tool for non-destructive evaluation (NDE) and structural health monitoring (SHM). This article presents a combined analytical finite element model (FEM) approach (CAFA) for the accurate, efficient, and versatile simulation of 2-D Lamb wave propagation and interaction with damage. CAFA used a global analytical solution to model wave generation, propagation, scattering, mode conversion, and detection, while the wave-damage interaction coefficients (WDICs) were extracted from harmonic analysis of local FEM with non-reflective boundaries (NRB). The analytical procedure was coded using MATLAB, and a predictive simulation tool called WaveFormRevealer 2-D was developed. The methodology of obtaining WDICs from local FEM was presented. Case studies were carried out for Lamb wave propagation in a pristine plate and a damaged plate. CAFA predictions compared well with full scale multi-physics FEM simulations and experiments with scanning laser Doppler vibrometry (SLDV), while achieving remarkable performance in computational efficiency and computer resource saving compared with conventional FEM.
FEM convergence of a segmentation approach to the electrical impedance tomography problem
Mendoza, Renier; Keeling, Stephen
2016-02-01
In Electrical Impedance Tomography (EIT), different current patterns are injected to the unknown object through the electrodes attached at the boundary ∂ Ω of Ω. The corresponding voltages V are then measured on its boundary surface. Based on these measured voltages, the image reconstruction of the conductivity distribution σ is done by solving an inverse problem of a generalized Laplace equation subject to a homogeneous Neumann boundary condition. In other words, with known V, we seek to solve for the typically piecewise values of σ, from which the geometry of internal objects may be inferred. We approach this problem by using a multi-phase segmentation method. We express σ as σ (x)= ∑m=1Mσm(x)χm (x) , where χm is the characteristic function of a subdomain Ωm such that Ωm ∩ Ωn = Ø, m ≠ n and Ω= ∪m=1MΩm. The expected number of phases for Ω is M, where M = 2 for this work. The number of segments is the number of connected components of the subdomains. Using a calculated optimality condition, the conductivity value σm is expressed as a function of χm. The total variation of χm is then introduced to regularize the resulting cost functional. Using a descent method, an update for χm is proposed. In this work, the Finite Element Method (FEM) convergence of all the resulting variational formulations are studied. A real analytic mollification of χm is introduced to guarantee convergence.
Investigation of Ice-PVC separation under Flexural Loading using FEM Analysis
Directory of Open Access Journals (Sweden)
H Xue
2016-08-01
Full Text Available This paper presents the FEM technique applied in the study of ice separation over a polyvinyl chloride (PVC surface. A two layer model of ice and PVC is analysed theoretically using Euler-Bernoulli beam theory and the rule of mixtures. The physical samples are prepared by freezing ice over the PVC surfaces. The samples are tested experimentally in a four-point loading setup. The experimental results contain strain data gathered through a data acquisition system using the LabView software. The data is collected at the rate of 1 kHz per load step. A model is also coded in MATLAB® and simulated using the finite element method (FEM in ANSYS® Multiphysics. The FEM model of the ice and PVC sample is built using solid elements. The mesh is tested for sensitively. A good agreement is found between the theoretical, experimental and numerical simulation results.
Three-dimensional FEM model of FBGs in PANDA fibers with experimentally determined model parameters
Lindner, Markus; Hopf, Barbara; Koch, Alexander W.; Roths, Johannes
2017-04-01
A 3D-FEM model has been developed to improve the understanding of multi-parameter sensing with Bragg gratings in attached or embedded polarization maintaining fibers. The material properties of the fiber, especially Young's modulus and Poisson's ratio of the fiber's stress applying parts, are crucial for accurate simulations, but are usually not provided by the manufacturers. A methodology is presented to determine the unknown parameters by using experimental characterizations of the fiber and iterative FEM simulations. The resulting 3D-Model is capable of describing the change in birefringence of the free fiber when exposed to longitudinal strain. In future studies the 3D-FEM model will be employed to study the interaction of PANDA fibers with the surrounding materials in which they are embedded.
Magnetic equations with FreeFem++: The Grad-Shafranov equation & the current hole
Directory of Open Access Journals (Sweden)
Sadaka Georges
2011-11-01
Full Text Available FreeFem++ [11] is a software for the numerical solution of partial differential equations. It is based on finite element method. The FreeFem++ platform aims at facilitating teaching and basic research through prototyping. For the moment this platform is restricted to the numerical simulations of problems which admit a variational formulation. Our goal in this work is to evaluate the FreeFem++ tool on basic magnetic equations arising in Fusion Plasma in the context of the ITER project. First we consider the Grad-Shafranov equation, which is derived from the static ideal MHD equations assuming axisymetry. Some of the properties of the equation and its analytical solutions are discussed. Second we discretize a reduced resistive MHD model which admits solutions of the Grad-Shafranov equation as stationary solutions. Then the physical stability of these stationary solutions is investigated through numerical experiments and the numerical stability of the algorithm is discussed.
General framework for dynamic large deformation contact problems based on phantom-node X-FEM
Broumand, P.; Khoei, A. R.
2017-08-01
This paper presents a general framework for modeling dynamic large deformation contact-impact problems based on the phantom-node extended finite element method. The large sliding penalty contact formulation is presented based on a master-slave approach which is implemented within the phantom-node X-FEM and an explicit central difference scheme is used to model the inertial effects. The method is compared with conventional contact X-FEM; advantages, limitations and implementational aspects are also addressed. Several numerical examples are presented to show the robustness and accuracy of the proposed method.
FEM COUPLING FIELD ITERATION AND ITS CONVERGENCE FOR A GMM ACTURATOR
Institute of Scientific and Technical Information of China (English)
Cao Zhitong; Cai Jiongjiong; Chen Hongping; He Guoguang
2005-01-01
The coupling iteration (CI) of the finite element method(FEM) is used to simulate the magnetic and mechanical characteristics for a GMM actuator. The convergent ability under different prestress and different load types is investigated. Then the calculated deformations are compared with the experimental values. The results convince that the CI of FEM is suitable for the simulation of energy coupling and transformation mechanism of the GMM. At last, the output deformation properties are studied under different input currents, showing that there is a good compromise between good linearity and large strain under the prestress 6 MPa.
3D finite elements method (FEM Analysis of basic process parameters in rotary piercing mill
Directory of Open Access Journals (Sweden)
Z. Pater
2012-10-01
Full Text Available In this paper 3D FEM analysis of process parameters and its infl uence in rotary piercing mill is presented. The FEM analyze of the rotary piercing process was made under the conditions of 3D state of strain with taking into consideration the thermal phenomena. The calculations were made with application of different rolls’ skew angles and different plug designs. In the result, progression of shapes, temperature and distributions of stress and strain were characterized. The numerical results of calculations were compared with results of stand test with use of 100Cr6 steel. The comparisons of numerical and experimental tests confirm good agreement between obtained results.
Development of X-FEM methodology and study on mixed-mode crack propagation
Institute of Scientific and Technical Information of China (English)
Zhuo Zhuang; Bin-Bin Cheng
2011-01-01
The extended finite element method (X-FEM) is a novel numerical methodology with a great potential for using in multi-scale computation and multi-phase coupling problems.The algorithm is discussed and a program is developed based on X-FEM for simulating mixed-mode crack propagation.The maximum circumferential stress criterion and interaction integral are deduced.Some numerical results are compared with the experimental data to prove the capability and efficiency of the algorithm and the program.Numerical analyses of sub-interfacial crack growth in bi-materials give a clear description of the effect on fracture made by interface and loading condition.
Energy Technology Data Exchange (ETDEWEB)
Sugimoto, Y. [DIA Consultants Co. Ltd., Tokyo (Japan)
1998-02-01
A new method to calculate 2.5-D electric potentials around line electrodes in an inhomogeneous medium was developed. While certain conventional analyses of electric potentials due to line sources have assumed that current density is constant along the line source, this assumption is invalid for electrically inhomogeneous media. In the newly developed method, line electrodes are modeled approximately using line elements of 1-D FEM. Since line elements cannot be combined directly with a 2.5-D FEM model, equivalent scattered sources were introduced to evaluate the effect of the line elements on the 2.5-D potentials (equivalent scattered source method). The equivalent scattered sources represent current interchange between the line elements and the 2.5-D FEM elements. A simulation test was carried out and the following results were obtained. 1. In the uniform formation model, potentials calculated by the equivalent scattered source method agreed with the solutions obtained by analytical and charge simulation methods. 2. The results of the equivalent scattered source method indicate that current density increases slightly as depth increases and is concentrated at the tip of the electrode. This phenomenon was also observed in the results of the charge simulation method. Current concentration is considered an effect of the finite radius of the electrode. 3. In the horizontal multi-layered model, calculated current density along line electrodes is inversely proportional to the layer resistivity. 13 refs., 15 figs.
Energy Technology Data Exchange (ETDEWEB)
Kienberger, Thomas
2010-07-01
The present work deals with a process for the methanation of the synthesis-gas from allothermal fluidized bed gasification. In the proposed process, the tar and sulfur contaminated syngas is used in a fixed-bed methanation reactor without further gas treatment. Commercial nickel catalysts are applied, which offer the opportunity to bring the gas to stoichiometry, in order to remove sulfur compounds by adsorption and to reform the synthesis-gas tar-content directly in the methanation reactor. An increased catalyst consumption turns out to be disadvantageous for the process. For process development in the course of this work, a biomass-fueled allothermic fluidized bed gasifier (Q{sub BR}=5kW) as well as a polytropic temperature-controlled methanation-reactor was constructed, built up and put into operation. It is possible to operate the system fully remote-controlled, which enables long-term tests without staff on site. Within the step of modelling with the software package ASPEN Plus in advance of experiments, parametric studies of both, the gasifier as well as of the process of methanation, were performed. As a major result, it can be shown that due to the use of nickel as methanation-catalyst-material, the educt gas-conversion is independent of the synthesis-gas's H{sub 2}/CO-ratio. Gasification tests were made to investigate the allothermic fluidized bed gasifier, in order to find an optimum point of operation for the downstream methane-synthesis. In the found point of operation, due to a sufficient water-content in the synthesis gas, from the thermodynamic perspective, carbon deposits on the methanation-catalyst can be avoided. The synthesis gas has a gravimetric tar-load of 10,4 g/Nm{sup 3}, furthermore hydrogen sulfide (H{sub 2}S) with a concentration of around 8 ppm{sub v} was measured as the representative sulfur component. It this gas is led to the methanation-reactor, in contrast to attempts with a clean synthesis-gas, the equilibrium
Tong, Z.; Zhang, Y.; Zhang, Z.; Hua, H.
2007-01-01
A direct-BEM/Fem method was proposed to analyze the vibration and acoustic radiation characteristics of a submerged structure. Model parameters of the structure and the fluid-structure interaction due to surrounding water were analyzed by using FEM and direct BEM. Vibration velocity of the outer hull surface and underwater sound pressure were computed through modal superposition technique. The direct-BEM/FEM method was first validated by analyzing a submerged cylindrical shell, then was used to analyze the vibro-acoustic behavior of a submarine stern structure. The results have demonstrated the direct-BEM/FEM method is more effective than FEM in computing the underwater sound radiation of the stern structure.
Nonlinear observer design for a nonlinear string/cable FEM model using contraction theory
DEFF Research Database (Denmark)
Turkyilmaz, Yilmaz; Jouffroy, Jerome; Egeland, Olav
Contraction theory is a recently developed nonlinear analysis tool which may be useful for solving a variety of nonlinear control problems. In this paper, using Contraction theory, a nonlinear observer is designed for a general nonlinear cable/string FEM (Finite Element Method) model. The cable...
Comprehensive material characterization and method of its validation by means of FEM simulation
Gromala, P.; Duerr, J.; Dressler, M.; Jansen, K.M.B.; Hawryluk, M.; Vreugd, J. de
2011-01-01
Numerical simulation plays an important role in product design. Its accuracy relays on a detailed description of geometry, material models, load and boundary conditions. This paper focuses on a new approach of FEM material modeling of three commercially available molding compounds. Curing shrinkage,
FEM Simulation Of Stress-Strain Fields in the Blooms with Casting Defect During Soaking
Directory of Open Access Journals (Sweden)
Miroslav KVÍČALA
2013-06-01
Full Text Available Round continuously cast blooms heating strategy is crucial in prevention of internal cracks initiation and propagation. Especially vanadium microalloyed Cr-Mo based steels are very sensitive to internal crack occurrence. This paper deals with two heating strategies that were realized in soaking pit. Using FEM simulation it was proved that proper heating strategy is essential to reduce internal crack propagation.
ESTABLISHMENT OF 3D FEM MODEL OF MULTI-PASS SPINNING
Institute of Scientific and Technical Information of China (English)
ZHAN Mei; ZHOU Qiang; YANG He; ZHANG Jinhui
2007-01-01
In order to improve the computational accuracy and efficiency, it is necessary to establish a reasonable 3D FEM model for multi-pass spinning including not only spinning process but also springback and annealing processes. A numerical model for multi-pass spinning is established using the combination of explicit and implicit FEM, with the advantages of them in accuracy and efficiency. The procedures for model establishment are introduced in detail, and the model is validated. The application of the 3D FEM model to a two-pass spinning shows the following: The field variables such as the stress, strahl and wall thickness during the whole spinning process can be obtained, not only during spinning process but also during springback and annealing processes, and the trends of their distributions and variations are in good agreement with a practical multi-spinning process. Thus the 3D FEM model for multi-pass spinning may be a helpful tool for determination and optimization of process Parameters of multi-pass spinning process.
Nonlinear observer design for a nonlinear string/cable FEM model using contraction theory
DEFF Research Database (Denmark)
Turkyilmaz, Yilmaz; Jouffroy, Jerome; Egeland, Olav
Contraction theory is a recently developed nonlinear analysis tool which may be useful for solving a variety of nonlinear control problems. In this paper, using Contraction theory, a nonlinear observer is designed for a general nonlinear cable/string FEM (Finite Element Method) model. The cable...
Meso-scale coupling of FEM/DEM for fluid-particle interactions,
Srivastava, S.; Yazdchi, K.; Luding, S.
2014-01-01
A new method for two-way fluid–particle coupling on an unstructured mesoscopically coarse mesh is presented. In this approach, we combine a (higher order) finite-element method (FEM) on the moving mesh for the fluid with a soft sphere discrete-element method for the particles. The novel feature of t
Energy Technology Data Exchange (ETDEWEB)
Kim, Kang Soo; Lee, Ho Jin; Woo, Wan Chuck; Seong, Baek Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Byeon, Jin Gwi; Park, Kwang Soo; Jung, In Chul [Doosan Heavy Industries and Construction Co., Changwon (Korea, Republic of)
2010-10-15
Much research has been done to estimate the residual stress on a dissimilar metal weld. There are many methods to estimate the weld residual stress and FEM (Finite Element Method) is generally used due to the advantage of the parametric study. And the X-ray method and a Hole Drilling technique for an experimental method are also usually used. The aim of this paper is to develop the appropriate FEM model to estimate the residual stresses of the dissimilar overlay weld pipe. For this, firstly, the specimen of the dissimilar overlay weld pipe was manufactured. The SA 508 Gr3 nozzle, the SA 182 safe end and SA376 pipe were welded by the Alloy 182. And the overlay weld by the Alloy 52M was performed. The residual stress of this specimen was measured by using the Neutron Diffraction device in the HANARO (High-flux Advanced Neutron Application ReactOr) research reactor, KAERI (Korea Atomic Energy Research Institute). Secondly, FEM Model on the dissimilar overlay weld pipe was made and analyzed by the ABAQUS Code (ABAQUS, 2004). Thermal analysis and stress analysis were performed, and the residual stress was calculated. Thirdly, the results of the FEM analysis were compared with those of the experimental methods
Fem Dewey-begreber til analyse af Facilitated Work Based Learning
DEFF Research Database (Denmark)
Thomassen, Anja Overgaard
teoretiske ramme er helt overvejende baseret på John Deweys (1859-1952) pragmatisme og herudfra er der udviklet modeller, som anvendes i analysen af de empiriske data. Det fremlægges i paperet, hvorledes disse modeller er blevet udviklet og anvendt i ph.d.-afhandlingen, og hvorledes de centrale fem begreber...
Bending of I-beam with the transvers shear effect included – FEM calculated
Energy Technology Data Exchange (ETDEWEB)
Grygorowicz, Magdalena; Lewiński, Jerzy [Poznan University of Technology, Institute of Applied Mechanics ul. Jana Pawła II No. 24, 60-138 Poznań POLAND (Poland)
2016-06-08
The paper is devoted to three-point bending of an I-beam with include of transvers shear effect. Numerical calculations were conducted independently with the use of the SolidWorks system and the multi-purpose software package ANSYS The results of FEM study conducted with the use of two systems were compared and presented in tables and figures.
Bending of I-beam with the transvers shear effect included - FEM calculated
Grygorowicz, Magdalena; Lewiński, Jerzy
2016-06-01
The paper is devoted to three-point bending of an I-beam with include of transvers shear effect. Numerical calculations were conducted independently with the use of the SolidWorks system and the multi-purpose software package ANSYS The results of FEM study conducted with the use of two systems were compared and presented in tables and figures.
Investigate of Mechanical Fuse in Cardan Shaft Using FEM
Sayed Poorya Rabiei; Reza Azarafza
2014-01-01
A Cardan shaft is a mechanical component for transmitting torque and rotation, usually used to connect drive shaft to driven shaft that cannot be connected directly because of distance or the need to allow for relative movement between them. If overload is applied to cardan shaft, failure can occur in each part of the cardan shaft and maybe some irreparable damage occur to the cardan shaft. Thus it is important to investigate the existence of mechanical fuse in cardan shaft, and this subjcet ...
FEM simulation of non-isothermal viscoelastic fluids
Damanik, Hogenrich
2011-01-01
Thermo-mechanically coupled transport processes of viscoelastic fluids are important components in many applications in mechanical and chemical engineering. The aim of this thesis is the development of efficient numerical techniques for incompressible, non-isothermal, viscoelastic fluids which take into account the multiscale behaviour in space and time, the multiphase character and significant geometrical changes. Based on special CFD techniques including adaptivity/local grid alignment in s...
Prediction of the properties of PVD/CVD coatings with the use of FEM analysis
Śliwa, Agata; Mikuła, Jarosław; Gołombek, Klaudiusz; Tański, Tomasz; Kwaśny, Waldemar; Bonek, Mirosław; Brytan, Zbigniew
2016-12-01
The aim of this paper is to present the results of the prediction of the properties of PVD/CVD coatings with the use of finite element method (FEM) analysis. The possibility of employing the FEM in the evaluation of stress distribution in multilayer Ti/Ti(C,N)/CrN, Ti/Ti(C,N)/(Ti,Al)N, Ti/(Ti,Si)N/(Ti,Si)N, and Ti/DLC/DLC coatings by taking into account their deposition conditions on magnesium alloys has been discussed in the paper. The difference in internal stresses in the zone between the coating and the substrate is caused by, first of all, the difference between the mechanical and thermal properties of the substrate and the coating, and also by the structural changes that occur in these materials during the fabrication process, especially during the cooling process following PVD and CVD treatment. The experimental values of stresses were determined based on X-ray diffraction patterns that correspond to the modelled values, which in turn can be used to confirm the correctness of the accepted mathematical model for testing the problem. An FEM model was established for the purpose of building a computer simulation of the internal stresses in the coatings. The accuracy of the FEM model was verified by comparing the results of the computer simulation of the stresses with experimental results. A computer simulation of the stresses was carried out in the ANSYS environment using the FEM method. Structure observations, chemical composition measurements, and mechanical property characterisations of the investigated materials has been carried out to give a background for the discussion of the results that were recorded during the modelling process.
Direkter WLAN-Zugang in gesicherte Institutsnetze
Inhoff, Helmut; Fries, Willi; Mall, Klara; Neuffer, Benedikt; Dreher, Christian
2015-01-01
Der seit Beginn des Jahres eingeführte WLAN-Dienst „wifi2vlan“, der einen direkten Zugang in institutseigene Netze aus dem WLAN heraus ermöglicht, befindet sich nach erfolgreichem Pilotbetrieb inzwischen im regulären Betrieb. Bislang haben bereits 22 Institute diesen Zugang beantragt.
Research on rotary forming mechanism of cartridge bottom by FEM
Institute of Scientific and Technical Information of China (English)
刘钢; 姚雄亮; 黄少东; 唐全波
2003-01-01
The rotary forging of a cartridge bottom is simulated by finite element method with DEFORMTM. The analysis of stress and strain rate results indicates that the deformation conditions and the final geometry of a product are not completely axis-symmetrical under the partial loading conditions during the rotary forging operations. It is therefore required to have a few more rotary forging cycles at the end of total feeding to eliminate nonuniformity. The results of simulation show that the optimization of rotary forging process conditions can be achieved to avoid the underfill defect resulting from improper process conditions. This technology can be used to manufacture ring components with thin bottoms by properly controlling the working process and the tooling motion.
Impact comparative study of phone carcasses behavior by FEM
Constantin, Cărăuşu; Plăvănescu, Simona; Dumitru, Nedelcu
2015-07-01
A constant concern of scientific research is based on plastics replace with biodegradable materials that reduce the adverse impact of waste on the environment. A biodegradable material that arouses interest lately is Arboform which is made of lignin, a component of wood and woody plants. Replacing plastic with Arboform in carrying components of products requires technical and economic studies on the implications of such replacement. Numerical simulation methods are a fast and economical way of analyzing the behavior of a product in various mechanical, thermal, electromagnetic and so on. The paper presents comparative results of numerical simulation using the software package SolidWorks impact behavior through the “Drop Test” of half shells made of High Density Polyethylene (HDPE) and of the Arboform LV3 Nature. Simulation watched the half-carcass behavior in three cases of accidental impact, “head”, “corner” and the “back side”. We analyzed the size and location of the maximum voltage and maximum deformation resulting from impact. Simulations have shown for all three cases a maximum voltage increase when using Arboform to use PEDH 93% for impact “forward” and “corner” and only 48.77% “back side” impact. If the maximum displacement, it increasing from carcasses of Arboform 4% for impact “head” and 6% for impact “corner”, but fell by 2.7% for the “back side” impact. The significant increase of stress can be attributed to the higher density of Arboform to PEDH, which led to different weights of the two half-carcasses.
Electromagnetic Scattering from Randomly Rough Surfaces with Hybrid FEM/BIE
Institute of Scientific and Technical Information of China (English)
LI Jie; GUO Li-Xin; HE Qiong; WEI Bing
2011-01-01
The hybrid finite element method (FEM) together with the boundary integral equation (BIE) is firstly applied to scattering from a conducting rough surface.The BIE is used as the truncation boundary condition for the special unbounled half space,whereas the FEM is used to solve the governing equation in the region surrounded by a rough surface and artificial boundary.Tapered wave incidence is employed to cancel the so-called “edge effect”.A hybrid FEM/BIE form ulation for generalized one-dimensional conducting rough surface scattering is presented,as well as examples that evaluate its validity compared to the method of moments.The bistatic scattering coefficients of a Gaussian rough surface are calculated for transverse-magnetic wave incidence.Conclusions are reached after analyzing the scattering patterns of rough surfaces with different rms heights and correlation lengths Analysis of electromagnetic scattering from a rough surface[1-3] is a very important issue in various areas of electromagnetic wave theory.Methods used to study rough surface scattering can be categorized into two groups:(1) analytical and approximate methods[4,5] and (2) numerical methods.[6,7] including method of moment (MoM)[8-10] and the finite difference in time domain method (FDTD).%The hybrid finite element, method (FEM) together with the boundary integral equation (BIE) in firstly applied to scattering from a conducting rough surface. The BIE is used an the truncation boundary condition for the special unbounded half space, whereas the FEM is used to solve the governing equation in the region surrounded by a rough surface and artificial boundary. Tapered wave incidence is employed to cancel the so-called "edge effect". A hybrid FEM/BIE formulation for generalized one-dimensional conducting rough surface scattering is presented, as well as examples that evaluate its validity compared to the method of moments, The bistatic scattering coefficients of a Gaussian rough surface are
Bionic optimization research of soil cultivating component design
Institute of Scientific and Technical Information of China (English)
GUO ZhiJun; ZHOU ZhiLi; ZHANG Yi; LI ZhongLi
2009-01-01
The basic biomechanical laws that apply to the clawed toes of animals with powerful digging abilities and the optimal bionic design of curved soil cultivating components with an analogous contour were researched in a novel way. First, the curvature and profile of the inside contour line of a field mouse's clawed toe were analyzed. The finite element method (FEM) was then used to simulate the working process in order to study the changing characteristics of the working resistance of bionic soil-engaging surfaces and the stress field of the processed soil. A straight-line cultivating component was used for comparative analysis. In accordance with the simulation results, a series of soil cultivating components of varying design were manufactured. An indoor soil bin experiment was carried out to measure their working resistance and validate the results of the FEM analysis. The results of this research would have important values in the optimization design of cultivating components for energy and cost savings.
Directory of Open Access Journals (Sweden)
R.Citarella
2015-01-01
Full Text Available An edge crack propagation in a steel bar of circular cross-section undergoing multiaxial fatigue loads is simulated by Finite Element Method (FEM. The variation of crack growth behaviour is studied under axial and combined in phase axial+torsional fatigue loading. Results show that the cyclic Mode III loading superimposed on the cyclic Mode I leads to a fatigue life reduction. Numerical calculations are performed using the FEM software ZENCRACK to determine the crack path and fatigue life. The FEM numerical predictions have been compared against corresponding experimental and numerical data, available from literature, getting satisfactory consistency.
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Compared with the traditional rigid-plastic/rigid-viscoplastic(RP/RVP) FEM(based on iteration solution),RP/RVP FEM based on linear programming (LP) has some remarkable advantages,such as it's free of convergence problem and its convenience in contact,rigid zone,and friction force treatment.The numerical model of RP/RVP FEM based on LP for axisymmetrical metal forming simulation is studied,and some related key factors and its treatment methods in formulation of constraint condition are proposed.Some solution examples are provided to validate its accuracy and efficiency.
Parallel Finite Element Computations Based on MPI and FreeFem++%基于MPI+FreeFem++的有限元并行计算
Institute of Scientific and Technical Information of China (English)
尚月强
2012-01-01
有限元方法是一种灵活而高效的数值求解偏微分方程的计算方法,是工程分析和计算中不可缺少的重要工具之一.在计算机技术的快速发展使得并行机的价格日益下降的今天,并行有限元计算方法受到了学术界和工程界的普遍关注.讨论了基于MPI+ FreeFem++的有限元并行计算环境的构建,阐述了在该环境下有限元并行程序的编写、编译及运行等过程,并通过具体编程实例,说明了MPI+ FreeFem++环境下的有限元并行编程的简单和高效.
EXPERIMENTAL AND FEM STUDY OF WINDSHIELD SUBJECTED TO HIGH SPEED BIRD IMPACT
Institute of Scientific and Technical Information of China (English)
杨嘉陵; 蔡序杰; 武存浩
2003-01-01
Both experimental and finite element model (FEM) results are presented for the dynamic strength behavior of windshield subjected to bird impact. The experimental data taken from a series of high speed photographs are compared with the numerical results predicted by using FEM in which the windshield was modeled entirely with solid elements and the bird body was approximately simulated by an elastic-plastic material with failure element behavior. Effective plastic strain and element pressure were adopted as the failure criteria and once the pressure or the effective plastic strain of an element reached the critical value, the element would lose the tensile resistance capability completely. The deflection and stress distribution in the windshield were obtained. It is shown that the result from the finite element analysis agrees with those from the full-scale bird impact test.
Energy Technology Data Exchange (ETDEWEB)
Baniassadi, Majid; Mortazavi, Behzad; Hamedani, Amani; Garmestani, Hamid; Ahzi, Said; Fathi-Torbaghan, Madjid; Ruch, David; Khaleel, Mohammad A.
2012-01-31
In this study, a previously developed reconstruction methodology is extended to three-dimensional reconstruction of a three-phase microstructure, based on two-point correlation functions and two-point cluster functions. The reconstruction process has been implemented based on hybrid stochastic methodology for simulating the virtual microstructure. While different phases of the heterogeneous medium are represented by different cells, growth of these cells is controlled by optimizing parameters such as rotation, shrinkage, translation, distribution and growth rates of the cells. Based on the reconstructed microstructure, finite element method (FEM) was used to compute the effective elastic modulus and effective thermal conductivity. A statistical approach, based on two-point correlation functions, was also used to directly estimate the effective properties of the developed microstructures. Good agreement between the predicted results from FEM analysis and statistical methods was found confirming the efficiency of the statistical methods for prediction of thermo-mechanical properties of three-phase composites.
IBC/FEM Analysis of Electromagnetic Scatter of Cavities Coated with Layered Medium
Institute of Scientific and Technical Information of China (English)
HE Xiao-xiang; XU Jin-ping
2006-01-01
The Leontovich impedance boundary condition (IBC) is combined with the edge-based finite element method (FEM) in this paper to analyze the electromagnetic (EM) scattering of cavities coated with a multilayered dielectric.The IBC on the surface of the medium and the boundary integral equation on the aperture of the cavity are transformed into the third boundary condition,and then the functional of the boundary value problem is obtained.The surface impedance of the layered dielectric is calculated by the generalized reflection coefficient; hence,the multi-reflection of the EM wave in the dielectric is involved.As a result,the IBC is improved.Numerical results are presented,which demonstrate that the presented IBC/FEM approach is accurate and convenient for the analysis of EM scattering of open-ended cavities coated with the dielectric.
FEM × DEM: a new efficient multi-scale approach for geotechnical problems with strain localization
Directory of Open Access Journals (Sweden)
Nguyen Trung Kien
2017-01-01
Full Text Available The paper presents a multi-scale modeling of Boundary Value Problem (BVP approach involving cohesive-frictional granular materials in the FEM × DEM multi-scale framework. On the DEM side, a 3D model is defined based on the interactions of spherical particles. This DEM model is built through a numerical homogenization process applied to a Volume Element (VE. It is then paired with a Finite Element code. Using this numerical tool that combines two scales within the same framework, we conducted simulations of biaxial and pressuremeter tests on a cohesive-frictional granular medium. In these cases, it is known that strain localization does occur at the macroscopic level, but since FEMs suffer from severe mesh dependency as soon as shear band starts to develop, the second gradient regularization technique has been used. As a consequence, the objectivity of the computation with respect to mesh dependency is restored.
A hybrid FEM-DEM approach to the simulation of fluid flow laden with many particles
Casagrande, Marcus V. S.; Alves, José L. D.; Silva, Carlos E.; Alves, Fábio T.; Elias, Renato N.; Coutinho, Alvaro L. G. A.
2017-04-01
In this work we address a contribution to the study of particle laden fluid flows in scales smaller than TFM (two-fluid models). The hybrid model is based on a Lagrangian-Eulerian approach. A Lagrangian description is used for the particle system employing the discrete element method (DEM), while a fixed Eulerian mesh is used for the fluid phase modeled by the finite element method (FEM). The resulting coupled DEM-FEM model is integrated in time with a subcycling scheme. The aforementioned scheme is applied in the simulation of a seabed current to analyze which mechanisms lead to the emergence of bedload transport and sediment suspension, and also quantify the effective viscosity of the seabed in comparison with the ideal no-slip wall condition. A simulation of a salt plume falling in a fluid column is performed, comparing the main characteristics of the system with an experiment.
3-D FEM Analysis, Prototyping and Tests of an Axial Flux Permanent-Magnet Wind Generator
Directory of Open Access Journals (Sweden)
Joya C. Kappatou
2017-08-01
Full Text Available This paper contributes to the research and development of Axial Flux Permanent Magnet Synchronous Machines (AFPMSM; and in particular the design, the construction stages and measurements of a double rotor single internal non-ferromagnetic stator with a trapezoidal-concentrated winding machine for wind power generation applications. The initial dimensions of the machine were calculated using analytical formulas and a model was created and analyzed using the 3D Finite Element Method (FEM. The shape of the magnets of the machine was optimized and presented in a previous paper and a prototype was constructed and tested in the laboratory. In addition, a temperature test of the stator was performed experimentally. Finally, the effect of the different axial widths of the two air gaps on the electrical magnitudes and the field of the machine were investigated using both FEM analysis and experiments.
Combination Approach of FEM and Circuit System in IR Drop Analysis and Its Applications
Institute of Scientific and Technical Information of China (English)
TANG Zhanghong; YUAN Jiansheng
2008-01-01
A method was developed to solve the combined system of the current field and the circuit. The "super-node" was used to transform the matdx for conventional nodal analyses of a circuit system from non-positive definite to positive definite. Then, a positive definite matdx for the overall system was obtained by combining the matrix from the circuit nodal analysis method and the matrix resulted from finite element method (FEM) formulation to solve the FEM fields. This approach has been successfully applied to simulate the electrical potential and current distributions on each metal layer of printed circuit boards (PCBs) and in-tegrated circuit (IC) packages for a given power supply. The simulation results can then be used to analyze the properties of the PCBs and IC packages such as the port resistances and IR drops. The results can also be used to optimize PCB and IC package designs, such as by adjusting the power/ground distribution networks.
AN APPROACH TO EFFICIENT FEM SIMULATIONS ON GRAPHICS PROCESSING UNITS USING CUDA
Directory of Open Access Journals (Sweden)
Björn Nutti
2014-04-01
Full Text Available The paper presents a highly efficient way of simulating the dynamic behavior of deformable objects by means of the finite element method (FEM with computations performed on Graphics Processing Units (GPU. The presented implementation reduces bottlenecks related to memory accesses by grouping the necessary data per node pairs, in contrast to the classical way done per element. This strategy reduces the memory access patterns that are not suitable for the GPU memory architecture. Furthermore, the presented implementation takes advantage of the underlying sparse-block-matrix structure, and it has been demonstrated how to avoid potential bottlenecks in the algorithm. To achieve plausible deformational behavior for large local rotations, the objects are modeled by means of a simplified co-rotational FEM formulation.
Directory of Open Access Journals (Sweden)
O. Chivu
2016-04-01
Full Text Available This paper presents the results of the practical trials carried out based on the calculation assumptions considered within the FEM of the reconditioning by welding of a crankshaft used in the automotive industry. For the validation of the analytical model it was considered the influence of the crankshaft fixing possibility as well as the influence of preheating temperatures on the structure of the deposited zone.
Applications of FEM and BEM in two-dimensional fracture mechanics problems
Min, J. B.; Steeve, B. E.; Swanson, G. R.
1992-08-01
A comparison of the finite element method (FEM) and boundary element method (BEM) for the solution of two-dimensional plane strain problems in fracture mechanics is presented in this paper. Stress intensity factors (SIF's) were calculated using both methods for elastic plates with either a single-edge crack or an inclined-edge crack. In particular, two currently available programs, ANSYS for finite element analysis and BEASY for boundary element analysis, were used.
Stability Analysis of Embankments Founded on Clay : a comparison between LEM & 2D/3D FEM
2014-01-01
Rapid constructed embankments founded on soft deposits have a negative influence on the short term stability. Many engineering constructions such as road and railway embankments are often constructed on soft clay deposits. In stability analysis calculation of safety factor (SF), as the primary design criteria can be evaluated through different numerous methods such as limit equilibrium method (LEM) and finite element method (FEM). It is of particular interest to determine/estimate appropriate...
FEM investigation of leaky modes in hollow core photonic crystal fibers
Pomplun, J.; Holzlöhner, R.; Burger, S.; Zschiedrich, L.; Schmidt, F
2007-01-01
Hollow-core holey fibers are promising candidates for low-loss guidance of light in various applications, e.g., for the use in laser guide star adaptive optics systems in optical astronomy. We present an accurate and fast method for the computation of light modes in arbitrarily shaped waveguides. Maxwell's equations are discretized using vectorial finite elements (FEM). We discuss how we utilize concepts like adaptive grid refinement, higher-order finite elements, and transparent boundary con...
FEM ANALYSIS OF THERMAL STRESSES IN GRADIENT THERMAL BARRIER COATINGS PRODUCED BY EB-PVD
Institute of Scientific and Technical Information of China (English)
H.B. Guo; H.B. Xu; S.K. Gong
2001-01-01
Gradient thermal barrier coatings (GTBCs) produced by co-deposition of mixtures ofAl-Al2 O3-YSZ onto metallic bond coat exhibited longer lifetimes than the two-layeredTBCs. The finite element method (FEM) numerical models were used to investigatestress and strain states in the GTBCs and traditional two-layered TBCs as they cooledto 750℃ from a stress-free state at 850℃.
Optimization of Vibration Reduction Ability of Ladder Tracks by FEM Coupled with ACO
Directory of Open Access Journals (Sweden)
Hao Jin
2015-01-01
Full Text Available Ladder track, which has drawn increased attention in scientific communities, is an effective method for reducing vibrations from underground railways. In order to optimize the vibration reduction ability of ladder track, a new method, that is, the finite element method (FEM coupled with ant colony optimization (ACO, has been proposed in this paper. We describe how to build the FEM model verified by the vibration tests in the Track Vibration Abatement and Control Laboratory and how to couple the FEM with ACO. The density and elasticity modulus of the sleeper pad are optimized using this method. After optimization, the vibration acceleration level of the supporting platform in the 1–200 Hz range was reduced from 102.8 dB to 94.4 dB. The optimized density of the sleeper pad is 620 kg/m3, and the optimized elasticity modulus of the sleeper pad is 6.25 × 106 N/m2.
Liu, Ying; Song, Huadong; Zhu, Panpan; Lu, Hao; Tang, Qi
2017-08-01
The elasticity of erythrocytes is an important criterion to evaluate the quality of blood. This paper presents a novel research on erythrocytes' elasticity with the application of optical tweezers and the finite element method (FEM) during blood storage. In this work, the erythrocytes with different in vitro times were linearly stretched by trapping force using optical tweezers and the time dependent elasticity of erythrocytes was investigated. The experimental results indicate that the membrane shear moduli of erythrocytes increased with the increasing in vitro time, namely the elasticity was decreasing. Simultaneously, an erythrocyte shell model with two parameters (membrane thickness h and membrane shear modulus H) was built to simulate the linear stretching states of erythrocytes by the FEM, and the simulations conform to the results obtained in the experiment. The evolution process was found that the erythrocytes membrane thicknesses were decreasing. The analysis assumes that the partial proteins and lipid bilayer of erythrocyte membrane were decomposed during the in vitro preservation of blood, which results in thin thickness, weak bending resistance, and losing elasticity of erythrocyte membrane. This study implies that the FEM can be employed to investigate the inward mechanical property changes of erythrocyte in different environments, which also can be a guideline for studying the erythrocyte mechanical state suffered from different diseases.
Influence of stress releasing ratio and boundary scope on 2D FEM simulate
Institute of Scientific and Technical Information of China (English)
ZHANG Xiao-ming; LIU Xiang-feng; HE Feng
2008-01-01
Give constrains of costs and technology in analysis,actual practice of 2D FEM is widely popular and demanded.In order to take advantage of 2D FEM to simulate 3Dstress state,the concept of stress releasing ratio was generally introduced to represent the 3D constraint effect.For example,the simulation analysis of tunnel excavation is based on the measured actual deformation to provide stress releasing ratio.In the engineering of open excavation,the construction is,most of the case,targeted on alluvial deposit with relatively soft stratum.However,the 2D FEM simulation lacks a clear and rational basis in how to represent the effects of 3D constraint.Thus,in order to investigate the problem above,the author analyzed same engineering using both 2D and 3D individually,and compared the corresponding results.Based on the 3D analysis,factors including the relationship between the model's scope,stress releasing ratio,and construction condition of 2D analysis were also examined.
Directory of Open Access Journals (Sweden)
Ying Liu
2017-08-01
Full Text Available The elasticity of erythrocytes is an important criterion to evaluate the quality of blood. This paper presents a novel research on erythrocytes’ elasticity with the application of optical tweezers and the finite element method (FEM during blood storage. In this work, the erythrocytes with different in vitro times were linearly stretched by trapping force using optical tweezers and the time dependent elasticity of erythrocytes was investigated. The experimental results indicate that the membrane shear moduli of erythrocytes increased with the increasing in vitro time, namely the elasticity was decreasing. Simultaneously, an erythrocyte shell model with two parameters (membrane thickness h and membrane shear modulus H was built to simulate the linear stretching states of erythrocytes by the FEM, and the simulations conform to the results obtained in the experiment. The evolution process was found that the erythrocytes membrane thicknesses were decreasing. The analysis assumes that the partial proteins and lipid bilayer of erythrocyte membrane were decomposed during the in vitro preservation of blood, which results in thin thickness, weak bending resistance, and losing elasticity of erythrocyte membrane. This study implies that the FEM can be employed to investigate the inward mechanical property changes of erythrocyte in different environments, which also can be a guideline for studying the erythrocyte mechanical state suffered from different diseases.
A New Approach For FEM Simulation of NC Machining Processes
Wang, Sheng Ping; Padmanaban, Shivakumar
2004-06-01
The paper describes a new method for a finite element based pseudo-simulation of Numerically Controlled (NC) machining (material removal) processes. Industrial machining of a component usually results in warping or distortion due to the re-establishment of equilibrium in the retained part along with the relief of the insitu residual stresses in the removed part. In many cases, these distortions can be so large that the part may no longer be able to serve its designated functionality. Considering that the machining process is fundamentally a material removal process, a new method based on an automated removal of finite elements in the cutting area has been developed in the finite element analysis (FEA) software MSC.Marc to conduct pseudo-simulation of the NC machining process., A number of key software enhancements have been made to facilitate the pseudo-simulation of the NC machining process. First, a seamless interface has been developed to import APT/CL data generated by CAD/CAM systems. Then, the cutting paths have been generated based on information in the APT/CL files and used for the automatic detection of the intersection between the cutter and the finite element mesh. With each incremental motion of the cutter, the FEA solver detects all the elements that are located within the cutting path. Such elements are then deactivated in a step-by-step manner that is consistent with the actual machining process. In order to improve the fidelity of the cut area, local adaptive mesh refinement in the vicinity of the cutting tool is undertaken. This enables relatively coarser meshes away from the cut area and provides more accurate representation of the actual volume that is removed. As demonstrated by an industrial example, the enhanced software features in MSC.Marc have made it possible to practically and efficiently analyze complex machining processes of 3D production parts and provide an elegant tool for predicting distortions in large structures due to the relief
National Research Council Canada - National Science Library
NODA, Nao-Aki; KIM, Bongkee; OTA, Kento; KAWAHARA, Hirofumi; SHINOZAKI, Takahiro
2013-01-01
.... In this study, three-dimensional FEM analysis has been applied to the crimped portion of hydraulic brake hose in order to investigate the effects of manufacturing errors upon the sealing performance...
Institute of Scientific and Technical Information of China (English)
J. Chen; Y.X. Wang; W.P. Dong; X.Y. Ruan
2004-01-01
Based on the characteristics of 3D bulk forming process, the arbitrary Lagrangian-Eulerian (ALE)formulation-based FEM is studied, and a prediction-correction ALE-based FEM is proposed which integrates the advantages of precisely predicting the boundary configuration of the deformed material, and of efficiently avoiding hexahedron remeshing processes. The key idea of the prediction-correction ALE FEM is elaborated in detail. Accordingly, the strategy of mesh quality control, one of the key enabling techniques for the 3D bulk forming process numerical simulation by the prediction-correction ALE FEM is carefully investigated, and the algorithm for hexahedral element refinement is formulated based on the mesh distortion energy.
Fischer, Bennet; Hopf, Barbara; Lindner, Markus; Koch, Alexander W.; Roths, Johannes
2017-04-01
A 3D FEM model of an FBG in a PANDA fiber with an extended fiber length of 25.4 mm is presented. Simulating long fiber lengths with limited computer power is achieved by using an iterative solver and by optimizing the FEM mesh. For verification purposes, the model is adapted to a configuration with transversal loads on the fiber. The 3D FEM model results correspond with experimental data and with the results of an additional 2D FEM plain strain model. In further studies, this 3D model shall be applied to more sophisticated situations, for example to study the temperature dependence of surface-glued or embedded FBGs in PANDA fibers that are used for strain-temperature decoupling.
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Backward ball spinning was applied for manufacturing thin-walled tubular parts with longitudinal inner ribs. Rigid-plastic finite element method(FEM) was used for simulating the backward ball spinning process in order to calculate the height of the inner ribs. With a view to guarantee a better simulation accuracy, it is essential to enhance and improve some general problems of FEM,such as generation of initial velocity field, choice of penalty factor, determination of boundary conditions, treatment of rigid region and description of convergence criteria. It is evident that whether the problems with respect to FEM are dealt with appropriately or not, they have a significant influence on the modeling accuracy and efficiency. By reasonable solving the general problems,rigid-plastic FEM can successfully simulate the height of the inner ribs and the calculated values are in good agreement with the measured values.
Makhrojan, Agus; Suprihadi, Agus; Budi, Sigit Setijo; Jamari, J.; Ismail, Rifky
2017-01-01
The electric car is transportation which growing and constantly put through improvisation vehicle design. One of the structural components of the electric car which holds a major role is a frame. The purpose of this study is to get monocoque frame design which lightweight and powerful for a city car with two passengers that was able to improve the efficiency of the battery voltage source. Monocoque frame should be able to accept the normal loads such as the weight of batteries, passenger, and body. The most important thing, monocoque frame should also be able to protect the driver and passengers in the event of a collision. Mild steel was chosen for the design because it is easy to obtain and reasonable price as well as easy to shaped for two-seater electric car. FEM (finite element method) was used to determine stress determination and rigidity of the monocoque frame when receiving a static load. The results show that the monocoque frame was still able to withstand the required loads with minimal deflection.
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
A new rigid-plastic/rigid-viscoplastic (RP/RVP) FEM based on linear programming (LP) for plane-strain metal forming simulation is proposed. Compared with the traditional RP/RVP FEM based on iteration solution, it has some remarkable advantages, such as it's free of convergence problem and its convenience in contact, incompressibility constraint and rigid zone treatment. Two solution examples are provided to validate its accuracy and efficiency.
Del Coz Díaz, J. J.; Nieto, P.J.García; Hernández, J. Domínguez; Álvarez Rabanal, F.P.
2010-01-01
Abstract This paper presents a comparative nonlinear thermal analysis for a total of eighteen different in situ cast floors varying both the constituent materials of the hollow blocks (clay, concrete and lightweight concrete) and the shape and number of recesses (six different block types) using the finite element method (FEM). Based on the non-linear thermal analysis of the different configurations by FEM and considering both upward and downward heat flows, it is possible to choos...
Experimental study of a high-current FEM with a broadband microwave system
Energy Technology Data Exchange (ETDEWEB)
Denisov, G.G.; Bratman, V.L.; Ginzburg, N.S. [Institute of Applied Physics, Nizhny Novgorod (Russian Federation)] [and others
1995-12-31
One of the main features of FELs and FEMs is the possibility of fast and wideband tuning of the resonant frequency of active media, which can be provided by changing the particle energy. For a frequency adjustable FEM-oscillator, a broadband microwave system, which is simply combined with an electron-optical FEM system and consists of an oversized waveguide and reflectors based on the microwave beams multiplication effect has been proposed and studied successfully in {open_quotes}cold{close_quotes} measurements. Here, the operating ability of a cavity, that includes some key elements of the broadband microwave system, was tested in the presence of an electron beam. To provide large particle oscillation velocities in a moderate undulator field and the presence of a guide magnetic field, the FEM operating regime of double resonance was chosen. In this regime the cyclotron as well as undulator resonance conditions were satisfied. The FEM-oscillator was investigated experimentally on a high-current accelerator {open_quotes}Sinus-6{close_quotes} that forms an electron beam with particle energy 500keV and pulse duration 25ns. The aperture with a diameter 2.5mm at the center of the anode allows to pass through only the central fraction of the electron beam with a current about 100A and a small spread of longitudinal velocities of the particles. Operating transverse velocity was pumped into the electron beam in the pulse plane undulator of a 2.4cm period. The cavity with a frequency near 45GHz consists of a square waveguide and two reflectors. The broadband up-stream reflector based on the multiplication effect had the power reflectivity coefficient more than 90% in the frequency band 10% for the H{sup 10} wave of the square waveguide with the maximum about 100% at a frequency 45GHz. The down-stream narrow-band Bragg reflector had the power reflection coefficient approximately 80% in the frequency band of 4% near 45GHz for the operating mode.
Directory of Open Access Journals (Sweden)
Ragnhild Engelskjøn
1997-10-01
Full Text Available Magnhild Bruheim: Varlset; Liv Marit Idsø og Anne Marie Seem: Midt i jakta og Liv H Willumsen: Havmannens datter. Regine Normann - et livsløp, anmeldt av Ragnhild Engelskjøn Tore Hoel: Trygve Gulbranssen og kritikken, anmeldt av Henning Howlid Wærp Harald Bache-Wiig: Nye veier til barneboka, anmeldt av Astrid Utnes Olav Solberg: Tekst møter tekst. Kristin Lavransdatter og mellomalderen, anmeldt av Elin Stokke
A coupling of FEM-BEM for a kind of Signorini contact problem
Institute of Scientific and Technical Information of China (English)
HU; Qiya
2001-01-01
［1］Carstensen,C.,Gwinner,J.,FEM and BEM coupling for a nonlinear transmission problem with Signorini contact,SIAM J.Numer.Anal.,1997,34(6):1845-1864.［2］Costabel,M.,Stephan,E.,Coupling of finite and boundary element methods for an elastoplastic interface problem,SIAM J.Numer.Anal.,1990,27(4):1212-1226.［3］Kikuchi,N.,Oden,J.,Contact problem in elasticity:a study of variational inequalities and finite element methods,Philadelphia,SIAM,1988.［4］Necas,J.,Introduction to the Theory of Nonlinear Elliptic Equations,Text 52,Leipzig:Teubner,1983.［5］Carstensen,C.,Interface problem in holonomic elastoplasticity,Math.Methods Appl.Sci.,1993,16(11):819-835.［6］Gatica,G.,Hsiao,G.,On the coupled BEM and FEM or a nonlinear exterior Dirichlet problem in R2,Numer.Math.,1992,61(2):171-214.［7］Mund,P.,Stephan,E.,An adaptive two-level method for the coupling of nonlinear FEM-BEM equations,SIAM J.Numer.Anal.,1999,36(3):1001-1021.［8］Meddahi,S.,An optimal iterative process for the Johnson-Nedelec method of coupling boundary and finite elements,SIAM J.Numer.Anal.,1998,35(4):1393-1415.［9］Yu,D.,The Mathematical Theory of the Natural Boundary Element Methods (in Chinese),Beijing:Science Press,1993.［10］Lions,J.,Magenes,E.,Non-homogeneous Boundary Value Problems and Applications,Vol.I,Berlin-Heidelberg-New York:Springer-Verlag,1972.［11］Zenisek,A.,Nonlinear Elliptic and Evolution Problems and Their Finite Element Approximations,London:Academic Press,1990.［12］Costabel,M.,Boundary integral operators on Lipschitz domains:Elementary results,SIAM J.Numer.Math.Anal.,1988,19(2):613-626.
On the Use of FEM for Pyro-Shock Propagation in Space Structures
Barboni, R.; Galluccio, G.; Collini, L.; de Benedetti, M.
2002-01-01
Within the context of Large Flexible Space Structures (LFSS), a Finite Elements Method has been applied to reproduce the effects of the accelerations induced by the ignition of a pyro-device on the structure of a satellite. Aim of this paper is to describe the starting hypotheses, the calculation procedure and the results of the structural mechanical shock analyses that have been performed on the numerical model of the RADARSAT2 ATD (Antenna Tie Down) assembly. The dynamic non- linear structural behaviour under the shock solicitation environment of the assembly has been investigated. The high- frequency structural analyses have been conducted basing on two domains: the time domain and the frequency domain, leading to the comprehension of the structure dynamic behaviour under the shock vibration environment. The analyses have been performed basing on a dedicated FEM model, where the number of degrees of freedom has been balanced between the computing effort and the requested accuracy on the results. As a first step, the model has been prepared and tested. Successively, the model has been correlated, in order to provide as an output the same main static and dynamic results as the 3D FEM model that has been used for the static analyses. After this process, the FEM model for shock analysis purpose (also indicated in the rest of the following document as "shock model") has been analysed with a specific non-linear transient-time solution, in order to obtain the time-history of the accelerations detected in several output points. The analysis has been conducted over the time interval included between 0 and 25 msec, and in the frequency band between 0 and approximately 10 kHz. As a conclusion, a transformation from the time domain to the frequency domain allows the presentation of the results in the acceleration-Vs.-frequency form, either with diagrams or in table exposition.
Conservative restoration of severely damaged endodontically treated premolar teeth: a FEM study.
Eraslan, Öznur; Eraslan, Oğuz; Eskitaşcıoğlu, Gürcan; Belli, Sema
2011-06-01
The aim of this finite element method (FEM) study was to test two different restorative techniques used for construction of severely damaged endodontically treated premolar teeth using Finite Element Stress Analysis Method. In this study, four types of three-dimensional (3-D) FEM mathematical models simulating (1) a sound lower single rooted premolar tooth with supporting structures; (2) a root-filled lower premolar tooth without lingual cusp, restored with resin composite; (3) a root-filled lower premolar tooth without lingual cusp restored with resin composite in combination with a polyethylene fiber which is placed circumferentially to help to create a composite lingual wall; (4) a root-filled lower premolar tooth without lingual cusp restored with resin composite in combination with a glass fiber post, were modeled. A 300-N static vertical occlusal load was applied on the node at the center of occlusal surface of the tooth to calculate stress distributions. Solidworks/Cosmosworks structural analysis programs were used for FEM analysis. The analysis of the von Mises stress values revealed that maximum stress concentrations were located at loading areas for all models. Root dentine tissue, lingual cortical bone, and apical bone structures were other stress concentration regions. There were stress concentration differences among the models at root dentine tissue. Although the distribution pattern was similar with composite resin restored tooth model, highest stress values were observed at root dentine in the model restored with post-and-core. Post structure accumulated more stress on its own body. Stress distribution patterns of sound tooth and fiber-reinforced restoration models were found as similar. The present study showed that the use of post material increased the stress values at root dentine structure while reinforcing the restoration with a fiber decreases stress transmission. Fiber-reinforced restoration provided stress distributions similar to sound
Mixed FEM for Second Order Elliptic Problems on Polygonal Meshes with BEM-Based Spaces
Efendiev, Yalchin
2014-01-01
We present a Boundary Element Method (BEM)-based FEM for mixed formulations of second order elliptic problems in two dimensions. The challenge, we would like to address, is a proper construction of H(div)-conforming vector valued trial functions on arbitrary polygonal partitions of the domain. The proposed construction generates trial functions on polygonal elements which inherit some of the properties of the unknown solution. In the numerical realization, the relevant local problems are treated by means of boundary integral formulations. We test the accuracy of the method on two model problems. © 2014 Springer-Verlag.
Motion Sensorless Control of BLDC PM Motor with Offline FEM Info Assisted State Observer
DEFF Research Database (Denmark)
Stirban, Alin; Boldea, Ion; Andreescu, Gheorghe-Daniel;
2010-01-01
This paper describes a new offline FEM assisted position and speed observer, for brushless dc (BLDC) PM motor drive sensorless control, based on the line-to-line PM flux linkage estimation. The zero-crossing of the line-to-line PM flux linkage occurs right in the middle of two commutation points...... on the fundamental model of the machine, a safe starting strategy under heavy load torque, called I-f control, is used, with seamless transition to the proposed sensorless control. The I-f starting method allows lowspeed sensorless control, without knowing the initial position, and without machine parameters...
Analysis of structural response under blast loads using the coupled SPH-FEM approach
Institute of Scientific and Technical Information of China (English)
Jun-xiang XU; Xi-la LIU
2008-01-01
A numerical model using the coupled smoothed particle hydrodynamics-finite element method(SPH-FEM)approach is presented for analysis of structures under blast loads.The analyses on two numerical cases,one for free field explosive and the other for structural response under blast loads,are performed to model the whole processes from the propagation of the pressure wave to the response of structures.Based on the simulation,it is concluded that this model can be used for reasonably accurte explosive analysis of structures.The resulting information would be valuable for protecting structures under blast loads.
Application of FEM to Hot Continuous Rolling Process for Inconel 718 Alloy Round Rod
Institute of Scientific and Technical Information of China (English)
SUI Feng-li; CHEN Li-qing; LIU Xiang-hua; XU Li-xia
2009-01-01
A finite element model for coupled thermo-mechanical analysis has been developed in hot continuous rolling process for Inconel 718 alloy round rod with diameter of 45 ram. The stability of this alloy is discussed by integration of FEM and processing map reported in literatures. The result shows that the stability of Inconel 718 alloy is analyzed effectively during that process and good stability appears as the initial temperature is 960 ℃ and the initial velocity is from 0. 15 to 0. 45 m · s-1 or the initial temperature is 980 "C and the initial velocity is from 0. 15 to 0. 25 m · s-1.
Analysis of rolls deflection of Sendzimir mill by 3D FEM
Institute of Scientific and Technical Information of China (English)
YU Hai-liang; LIU Xiang-hua; LEE Gyoo Taek
2007-01-01
The deflection of rolls of Sendzimir mill with double AS-U-Roll was simulated by finite element method(FEM). The influences of rolling pressure, strip width and rolls-assignment on rolls deflection were analyzed. The results show that the work roll deflection increases with the increase of rolling pressure and the reduction of work roll radius, but the rigid displacement of work roll slightly changes; the work roll end might appear negative displacement for the narrow strip width and high rolling pressure that might cause the contact of work rolls. The research results are significant for guiding production and theoretical analysis of the rolls system of Sendzimir mill.
Environmental equipment for usages of FEM software. ADVENTURE system user's guide
Energy Technology Data Exchange (ETDEWEB)
Yamasaki, Ichirou [Japan Atomic Energy Research Inst., Center for Promotion of Computional Science and Engineering, Kizu, Kyoto (Japan); Yoshimura, Shinobu [Tokyo Univ., Tokyo (Japan)
2003-05-01
The community softwares, databases, and other various tools have been installed in the ITBL environment by the Office of ITBL Promotion as a common utility property for each research field. Among those softwares, Finite Element Method (FEM) code, Adventure (which was originally developed by Prof. Yoshimura, the University of Tokyo), is provided as one of structure analysis programs for ITBL users. The code is well known to possess a high performance ability for parallel processing, especially for massively parallel environments. In this report, a chain of processes for usages of the system as well as the installation method to PC cluster are described. (author)
A Numerical Method for Rigid-plastic FEM Analysis Basing on Mathematical Programming
Institute of Scientific and Technical Information of China (English)
Li Di; Lin Zhongqin; Chen Guanlong; Zhang Weigang; Li Shuhui
2004-01-01
The rigid-plastic analysis of mental forming simulation is formulated as a discrete nonlinear mathematical programming problem with equality and inequality constraints by means of the finite element technique. An iteration algorithm is used to solve this formulation, which distinguishes the integration points of the rigid zones and the plastic zones and solves a series of the quadratic programming to overcome the difficulties caused by the nonsmoothness and the nonlinearity of the objective function. This method has been used to carry out the rigid-plastic FEM analysis. An example is given to demonstrate the effectiveness of this method.
Tong-chun LI; Li, Dan-Dan; Wang, Zhi-Qiang
2010-01-01
In the paper, the limit state equation of tensile reliability of foundation base of gravity dam is established. The possible crack length is set as action effect and the allowance crack length is set as resistance in this limit state. The nonlinear FEM is applied to obtain the crack length of foundation base of gravity dam, and linear response surface method based on the orthogonal test design method is used to calculate the reliability,which offered an reasonable and simple analysis method t...
A coupling of FEM-BEM for a kind of Signorini contact problem
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
In this paper,we consider a kind of coupled nonlinear problem with Signorini contact conditions.To solve this problem,we discuss a new coupling of finite element and boundary element by adding an auxiliary circle.We first derive an asymptotic error estimate of the approximation to the coupled FEM-BEM variational inequality.Then we design an iterative method for solving the coupled system,in which only three standard subproblems without involving any boundary integral equation are solved.It will be shown that the convergence speed of this iteration method is independent of the mesh size.
FEM Analysis of Rolling Pressure Along Strip Width in Cold Rolling Process
Institute of Scientific and Technical Information of China (English)
LIU Xiang-hua; SHI Xu; LI Shan-qing; XU Jian-yong; WANG Guo-dong
2007-01-01
Using 3-D elastic-plastic FEM, the cold strip rolling process in a 4-high mill was simulated. The elastic deformation of rolls, the plastic deformation of the strip, and the pressure between the work roll and the backup roll were taken into account. The distribution of rolling pressure along the strip width was obtained. Based on the simulation results, the peak value of rolling pressure and the location of the peak were analyzed under different rolling conditions. The effects of the roll bending force and the strip width on the distribution of rolling pressure along the width direction were determined.
Noise Analysis of an Lightweight Auto-body Using FEM/BEM
Institute of Scientific and Technical Information of China (English)
LI Zai-wei; ZHU Ping; LIANG Xin-hua
2007-01-01
Since numeric simulation can save much costs, it is widely used in automobile design. Besides, noise, vibration and harshness(NVH) performance is one major target for enginer to design a competitive product. In this paper, NVH performance of a lightweight auto-body prototype using alternative materials and gauge thickness were studied by finite element method (FEM) and boundary element method (BEM). In order to find the most contributing panel to the peak value of response, the panel acoustic contribution analysis (PACA) was performed and the most effective modification area was located. Finally, the sound pressure was reduced by putting damping material on these parts.
Mechanical evaluation and fem analysis of stress in fixed partial dentures zirconium-ceramic.
Cardelli, P L; Vertucci, V; Balestra, F; Montani, M; Arcuri, C
2013-03-01
Over the last several years, the Finite Element Analysis (FEM) has been widely recognized as a reference method in different fields of study, to simulate the distribution of mechanical stress, in order to evaluate the relative distribution of loads of different nature. The aim of this study is to investigate through the FEM analysis the stress distribution in fixed prostheses that have a core in Zirconia and a ceramic veneer supported by implants. In this work we investigated the mechanical flexural strength of a ceramic material (Noritake(®)) and a of zirconium framework (Zircodent(®)) and the effects of the manufacturing processes of the material commonly performed during the production of fixed prostheses with CAD/CAM technology. Specifically three point bending mechanical tests were performed (three-point-bending) (1-3), using a machine from Test Equipment Instron 5566(®), on two structures in zirconium framework-ceramic (structures supported by two implant abutments with pontic elements 1 and 2). A further in-depth analysis on the mechanical behavior in flexure of the specimens was conducted carrying out FEM studies in order to compare analog and digital data. The analysis of the data obtained showed that the stresses are distributed in a different way according to the intrinsic elasticity of the structure. The analysis of FPD with four elements, the stresses are mainly concentrated on the surface of the load, while, in the FPD of three elements, much more rigid, the stresses are concentrated near the inner margins of the abutments. The concentration of many stresses in this point could be correlated to chipping (4) that is found in the outer edges of the structure, as a direct result of the ceramic brittleness which opposes the resilience of the structure subjected to bending. The analysis of the UY linear displacement confirms previous data, showing, in a numerical way, that the presence of the ceramic is related to the lowering of the structure. So, the
Institute of Scientific and Technical Information of China (English)
Xiangfei Chen; Yan Lu; Chunhong Wang; Zhenping Huang
2015-01-01
The femtosecond laser has a number of advantages,.such as short pulse time,.high instantaneous power,.high repetition rate, low monopulse energy, and small thermal effect. Fem-tosecond laser-assisted small incision lenticule extraction (SMILE) is becoming the new direction in refractive surgery, and the ocular surface changes after SMILE are attracting in-creasingly more attention. This article reviews adverse effects, including dry eye, injury of corneal nerves, and ocular sur-face inflammation,.occurring after SMILE.
FEM simulation of formation of metamorphic core complex with ANSYS software
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
This study utilizes ANSYS to establish FEM's model of metamorphic core complex,and used thermal-structure analysis to simulate metamorphic core complex's temperature field and stress field.The metamorphic core complex formation mechanism is discussed.The simulation results show that the temperature field change appearing as the earth surface's temperature is the lowest,and the temperature of metamorphic core complex's nucleus is the highest.The temperature field is higher along with depth increase,and the stress field change appearing as the biggest stress occurs in the nucleus.The next stress field occurs at the top of the cover.
Institute of Scientific and Technical Information of China (English)
Qin Weiping; Fang Dagang
2001-01-01
The anisotropic Perfectly Matched Layer(PML) absorbing boundary condition is implemented in a 2-D finite element formulation to solve dielectric waveguide discontinuity problems. The choice of parameters of anisotropic PML has been investigated. Using the boundary truncating technique, the solution process of Finite-Element Method (FEM) has been greatly simplified compared with other hybrid methods. The required computational resources have also significantly declined since the anisotropic PML interface can be placed much closer to the scatterer compared to other well known artificial boundary.
DOMAIN DECOMPOSITION WITH NON-MATCHING GRIDS FOR COUPLING OF FEM AND NATURAL BEM
Institute of Scientific and Technical Information of China (English)
YANG Jue; HU Qiya; YU Dehao
2005-01-01
In this paper, we introduce a domain decomposition method with non-matching grids for solving Dirichlet exterior boundary problems by coupling of finite element method(FEM) and natural boundary element method(BEM). We first derive the optimal energy error estimate of the nonconforming approximation generated by this method. Then we apply a Dirichlet-Neumann(D-N) alternating algorithm to solve the coupled discrete system. It will be shown that such iterative method possesses the optimal convergence. The numerical experiments testify our theoretical results.
Energy Technology Data Exchange (ETDEWEB)
Park, Byoung Yoon; Leavy, Richard Brian [U.S. Army Research Laboratory, Aberdeen Proving Grounds, MD; Niederhaus, John Henry J.
2013-03-01
The finite-element shock hydrodynamics code ALEGRA has recently been upgraded to include an X-FEM implementation in 2D for simulating impact, sliding, and release between materials in the Eulerian frame. For validation testing purposes, the problem of long-rod penetration in semi-infinite targets is considered in this report, at velocities of 500 to 3000 m/s. We describe testing simulations done using ALEGRA with and without the X-FEM capability, in order to verify its adequacy by showing X-FEM recovers the good results found with the standard ALEGRA formulation. The X-FEM results for depth of penetration differ from previously measured experimental data by less than 2%, and from the standard formulation results by less than 1%. They converge monotonically under mesh refinement at first order. Sensitivities to domain size and rear boundary condition are investigated and shown to be small. Aside from some simulation stability issues, X-FEM is found to produce good results for this classical impact and penetration problem.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Dongping
2009-10-26
Lateral forced cooling can significantly increase the temporary overload capacity of a cable system, but the design of such systems requires a time-dependent 3D analysis of the nonlinear thermal behavior as the cooling water along the cable is heated up, resulting in position-dependent and time-dependent heat uptake. For this, a new calculation method was developed on the basis of an available 3D FEM software. The new method enables 3D simulation of force-cooled cables in consideration of the potential partial dryout of soil and of thermal stabilizations. The new method was first applied to a 110 kV wind power transmission cable for different configurations and grid conditions. It was found that with lateral forced cooling, the 110 kV will have a temporal 50 percent overload capacity. Further, the thermal characteristics and limiting capacity of a force-cooled 380 kV cable system were investigated. According to the results so far, laterally cooled cable systems open up new operating options, with advantages in terms of availability, economic efficiency, and flexibility. (orig.) [German] Eine laterale Zwangskuehlung kann die temporaere Ueberlastbarkeit einer Kabelanlage signifikant erhoehen. Der Entwurf solcher zwangsgekuehlter Kabelanlagen erfordert jedoch eine zeitabhaengige, dreidimensionale Analyse des nichtlinearen thermischen Verhaltens, da sich das Kuehlwasser entlang der Trasse erwaermt und sich so eine orts- und zeitabhaengige Waermeaufnahme ergibt. Zu diesem Zweck wurde auf der Basis eines vorhandenen zweidimensionalen FEM-Programms ein neues Berechnungsverfahren entwickelt, das die dreidimensionale Simulation zwangsgekuehlter Kabelanlagen unter Beruecksichtigung einer moeglicherweise auftretenden partiellen Bodenaustrocknung und von thermischen Stabilisierungen erlaubt. Mit Hilfe dieses Berechnungsverfahrens wurde zuerst eine 110-kV-Kabelanlage zur Windenergieuebertragung bei unterschiedlichen Anordnungen und unterschiedlichen Netzsituationen untersucht
Wang, Shenglong; Yu, Xiaoyi; Yang, Bin; Zhang, Mingxian; Wu, Huanchun
2016-10-01
AP1000 primary coolant pipes must be manufactured by integral forging technology according to the designer—Westinghouse Electric Co. The characteristics of these large, special-shaped pipes create nonuniform temperatures, effective stress, and effective strain during shaping of the pipes. This paper presents a three-dimensional finite element simulation (3D FEM) of the integral forging process, and qualitatively evaluates the likelihood of forging defects. By analyzing the evolution histories of the three field variables, we concluded that the initial forging temperature should be strictly controlled within the interval 1123 K to 1423 K (850 °C to 1150 °C) to avoid second-phase precipitation. In the hard deformation zones, small strains do not contribute to recrystallization resulting in coarse grains. Conversely, in the free deformation zone, the large strains can contribute to the dynamic recrystallization, favoring grain refinement and closure of voids. Cracks are likely to appear, however, on the workpiece surface when forging leads to large deformations. Based on the simulation results, an eligible workpiece with good mechanical properties, few macroscopic defects, and favorable grain size has been successfully forged by experiments at an industrial scale, which validates the FEM simulation.
A coupled BEM-FEM method for finite strain magneto-elastic boundary-value problems
Nedjar, B.
2016-12-01
The first objective of this contribution is the formulation of nonlinear problems in magneto-elasticity involving finite geometry of the surrounding free space. More specifically for the magnetic part of the problem, the surrounding free space is described by means of a boundary integral equation for which boundary elements are used that are appropriately coupled with the finite element discretization used inside the material. The second objective is to develop a numerical strategy to solve the strongly coupled magneto-mechanics problem at hand. Herein we provide a staggered scheme consisting of a magnetostatic resolution employing the above coupled BEM-FEM procedure at fixed deformation, followed by a mechanical resolution at fixed magnetic fields. This decoupled method renders the whole solution strategy very appealing since, among others, the first BEM-FEM resolution is linear for some prototype models, and the remaining mechanical resolution is analogous to nowadays classical nonlinear elastostatic problems in the finite strain range. Some nonlinear boundary-value problems are simulated to demonstrate the applicability of the proposed framework.
Non-linear analysis and calculation of the performance of a shelving protection system by FEM
García Nieto, P. J.; del Coz Díaz, J. J.; Vilán Vilán, J. A.; Suárez Sierra, J. L.
2012-12-01
The aim of this paper consists on the study, analysis and calculation of the efficiency of a shelving protection system by means of the finite element method (FEM). These shelving protection systems are intended to prevent the eventual damage due to the impacts of transport elements in motion, such as: forklifts, dumpers, hand pallet trucks, and so on. The impact loads may threaten the structural integrity of the shelving system. The present structural problem is highly non-linear, due to the simultaneous presence of the following nonlinearities: material non-linearity (plasticity in this case), geometrical non-linearity (large displacements) and contact-type boundary conditions (between the rigid body and the protection system). A total of forty eight different FEM models are built varying the thickness of the steel plate (4, 5 and 6 mm), the impact height (0.1, 0.2, 0.3 and 0.4 meters) and the impact direction (head-on collision and side impact). Once the models are solved, the stress distribution, the overall displacements and the absorbed impact energy were calculated. In order to determine the best shelving protection's candidate, some constraints must be taken into account: the maximum allowable stress (235 MPa), the maximum displacement (0.05 m) and the absorbed impact energy (400 J according to the European Standard Rule PREN-15512). Finally, the most important results are shown and conclusions of this study are exposed.
Classical FEM-BEM coupling methods: nonlinearities, well-posedness, and adaptivity
Aurada, Markus; Feischl, Michael; Führer, Thomas; Karkulik, Michael; Melenk, Jens Markus; Praetorius, Dirk
2013-04-01
We consider a (possibly) nonlinear interface problem in 2D and 3D, which is solved by use of various adaptive FEM-BEM coupling strategies, namely the Johnson-Nédélec coupling, the Bielak-MacCamy coupling, and Costabel's symmetric coupling. We provide a framework to prove that the continuous as well as the discrete Galerkin solutions of these coupling methods additionally solve an appropriate operator equation with a Lipschitz continuous and strongly monotone operator. Therefore, the original coupling formulations are well-defined, and the Galerkin solutions are quasi-optimal in the sense of a Céa-type lemma. For the respective Galerkin discretizations with lowest-order polynomials, we provide reliable residual-based error estimators. Together with an estimator reduction property, we prove convergence of the adaptive FEM-BEM coupling methods. A key point for the proof of the estimator reduction are novel inverse-type estimates for the involved boundary integral operators which are advertized. Numerical experiments conclude the work and compare performance and effectivity of the three adaptive coupling procedures in the presence of generic singularities.
FEM model of flat-to-shear transition in a pipeline steel DWTT specimen
Energy Technology Data Exchange (ETDEWEB)
Roy, G.; Xu, S.; Tyson, W.R. [Natural Resources Canada, Ottawa, ON (Canada). CANMET Materials Technology Lab
2009-07-01
This paper described a finite element method (FEM) model of a drop-weight tear test (DWTT) sample of a grade X52 steel pipeline. A quarter of the total geometry was simulated in order to characterize its 2-fold symmetry. Proper boundary conditions were set at all surfaces and lines. The Gurson-Tvergaard-Needleman (GTN) constitutive potential was used to define the initiation of voids as well as their growth and coalescence. A void volume fraction was used to determine the location of flat tunnelling and loss of stress triaxiality. The location of the transition from a flat to a slanted fracture surface was also identified. The study showed that triaxiality and tension both drove the straight notch root into a curvilinear tunnel which then narrowed down to a small point. The crack then advanced along a slanted surface inclined at a 45 degree angle. The model showed good agreement with results obtained from a scanning electron microscopy (SEM) fractographic analysis of a specimen. It was concluded that the FEM model accurately simulated the development of triaxiality and shear lips in the steel specimen. 6 refs., 6 figs.
Directory of Open Access Journals (Sweden)
Dheeraj Gunwant
2016-02-01
Full Text Available Stress concentration is the localization of stress around stress raisers. Sudden changes in the geometry of structures give rise to stress values that are higher than those obtained by elementary equations of solid mechanics. Therefore the evaluation of stress state at such locations needs specialized techniques such as Finite Element Method (FEM.The finite element method is a numerical procedure that can be used to obtain solution to a large variety of engineering problems such as structural, thermal, heat transfer, electromagnetism and fluid flow. In the present investigation, focus has been kept on the finite element modeling and determination of stress concentration factor (SCF in linearly elastic structures with different stress-raisers such as circular and elliptical holes and double semicircular notch at different locations in a finite plate. The results obtained from FEM are compared with those obtained by analytical relations as given in literature. A commercially available finite element solver ANSYS has been used for the modeling and analysis in the investigation. Throughout the investigation, plane82, which is an eight node two-dimensional element is used for the discretization.
Feminismos en clave latinoamericana: un recorrido sobre Fem, Isis y Fempress
Directory of Open Access Journals (Sweden)
Karin Grammático
2011-09-01
Full Text Available En este artículo presentamos un recorrido histórico de tres de los más destacados proyectos de comunicación que el feminismo contemporáneo latinoamericano llevó adelante en el último cuarto del siglo XX: la revista mexicana Fem, iniciativa pionera que se esforzó por combinar la producción teórica y creación feministas con las demandas políticas del movimiento de mujeres, y los emprendimientos comunicacionales que llevaron adelante Isis Internacional y Fempress.In this paper we present a historical overview of the three most outstanding projects of communication that the contemporary Latin American feminism carried on in the last quarter of the last century: the Mexican magazine Fem, a pioneering initiative which attempted to combine the theoretical and creative productions with the political demands of women's movement, and the communication enterprises carried out by Fempress and Isis International.
Numerical simulation of a sheet metal extrusion process by using thermal-mechanical coupling EAS FEM
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The thermal-mechanical coupling finite element method (FEM) was used to simulate a non-isothermal sheet metal extrusion process. On the basis of the finite plasticity consistent with multiplicative decomposition of the deformation gradient, the enhanced assumed strain (EAS) FEM was applied to carry out the numerical simulation. In order to make the computation reliable and avoid hourglass mode in the EAS element under large compressive strains, an alterative form of the original enhanced deformation gradient was employed. In addition, reduced factors were used in the computation of the element local internal parameters and the enhanced part of elemental stiffness. Numerical resultsshow that the hourglass can be avoided in compression region. In the thermal phase, the boundary energy dissipation due to heat convection was taken into account. As an example, a circular steel plate protruded by cylindrical punch was simulated. The step-wise decoupled strategyis adopted to handle coupling between mechanical deformation and the temperature variation. By comparing with the experimental results, thenumerical simulation was verified.
Hydro-elastic analysis of marine propellers based on a BEM-FEM coupled FSI algorithm
Directory of Open Access Journals (Sweden)
Hyoungsuk Lee
2014-09-01
Full Text Available A reliable steady/transient hydro-elastic analysis is developed for flexible (composite marine propeller blade design which deforms according to its environmental load (ship speed, revolution speed, wake distribution, etc. Hydro-elastic analysis based on CFD and FEM has been widely used in the engineering field because of its accurate results however it takes large computation time to apply early propeller design stage. Therefore the analysis based on a boundary element method-Finite Element Method (BEM-FEM Fluid-Structure Interaction (FSI is introduced for computational efficiency and accuracy. The steady FSI analysis, and its application to reverse engineering, is designed for use regarding optimum geometry and ply stack design. A time domain two-way coupled transient FSI analysis is developed by considering the hydrodynamic damping ffects of added mass due to fluid around the propeller blade. The analysis makes possible to evaluate blade strength and also enable to do risk assessment by estimating the change in performance and the deformation depending on blade position in the ship's wake. To validate this hydro-elastic analysis methodology, published model test results of P5479 and P5475 are applied to verify the steady and the transient FSI analysis, respectively. As the results, the proposed steady and unsteady analysis methodology gives sufficient accuracy to apply flexible marine propeller design.
Deformation Mechanism of Hot Spinning of NiTi Shape Memory Alloy Tube Based on FEM
Institute of Scientific and Technical Information of China (English)
JIANG Shuyong; ZHANG Yanqiu; ZHENG Yufeng; LI Chunfeng
2012-01-01
As a successively and locally plastic deformation process,ball spinning is applied to manufacturing thin-walled Nickel-Titanium shape memory alloy (NiTi SMA) tube at high temperature.NiTi SMA tube blank belongs to the as-cast state which consists of a lot of dendritic grains and a few equiaxed grains.The compression tests of NiTi SMA were carried out at various strain rates at high temperature in order to obtain the constitutive model of NiTi SMA.Because NiTi SMA is sensitive to the strain rates at high temperature,rigid-viscoplastic finite element method (FEM) is used to simulate ball spinning of thin-walled NiTi SMA tube in order to analyze the deformation behavior of ball spinning of NiTi SMA tube.Stress fields,strain fields as well as velocity fields is obtained by means of rigid-viscoplastic FEM,which lays the profound foundations for studying the metal flow rule in ball spinning and forming perfect spun NiTi SMA tube.
Structural Analysis of Composite Flywheels: an Integrated NDE and FEM Approach
Abdul-Aziz, Ali; Baaklini, George; Trudell, Jeffrey
2001-01-01
A structural assessment by integrating finite-element methods (FEM) and a nondestructive evaluation (NDE) of two flywheel rotor assemblies is presented. Composite rotor A is pancake-like with a solid hub design, and composite rotor B is cylindrical with a hollow hub design. Detailed analyses under combined centrifugal and interference-fit loading are performed. Two- and three-dimensional stress analyses and two-dimensional fracture mechanics analyses are conducted. A comparison of the structural analysis results obtained with those extracted via NDE findings is reported. Contact effects due to press-fit conditions are evaluated. Stress results generated from the finite-element analyses were corroborated with the analytical solution. Cracks due to rotational loading up to 48,000 rpm for rotor A and 34,000 rpm for rotor B were successfully imaged with NDE and predicted with FEM and fracture mechanics analyses. A procedure that extends current structural analysis to a life prediction tool is also defined.
Electrical performance analysis of HTS synchronous motor based on 3D FEM
Baik, S. K.; Kwon, Y. K.; Kim, H. M.; Lee, J. D.; Kim, Y. C.; Park, G. S.
2010-11-01
A 1-MW class superconducting motor with High-Temperature Superconducting (HTS) field coil is analyzed and tested. This machine is a prototype to make sure applicability aimed at generator and industrial motor applications such as blowers, pumps and compressors installed in large plants. This machine has the HTS field coil made of Bi-2223 HTS wire and the conventional copper armature (stator) coils cooled by water. The 1-MW class HTS motor is analyzed by 3D electromagnetic Finite Element Method (FEM) to get magnetic field distribution, self and mutual inductance, and so forth. Especially excitation voltage (Back EMF) is estimated by using the mutual inductance between armature and field coils and compared with experimental result. Open and short circuit tests were conducted in generator mode while a 1.1-MW rated induction machine was rotating the HTS machine. Electrical parameters such as mutual inductance and synchronous inductance are deduced from these tests and also compared with the analysis results from FEM.
Cicciù, M.; Cervino, G.; Bramanti, E.; Lauritano, F.; Lo Gudice, G.; Scappaticci, L.; Rapparini, A.; Guglielmino, E.; Risitano, G.
2015-01-01
Prosthetic rehabilitation of total edentulous jaws patients is today a common technique that clinicians approach in their daily practice. The use of dental implants for replacing missing teeth is going to be a safe technique and the implant-prosthetic materials give the possibility of having long-term clinical success. Aim of this work is to evaluate the mechanical features of three different prosthetic retention systems. By applying engineering systems of investigations like FEM and von Mises analyses, how the dental implant material holds out against the masticatory strength during the chewing cycles has been investigated. Three common dental implant overdenture retention systems have been investigated. The ball attachment system, the locator system, and the common dental abutment have been processed by Ansys Workbench 15.0 and underwent FEM and von Mises investigations. The elastic features of the materials used in the study have been taken from recent literature data. Results revealed different response for both types of device, although locator system showed better results for all conditions of loading. The data of this virtual model show all the features of different prosthetic retention systems under the masticatory load. Clinicians should find the better prosthetic solution related to the patients clinical condition in order to obtain long-term results. PMID:26798405
Directory of Open Access Journals (Sweden)
M. Cicciù
2015-01-01
Full Text Available Prosthetic rehabilitation of total edentulous jaws patients is today a common technique that clinicians approach in their daily practice. The use of dental implants for replacing missing teeth is going to be a safe technique and the implant-prosthetic materials give the possibility of having long-term clinical success. Aim of this work is to evaluate the mechanical features of three different prosthetic retention systems. By applying engineering systems of investigations like FEM and von Mises analyses, how the dental implant material holds out against the masticatory strength during the chewing cycles has been investigated. Three common dental implant overdenture retention systems have been investigated. The ball attachment system, the locator system, and the common dental abutment have been processed by Ansys Workbench 15.0 and underwent FEM and von Mises investigations. The elastic features of the materials used in the study have been taken from recent literature data. Results revealed different response for both types of device, although locator system showed better results for all conditions of loading. The data of this virtual model show all the features of different prosthetic retention systems under the masticatory load. Clinicians should find the better prosthetic solution related to the patients clinical condition in order to obtain long-term results.
FEM-based simulation of a fluorescence tomography experiment using anatomical MR images
Ren, Wuwei; Elmer, Andreas; Augath, Mark-Aurel; Rudin, Markus
2016-03-01
A hybrid system combining fluorescence molecular tomography (FMT) and magnetic resonance imaging (MRI) is attractive for preclinical imaging as it allows fusion of molecular information derived from FMT and anatomical reference data derived from MRI. We have previously developed such a system and demonstrated its performance in biological applications. For reconstruction slab geometry with homogeneous optical parameters was assumed, which led to undesirable artifacts. In order to exploit the power of the hybrid system, the use of MRI derived anatomical information, as a constraint for FMT reconstruction, appears logical. Heterogeneity of tissues and irregular surface derived from MRI can be accounted for by generating a mesh using the finite element method (FEM), and attributing optical parameters to individual mesh points. We have established a forward simulation tool based on TOAST++ to mimic an FMT experiment. MRI images were recorded on a 9.4T MR scanner using a T1-weighted pulse sequence. The voxelized dataset was processed by iso2mesh to yield a 3D-mesh. Four steps of FMT simulation were included: 1) Assignment of optical properties, 2) Specification of boundary conditions and generation of 3) excitation and 4) emission maps. FEM-derived results were compared with those obtained using the analytical solution of Green's function and with experimental data with a single fluorescent inclusion in a silicon phantom. Once, the forward modeling method is properly validated it will be used as a central element of a reconstruction algorithm for analyzing data derived from a hybrid FMT/MRI setup.
Nega, Mulugeta; Dube, Linda; Kull, Melanie; Ziebandt, Anne-Kathrin; Ebner, Patrick; Albrecht, Dirk; Krismer, Bernhard; Rosenstein, Ralf; Hecker, Michael; Götz, Friedrich
2015-04-01
FemABX peptidyl transferases are involved in non-ribosomal pentaglycine interpeptide bridge biosynthesis. Here, we characterized the phenotype of a Staphylococcus carnosus femB deletion mutant, which was affected in growth and showed pleiotropic effects such as enhanced methicillin sensitivity, lysostaphin resistance, cell clustering, and decreased peptidoglycan cross-linking. However, comparative secretome analysis revealed a most striking difference in the massive secretion or release of proteins into the culture supernatant in the femB mutant than the wild type. The secreted proteins can be categorized into typical cytosolic proteins and various murein hydrolases. As the transcription of the murein hydrolase genes was up-regulated in the mutant, they most likely represent an adaption response to the life threatening mutation. Even though the transcription of the cytosolic protein genes was unaltered, their high abundance in the supernatant of the mutant is most likely due to membrane leakage triggered by the weakened murein sacculus and enhanced autolysins.
DEFF Research Database (Denmark)
Barkmann, R; Dencks, S; Laugier, P
2010-01-01
A quantitative ultrasound (QUS) device for measurements at the proximal femur was developed and tested in vivo (Femur Ultrasound Scanner, FemUS). Hip fracture discrimination was as good as for DXA, and a high correlation with hip BMD was achieved. Our results show promise for enhanced QUS......-based assessment of osteoporosis. INTRODUCTION: Dual X-ray absorptiometry (DXA) at the femur is the best predictor of hip fractures, better than DXA measurements at other sites. Calcaneal quantitative ultrasound (QUS) can be used to estimate the general osteoporotic fracture risk, but no femoral QUS measurement...... has been introduced yet. We developed a QUS scanner for measurements at the femur (Femur Ultrasound Scanner, FemUS) and tested its in vivo performance. METHODS: Using the FemUS device, we obtained femoral QUS and DXA on 32 women with recent hip fractures and 30 controls. Fracture discrimination...
A novel hybrid FEM-BEM method for 3D eddy current field calculation using current density J
Institute of Scientific and Technical Information of China (English)
LIU; Zhizhen(刘志珍); WANG; Yanzhang(王衍章); JIA; Zhiping(贾智平); SUN; Yingming(孙英明)
2003-01-01
This paper introduces a novel hybrid FEM-BEM method for calculating 3D eddy current field. In the eddy current region, the eddy current density J is solved by the finite element method (FEM) which is discretized by brick finite element mesh, while in the eddy current free region, the magnetic field intensity H is solved by the boundary element method (BEM) which is discretized by rectangular boundary element mesh. Under the boundary conditions, an algebraic equation group is obtained that only includes J by eliminating H. This method has many advantages over traditional ones, such as fewer variables, more convenient coupling between the FEM and the BEM and wider application to multiply-connected regions. The calculated values of two models are in good agreement with experimental results. This shows the validity of our method.
Directory of Open Access Journals (Sweden)
Nicolae APOSTOLESCU
2010-12-01
Full Text Available The main objective of this paper is to describe a code for calculating an equivalent systemof concentrate loads for a FEM analysis. The tables from the Aerodynamic Department containpressure field for a whole bearing surface, and integrated quantities both for the whole surface andfor fixed and mobile part. Usually in a FEM analysis the external loads as concentrated loadsequivalent to the distributed pressure field are introduced. These concentrated forces can also be usedin static tests. Commercial codes provide solutions for this problem, but what we intend to develop isa code adapted to the user’s specific needs.
Sladek, Jan; Sladek, Vladimir; Stanak, Peter; Pan, Ernian
2017-01-01
The finite element method (FEM) is developed to analyze general two-dimensional boundary value problems in size-dependent magnetoelectroelastic solids. The size-effect phenomena in micro/nano electronic structures are described by the strain gradient effect. The electric and magnetic field-strain gradient coupling is considered in the constitutive equations of the material and the governing equations are derived with the corresponding boundary conditions by virtue of the variational principle. The FEM formulation is subsequently developed and implemented for strain-gradient magnetoelectroelasticity and a couple of numerical examples are presented to illustrate the strain gradient effect on the fields.
Stress and displacement analysis of a modern design lathe body by the fi nite element method (FEM
Directory of Open Access Journals (Sweden)
R. Staniek
2012-01-01
Full Text Available The Finite element method (FEM was used in this study for the analysis of the strain and stress of a turning machine body. The fi nal design decisions were made on the basis of stress and displacement fi eld analysis of various design versions related to the structure of the considered machine tool. The results presented in this paper will be helpful for practical static and dynamic strength evaluation as well as for the appropriate design of machine tools using the FEM.
Analysis of infilled beams using method of initial functions and comparison with FEM
Directory of Open Access Journals (Sweden)
Rakesh Patel
2014-09-01
Full Text Available This paper presents a study carried out on reinforced concrete infilled beams. In reinforced concrete beams, less stressed concrete near neutral axis can be replaced by some light weight material like bricks to reduce the weight of the structure and also achieve the economy. Infilled zone is obtained with the help of stress block diagram, used for limit state design of reinforced concrete beams as per IS 456. Method of initial functions is used for the analysis of infilled reinforced concrete composite beams. The method of initial function (MIF is an analytical method of elasticity theory. The results obtained by MIF are compared with those predicting by Finite Element Method (FEM based software ANSYS, and it is observed that they are comparable.
FEM Analysis of Spring-backs in Age Forming of Aluminum Alloy Plates
Institute of Scientific and Technical Information of China (English)
Huang Lin; Wan Min; Chi Cailou; Ji Xiusheng
2007-01-01
The age forming technology, characterized by huge spring-backs, has been developed to manufacture large integral wing-skin panel parts, which necessitates devising a method of predicting spring-backs. A 7B04-T7451 aluminum alloy creep test in tension is accomplished at 155 ℃, and the creep curves are obtained. The material constants of the mechanism-based creep constitutive equations are determined through experiments. The age forming process and the spring-backs of 7B04 aluminum alloy plates are analyzed using the commercial finite element software ABAQUS. The effects of plate thickness and formingtime on spring-backs are researched. The spring-backs decrease with the increase of plate thickness and forming time. The test results verify the reliability of the finite element method (FEM) analysis.
Institute of Scientific and Technical Information of China (English)
Yanli Wang; Junpin Lin; Zhi Lin; Xinfa Cui; Guoliang Chen
2005-01-01
The deformation behavior and the contact area of conductive particles in anisotropically conductive adhesives (ACA) were investigated by finite element method (FEM). The solid conductive particles are made of pure Ni and Cu. The results indicate that the deformation of the conductive particles is inhomogeneous during fabrication. When the reduction in height is small the deformation concentrates in the area near the contact area. As the reduction in height increases, the strain in the area near the contact area increases, and the metal flows toward the circumference, resulting in the increase of the contact area between the conductive particles and pad. The higher the degree of deformation, the larger the contact area. The regression equations were offered to express the relations between the bounding force and the contact area or the reduction in height. An approach of how to obtain the maximum contact area in ACA was discussed.
FEM Thermal Modeling and Improvement for High Power IGBT Modules Used in Wind Turbine Systems
DEFF Research Database (Denmark)
Bahman, Amir Sajjad; Ma, Ke; Blaabjerg, Frede
2014-01-01
Thermal management of high power IGBT (Insulated Gate Bipolar Transistor) modules is crucial to ensure the reliable operation of power electronic systems especially in wind power applications. The important stage in thermal management of power modules is temperature estimation inside the IGBT...... cooling conditions on thermal behavior of power module. In this paper, a detailed 3D thermal network of high power module is presented based on FEM (Finite Element Method) simulation. The thermal coupling impact between chips will be studied and the transient thermal impedances will be examined under...... different cooling conditions. Finally, the extracted thermal network will be validated with a circuit simulator for a fast temperature estimation with a given loss profile....
Sethy, Ritanjali; Galdos, Lander; Mendiguren, Joseba; Sáenz de Argandoña, Eneko
2016-10-01
Few studies have been undertaken to understand the friction in hot forming, especially when addressing the issue of varying input parameters. Better understanding of their role is therefore needed in order to obtain accurate results in numerical simulations. This paper numerically investigates the high temperature ring compression test to evaluate how frictional behaviour is affected by variations of input parameters (i.e. press velocity, Heat Transfer Coefficient (HTC), processing time, mesh size, material and tool temperature). The high temperature ring-compression process was simulated by means of Finite Element Modelling (FEM) using FORGE-3D software with the ring made of AISI 304L having ratio of outer diameter, inner diameter and height of 30:15:10. According to the results, the HTC and the press velocity have most significant effects on frictional behavior and the calibration curves needed to calculate the friction coefficients after experimental testing.
An FEM-Based State Estimation Approach to Nonlinear Hybrid Positioning Systems
Directory of Open Access Journals (Sweden)
Yu-Xin Zhao
2013-01-01
Full Text Available For hybrid positioning systems (HPSs, the estimator design is a crucial and important problem. In this paper, a finite-element-method- (FEM- based state estimation approach is proposed to HPS. As the weak solution of hybrid stochastic differential model is denoted by the Kolmogorov's forward equation, this paper constructs its interpolating point through the classical fourth-order Runge-Kutta method. Then, it approaches the solution with biquadratic interpolation function to obtain a prior probability density function of the state. A posterior probability density function is gained through Bayesian formula finally. In theory, the proposed scheme has more advantages in the performance of complexity and convergence for low-dimensional systems. By taking an illustrative example, numerical experiment results show that the new state estimator is feasible and has good performance than PF and UKF.
Numerical simulation of azimuth electromagnetic wave tool response based on self-adaptive FEM
Li, Hui; Shen, Yi-Ze
2017-07-01
Azimuth electromagnetic wave is a new type of electromagnetic prospecting technology. It can detect weak electromagnetic wave signal and realize real-time formation conductivity imaging. For effectively optimizing measurement accuracy of azimuth electromagnetic wave imaging tool, the efficient numerical simulation algorithm is required. In this paper, self-adaptive finite element method (FEM) has been used to investigate the azimuth electromagnetic wave logging tool response by adjusting antenna array system in different geological conditions. Numerical simulation examples show the accuracy and efficiency of the method, and provide physical interpretation of amplitude attenuation and phase shift of electromagnetic wave signal. Meanwhile, the high-accuracy numerical simulation results have great value to azimuth electromagnetic wave imaging tool calibration and data interpretation.
2-D elastic FEM simulation on stress state in the deep part of a subducted slab
Institute of Scientific and Technical Information of China (English)
毛兴华; 刘亚静; 叶国扬; 宁杰远
2002-01-01
Based upon some simplified numerical models, a 2-D plain strain elastic FEM program is compiled to study the distributions of the stress fields produced by the volume change of the phase transformation from olivine to spinel, by the volume change from temperature variation, and by density difference and boundary action in a piece of subducted slab located in transition zone of the mantle. Thermal stress could explain the fault plane solutions of deep focus earthquakes, but could not explain the distribution of deep seismicity. When large extent metastable olivine is included, the stress field produced by the density difference contradicts with the results of fault plane solutions and with the distribution of deep seismicity. Although the stress produced by volume change of the phase transformation from olivine to spinel dominates the stress state, its main direction is different from the observed results. We conclude that the deep seismicity could not be simply explained by elastic simulation.
Unstructured nodal DG-FEM solution of high-order Boussinesq-type equations
DEFF Research Database (Denmark)
Engsig-Karup, Allan Peter
2007-01-01
is not subject to severe restrictions which can affect the performance of the scheme. It is demonstrated that the discrete properties of both DG-FEM and finite difference methods can be discretized to mimic the analytical properties. It is investigated mathematically and demonstrated numerically how......The main objective of the present study has been to develop a numerical model and investigate solution techniques for solving the recently derived high-order Boussinesq equations of \\cite{MBL02} in irregular domains in one and two horizontal dimensions. The Boussinesq-type methods are the simplest...... alternative to solving full three-dimensional wave problems by e.g. Navier-Stokes equations, which can capture all the important wave phenomena such as diffraction, refraction, nonlinear wave-wave interactions and interaction with structures. The main goal can be reached by using multi-domain methods...
Numerical simulation for 1975 Haicheng and 1999 Xiuyan earthquake processes by DDA+FEM
Institute of Scientific and Technical Information of China (English)
ZHANG Rui-qing; WEI Fu-sheng; QIAO Cheng-bin; LIN Bang-hui
2005-01-01
In this paper, using discontinuous deformation analysis, we simulate numerically the processes of the 1975 Haicheng earthquake and the 1999 Xiuyan earthquake in the tectonic environment of North China where blocks restrict each other by DDA+FEM. Based on the research on the distribution of foreshocks and recent aftershocks of Xiuyan earthquake and the results from our study and other study on Haicheng earthquake, we present a tectonic block model of Haicheng and Xiuyan earthquakes. The results from numerical simulation include the variation of principal stress field released by these two earthquakes, contour patterns of maximum shear stress change, variation patterns of displacement vectors before and after the earthquakes and variation of the earthquake fault slip with time, which agree basically with the focal mechanisms, macroscopic isoseismal and horizontal displacement characters from observations.
An Experimental Simulation to Validate FEM to Predict Transverse Young’s Modulus of FRP Composites
Directory of Open Access Journals (Sweden)
V. S. Sai
2013-01-01
Full Text Available Finite element method finds application in the analysis of FRP composites due to its versatility in getting the solution for complex cases which are not possible by exact classical analytical approaches. The finite element result is questionable unless it is obtained from converged mesh and properly validated. In the present work specimens are prepared with metallic materials so that the arrangement of fibers is close to hexagonal packing in a matrix as similar arrangement in case of FRP is complex due to the size of fibers. Transverse Young’s moduli of these specimens are determined experimentally. Equivalent FE models are designed and corresponding transverse Young’s moduli are compared with the experimental results. It is observed that the FE values are in good agreement with the experimental results, thus validating FEM for predicting transverse modulus of FRP composites.
A Two-Dimensional Fem Code for Impedance Calculation in High Frequency Domain
Energy Technology Data Exchange (ETDEWEB)
Wang, Lanfa; /SLAC; Lee, Lie-Quan; /SLAC; Stupakov, Gennady; /SLAC
2010-08-25
A new method, using the parabolic equation (PE), for the calculation of both high-frequency impedances of small-angle taper (or collimator) is developed in [1]. One of the most important advantages of the PE approach is that it eliminates the spatial scale of the small wavelength from the problem. As a result, only coarser spatial meshes are needed in calculating the numerical solution of the PE. We developed a new code based on Finite Element Method (FEM) which can handle arbitrary profile of a transition and speed up the calculation by orders of magnitude. As a first step, we completed and benchmarked a two-dimensional code. It can be upgraded to three-dimensional geometry.
Numerical Simulation of Sloshing in Rectangular Storage Tank Using Coupled FEM-BEM
Institute of Scientific and Technical Information of China (English)
Hassan Saghi; Mohammad Javad Ketabdari
2012-01-01
Sloshing of liquid can increase the dynamic pressure on the storage sidewalls and bottom in tanker ships and LNG careers.Different geometric shapes were suggested for storage tank to minimize the sloshing pressure on tank perimeter.In this research,a numerical code was developed to model liquid sloshing in a rectangular partially filled tank.Assuming the fluid to be inviscid,Laplace equation and nonlinear free surface boundary conditions are solved using coupled FEM-BEM.The code performance for sloshing modeling is validated against available data.To minimize the sloshing pressure on tank perimeter,rectangular tanks with specific volumes and different aspect ratios were investigated and the best aspect ratios were suggested.The results showed that the rectangular tank with suggested aspect ratios,not only has a maximum surrounded tank volume to the constant available volume,but also reduces the sloshing pressure efficiently.
Application of a SPH Coupled FEM Method for Simulation of Trimming of Aluminum Autobody Sheet
Directory of Open Access Journals (Sweden)
Bohdal Łukasz
2016-03-01
Full Text Available In this paper, the applications of mesh-free SPH (Smoothed Particle Hydrodynamics continuum method to the simulation and analysis of trimming process is presented. In dealing with shearing simulations for example of blanking, piercing or slitting, existing literatures apply finite element method (FEM to analysis of this processes. Presented in this work approach and its application to trimming of aluminum autobody sheet allows for a complex analysis of physical phenomena occurring during the process without significant deterioration in the quality of the finite element mesh during large deformation. This allows for accurate representation of the loss of cohesion of the material under the influence of cutting tools. An analysis of state of stress, strain and fracture mechanisms of the material is presented. In experimental studies, an advanced vision-based technology based on digital image correlation (DIC for monitoring the cutting process is used.
Institute of Scientific and Technical Information of China (English)
Tong-chun LI; Dan-dan LI; Zhi-qiang WANG
2010-01-01
In this study,the limit state equation for tensile reliability analysis of the foundation surface of a gravity dam was established.The possible crack length was set as the action effect and allowable crack length was set as the resistance in the limit state.The nonlinear FEM was used to obtain the crack length of the foundation surface of the gravity dam,and the linear response surface method based on the orthogonal test design method was used to calculate the reliability,providing a reasonable and simple method for calculating the reliability of the serviceability limit state.The Longtan RCC gravity dam was chosen as an example.An orthogonal test,including eleven factors and two levels,was conducted,and the tensile reliability was calculated.The analysis shows that this method is reasonable.
Energy Technology Data Exchange (ETDEWEB)
Tobita, Masahiro; Matsui, Yoshinori [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment
2003-03-01
Prediction of irradiation temperature is one of the important issues in the design of the capsule for irradiation test. Many kinds of capsules with complex structure have been designed for recent irradiation requests, and three-dimensional (3D) temperature calculation becomes inevitable for the evaluation of irradiation temperature. For such 3D calculation, however, many works are usually needed for input data preparation, and a lot of time and resources are necessary for parametric studies in the design. To improve such situation, JAERI introduced 3D-FEM (finite element method) code NISA (Numerically Integrated elements for System Analysis) and developed several subprograms, which enabled to support input preparation works in the capsule design. The 3D temperature calculation of the capsule are able to carried out in much easier way by the help of the subprograms, and specific features in the irradiation tests such as non-uniform gamma heating in the capsule, becomes to be considered. (author)
FEM enhanced signal processing approach for pattern recognition in the SQUID based NDE system
Energy Technology Data Exchange (ETDEWEB)
Sarreshtedari, F; Jahed, N M S; Hosseni, N; Pourhashemi, A; Fardmanesh, M [Department of Electrical Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Banzet, Marko; Schubert, Juergen, E-mail: fardmanesh@sharif.ed [Forschungszentrum Juelich, Institute of Bio and Nanosystems, 52425 Juelich (Germany)
2010-06-01
An efficient Non-Destructive Evaluation algorithm has been developed in order to extract the required information for pattern recognition of defects in the conductive samples. Using high-Tc gradiometer RF-SQUIDs in unshielded environments and incorporating an automated two dimensional non-magnetic scanning robot, samples with different intentional defects have been tested. We have used a developed noise cancellation approach for the improvement of the effectiveness of the used inverse-problem technique. In this approach we have used a well examined Finite Element Method (FEM) to apply a noise reduction filtering on the obtained raw magnetic image data before incorporating the signal processing analysis. By applying this noise cancellation filter and incorporating three different signal processing algorithms and comparing the results of the predicted images by the pattern of the intentionally made defects, we have investigated the ability of these methods for pattern recognition of unknown defects.
Mass conservation for instantaneous sources in FEM3 simulations of material dispersion
Energy Technology Data Exchange (ETDEWEB)
Rodean, H.C.
1987-11-01
This report presents the results of a systematic study in which it is shown that the numerical integration errors in determining material mass content are negligible; the material phase-change model by itself is not a cause of material mass variation; and a linear relation between fractional mass change and fractional density change at the source center for given mesh and source geometries exists over a range of values from 10/sup -5/ to 10/sup -1/. This suggests that the omission of the par. delta rho/par. deltat term from the mass conservation equation is the cause of the observed non-conservation of mass by FEM3. It is shown that these mass variations can be minimized by minimizing the initial density gradients in the source region. 5 refs., 18 figs., 4 tabs.
FEM analysis of an single stator dual PM rotors axial synchronous machine
Tutelea, L. N.; Deaconu, S. I.; Popa, G. N.
2017-01-01
The actual e - continuously variable transmission (e-CVT) solution for the parallel Hybrid Electric Vehicle (HEV) requires two electric machines, two inverters, and a planetary gear. A distinct electric generator and a propulsion electric motor, both with full power converters, are typical for a series HEV. In an effort to simplify the planetary-geared e-CVT for the parallel HEV or the series HEV we hereby propose to replace the basically two electric machines and their two power converters by a single, axial-air-gap, electric machine central stator, fed from a single PWM converter with dual frequency voltage output and two independent PM rotors. The proposed topologies, the magneto-motive force analysis and quasi 3D-FEM analysis are the core of the paper.
FEM analysis of springback control with lump-punch penetration after V-bending
Aso, Takayuki; Iizuka, Takashi
2016-08-01
In actual manufacturing, some empirical methods such as the bottoming technique are generally used in order to adjust the bend angles of products. However, the problem with this is that it relies on the technique of the engineer. In this study, quantitative springback control by lump-punch penetration after V-bending is investigated with FEM analysis and experimentation. The lump at the punch tip is pushed into a bent section at the final stage of V-bending and stretches the inside surface at the bent section. The method of springback control is suggested based on the deformation state. Then, the suitability of springback control using this mechanism is investigated. It is confirmed that the springback amount is reduced by lump-punch penetration. Accordingly, it is recommended to control springback by sheet forging with a lump punch.
Nodal DG-FEM solution of high-order Boussinesq-type equations
DEFF Research Database (Denmark)
Engsig-Karup, Allan Peter; Hesthaven, Jan S.; Bingham, Harry B.;
2006-01-01
We present a discontinuous Galerkin finite element method (DG-FEM) solution to a set of high-order Boussinesq-type equations for modelling highly nonlinear and dispersive water waves in one and two horizontal dimensions. The continuous equations are discretized using nodal polynomial basis...... functions of arbitrary order in space on each element of an unstructured computational domain. A fourth order explicit Runge-Kutta scheme is used to advance the solution in time. Methods for introducing artificial damping to control mild nonlinear instabilities are also discussed. The accuracy...... and convergence of the model with both h (grid size) and p (order) refinement are verified for the linearized equations, and calculations are provided for two nonlinear test cases in one horizontal dimension: harmonic generation over a submerged bar; and reflection of a steep solitary wave from a vertical wall...
Convergence and quasi-optimality of adaptive FEM with inhomogeneous Dirichlet data.
Feischl, M; Page, M; Praetorius, D
2014-01-01
We consider the solution of a second order elliptic PDE with inhomogeneous Dirichlet data by means of adaptive lowest-order FEM. As is usually done in practice, the given Dirichlet data are discretized by nodal interpolation. As model example serves the Poisson equation with mixed Dirichlet-Neumann boundary conditions. For error estimation, we use an edge-based residual error estimator which replaces the volume residual contributions by edge oscillations. For 2D, we prove convergence of the adaptive algorithm even with optimal convergence rate. For 2D and 3D, we show convergence if the nodal interpolation operator is replaced by the [Formula: see text]-projection or the Scott-Zhang quasi-interpolation operator. As a byproduct of the proof, we show that the Scott-Zhang operator converges pointwise to a limiting operator as the mesh is locally refined. This property might be of independent interest besides the current application. Finally, numerical experiments conclude the work.
Milenin, Andriy; Muskalski, Z.
2007-05-01
In paper the wire drawing processes was investigated in two levels — steady-state solve using the 2-dimensional rigid-plastic finite element method (macro-level) and modeling of a microstructure change (micro-level). In macro level the joint deformation-temperature problem was considered. In micro-level the process of deformation of representative volume element — RVE was considered. The pearlitic colony deformation and orientation of cementite lamellas change in RVE was modeled with help of a FEM. The micro-level model to rigid-plastic finite element code was implemented. The experimental data of microstructure and orientation of cementite lamellas change was compared with results of a simulations. The influence of multi-pass drawing parameters (as friction, drawing schedule) on orientation of cementite lamellas was investigated.
Oblique and Herringbone Buckling Analysis of Steel Strip by Spline FEM
Institute of Scientific and Technical Information of China (English)
QIN Jian; ZHANG Qing-dong; HUANG Ke-fu
2011-01-01
The tilted waves in steel strip during rolling and leveling of sheet metal can be classified into two different types of buckling, oblique and herringbone buckling, respectively. Numerical considerations of oblique and herringbone buckling phenomena are dealt with by the spline finite element method （FEM）. It is pointed out that the shear stress due to residual strains caused by the rolling process or applied non-uniform loading is the main reason of oblique and herringbone buckle. According to the analysis of stress distribution in plane, the appropriate initial strain patterns are adopted and the corresponding buckling modes are calculated by the spline FEM. The developed numerical model provides an estimation of buckling critical load and wave configuration.
An Effective Fem-Based Approach for Discrete 3D Crack Growth
DEFF Research Database (Denmark)
Nielsen, Morten Eggert; Lambertsen, Søren Heide; Pedersen, Erik B.
2015-01-01
A new geometric approach for discrete crack growth modeling is proposed and implemented in a commercial FEM software. The basic idea is to model the crack growth by removing volumes of material as the crack front advances. Thereby, adaptive meshing techniques, found in commercial software, is well......-suited for relatively fast and reasonable meshing of the updated geometry. Influence on structural stiffness is negligible, as the amount of removed material is kept insignificant. The approach is automatized in ANSYS APDL and demonstrated by means of energy-based mixed mode stress intensity factors and the crack...... growth direction criterion by Richard. The applicability of the implemented approach is validated against a previously published experimental result, which tests a mixed mode I + III fatigue loading of a modified CT specimen. The proposed approach may be used as a computational framework for modeling...
Optimization of a Centrifugal Boiler Circulating Pump's Casing Based on CFD and FEM Analyses
Directory of Open Access Journals (Sweden)
Zhigang Zuo
2014-04-01
Full Text Available It is important to evaluate the economic efficiency of boiler circulating pumps in manufacturing process from the manufacturers' point of view. The possibility of optimizing the pump casing with respect to structural pressure integrity and hydraulic performance was discussed. CFD analyses of pump models with different pump casing sizes were firstly carried out for the hydraulic performance evaluation. The effects of the working temperature and the sealing ring on the hydraulic efficiency were discussed. A model with casing diameter of 0.875D40 was selected for further analyses. FEM analyses were then carried out on different combinations of casing sizes, casing wall thickness, and materials, to evaluate its safety related to pressure integrity, with respect to both static and fatigue strength analyses. Two models with forging and cast materials were selected as final results.
FEM-models for the propagation period of chloride induced reinforcement corrosion
Energy Technology Data Exchange (ETDEWEB)
Redaelli, E.; Bertolini, L. [Politecnico di Milano, Dipartimento di Chimica, Materiali e Ingegneria Chimica ' ' G. Natta' ' , Via Mancinelli 7, 20131 Milan (Italy); Peelen, W.; Polder, R. [TNO Structures and Safety, P.O. Box 49, 2600 AA Delft (Netherlands)
2006-08-15
The paper reports the results of numerical simulations carried out with FEM and aimed at evaluating the corrosion conditions of steel bars in concrete elements subjected to chlorides. Two case studies were analysed: a reinforced concrete element subjected to de-icing salt in the presence of a crack and a concrete tunnel in a chloride-contaminated, water saturated soil. Attention was focused on the selection of proper values of concrete resistivity and of the parameters suitable to describe the electrochemical behaviour of steel in the different conditions of exposure. The results allowed to quantify the effects of the galvanic coupling between active and passive areas on the corrosion rate of steel. (Abstract Copyright [2006], Wiley Periodicals, Inc.)
FEM SIMULATION OF RESIDUAL STRESSES INDUCED BY LASER SHOCK WITH OVERLAPPING LASER SPOTS
Institute of Scientific and Technical Information of China (English)
Y.X. Hu; Z.Q. Yao
2008-01-01
The finite element method is presented to attain the numerical simulation of the residual stresses field in the material treated by laser shock processing. The distribution of residual stresses generated by a single laser shock with square and round laser spot is predicted and validated by experimental results. With the Finite Element Method (FEM) model, effects of different overlapping rates and impact sequences on the distribution of residual stresses are simulated. The results indicate that: (1) Overlapping laser shock can increase the compressive residual stresses. However, it is not effective on the growth of plastically affected depth; (2) Overlapping rate should be optimized and selected carefully for the large area treatment. Appropriate overlapping rate is beneficial to obtain a homogeneous residual stress field; (3) The impact sequence has a great effect on the residual stress field. It can greatly attenuate the phenomenon of the "residual stress hole" to obtain a homogeneous residual stress field.
Anomalous Surface Deformation of Sapphire Clarified by 3D-FEM Simulation of the Nanoindentation
Nowak, Roman; Manninen, Timo; Li, Chunliang; Heiskanen, Kari; Hannula, Simo-Pekka; Lindroos, Veikko; Soga, Tetsuo; Yoshida, Fusahito
This work clarifies the origin of anomalous surface deformation reflected by peculiar surface patterns around indentation impressions on various crystallographic planes of sapphire. The three-dimensional finite element simulation (3D-FEM) of nanoindentation in Al2O3 crystal allowed the authors to localize the regions in which various kinds of twinning and slip are most prone to be activated. The work provides a novel approach to the “hardness anisotropy”, which was modeled so far using a modified uniaxial-stress approximation of this essentially 3D, non-isotropic contact problem. The calculated results enabled the authors to unravel the asymmetric surface deformation detected on prismatic planes by the high-resolution microscopy, which cannot be explained using simple crystallographic considerations.
Völlinger, Christine; Russenschuck, Stephan
2001-01-01
Field variations in the LHC superconducting magnets, e. g. during the ramping of the magnets, induce magnetization currents in the superconducting material, the so-called persistent currents that do not decay but persist due to the lack of resistivity. This paper describes a semi-analytical hysteresis model for hard superconductors, which has been developed for the computation of the total field errors arising from persistent currents. Since the superconducting coil is surrounded by a ferromagnetic yoke structure, the persistent current model is combined with the finite element method (FEM), as the non-linear yoke can only be calculated numerically. The used finite element method is based on a reduced vector potential formulation that avoids the meshing of the coil while calculating the part of the field arising from the source currents by means of the Biot-Savart Law. The combination allows to determine persistent current induced field errors as function of the excitation and for arbitrarily shaped iron yoke...
Simulation and Analysis of Microstructure Evolution of IN718 in Rotary Forgings by FEM
Institute of Scientific and Technical Information of China (English)
YU Zhong-qi; MA Qiu; LIN Zhong-qin
2008-01-01
A numerical analysis was performed to study the influence of process parameters on the microstructure evolution of IN718 alloy in rotary forging using the finite element method (FEM).For this purpose,a constitutive equation considering the effects of strain hardening and dynamic softening of IN718 alloy was built.The constitutive equation and microstructure models were implemented into the finite element code to investigate the microstructure evolution during rotary forging subject to large deformations.The simulations were carried out in the ratio of initial height to diameter range 0.2-0.8,the angle of the rocker 3°-7° and the relative feed per revolution range 0.01-0.1 r-1.The research results revealed the deformation mechanism and the correlation of process parameters with the grain size evolution of IN718 alloy during rotary forging.These provide evidence for the selection of rotary forging parameters.
FEM Analysis of Brushless DC Servomotor with Fractional Number of Slots per Pole
Directory of Open Access Journals (Sweden)
BALUTA, G.
2014-02-01
Full Text Available The authors present in this paper the analysis with Finite Element Method (FEM of the magnetic circuit for a Brushless DC servomotor with fractional number of slots/pole (9 slots and 10 poles. For this purpose, FEMM 4.2 software package was used for the analysis. To obtain the waveforms of Back-ElectroMotive Forces (BEMFs, electromagnetic and cogging torque for servomotor a program in LUA scripting language (integrated into interactive shell of FEMM4.2 has been created. A comparation with a structure with integer number of slots/pole (18 slots and 6 poles was also realized. The analysis results prove that the structure chosen is an optimal solution: sinusoidal waveforms of BEMFs, improved electromagnetic torque and reduced cogging torque. Therefore, the operating characteristics of the servomotor with 9/10 slots/poles manufactured by Sistem Euroteh Company and included in an integrated electrical drives system are presented in this paper.
Tutelea, L. N.; Muntean, N.; Deaconu, S. I.; Cunţan, C. D.
2016-02-01
The authors carried out a theoretical and experimental study of dual stator winding squirrel cage asynchronous generator (DSWA) behaviour in the presence of saturation regime (non-sinusoidal) due to the variable speed operation. The main aims are the determination of the relations of calculating the equivalent parameters of the machine windings, FEM validation of parameters and characteristics with free FEMM 4.2 computing software and the practice experimental tests for verifying them. Issue is limited to three phase range of double stator winding cage-asynchronous generator of small sized powers, the most currently used in the small adjustable speed wind or hydro power plants. The tests were carried out using three-phase asynchronous generator having rated power of 6 [kVA].
Research of thermal stress between long linear MCT arrays and lead board using FEM
Wu, Wen; Wu, Yonghong; Liu, Dafu
2010-10-01
For the long wavelength infrared detection, HgCdTe (MCT) photoconductive devices are selected as the core of next-generation meteorological because of its mature fabrication technique and stable performance. During the assembly process, an innovative multilayer ceramic board providing mechanical support is designed as the electrical interconnection between MCT chips and external circuits for cryogenic application. Furthermore, due to its brittleness, long linear MCT device is normally glued to sapphire substrates on the multilayer ceramic board with cryogenic glue. Thus, it can be seen clearly that the assembly structure is a multilayer configuration which comprises various kinds of materials, including ceramic broad, sapphire, MCT and glues. As a result, the difference in Thermal Expansion Coefficient (TEC) between the layers could create the potential to introduce thermal stress at working environmental temperature (approximately 70K), which could result in device performance degradation, even die crack. This article analyzes the thermal stress between long linear MCT devices and a multilayer ceramic board by using Finite Element Method (FEM). According to analysis results, two factors are revealed as the most significant causes for introducing thermal stress: one is the sapphire substrate thickness; the other is the parameters of various materials, for instance Yong's modulus and TEC. Since the structure of MCT detector is determined by system requirements and is under the limitation of manufacture technology, this article reveals two effective approaches to reduce the unavoidable thermal stress: first, choosing the appropriate thickness of ceramic board which is made by Al2O3; second, adding another metal cushion Invar. With the above considerations, the distribution of thermal stress is simulated using FEM under different parameter conditions. Based on the results of simulations, an optimal design of package structure which could improve the reliability of
Fracture Capabilities in Grizzly with the extended Finite Element Method (X-FEM)
Energy Technology Data Exchange (ETDEWEB)
Dolbow, John [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zhang, Ziyu [Idaho National Lab. (INL), Idaho Falls, ID (United States); Spencer, Benjamin [Idaho National Lab. (INL), Idaho Falls, ID (United States); Jiang, Wen [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2015-09-01
Efforts are underway to develop fracture mechanics capabilities in the Grizzly code to enable it to be used to perform deterministic fracture assessments of degraded reactor pressure vessels (RPVs). A capability was previously developed to calculate three-dimensional interaction- integrals to extract mixed-mode stress-intensity factors. This capability requires the use of a finite element mesh that conforms to the crack geometry. The eXtended Finite Element Method (X-FEM) provides a means to represent a crack geometry without explicitly fitting the finite element mesh to it. This is effected by enhancing the element kinematics to represent jump discontinuities at arbitrary locations inside of the element, as well as the incorporation of asymptotic near-tip fields to better capture crack singularities. In this work, use of only the discontinuous enrichment functions was examined to see how accurate stress intensity factors could still be calculated. This report documents the following work to enhance Grizzly’s engineering fracture capabilities by introducing arbitrary jump discontinuities for prescribed crack geometries; X-FEM Mesh Cutting in 3D: to enhance the kinematics of elements that are intersected by arbitrary crack geometries, a mesh cutting algorithm was implemented in Grizzly. The algorithm introduces new virtual nodes and creates partial elements, and then creates a new mesh connectivity; Interaction Integral Modifications: the existing code for evaluating the interaction integral in Grizzly was based on the assumption of a mesh that was fitted to the crack geometry. Modifications were made to allow for the possibility of a crack front that passes arbitrarily through the mesh; and Benchmarking for 3D Fracture: the new capabilities were benchmarked against mixed-mode three-dimensional fracture problems with known analytical solutions.
Esterhazy, Sofi; Schneider, Felix; Schöberl, Joachim; Perugia, Ilaria; Bokelmann, Götz
2016-04-01
The research on purely numerical methods for modeling seismic waves has been more and more intensified over last decades. This development is mainly driven by the fact that on the one hand for subsurface models of interest in exploration and global seismology exact analytic solutions do not exist, but, on the other hand, retrieving full seismic waveforms is important to get insides into spectral characteristics and for the interpretation of seismic phases and amplitudes. Furthermore, the computational potential has dramatically increased in the recent past such that it became worthwhile to perform computations for large-scale problems as those arising in the field of computational seismology. Algorithms based on the Finite Element Method (FEM) are becoming increasingly popular for the propagation of acoustic and elastic waves in geophysical models as they provide more geometrical flexibility in terms of complexity as well as heterogeneity of the materials. In particular, we want to demonstrate the benefit of high-order FEMs as they also provide a better control on the accuracy. Our computations are done with the parallel Finite Element Library NGSOLVE ontop of the automatic 2D/3D mesh generator NETGEN (http://sourceforge.net/projects/ngsolve/). Further we are interested in the generation of synthetic seismograms including direct, refracted and converted waves in correlation to the presence of an underground cavity and the detailed simulation of the comprehensive wave field inside and around such a cavity that would have been created by a nuclear explosion. The motivation of this application comes from the need to find evidence of a nuclear test as they are forbidden by the Comprehensive Nuclear-Test Ban Treaty (CTBT). With this approach it is possible for us to investigate the wave field over a large bandwidth of wave numbers. This again will help to provide a better understanding on the characteristic signatures of an underground cavity, improve the protocols for
DEFF Research Database (Denmark)
Bottasso, C. L.; Campagnolo, F.; Croce, A.
2014-01-01
level. At first, a "coarse"-level constrained design optimization is performed by using a 1D spatial geometrically exact beam model for aero-servo-elastic multibody analysis and load calculation, integrated with a 2D FEM cross sectional model for stress/strain analysis, and the evaluation of the 1D...
Demonstration of low-loss electron beam transport and mm-wave experiments of the fusion-FEM
Urbanus, W. H.; Bongers, W. A.; van Dijk, G.; van der Geer, C. A. J.; de Kruif, R.; Manintveld, P.; Pluygers, J.; Poelman, A. J.; Schüller, F. C.; Smeets, P. H. M.; Sterk, A. B.; Verhoeven, A. G. A.; Valentini, M.; van der Wiel, M. J.
1998-01-01
In the Fusion-FEM electrostatic Free Electron Maser, an electron beam loss current of less than 0.2% is essential for long-pulse operation. At reduced beam current, 3 A instead of the nominal 12 A, we have demonstrated electron beam acceleration and transport through the undulator at current losses
Effect of the drift gap between the undulator sections on the operation of the Fusion-FEM
van der Geer, C. A. J.; Militsyn, B. L.; Bongers, W. A.; Bratman, V. L.; Denisov, G. G.; Manintveld, P.; Savilov, A. V.; Varfolomeev, A. A.; Verhoeven, A. G. A.; Urbanus, W. H.
2000-01-01
The 'Fusion-FEM' is a free electron MASER based on an electrostatic accelerator. An electron beam of 12 A, 1.35-2 MeV is injected into a step-tapered undulator to generate 1 MW of radiation in the range 130-250 GHz. The undulator is built from two sections with different field strength
Directory of Open Access Journals (Sweden)
Vasile Cojocaru
2016-12-01
Full Text Available Several methods can be used in the FEM studies to apply the loads on a plain bearing. The paper presents a comparative analysis of maximum stress obtained for three loading scenarios: resultant force applied on the shaft – bearing assembly, variable pressure with sinusoidal distribution applied on the bearing surface, variable pressure with parabolic distribution applied on the bearing surface.
DEFF Research Database (Denmark)
Sonne, Mads Rostgaard; Carlone, P.; Citarella, R.
2015-01-01
of the welding process of precipitation hardenable AA2024-T3 aluminum alloy is employed to infer the process induced residual stress field. The reliability of the FEM simulations with respect to the induced residual stresses is assessed comparing numerical outcomes with experimental data obtained by means...
Shen, Yanfeng; Cesnik, Carlos E. S.
2015-03-01
This paper presents a hybrid modeling technique for the efficient simulation of guided wave propagation and interaction with damage in composite structures. This hybrid approach uses a local finite element model (FEM) to compute the excitability of guided waves generated by piezoelectric transducers, while the global domain wave propagation, wave-damage interaction, and boundary reflections are modeled with the local interaction simulation approach (LISA). A small-size multi-physics FEM with non-reflective boundaries (NRB) was built to obtain the excitability information of guided waves generated by the transmitter. Frequency-domain harmonic analysis was carried out to obtain the solution for all the frequencies of interest. Fourier and inverse Fourier transform and frequency domain convolution techniques are used to obtain the time domain 3-D displacement field underneath the transmitter under an arbitrary excitation. This 3-D displacement field is then fed into the highly efficient time domain LISA simulation module to compute guided wave propagation, interaction with damage, and reflections at structural boundaries. The damping effect of composite materials was considered in the modified LISA formulation. The grids for complex structures were generated using commercial FEM preprocessors and converted to LISA connectivity format. Parallelization of the global LISA solution was achieved through Compute Unified Design Architecture (CUDA) running on Graphical Processing Unit (GPU). The multi-physics local FEM can reliably capture the detailed dimensions and local dynamics of the piezoelectric transducers. The global domain LISA can accurately solve the 3-D elastodynamic wave equations in a highly efficient manner. By combining the local FEM with global LISA, the efficient and accurate simulation of guided wave structural health monitoring procedure is achieved. Two numerical case studies are presented: (1) wave propagation in a unidirectional CFRP composite plate
Institute of Scientific and Technical Information of China (English)
M. H. NGUYEN-THOI[1,2; L. Le-ANH[1,2; V. Ho-HUU[1,2; H. Dang-TRUNG[1,2; T. NGUYEN-THOI[1,2
2015-01-01
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.
Liu, G. R.; Nguyen-Xuan, H.; Nguyen-Thoi, T.; Xu, X.
2009-06-01
A carefully designed procedure is presented to modify the piecewise constant strain field of linear triangular FEM models, and to reconstruct a strain field with an adjustable parameter α. A novel Galerkin-like weakform derived from the Hellinger-Reissner variational principle is proposed for establishing the discretized system equations. The new weak form is very simple, possesses the same good properties of the standard Galerkin weakform, and works particularly well for strain construction methods. A superconvergent alpha finite element method (S αFEM) is then formulated by using the constructed strain field and the Galerkin-like weakform for solid mechanics problems. The implementation of the S αFEM is straightforward and no additional parameters are used. We prove theoretically and show numerically that the S αFEM always achieves more accurate and higher convergence rate than the standard FEM of triangular elements (T3) and even more accurate than the four-node quadrilateral elements (Q4) when the same sets of nodes are used. The S αFEM can always produce both lower and upper bounds to the exact solution in the energy norm for all elasticity problems by properly choosing an α. In addition, a preferable- α approach has also been devised to produce very accurate solutions for both displacement and energy norms and a superconvergent rate in the energy error norm. Furthermore, a model-based selective scheme is proposed to formulate a combined S αFEM/NS-FEM model that handily overcomes the volumetric locking problems. Intensive numerical studies including singularity problems have been conducted to confirm the theory and properties of the S αFEM.
Colwell, Morris A
1976-01-01
Electronic Components provides a basic grounding in the practical aspects of using and selecting electronics components. The book describes the basic requirements needed to start practical work on electronic equipment, resistors and potentiometers, capacitance, and inductors and transformers. The text discusses semiconductor devices such as diodes, thyristors and triacs, transistors and heat sinks, logic and linear integrated circuits (I.C.s) and electromechanical devices. Common abbreviations applied to components are provided. Constructors and electronics engineers will find the book useful
Roellig, Mike; Boehme, Bjoern; Meier, Karsten; Metasch, René
2011-09-01
Conventional and future electronic packages merge several different materials. Polymers, metals, solders, dielectrics, glasses, silicon, composites come together and show strong mechanical and material interaction. These interfacial effects increase if the miniaturization and diversification keep on rising as it is proposed. Many efforts have to be done to assure the system reliability of new electronic packages. The Finite Element Simulation has the ability to support the development process of new packages. The application of the FEM-analysis requires the knowledge about the precise mechanical and thermal behaviour of the materials. The paper presents different measurement methods to determine accurate mechanical material properties of moulding compound polymers, underfillers, solder mask, and wafer photo resist and solder joints. The temperature dependency is essential to be respected. The polymer materials moulding compound as well as solder mask were characterized by Dynamic Mechanical Analysis under humidity influences to determine mechanical properties as function of moisture and temperature. Further experiments on polymer were conducted to extract the cure kinetics by Differential Scanning Calorimetry and to determine Bulk Modulus by Pressure-Volume-Temperature experiments (PVT). Altogether, these material properties need to be modeled in a comprehensive way fitting to each other. The common practice of just compiling data from different sources has been found to fail yielding in reliable and accurate results. The conditions under which the data were determined may cause mismatches between them and cause inconsistencies within the model. If a convergent solution was obtained at all, much simulation time would be needed as many iterations with small time steps were needed. In order to avoid this, the paper reports an approach of characterizing the temperature and time dependent mechanical material properties in one comprehensive scheme. The solder
Chen, Xiaodong; Sadineni, Vikram; Maity, Mita; Quan, Yong; Enterline, Matthew; Mantri, Rao V
2015-12-01
Lyophilization is an approach commonly undertaken to formulate drugs that are unstable to be commercialized as ready to use (RTU) solutions. One of the important aspects of commercializing a lyophilized product is to transfer the process parameters that are developed in lab scale lyophilizer to commercial scale without a loss in product quality. This process is often accomplished by costly engineering runs or through an iterative process at the commercial scale. Here, we are highlighting a combination of computational and experimental approach to predict commercial process parameters for the primary drying phase of lyophilization. Heat and mass transfer coefficients are determined experimentally either by manometric temperature measurement (MTM) or sublimation tests and used as inputs for the finite element model (FEM)-based software called PASSAGE, which computes various primary drying parameters such as primary drying time and product temperature. The heat and mass transfer coefficients will vary at different lyophilization scales; hence, we present an approach to use appropriate factors while scaling-up from lab scale to commercial scale. As a result, one can predict commercial scale primary drying time based on these parameters. Additionally, the model-based approach presented in this study provides a process to monitor pharmaceutical product robustness and accidental process deviations during Lyophilization to support commercial supply chain continuity. The approach presented here provides a robust lyophilization scale-up strategy; and because of the simple and minimalistic approach, it will also be less capital intensive path with minimal use of expensive drug substance/active material.
Directory of Open Access Journals (Sweden)
Hosein Hemmatian
2012-10-01
Full Text Available Carbon nanotube (CNT is considered as a new generation of material possessing superior mechanical, thermal and electrical properties. The applications of CNT, especially in composite materials, i.e. carbon nanotube reinforced polymer have received great attention and interest in recent years. To characterize the influence of CNT on the stress intensity factor of nanocomposites, three fracture modes (opening, shearing and tearing are considered. The stress intensity factor of nanocomposites is evaluated using a representative volume element (RVE based on the continuum mechanics and finite element method (FEM. Inter-atomic interactions of CNT are simulated by beam elements in the finite element (FE model. Non-linear springbased line elements are employed to simulate the van der Waals (vdW bonds. In all fracture modes, the stress intensity factor was determined for pure matrix and matrix reinforced with single-walled carbon nanotube (SWCNT. Numerical results indicate that the load carrying capacities of the CNTs in a matrix are evident. Addition of CNTs in a matrix can increase the stiffness of the composite. Finally, the results showed that utilizing of SWCNT decreased the stress intensity factor and improved crack resistance.
New method of designing anti-slide piles-the strength reduction FEM
Institute of Scientific and Technical Information of China (English)
Zheng Yingren; Zhao Shangyi; Lei Wenjie; Tang Xiaosong
2010-01-01
At present,the thrust of an anti-slide pile can be worked out with some calculation methods.However,the resistance in front of the pile,the distributions of resistance and thrust,and appropriate pile length cannot be easily obtained.In this paper,the authors applied the strength-reduction finite element method(FEM)to several design cases of anti-slide piles.Using this method,it is possible to take the pile-soil interactions into consideration,obtain reasonable resistance in front of pile and the distributions of thrust and resistance,and reasonable lengths of anti-slide piles.In particular,the thrust and resistance imposed on embedded anti-slide piles can be calculated and composite anti-slide pile structures such as anchored piles and braced piles can be optimized.It is proved through the calculation examples that this method is more reliable and economical in the design of anti-slide pile.
Stator Design and Air Gap Optimization of High Speed Drag-Cup Induction Motor using FEM
Directory of Open Access Journals (Sweden)
VUKOSAVIC, S. N.
2013-08-01
Full Text Available A huge number of modern applications nowadays require the use of high speed electrical machines which need to be highly optimized in order to achieve the best efficiency and the lowest mass and price. The low rotor inertia is also an important requirement in order to reduce rotor kinetic energy. The subject of this paper is high speed drag-cup induction motor (IM with low inertia which is designed for use as an auxiliary motor in automotive systems such as Kinetic Energy Recovery System (KERS in Formula 1. This work presents the procedure for stator design and optimization of the air gap length and rotor thickness of this kind of motor in order to achieve the highest efficiency in the speed range of interest. Simple procedure for stator dimensioning was developed and it was shown how the optimal number of stator conductors could be calculated. The effect of change in rotor thickness and air gap lengths on motor performance is demonstrated through some analytical considerations. The machine is then modeled in FEM software by means of which the optimization of the air gap and rotor thickness was performed. At the end, the simulation results were presented and analyzed and conclusions were drawn.
Pivovarov, Dmytro; Steinmann, Paul
2016-12-01
In the current work we apply the stochastic version of the FEM to the homogenization of magneto-elastic heterogeneous materials with random microstructure. The main aim of this study is to capture accurately the discontinuities appearing at matrix-inclusion interfaces. We demonstrate and compare three different techniques proposed in the literature for the purely mechanical problem, i.e. global, local and enriched stochastic basis functions. Moreover, we demonstrate the implementation of the isoparametric concept in the enlarged physical-stochastic product space. The Gauss integration rule in this multidimensional space is discussed. In order to design a realistic stochastic Representative Volume Element we analyze actual scans obtained by electron microscopy and provide numerical studies of the micro particle distribution. The SFEM framework described in our previous work (Pivovarov and Steinmann in Comput Mech 57(1): 123-147, 2016) is extended to the case of the magneto-elastic materials. To this end, the magneto-elastic energy function is used, and the corresponding hyper-tensors of the magneto-elastic problem are introduced. In order to estimate the methods' accuracy we performed a set of simulations for elastic and magneto-elastic problems using three different SFEM modifications. All results are compared with "brute-force" Monte-Carlo simulations used as reference solution.
Performance Analysis of FEM Algorithmson GPU and Many-Core Architectures
Khurram, Rooh
2015-04-27
The roadmaps of the leading supercomputer manufacturers are based on hybrid systems, which consist of a mix of conventional processors and accelerators. This trend is mainly due to the fact that the power consumption cost of the future cpu-only Exascale systems will be unsustainable, thus accelerators such as graphic processing units (GPUs) and many-integrated-core (MIC) will likely be the integral part of the TOP500 (http://www.top500.org/) supercomputers, beyond 2020. The emerging supercomputer architecture will bring new challenges for the code developers. Continuum mechanics codes will particularly be affected, because the traditional synchronous implicit solvers will probably not scale on hybrid Exascale machines. In the previous study[1], we reported on the performance of a conjugate gradient based mesh motion algorithm[2]on Sandy Bridge, Xeon Phi, and K20c. In the present study we report on the comparative study of finite element codes, using PETSC and AmgX solvers on CPU and GPUs, respectively [3,4]. We believe this study will be a good starting point for FEM code developers, who are contemplating a CPU to accelerator transition.
Isogeometric FEM-BEM simulations of drop, capsule and vesicle dynamics in Stokes flow
Boedec, Gwenn; Leonetti, Marc; Jaeger, Marc
2017-08-01
We develop an algorithm for the three dimensional simulation of the dynamics of soft objects (drops, capsules, vesicles) under creeping flow conditions. Loop elements are used to describe the shape of the soft objects. This surface representation is used both for membrane solver based on finite element method (FEM) and for the fluid solver based on the boundary element method (BEM). This isogeometric analysis of the low Reynolds fluid-structure interaction problem is then coupled to high-order explicit time stepping or second-order implicit time stepping algorithm. For vesicles simulation, a preconditioner is designed for the resolution of the surface velocity incompressibility constraint, which is treated by the use of a local Lagrange multiplier. A mesh quality preserving algorithm is introduced to improve the control mesh quality over long simulation times. We test the proposed algorithm on capsule and vesicle dynamics in various flows, and study its convergence properties, showing a second-order convergence O (N-2) with mesh number of elements.
Fourier finite element modeling of light emission in waveguides: 2.5-dimensional FEM approach.
Ou, Yangxin; Pardo, David; Chen, Yuntian
2015-11-16
We present a Fourier finite element modeling of light emission of dipolar emitters coupled to infinitely long waveguides. Due to the translational symmetry, the three-dimensional (3D) coupled waveguide-emitter system can be decomposed into a series of independent 2D problems (2.5D), which reduces the computational cost. Moreover, the reduced 2D problems can be extremely accurate, compared to its 3D counterpart. Our method can precisely quantify the total emission rates, as well as the fraction of emission rates into different modal channels for waveguides with arbitrary cross-sections. We compare our method with dyadic Green's function for the light emission in single mode metallic nanowire, which yields an excellent agreement. This method is applied in multi-mode waveguides, as well as multi-core waveguides. We further show that our method has the full capability of including dipole orientations, as illustrated via a rotating dipole, which leads to unidirectional excitation of guide modes. The 2.5D Finite Element Method (FEM) approach proposed here can be applied for various waveguides, thus it is useful to interface single-photon single-emitter in nano-structures, as well as for other scenarios involving coupled waveguide-emitters.
C~0 and C~1 theories and test functions for FEM patch test in microstructures
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
Among many theories and categories in microstructures,rotation-displacement used as "independent" or "dependent" variables,is a noticeable topic. In FEM,it is called C0 and C1 theory. The convergence criteria of finite elements for microstructures are less mature than those for the conventional thin plate bending problem. In this paper,the patch test functions for assessing convergence of the C0 and C1 finite elements in microstructures is established based on the enhanced patch test theory. The author has further explored the C0 and C1 finite element theories and investigated the difference and correlation between their finite element formulations. Newly proposed finite element theories for microstructures are as follows:(1) the displacement-rotation dependent C1 element that requires the element function satisfying both C0 and C1 continuity;(2) the displacement-rotation independent C0 element which requires new convergence criteria,such as non-zero constant shear stress patch test and zero constant shear stress patch test for approximating C1 element.
Hybrid CFD/FEM-BEM simulation of cabin aerodynamic noise for vehicles traveling at high speed
Institute of Scientific and Technical Information of China (English)
WANG; YiPing; ZHEN; Xin; WU; Jing; GU; ZhengQi; XIAO; ZhenYi; YANG; Xue
2013-01-01
Flow passing a vehicle may lead to the increase of the cabin interior noise level through a variety of mechanisms. These mechanisms include vibrations caused by aerodynamic excitations and reradiation from the glass panels, exterior noise trans-mitted and leaked through door seals including gaps and glass edge, and transmission of airborne noise generated by the interaction of flow with body panels. It is of vital importance to predict both the flow fields and the acoustic sources around the ve-hicle to accurately assess the impact of wind induced noise inside the cabin. In the present study, an unstructured segregated finite volume model was used to calculate the flow fields in which a hexahedron grid is used to simplify the vehicle geometry.A large eddy simulation coupled with a wall function model was applied to predict the exterior transient flow fields. The mean flow quantities were thus calculated along the symmetry plane and the vehicle’s side windows. A coupled FEM/BEM method was used to compute the vehicle’s interior noise level. The total contribution of the interior noise level due to the body panels of the vehicle was subsequently analyzed.
Torsional inertia moment of beam element with complex section analysis based on FEM
Institute of Scientific and Technical Information of China (English)
Zhao An; Huang Jun; Lu Jianming
2012-01-01
Currently, for the analysis of complex bridge based on beam element, the calculation of cross-section torsional inertia moment is still an unresolved technical problem. Most current calculation of section torsional inertia moment is an approximate analytic method for two-dimensional cross-section, which is not fully consistent with the actual situation, and do not consider the effects of diaphragm in bridge. In order to analyze accurately cable-stayed bridge, suspension bridge and other complex bridge structures based on beam element, the calculation method of section torsional inertia moment based on finite element method （FEM） is invented in this paper. Firstly, setting up local cantilever fine model with solid element or shell element and applying torsion on the end of cantilever. Secondly, calculating the torsion angle of cantilever by FEM method and then the torsional moment through equivalent beam method. Finally, the examples of the section torsional moment calculation of concrete model with solid element with diaphragm and steel girder box model with shell element with diaphragm are used to verify the calculation method, which is applied to the suspension bridge design and construction control special software SBNA developed by Research Institute of Highway Ministry of Transport. Taizhou Bridge under construction is one of the examples.
FEM Analysis of Force Parameters During Hot Extrusion Expanding and Reducing Tube Process
Institute of Scientific and Technical Information of China (English)
WANG Fenghui; JIAO Anyuan; LI Haidong; GAO Xingqi; YANG Siqiong
2006-01-01
In this paper, based on the plastic forming large deformation theory and thermodynamic elastic-plastic FEM, the process of expanding and reducing tube was analyzed by using nonlinear finite element software MARC. The coupled thermal-mechanical models for the thermal-extrusion tube process were established, and the dynamic simulation to them was carried out. By the study on 3D deformation regulation of the thermal-extrusion tube, the distribution of stress,strain and the curves between the force of extrusion and the distance were obtained. As a result, with only a small quantity of necessary experiments, the select of the schemes and parameters can conveniently be performed in the computers. So, not only large numbers of experiments can be avoided, but also trial-manufacture period is consumedly shortened and some costs may be saved. In addition, in order to validate our numerical calculation, an experiment of the tube made of 20 steel is presented in this paper. Good agreement is shown between measured and predicted results of the theoretical analysis model. The study provides a scientific basis for parametric optimizations of the thermal extrusion expanding and reducing tube production equipment. At the same time, the method used in the present paper has important referential value for studying the similar thermal extrusion parts.
A study on material flow in isothermal extrusion by FEM simulation
Peng, Zhi; Sheppard, Terry
2004-09-01
Numerous methods have been suggested or are being used to employ isothermal extrusion operation in commercial presses. The most popular methods may be broadly divided into two types: setting up a longitudinal thermal gradient in the billet or controlling the extrudate exit temperature by varying the ram speed. If the velocity gradient varies it could cause the extrusion to bend or twist, creating residual stress, and the same is true for variation in temperature. So, it is relevant to understand how the material flows through the die and ascertain how the flow pattern in isothermal extrusion differs from the normal extrusion process. In this study, with the help of previous experiments and finite element method (FEM) simulations, isothermal extrusion by two differing methodologies are investigated and discussed: the material flow pattern and the extrudate surface formation in isothermal extrusion. The extrusion force, the exit temperature, the temperature distribution in the transverse direction of the extrudate, the pressure on the tooling, the strain and strain rate distribution are also discussed to assist in the evaluation of isothermal extrusion.
Non-isothermal FEM analyses of large-strain back extrusion forging
Energy Technology Data Exchange (ETDEWEB)
Flower, E.C.; Hallquist, J.O.; Shapiro, A.B.
1986-06-19
Back extrusion forging is a complex metal forming operation dominated by large-strain, non-isothermal deformation. NIKE2D, a fully vectorized implicit finite-element program developed at Lawrence Livermore National Laboratory, was applied to a two-stage isothermal back extrusion forging process. Modeling of the forging process required special features in the FEM code such as friction and interactive rezoning that allows for remeshing of the distorted mesh while maintaining a complete history of all the state variables. To model conditions of the non-isothermal forging process required implementing TOPAZ2D, our LLNL-developed two-dimensional implicit finite element code for heat conduction analysis, as a subroutine into NIKE2D. The fully coupled version maintains all the original features of both codes and can account for the contribution of heat generation during plastic deformation. NIKE/TOPAZ-2D was applied to the piercing operation of the back extrusion forging process. The thermal deformation history of the die, punch, and workpiece and the effective plastic strains were calculated.
First lasing of the Dutch fusion-FEM in the long-pulse configuration
Energy Technology Data Exchange (ETDEWEB)
Militsyn, B.L. E-mail: militsyn@rijnh.nl; Bongers, W.A.; Bratman, V.L.; Caplan, M.; Denisov, G.G.; Geer, C.A.J. van der; Manintveld, P.; Oomens, A.A.M.; Plomp, J.; Pluygers, J.; Poelman, A.J.; Riet, M.; Savilov, A.V.; Smeets, P.H.M.; Tito, C.J.; Turk, G.H.B.; Varfolomeev, A.A.; Urbanus, W.H
2002-05-01
The Dutch Fusion-FEM is the prototype of a high-power, long-pulse, rapid-tunable free-electron maser. The target is to generate mm-wave power in a frequency range of 130-260 GHz, e.g. for tokamak heating and diagnostics experiments in fusion devices. For these applications a high system efficiency is needed. The electron beam is first DC-accelerated to the FEL interaction region. The unused electron beam energy is recovered by a DC-decelerator and a three-stage depressed collector. In short-pulse regime, without energy recovery system, 730 kW, 200 GHz of net output power was generated. Single-frequency operation and tunability have been demonstrated. In the present set-up, with the energy recovery system being operational, initial experiments showed a net output power of 110 kW on average and 140 kW peak power at a pulse length of 40 {mu}s. During the full-pulse length, a stable-frequency operation around 170 GHz has been observed.
Evaluation of Bogie Frame Safety of Shanghai Metro Line 1 by 3D FEM Analysis
Xiongyao, Xie; Guolong, Jin; Rulu, Wang
2010-05-01
The vehicle bogies of Shanghai metro line 1 began to crack just in the third year after the trains operated. More than 50 cracks occurred in the succeeding six year during the train operation. This paper evaluated the safety of the motorized bogies. First, the loading conditions imposed on the vehicle structure were calculated based on the measured data in service of the train, and compared with the original design load. Then, this paper calculated simulated the stress of the vehicle bogie by 3D FEM, and presented the distribution of every stress concentration point in Goodman fatigue diagram. The computational locations of the strength less than the safety are agreed with where cracks have happened. Finally, this paper calculated the fatigue life of the motor bracket of the bogie through S-N curve based on revised Miner theory. In conclusion, this paper think that the bogie cracks of Shanghai metro line 1 are contributed by the overburden fatigue load, and ignoring the lateral vibration load in the design of the vehicle bogie is the important cause that bogie cracks occurred far earlier than in the designed time.
A new meshless approach to map electromagnetic loads for FEM analysis on DEMO TF coil system
Energy Technology Data Exchange (ETDEWEB)
Biancolini, Marco Evangelos, E-mail: biancolini@ing.uniroma2.it [Università di Roma Tor Vergata, Dip. Ingegneria dell’Impresa “Mario Lucertini”, Via del Politecnico 1, 00133 Roma (Italy); Brutti, Carlo, E-mail: brutti@uniroma2.it [Università di Roma Tor Vergata, Dip. Ingegneria dell’Impresa “Mario Lucertini”, Via del Politecnico 1, 00133 Roma (Italy); Giorgetti, Francesco, E-mail: francesco.giorgetti@uniroma2.it [Università di Roma Tor Vergata, Dip. Ingegneria dell’Impresa “Mario Lucertini”, Via del Politecnico 1, 00133 Roma (Italy); Muzzi, Luigi, E-mail: luigi.muzzi@enea.it [ENEA, Laboratorio Superconduttività, Unità Tecnica Fusione, Via E. Fermi 45, 00044 Frascati (RM) (Italy); Turtù, Simonetta, E-mail: simonetta.turtu@enea.it [ENEA, Laboratorio Superconduttività, Unità Tecnica Fusione, Via E. Fermi 45, 00044 Frascati (RM) (Italy); Anemona, Alessandro, E-mail: alessandro.anemona@enea.it [ENEA, Laboratorio Superconduttività, Unità Tecnica Fusione, Via E. Fermi 45, 00044 Frascati (RM) (Italy)
2015-11-15
Graphical abstract: - Highlights: • Generation and mapping of magnetic load on DEMO using radial basis function. • Good agreement between RBF interpolation and EM TOSCA computations. • Resultant forces are stable with respect to the target mesh used. • Stress results are robust and accurate even if a coarse cloud is used for RBF interpolation. - Abstract: Demonstration fusion reactors (DEMO) are being envisaged to be able to produce commercial electrical power. The design of the DEMO magnets and of the constituting conductors is a crucial issue in the overall engineering design of such a large fusion machine. In the frame of the EU roadmap of the so-called fast track approach, mechanical studies of preliminary DEMO toroidal field (TF) coil system conceptual designs are being enforced. The magnetic field load acting on the DEMO TF coil conductor has to be evaluated as input in the FEM model mesh, in order to evaluate the stresses on the mechanical structure. To gain flexibility, a novel approach based on the meshless method of radial basis functions (RBF) has been implemented. The present paper describes this original and flexible approach for the generation and mapping of magnetic load on DEMO TF coil system.
Micromechanics of breakage in sharp-edge particles using combined DEM and FEM
Institute of Scientific and Technical Information of China (English)
Ahad Bagherzadeh-Khalkhali; Ali Asghar Mirghasemi; Soheil Mohammadi
2008-01-01
By combining DEM (Discrete Element Method) and FEM (Finite Element Method),a model is established to simulate the breakage of two-dimensional sharp-edge particles,in which the simulated particles are assumed to have no cracks.Particles can,however,crush during different stages of the numerical analysis,if stress-based breakage criteria are fulfilled inside the particles.With this model,it is possible to study the influence of particle breakage on macro- and micro-mechanical behavior of simulated angular materials.Two series of tests,with and without breakable particles,are simulated under different confining pressures based on conditions of biaxial tests.The results,presented in terms of micromechanical behavior for different confining pressures,are compared with macroparameters.The influence of particle breakage on microstructure of sharp-edge materials is discussed and the related confining pressure effects are investigated.Breakage of particles in rockfill materials are shown to reduce the anisotropy coefficients of the samples and therefore their strength and dilation behaviors.
Optimization Design and Performance Analysis of a PM Brushless Rotor Claw Pole Motor with FEM
Directory of Open Access Journals (Sweden)
Zhenyang Zhang
2016-07-01
Full Text Available A new type of permanent magnet (PM brushless claw pole motor (CPM with soft magnetic composite (SMC core is designed and analyzed in this paper. The PMs are mounted on the claw pole surface, and the three-phase stator windings are fed by variable-frequency three-phase AC currents. The advantages of the proposed CPM are that the slip rings on the rotor are cast off and it can achieve the efficiency improvement and higher power density. The effects of the claw-pole structure parameters, the air-gap length, and the PM thinner parameter of the proposed CPM on the output torque are investigated by using three-dimensional time-stepping finite element method (3D TS-FEM. The optimal rotor structure of the proposed CPM is obtained by using the response surface methodology (RSM and the particle swarm optimization (PSO method and the comparison of full-load performances of the proposed CPM with different material cores (SMC and silicon steel is analyzed.
FEM analyses of stress and deformation of a flexible inner pressure bolt
Institute of Scientific and Technical Information of China (English)
CHEN Zhong-he; WANG Wei-qiang; ZHANG Le-wen
2008-01-01
The flexible inner pressure bolt is a new kind and new structural bolt (anchor rod). A number of structural improvements and performance test have been carried out. The bolt has superior compatibility to the soft crag and the large distortion tunnel with its flexibility. In order to study its stress, deformation and interaction mechanism thoroughly, a number of large distortion calculations and analyses have been carried out on the bolt by FEM (finite element method), especially with the ANSYS software, based on the updated Lagrangian law. The results show that the maximum stress of the inner wall of the bolt is consistent with an elastic analytic solution. The maximum stress on the body occurs in the vicinity of the enhancement material. The link enhancement of the body seems to be quite essential. The experimental results indicate that the maximum injection pressure in the bolt is 2.5 MPa without link enhancement and 8.3 MPa with the enhancement. This link enhancement effect is highly significant. These results provide some basis for the design, application and anchoring stress analysis of the holt.
Crack growth simulation in heterogeneous material by S-FEM and comparison with experiments
Directory of Open Access Journals (Sweden)
Masanori Kikuchi
2015-10-01
Full Text Available Fully automatic fatigue crack growth simulation system is developed using S-version FEM (SFEM. This system is extended to fracture in heterogeneous material. In the heterogeneous material, crack tip stress field becomes mixed mode condition, and crack growth path is affected by inhomogeneous materials and mixed mode conditions. Stress Intensity Factors (SIF in mixed mode condition are evaluated using Virtual Crack Closure Method (VCCM. Criteria for crack growth amount and crack growth path are used based on these SIFs, and growing crack configurations are obtained. Three crack growth problems are simulated. One is crack growth in bi-materila made of CFRP plate and Aluminum alloy. Initial crack is located in CFRP plate, and grows toward Aluminum alloy. Crack growing direction changes and results are compared with experimental one. Second problem is crack growth in bimaterial made of PMMA and Aluminum alloy. Initial crack is located in PMMA plate and parallel to phase boundary. By cahnging loading conditions, several cases are simulated and compared with experimental ones. In the experiment, crack grows into pahse boundary and grow along it. This case is simulated precisely, and the effect of pahse boundary is discussed. Last case is Stress Corrosion Cracking (SCC at Hot-Leg Safe-End of Pressurized Water Rreactor. This location is made of many kinds of steels by welding. In some steel, SCC does not occur and in other steel, SCC is accelerated. As a result, small surface crack grows in complicated manner.
Design and beam transport simulations of a multistage collector for the Israeli EA-FEM
Tecimer, M; Efimov, S; Gover, A; Sokolowski, J
2001-01-01
A four stage asymmetric type depressed collector has been designed for the Israeli mm-wave FEM that is driven by a 1.4 MeV, 1.5 A electron beam. After leaving the interaction section the spent beam has an energy spread of 120 keV and 75 pi mm mrad normalized beam emittance. Simulations of the beam transport system from the undulator exit through the decelerator tube into the collector have been carried out using EGUN and GPT codes. The latter has also been employed to study trajectories of the primary and scattered particles within the collector, optimizing the asymmetrical collector geometry and the electrode potentials at the presence of a deflecting magnetic field. The estimated overall system and collector efficiencies reach 50% and 70%, respectively, with a beam recovery of 99.6%. The design is aimed to attain millisecond long pulse operation and subsequently 1 kW average power. Simulation results are implemented in a mechanical design that leads to a simple, cost efficient assembly eliminating ceramic i...
Process optimization diagram based on FEM simulation for extrusion of AZ31 profile
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
The ram speed and the billet temperature are the primary process variables that determine the quality of the extruded magnesium profile and the productivity of the extrusion operation.The optimization of the extrusion process concerns the interplay between these two variables in relation to the extrudate temperature and the peak extrusion pressure The 3D computer simulations were performed to determine the eriects of the ram speed and the billet temperature on the extrudate temperature and the peak extrusion pressure,thereby providing guidelines for the process optimization and minimizing the number of trial extrusion runs needed for the process optimization.A case study on the extrusion of an AZ31 X-shaped profile was conducted.The correlations between the process variables and the response from the deformed material,extrudate temperature and peak extrusion pressure,were established from the 3D FEM simulations and verified by the experiment.The research opens up a way to rational selection of the process variables for ensured quality and maximum productivity of the magnesium extrusion.
Pivovarov, Dmytro; Steinmann, Paul
2016-09-01
In the current work we apply the stochastic version of the FEM to the homogenization of magneto-elastic heterogeneous materials with random microstructure. The main aim of this study is to capture accurately the discontinuities appearing at matrix-inclusion interfaces. We demonstrate and compare three different techniques proposed in the literature for the purely mechanical problem, i.e. global, local and enriched stochastic basis functions. Moreover, we demonstrate the implementation of the isoparametric concept in the enlarged physical-stochastic product space. The Gauss integration rule in this multidimensional space is discussed. In order to design a realistic stochastic Representative Volume Element we analyze actual scans obtained by electron microscopy and provide numerical studies of the micro particle distribution. The SFEM framework described in our previous work (Pivovarov and Steinmann in Comput Mech 57(1): 123-147, 2016) is extended to the case of the magneto-elastic materials. To this end, the magneto-elastic energy function is used, and the corresponding hyper-tensors of the magneto-elastic problem are introduced. In order to estimate the methods' accuracy we performed a set of simulations for elastic and magneto-elastic problems using three different SFEM modifications. All results are compared with "brute-force" Monte-Carlo simulations used as reference solution.
Study on generalized magneto-thermoelastic problems by FEM in time domain
Institute of Scientific and Technical Information of China (English)
Xiaogeng Tian; Yapeng Shen; Yunming Chen
2005-01-01
This paper presents an investigation of temperature, displacement, stress, and induced magnetic field in a half space perfectly-conductive plate. Finite element equations regarding generalized magneto-thermoelasticity problems with two relaxation times (i.e., the G-L theory) are derived using the principle of virtual work. For avoiding numerical complication involved in inverse Laplace and Fourier transformation and low precision thereof, the equations are solved directly in time-domain. As a numerical example, the derived equation is used to investigate the generalized magneto-thermoelastic behavior of a semi-infinite plate under magnetic field and subjecting to a thermal shock loading. The results demonstrate that FEM can faithfully predict the deformation of the plate and the induced magnetic field, and most importantly can reveal the sophisticated second sound effect of heat conduction in two-dimensional generalized thermo elastic solids, which is usually difficult to model by routine transformation methods. A peak can be observed in the distribution of stress and induced magnetic field at the heat wave front and the magnitude of the peak decreases with time, which can not be obtained by transformation methods. The new method can also be used to study generalized piezo-thermoelastic problems.
Kurz, S
1999-01-01
In this paper a new technique for the accurate calculation of magnetic fields in the end regions of superconducting accelerator magnets is presented. This method couples Boundary Elements (BEM) which discretize the surface of the iron yoke and Finite Elements (FEM) for the modelling of the nonlinear interior of the yoke. The BEM-FEM method is therefore specially suited for the calculation of 3-dimensional effects in the magnets, as the coils and the air regions do not have to be represented in the finite-element mesh and discretization errors only influence the calculation of the magnetization (reduced field) of the yoke. The method has been recently implemented into the CERN-ROXIE program package for the design and optimization of the LHC magnets. The field shape and multipole errors in the two-in-one LHC dipoles with its coil ends sticking out of the common iron yoke is presented.
Directory of Open Access Journals (Sweden)
Seyed Abbas Taher
2011-01-01
Full Text Available In this article, a new fault detection technique is proposed for squirrel cage induction motor (SCIM based on detection of rotor bar failure. This type of fault detection is commonly carried out, while motor continues to work at a steady-state regime. Recently, several methods have been presented for rotor bar failure detection based on evaluation of the start-up transient current. The proposed method here is capable of fault detection immediately after bar breakage, where a three-phase SCIM is modelled in finite element method (FEM using Maxwell2D software. Broken rotor bars are then modelled by the corresponding outer rotor impedance obtained by GA, thereby presenting an analogue model extracted from FEM to be simulated in a flexible environment such as MATLAB/SIMULINK. To improve the failure recognition, the stator current signal was analysed using discrete wavelet transform (DWT.
Fatigue FEM analysis in the case of brazed aluminium alloy 3L59 used in aeronautical industry
Dimitrescu, A.; Amza, Gh; Niţoi, D. F.; Amza, C. Gh; Apostolescu, Z.
2016-08-01
The use, on a larger scale, of brazed aluminum alloys in the aerospace industry led to the need for a detailed study of the assemblies behavior. These are built from 6061 aluminum aloy (3L59) brazed with aluminum aloy A103. Therefore, a finit element simulation (FEM) of durability is necessary, that consists in the observation of gradual deterioration until failure. These studies are required and are previous to the stage of the producing the assembly and test it by traditional methods.
Limit cycles by FEM for a one - parameter dynamical system associated to the Luo - Rudy I model
Bichir, Cătălin Liviu; Amuzescu, Bogdan; Nistor, Gheorghe; Popescu, Marin; Flonta, Maria-Luiza; Corlan, Alexandru Dan; Svab, Istvan
2011-01-01
An one - parameter dynamical system is associated to the mathematical problem governing the membrane excitability of a ventricular cardiomyocyte, according to the Luo-Rudy I model. Limit cycles are described by the solutions of an extended system. A finite element method time approximation (FEM) is used in order to formulate the approximate problem. Starting from a Hopf bifurcation point, approximate limit cycles are obtained, step by step, using an arc-length-continuation method and Newton's method. Some numerical results are presented.
Slope stability FEM analysis and retaining wall design: a case study of clinker in Benxi of Liaoning
Institute of Scientific and Technical Information of China (English)
Aref M. O. AL-JABALI; Lei NIE; Jianlei LIU; Huangping DING; Nengjuan ZHOU; Mohammed HAZAEA
2008-01-01
Stability is always the most important problem after high slope was excavated. The study analyzed the stress and strain inside the slope by Finite Element Method (FEM) and carried through stress distribution and failure zone, then analyzed the stability of the slope using three different methods and came to the conclusion that it is in unstable condition, so the designed retaining wall was put forward which makes the slope stable.
Energy Technology Data Exchange (ETDEWEB)
Hartman, P.S.; De Wilde, D.; Dwarakanath, V.N. [Texas Christian Univ., Fort Worth, TX (United States). Dept. of Biology
1995-06-01
The utility of a new target gene (fem-3) is described for investigating the molecular nature of mutagenesis in the nematode Caenorhabditis elegans. As a principal attribute, this system allows for the selection, maintenance and molecular analysis of any type of mutation that disrupts the gene, including deletions. In this study, 86 mutant strains were isolated, of which 79 proved to have mutations in fem-3. Twenty of these originally tested as homozygous inviable. Homozygous inviability was expected, as Stewart and coworkers had previously observed that, unlike in other organisms, most UV radiation-induced mutations in C. elegans are chromosomal rearrangements of deficiencies (Mutat. Res 249, 37-54, 1991). However, additional data, including Southern blot analyses on 49 of the strains, indicated that most of the UV radiation-induced fem-3 mutations were not deficiencies, as originally inferred from their homozygous inviability. Instead, the lethals were most likely ``coincident mutations`` in linked, essential genes that were concomitantly induced. As such, they were lost owing to genetic recombination during stock maintenance. As in mammalian cells, yeast and bacteria, the frequency of coincident mutations was much higher than would be predicted by chance. (Author).
Directory of Open Access Journals (Sweden)
ISAM M. Mahammed
2012-03-01
Full Text Available The objective of this research is to evaluate Method of Line (MOL used for solution of water flow equations through porous media using MATLAB package functions for solution of ordinary differential equations ODE,s , instead of writing long programs codes. sink & source term to MOL model were included. Then Comparing MOL model with another model that uses finite element method in solving water flow equations (FEM in one dimensional flow using computer program code in FORTRAN. Two cases were examined for evaluation and comparison of these two models. Firstly, infiltration phenomena using sandy soil was studied with the same parameter for both models. Results show that there is a divergence between the two models along time of 60 minutes of infiltration. Changes of moisture content with soil depth were sharp with FEM model. Second case, data of the volume of water content for wheat field where used taking irrigation and evaporation into account, along the growth period of wheat crop and different depths up to 100 cm. Results show that output of FEM model has high degree of agreement with the measured data for all depths and along all period of growth. Data given by MOL model were less in values than measured data for all depths and along all period of wheat growth time.
Hemanth, M; Deoli, Shilpi; Raghuveer, H P; Rani, M S; Hegde, Chatura; Vedavathi, B
2015-09-01
Simulation of periodontal ligament (PDL) using non-linear finite element method (FEM) analysis gives better insight into understanding of the biology of tooth movement. The stresses in the PDL were evaluated for intrusion and lingual root torque using non-linear properties. A three-dimensional (3D) FEM model of the maxillary incisors was generated using Solidworks modeling software. Stresses in the PDL were evaluated for intrusive and lingual root torque movements by 3D FEM using ANSYS software. These stresses were compared with linear and non-linear analyses. For intrusive and lingual root torque movements, distribution of stress over the PDL was within the range of optimal stress value as proposed by Lee, but was exceeding the force system given by Proffit as optimum forces for orthodontic tooth movement with linear properties. When same force load was applied in non-linear analysis, stresses were more compared to linear analysis and were beyond the optimal stress range as proposed by Lee for both intrusive and lingual root torque. To get the same stress as linear analysis, iterations were done using non-linear properties and the force level was reduced. This shows that the force level required for non-linear analysis is lesser than that of linear analysis.
Parashar, Abhishek; Aileni, Kaladhar Reddy; Rachala, Madhukar Reddy; Shashidhar, Nagam Reddy; Mallikarjun, Vankre; Parik, Nupur
2014-01-01
Objective: This FEM study was conducted to quantify the amount of torque loss in maxillary anterior teeth by applying force vectors from different levels to the anterior retraction hook at various heights and comparing with that of molar anchorage system.
Investigation of a digital FEM height reference surface as vertical reference system
Schneid, Sascha
In recent years, the number of precise online DGNSS (Differential Global Navigation Satellite System) applications has significantly increased. Precise DGNSS correction services have been created that enable an online positioning with accuracy in the centimetre region, hi contrast to the co-ordinates found by DGNSS, the measured height needs to be transformed. This is because national height systems refer to a physically defined Height Reference Surface, HRS, that approximates the mean sea level, while the height derived from DGNSS positioning is the height above the WGS84 (World Geodetic System 1984), a mathematical model of the earth and is therefore called "ellipsoidal height". So for the application of precise DGNSS services and for the generation of transformation messages, such as RTCM 3.0, there is an urgent need for a HRS, in a unified datum with appropriate accuracy. This thesis deals with the concept of the Digital FEM (Finite Element Method) Height Reference Surface, DFHRS. This concept enables the rigorous least squares adjustment of any HRS related observation. The HRS is modelled as continuous surface by a local Taylor-series expansion in a grid of FEM-meshes. With this, areas of any size may be computed. The theory of the DFHRS and further development of the mathematical model, especially the incorporation of observed gravity accelerations, are the main parts of this thesis. As the applied Taylor-series expansion of the DFHRS concept only holds for a two- dimensional approximation. Spherical Cap Harmonics, SCH, had to be introduced as auxiliary parameter, to give a complete representation of the local gravity field. Spherical Cap Harmonics, SCH, may be interpreted as the general case of Spherical Harmonics, SH, that have been applied in geodetic applications for decades. The goal of the SCH coefficients, in contrast to the SH coefficients is that they may be applied over areas with limited extent. Due to numerical reasons, the combined least squares
Energy Technology Data Exchange (ETDEWEB)
Grandum, Oddbjoern
1997-12-31
In optimizing solar systems, it is necessary to know the spectral and angular dependence of the radiation. The general nonlinear character of most solar energy systems accentuates this. This thesis describes a spectroradiometer that will measure both the direct component of the solar radiation and the angular dependence of the diffuse component. Radiation from a selected part of the sky is transported through a movable set of tube sections on to a stationary set of three monochromators with detectors. The beam transport system may effectively be looked upon as a single long tube aimed at a particular spot in the sky. The half value of the effective opening angle is 1.3{sup o} for diffuse radiation and 2.8{sup o} for direct radiation. The whole measurement process is controlled and operated by a PC and normally runs without manual attention. The instrument is built into a caravan. The thesis describes in detail the experimental apparatus, calibration and measurement accuracies. To map the diffuse radiation, one divides the sky into 26 sectors of equal solid angle. A complete measurement cycle is then made at a random point within each sector. These measurements are modelled by fitting to spherical harmonics, enforcing symmetry around the solar direction and the horizontal plane. The direct radiation is measured separately. Also the circumsolar sector is given special treatment. The measurements are routinely checked against global radiation measured in parallel by a standard pyranometer, and direct solar radiation by a pyrheliometer. An extensive improvement programme is being planned for the instrument, including the use of a photomultiplier tube to measure the UV part of the spectrum, a diode array for the 400-1100 nm range, and use of a Ge diode for the 1000-1900 nm range. 78 refs., 90 figs., 31 tabs.
A FEM-based method to determine the complex material properties of piezoelectric disks.
Pérez, N; Carbonari, R C; Andrade, M A B; Buiochi, F; Adamowski, J C
2014-08-01
Numerical simulations allow modeling piezoelectric devices and ultrasonic transducers. However, the accuracy in the results is limited by the precise knowledge of the elastic, dielectric and piezoelectric properties of the piezoelectric material. To introduce the energy losses, these properties can be represented by complex numbers, where the real part of the model essentially determines the resonance frequencies and the imaginary part determines the amplitude of each resonant mode. In this work, a method based on the Finite Element Method (FEM) is modified to obtain the imaginary material properties of piezoelectric disks. The material properties are determined from the electrical impedance curve of the disk, which is measured by an impedance analyzer. The method consists in obtaining the material properties that minimize the error between experimental and numerical impedance curves over a wide range of frequencies. The proposed methodology starts with a sensitivity analysis of each parameter, determining the influence of each parameter over a set of resonant modes. Sensitivity results are used to implement a preliminary algorithm approaching the solution in order to avoid the search to be trapped into a local minimum. The method is applied to determine the material properties of a Pz27 disk sample from Ferroperm. The obtained properties are used to calculate the electrical impedance curve of the disk with a Finite Element algorithm, which is compared with the experimental electrical impedance curve. Additionally, the results were validated by comparing the numerical displacement profile with the displacements measured by a laser Doppler vibrometer. The comparison between the numerical and experimental results shows excellent agreement for both electrical impedance curve and for the displacement profile over the disk surface. The agreement between numerical and experimental displacement profiles shows that, although only the electrical impedance curve is
Revised Estimates of Hikurangi Slow Slip Using FEM-Generated Green's Functions
Williams, C. A.; Wallace, L. M.
2013-12-01
Slow slip events (SSEs) occur along nearly the entire Hikurangi subduction margin adjacent to the North Island, New Zealand. The occurrence of both shallow and deep SSEs and the change in locking behavior observed along the Hikurangi Margin provide a unique opportunity to examine the factors controlling both seismic and aseismic behavior. It is therefore critical that our slip estimates are as accurate as possible. Existing SSE slip estimates use geodetic data in conjunction with an elastic half-space dislocation model to infer the slip distributions for these events. Two recent developments provide the potential to obtain more accurate estimates for these events, however. First, a New Zealand-wide seismic velocity model (Eberhart-Phillips et al., 2010) allows us to accurately represent the effects of complex variations in elastic properties. Second, a revised interface geometry has just been developed (Williams et al., 2013), allowing us to represent more accurately the interface on which the events are assumed to occur. We use the finite element code PyLith to generate Green's functions for the entire Hikurangi interface, and we then use these in place of the elastic half-space Green's functions used previously. We do our work in two stages. In the first stage, we replace the existing geometry for the Hikurangi interface with the new geometry, thus allowing us to isolate the changes due purely to the revised geometry. In the second phase, we use the FEM-generated Green's functions in the DEFNODE inversion program, which allows us to isolate the changes that are due to changes in the assumed elastic properties. In this initial work, we apply the method to two Hikurangi SSEs: one deep event and one shallow one. The differences observed for these two events will allow us to evaluate the relative importance of interface geometry and assumed elastic structure for future SSE slip inversions.
The multi-scale FEM simulation of the drawing processes of high carbon steel
Directory of Open Access Journals (Sweden)
A. Milenin
2007-08-01
Full Text Available Purpose: The influence of cementite lamellas orientation on mechanical and technological properties of wire experimentally show up during investigation of drawing processes with change the direction of drawing between passes. The purpose of this paper is to develop a mathematical model of cementite and ferrite deformation during drawing processes and receive an information about transformation of a pearlitic structure of wire during drawing.Design/methodology/approach: The wire drawing processes was investigated in two levels - using the 2-dimensional rigid-plastic finite element method (macro-level and modelling of a microstructure change (micro-level. In micro-level the process of deformation of representative volume element (RVE is considered. The pearlitic colony deformation and stress-strain state in RVE is modelled with help of the FEM.Research limitations/implications: The influence of initial cementite lamellas orientation on triaxity factor and localization of deformation in micro-level is investigated. The numerical simulation is shown a maximal non-uniform deformation of pearlite phases for the canting positions of the cementite lamellas relative the drawing direction.Practical implications: The results of article will be helpful for a fundamental understanding of pearlitic deformation during development of high strength steel wires for tire cord applications.Originality/value: A new model of two-phase grain deformation for wire drawing is proposed. The new conception of simulation of the boundary conditions for the RVE is based on the penalty method and uses a solution of the problem on macro-level.
Institute of Scientific and Technical Information of China (English)
WEI Ying-san; WANG Yong-sheng; CHANG Shu-ping; FU Jian
2012-01-01
A mesh-less Refined Integral Algorithm (RIA) of Boundary Element Method (BEM) is proposed to accurately solve the Helmholtz Integral Equation (HIE).The convergence behavior and the practicability of the method are validated.Computational Fluid Dynamics (CFD),Finite Element Method (FEM) and RIA are used to predict the propeller excited underwater noise of the submarine hull structure.Firstly the propeller and submarine's flows are independently validated,then the self propulsion of the “submarine+propeller” system is simulated via CFD and the balanced point of the system is determined as well as the self propulsion factors.Secondly,the transient response of the “submarine + propeller” system is analyzed at the balanced point,and the propeller thrust and torque excitations are calculated.Thirdly the thrust and the torque excitations of the propeller are loaded on the submarine,respectively,to calculate the acoustic response,and the sound pover and the main peak frequencies are obtained.Results show that:(1) the thrust mainly excites the submarine axial mode and the high frequency area appears at the two conical-type ends,while the torque mainly excites the circumferential mode and the high frequency area appears at the broadside of the cylindrical section,but with rather smaller sound power and radiation efficiency than the former,(2) the main sound source appears at BPF and 2BPF and comes from the harmonic propeller excitations.So,the main attention should be paid on the thrust excitation control for the sound reduction of the propeller excited submarine structure.
Stresses around a miniscrew. 3-D analysis with the finite element method (FEM).
Geramy, Allahyar
2009-11-01
Miniscrews used for absolute anchorage may induce stresses in the surrounding tissues that are dependent on their proximity to the miniscrew. To determine the stresses in the buccal walls of the sockets of lower molars adjacent to a miniscrew under load when the position and angulation of the miniscrew are changed. Five 3-D FEM models containing the first and second lower molars, their periodontal ligaments and the surrounding spongy and cortical bone, were modelled in SolidWorks 2006 (SolidWorks, Concord, MA, USA) and transferred to the ANSYS Workbench (ANSYS Inc., Southpointe, Canonsburg, PA, U.S.A.). A tensile force of 2 N, decomposed in 3-D space, was applied to a miniscrew inserted between the lower first and second molars. The von Mises (equivalent) stresses along the buccal walls of the sockets of the first and second molars were derived following changes in miniscrew position and angulation. No direct force was applied to the molars. When the miniscrew was inserted at right angles to the bone and midway between the molars the stress in the crestal area was 0.093 MPa. This stress increased proportionally in the first molar socket as the miniscrew was moved towards the first molar and declined when the miniscrew was tipped towards the second molar. Stresses also decreased in the crestal area of the second molar as the miniscrew was moved towards the first molar, but increased when it was tipped towards the second molar. A 30-55 per cent increase in crestal stress in the first molar socket was detected. Stress occurred in the tissues surrounding a miniscrew subjected to a force vector. Changes in the position or angulation of a miniscrew can affect the stress in the socket walls of adjacent teeth.
Machining distortion prediction of aerospace monolithic components
Institute of Scientific and Technical Information of China (English)
Yun-bo BI; Qun-lin CHENG; Hui-yue DONG; Ying-lin KE
2009-01-01
To predict the distortion of aerospace monolithic components.a model is established to simulate the numerical control (NC)milling process using 3D finite element method(FEM).In this model,the cutting layer is simplified firstly.Then,the models of cutting force and cutting temperature are established to gain the cutting loads,which are applied to the mesh model of the part.Finally,a prototype of machining simulation environment is developed to simulate the milling process of a spar.Key factors influencing the distortion,such as initial residual stress,cutting loads,fixture layout,cutting sequence,and tool path are considered all together.The total distortion of the spar is predicted and an experiment is conducted to validate the numerical results.It is found that the maximum discrepancy between the simulation results and experiment values is 19.0%
Energy Technology Data Exchange (ETDEWEB)
Noelke, M.
2006-10-20
The attractiveness of electrical conversion of liquid methanol in a fuel cell is defined by its simple storage and high energy density. Therefore, direct-methanol fuel cell (DMFC) qualifies for applications in portable systems and mobile application in the kW-class. The goal of this work is to develop and demonstrate an improved and optimized peripheral DMFC system compared to the current level of technology. The selected mobile application is the retrofit of the energy supply of a ''Scooter'' with a fuel cell system. The required size reduction and the simplification of the DMFC system are realized by an integrated concept, which combines ideally the peripheral system and the fuel cell. A profound analysis of the stack and the peripheral components is a prerequisite for an optimized design. A detailed modelling and understanding of the stack behaviour establish the starting point of this work. The influence of the most important operating parameters like stack temperature, cell voltage, current density, air ratio and methanol concentration is captured accurately by the developed model and validated by experimental data. This shapes the frame work of the following system design approach. For this the clearly defined task of the peripheral system are investigated individually for alternatives and the best option is selected for the final solution. For selecting the right pumps and blowers available products and prototypes are characterized and checked for the system requirements. The investigation and the modelling of the exhaust gas condenser lead to an optimized component design for the ''Scooter'' DMFC design. Additionally, the integration of the anode loop is accomplished consisting of the supply lines, the circulating pump, the gas separator and the exhaust line. The direct coupling of the fuel cell with a lithium-ion battery as an option for electrical conditioning is investigated. In the system modelling the influence
Strain Distribution in Central Europe: FEM Modeling and Comparison with GPS Data
Araszkiewicz, A.; Bogusz, J.; Jarosinski, M.; Lenik, K.
2012-12-01
The main aim of this research is to demonstrate how the results of permanent GPS measurements can be understand in terms of recent geodynamics by applying numerical modeling method. On the other hand, the results of modeling are testing the consistency of the GPS measurements. The method of finite element analysis was applied to develop two-dimensional model of strain and stress field in Central Europe. The FEM model was prepared in the ABAQUS software, consisting of graphic modules and ABAQUS/CAE and ABAQUS Standard modules for solving the static task. The structure of the model was created in the plane Cartesian coordinate system, assuming that for this size of model the earth curvature will not affect the stress and strain direction significantly. Simplified elastic model with frictional contact elements was used for defining mechanical properties of the model. The model consists of 48 parts representing major tectonic units/blocks characterized by different material properties. The stiffness of tectonic blocks expressed by Young's modulus and Poisson's ratio was determined based on the lithospheric thickness, surface heat flow and simplified lithological column of the lithosphere. For dislocations, different values of friction coefficient was tested in course of the trial-and-error modeling than the best fitted options were finally adopted in the model. The dynamic (force and pressure) boundary conditions were applied to the elastic model based on the recent tectonic stress directions from the World Stress Map Database. To allow fast changes of the loads the model boundary were designed normal to tectonic stresses. After each computing round the simulated stress and strain were compared with that measured, paying special attention to the GPS measurements from Poland and the adjacent areas. We have used coordinates and velocities from EPN (EUREF Permanent Network) densified by Polish national Ground-Based Augmentation System (GBAS) ASG-EUPOS. They were obtained
Bionic optimization research of soil cultivating component design
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
The basic biomechanical laws that apply to the clawed toes of animals with powerful digging abilities and the optimal bionic design of curved soil cultivating components with an analogous contour were researched in a novel way. First, the curvature and profile of the inside contour line of a field mouse’s clawed toe were analyzed. The finite element method (FEM) was then used to simulate the working process in order to study the changing characteristics of the working resistance of bionic soil- engag- ing surfaces and the stress field of the processed soil. A straight-line cultivating component was used for comparative analysis. In accordance with the simulation results, a series of soil cultivating com- ponents of varying design were manufactured. An indoor soil bin experiment was carried out to meas- ure their working resistance and validate the results of the FEM analysis. The results of this research would have important values in the optimization design of cultivating components for energy and cost savings.
The Vibration Impact Determination of the Helicopter Structural Components
Directory of Open Access Journals (Sweden)
Khaksar Zeinab
2017-01-01
Full Text Available This paper presents the determination of the vibration impact of the helicopter structural components and skin repairs in terms of frequency characteristics. To address this issue, a 3D Finite Element Method (FEM model of 349 Gazelle helicopter has been developed in ABAQUS and the frequency analysis is conducted. The results on the natural frequencies of the full structure reasonably match with the literature giving confidence in the baseline model. The main advantage of this FEM model is that, it can be used to predict the natural frequencies of the full structure, precisely. In addition, the material properties and conditions of the components can be updated based on the applied conditions during the repair and maintenance period. Thus, the model gives a comprehensive design tool for analysing the frequencies of the helicopter with differing components. The effective variations in the frequency changes due to repair are predicted numerically. The discussion of these results helps in developing leads to improved selection of replacement materials and their properties.
van de Groes, S.A.W.; De Waal Malefijt, M.C.; Verdonschot, Nicolaas Jacobus Joseph
2014-01-01
Background: Some follow-up studies of highflexion total knee arthoplasties report disturbingly high incidences of femoral component loosening. Femoral implantfixation is dependant on two interfaces: the cement–implant and the cement–bone interface. The present finite-element model (FEM) is the first
Groes, S.A.W. van de; Waal Malefijt, M.C. de; Verdonschot, N.J.J.
2014-01-01
BACKGROUND: Some follow-up studies of high flexion total knee arthoplasties report disturbingly high incidences of femoral component loosening. Femoral implant fixation is dependant on two interfaces: the cement-implant and the cement-bone interface. The present finite-element model (FEM) is the
Han, Zhaolong; Li, Jiasong; Singh, Manmohan; Vantipalli, Srilatha; Aglyamov, Salavat R.; Wu, Chen; Liu, Chih-hao; Twa, Michael D.; Larin, Kirill V.
2016-03-01
The biomechanical properties of the cornea have a profound influence on its health and function. Rose bengal/green light corneal collagen cross-linking (RGX) has been proposed as an alternative to UV-A Riboflavin collagen cross-linking (UV-CXL) for treatment of keratoconus. However, the effects of RGX on the biomechanical properties of the cornea are not as well understood as UV-CXL. In this work, we demonstrate the feasibility of quantifying the viscoelasticity of the rabbit cornea before and after RGX using a noncontact method of phase-stabilized swept source optical coherence elastography (PhS-SSOCE) and finite element modeling (FEM). Viscoelastic FE models of the corneas were constructed to simulate the elastic wave propagation based on the OCE measurements. In addition, the effect of the fluid-structure interface (FSI) between the corneal posterior surface and aqueous humor on the elastic wave group velocity was also investigated. The effect of the FSI was first validated by OCE measurements and FEM simulations on contact lenses, and the OCE and FEM results were in good agreement. The Young's modulus of the rabbit cornea before RGX was assessed as E=80 kPa, and the shear viscosity was η=0.40 Pa•s at an intraocular pressure (IOP) of 15 mmHg. After RGX, the Young's modulus increased to E=112 kPa and shear viscosity decreased to η=0.37 Pa•s. Both the corneal OCE experiments and the FE simulations also demonstrated that the FSI significantly reduced the group velocity of the elastic wave, and thus, the FSI should be considered when determining the biomechanical properties of the cornea.
FEM modeling for 3D dynamic analysis of deep-ocean mining pipeline and its experimental verification
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
3D dynamic analysis models of 1000 m deep-ocean mining pipeline, including steel lift pipe, pump, buffer and flexible hose, were established by finite element method (FEM). The coupling effect of steel lift pipe and flexible hose, and main external loads of pipeline were considered in the models, such as gravity, buoyancy, hydrodynamic forces, internal and external fluid pressures, concentrated suspension buoyancy on the flexible hose, torsional moment and axial force induced by pump working.Some relevant FEM models and solution techniques were developed, according to various 3D transient behaviors of integrated deep-ocean mining pipeline, including towing motions of track-keeping operation and launch process of pipeline. Meanwhile, an experimental verification system in towing water tank that had similar characteristics of designed mining pipeline was developed to verify the accuracy of the FEM models and dynamic simulation. The experiment results show that the experimental records and simulation results of stress of pipe are coincided. Based on the further simulations of 1 000 m deep-ocean mining pipeline, the simulation results show that, to form configuration of a saddle shape, the total concentrated suspension buoyancy of flexible hose should be 95%-105% of the gravity of flexible hose in water, the first suspension point occupies 1/3 of the total buoyancy, and the second suspension point occupies 2/3 of the total buoyancy. When towing velocity of mining system is less than 0.5 m/s, the towing track of buffer is coincided with the setting route of ship on the whole and the configuration of flexible hose is also kept well.
Control para máquinas de CA de imanes permanentes con FEM arbitraria, sin sensores mecánicos
De Angelo, Cristian Hernán
2004-01-01
En este trabajo de tesis se proponen nuevas soluciones a dos problemáticas de control de máquinas de corriente alterna con imanes permanentes: la minimización del ripple de par y la eliminación de sensores mecánicos de posición y/o velocidad. Para minimizar el ripple de par, producido por formas de onda de fem inducida no sinusoidales ni trapezoidales, se propone una nueva técnica para realizar la regulación de las corrientes de la máquina, basado en las ideas de control vectorial, lo que per...
FEM Simulation of Effect of Process Parameters on Static Recrystallization in 60SiMnA Spring Steel
Institute of Scientific and Technical Information of China (English)
Jiahe AI; Tongchun ZHAO; Huiju GAO; Xishan XIE
2004-01-01
Two-dimensional rigid-plastic finite element method (FEM) was used for simulation of the effect of process parameters on the static recrystallization of 60SiMnA spring steel using MARC/AutoForge 3.1 software. A thermo-mechanical coupled analysis was conducted considering the heat transfer between the workpiece, the roll and the environment, and the heat generation due to plastic work. The static recrystallization laws under different processing conditions and the predicted distribution of the static recrystallization volume fraction on the deformation cross section are presented.
Mosallanejad, Ali; Shoulaie, Abbas
2011-07-01
This paper reports a study of coil inductance profile in all positions of plunger in tubular linear reluctance motors (TLRMs) with open type magnetic circuits. In this paper, maximum inductance calculation methods in winding of tubular linear reluctance motors are described based on energy method. Furthermore, in order to calculate the maximum inductance, equivalent permeability is measured. Electromagnetic finite-element analysis for simulation and calculation of coil inductance in this motor is used. Simulation results of coil inductance calculation using 3-D FEM with coil current excitation is compared to theoretical and experimental results. The comparison yields a good agreement.
Estimation of Young’s Modulus of the Porous Titanium Alloy with the Use of Fem Package
Directory of Open Access Journals (Sweden)
Rotta G.
2015-12-01
Full Text Available Porous structures made of metal or biopolymers with a structure similar in shape and mechanical properties to human bone can easily be produced by stereolithographic techniques, e.g. selective laser melting (SLM. Numerical methods, like Finite Element Method (FEM have great potential in testing new scaffold designs, according to their mechanical properties before manufacturing, i.e. strength or stiffness. An example of such designs are scaffolds used in biomedical applications, like in orthopedics’ and mechanical properties of these structures should meet specific requirements. This paper shows how mechanical properties of proposed scaffolds can be estimated with regard to total porosity and pore shape.
Directory of Open Access Journals (Sweden)
Parker C
2014-12-01
Full Text Available Caleb Parker,1 Amy Corneli,1 Kawango Agot,2 Jacob Odhiambo,2 Jesse Asewe,2 Khatija Ahmed,3 Joseph Skhosana,3 Malebo Ratlhagana,3 Michele Lanham,1 Christina Wong,1 Jennifer Deese,1 Rachel Manongi,4 Lut Van Damme,1On behalf of the FEM-PrEP recruitment group 1FHI 360, Global Health, Population and Nutrition, Durham, NC, USA; 2Impact Research and Development Organization, Kisumu, Kenya; 3Setshaba Research Centre, Soshanguve, Pretoria, South Africa; 4Kilimanjaro Christian Medical Centre, Moshi, Tanzania Abstract: We implemented an empirically informed, geographically based recruitment approach for FEM-PrEP, a human immunodeficiency virus (HIV prevention clinical trial of daily oral emtricitabine (FTC and tenofovir disoproxil fumarate (TDF for HIV prevention. During the formative research phase, we conducted a modification of the Priorities for Local AIDS Control Efforts (PLACE method and used those data and staff experiences to identify and prioritize for recruitment geographic areas where HIV incidence might be high. During the clinical trial, we implemented a routinely monitored and flexible recruitment plan in the geographical areas identified in the formative research. We describe three lessons learnt from implementing this approach: 1 the PLACE data were critical in identifying places presumed to be high risk; 2 staff experiences, in combination with PLACE data, were needed to inform a practical recruitment strategy; and 3 recruiting in establishments in priority areas identified by the PLACE data led to screening many HIV-positive women at the Bondo site (Kenya, placing additional burden on clinic staff. These lessons learnt highlight the critical importance of having a flexible and monitored recruitment strategy. Although we successfully recruited a study population at higher risk for HIV, FEM-PrEP was unable to determine the effectiveness of FTC/TDF for HIV prevention, due to low adherence to the study product among participants. We must
FEM Analysis of Beam-coupling Impedance and RF Contacts Criticality on the LHC UA9 Piezo Goniometer
Danisi, A; Passarelli, A; Masi, A; Losito, R; Salvant, B
2014-01-01
The UA9 piezo-goniometer has been designed to guarantee micro-radians-accuracy angular positioning of a silicon crystal for a crystal collimation experiment in the LHC, and to minimize the impact on the LHC beam coupling impedance. This paper presents a Finite Element Method (FEM) study of the device, in both parking and operational positions, to evaluate its impact on the LHC impedance budget. In addition, the shielding contribution of the RF gaskets has been carefully evaluated, with the objective to assess the consequences for operation in case of their failure. A final word is drawn on the overall device impedance criticality.
Energy Technology Data Exchange (ETDEWEB)
Yao, T.; Fujikubo, M.; Yanagihara, D.; Irisawa, M. [Hiroshima University, Hiroshima (Japan). Faculty of Engineering
1997-10-01
Buckling and plastic collapse of upper decks and bottom outer plates of a hull results directly in longitudinal bending collapse of the hull. Therefore, discussions were given on analysis for pressure destruction strength of a detection control panel which assumes an upper deck and a bottom outer plate. Pressure destruction behavior of the panting panel is a complex phenomenon accompanying non-linearity and geometrical non-linearity of the materials. Its whole phenomenon may be analyzed by using the finite element method (FEM) as a principle, but the analysis is not efficient. Therefore, considerations were given in relation to modeling when using the FEM. The considerations were given on a panel attached with flat steel panting members with respect to the modeling scope which considers the buckling mode according to the aspect ratio of the panel partitioned by the deflection control members. If the local buckling mode of the panel is an even number wave mode in the longitudinal direction, a triple span model is required. A modeling scope for a case of being subjected to water pressure and in-plane compression was considered on a panel attached with angle-type steel members having non-symmetric cross section. In this case, a triple bay model is more preferable to reproduce the behavior under water pressure loading. 1 ref., 6 figs.
Analysis of whisker-toughened ceramic components - A design engineer's viewpoint
Duffy, Stephen F.; Manderscheid, Jane M.; Palko, Joseph L.
1989-01-01
The analysis of components fabricated from whisker-toughened ceramic matrix composites requires a departure from the 'factor-of-safety' design philosophy prevalent in the design of metallic structural component, which are more tolerant of flaws. A public-domain computer algorithm has been developed which, in conjunction with a general-purposed FEM program, can predict the fast-fracture reliability of a structural component under multiaxial loading conditions. The present version of the algorithm, designated 'Toughened Ceramics Analysis and Reliability Evaluation of Structures', accounts for material symmetry imposed by whisker orientation; the processes of crack deflection and crack pinning are also addressed.
Institute of Scientific and Technical Information of China (English)
周杰; 潘成海; 黎燕; 王元宁
2014-01-01
Based on the precision roll forging of one coupler yoke ,the key problems of controlling the length of precision roll forgings were researched firstly with response surface method (RSM ) and fi-nite element method (FEM ) .First of all ,in order to meet the appropriate length of roll forgings and reduce the maximum torque of roller ,the second-order analysis model combined RSM and FEM was established in FORGE3 program ,and the influences of roller clearance ,friction factor ,roller speed and billet temperature on the length of roll forgings and the maximum torque of roller were studied . Secondly ,the roll forging was simulated with optimized process parameters ,the principle of debug-ging the length of roll forgings was firstly presented ,the roll forging dies were redesigned using the principle and point anti-tracking technology ,and the lengths of designed ,simulated and produced roll forgings and the power dissipation and distribution in one roll process were analyzed .The contrastive results of optimized simulation and products indicate that using RSM and FEM can accurately and ef-fectively grasp the technology of controlling the length of precision roll forgings .%以某钩尾框精密辊锻工艺为研究对象，首次应用响应面法（RSM ）和有限元数值模拟法（FEM ）对精密辊锻件的长度控制问题进行了研究。首先以满足辊锻件长度和降低轧辊最大扭矩为目标，采用FORGE3有限元软件建立了RSM与FEM相结合的二阶分析模型，研究了轧辊间隙、摩擦因子、轧辊转速和坯料温度对辊锻件的长度和轧辊最大扭矩的显著性和影响规律；其次采用优化后的工艺参数对该辊锻工艺进行了再模拟，提出了辊锻件长度的调试原则，利用该原则和点的反追踪技术对辊锻模具进行了再设计，同时分析了设计、模拟和生产辊锻件的长度和辊锻过程的功率耗散和分布。研究结果表明：应用RSM和FEM 可准确有效地
Directory of Open Access Journals (Sweden)
Sorin-Ştefan Biriş
2009-03-01
Full Text Available It is known that the compaction phenomenon of agricultural soil can be defined as an increase in its dry density, respectively as in reduction of its porosity, and it can result from any natural causes as: rainfall impact, soaking, internal water stress from soil, and other. An important role has the artificial compaction, which is generated by the contact with tyres or caterpillars of tractors and agricultural machines. In present, one of the most advanced methods for modelling the phenomenon of stresses propagation in agricultural soil is the Finite Element Method (FEM, which is a numerical method for obtaining approximate solutions of ordinary and partial differential equations of this distribution. In this paper, the soil has been idealised as an elastic-plastic material by Drucker- Prager yield criteria. This paper presents a model for prediction of the stress state in agricultural soil below agricultural tyres in the driving direction and perpendicular to the driving direction, which are different from one another, using the Finite Element Method. General model of analysis was created using FEM, which allows the analysis of equivalent stress distribution and the total displacements distribution in the soil volume, making evident both of the conditions in which the soil compaction is favour and of the study of graphic variation of equivalent stress and the study of shifting in the depth of the soil volume. Using an acquisition data system and pressure sensors, the theoretical model was experimentally checked in the laboratory.
3D-FEM electrical-thermal-mechanical analysis and experiment of Si-based MEMS infrared emitters
Wang, Xiang; Wang, Na; Chen, Ran-Bin; San, Hai-Sheng; Chen, Xu-Yuan
2016-11-01
Designs, simulations, and fabrications of silicon-based MEMS infrared (IR) emitters for gas sensing application are presented. A 3D finite element method (3D-FEM) was used to analyze the coupled electrical-thermal-mechanical properties of a bridge hotplate structure (BHS) IR emitter and closed hotplate structure (CHS) IR emitter using Joule heating and thermal expansion models of COMSOL™. The IR absorptions of n- and p-silicon were calculated for the design of self-heating structure. The BHS and CHS IR emitters were fabricated synchronously using micro-electromechanical systems technology for a direct performance comparison. Both types of IR emitters were characterized by electrical and optical measurements. The experimental results show that BHS IR emitters have higher radiation density, lower power consumption, and faster frequency-response than CHS IR emitters due to the use of a thermal isolation structure and self-heating structure. Meanwhile, the simulated results agree well with the corresponding measured results, which indicate that the 3D-FEM-model is effective and can be used in the optimal design of electro-thermal devices.
Faugeras, Blaise; Heumann, Holger
2017-08-01
Incorporating boundary conditions at infinity into simulations on bounded computational domains is a repeatedly occurring problem in scientific computing. The combination of finite element methods (FEM) and boundary element methods (BEM) is the obvious instrument, and we adapt here for the first time the two standard FEM-BEM coupling approaches to the free-boundary equilibrium problem: the Johnson-Nédélec coupling and the Bielak-MacCamy coupling. We recall also the classical approach for fusion applications, dubbed according to its first appearance von-Hagenow-Lackner coupling and present the less used alternative introduced by Albanese, Blum and de Barbieri in [2]. We show that the von-Hagenow-Lackner coupling suffers from undesirable non-optimal convergence properties, that suggest that other coupling schemes, in particular Johnson-Nédélec or Albanese-Blum-de Barbieri are more appropriate for non-linear equilibrium problems. Moreover, we show that any of such coupling methods requires Newton-like iteration schemes for solving the corresponding non-linear discrete algebraic systems.
Maciejewska, Beata; Łabędzki, Paweł; Piasecki, Artur; Piasecka, Magdalena
The paper presents the methods of heat transfer coefficient determination for boiling research during FC-72 flow in a minichannel. The boundary condition in the form of distributions of temperature on the outer side of the minichannel heated wall was obtained using infrared thermography. It was assumed two-dimensional steady-state heat flow. The local values of the heat transfer coefficients on the surface between the heated foil and boiling liquid, were determined from the Robin boundary condition. Data necessary for the heat transfer coefficient evaluation were obtained from numerical computations using two approaches: calculation procedure based on the Trefftz functions and FEM simulations by ADINA software. The shape functions were linear combinations of the Trefftz functions. Combinations of the Trefftz functions exactly satisfy the differential equation. Coefficients of the linear combination of the shape function in the approximate solution were chosen to minimize residuals on domain boundary and along common edges of adjacent elements. Temperature measurement points were located in boundary nodes. During FEM simulations 4-node FCBI elements were used, fluid flow was assumed to be laminar, incompressible and material constants of the fluid and of the foil were independent on temperature. The results of the comparative analysis were presented and discussed.
FEM3C, An improved three-dimensional heavy-gas dispersion model: User`s manual
Energy Technology Data Exchange (ETDEWEB)
Chan, S.T.
1994-03-01
FEM3C is another upgraded version of FEM3 (a three-dimensional Finite Element Model), which was developed primarily for simulating the atmospheric dispersion of heavier-than-air gas (or heavy gas) releases, based on solving the fully three-dimensional, time-dependent conservation equations of mass, momentum, energy, and species of an inert gas or a pollutant in the form of vapor/droplets. A generalized anelastic approximation, together with the ideal gas law for the density of the gas/air mixture, is invoked to preclude sound waves and allow large density variations in both space and time. Thee numerical algorithm utilizes a modified Galerkin finite element method to discretize spatially the time-dependent conservation equations of mass, momentum, energy, and species. A consistent pressure Poisson equation is formed and solved separately from the time-dependent equations, which are sequentially solved and integrated in time via a modified forward Euler method. The model can handle instantaneous source, finite-duration, and continuous releases. Also, it is capable of treating terrain and obstructions. Besides a K-theory model using similarity functions, an advanced turbulence model based on solving the k - {var_epsilon} transport equations is available as well. Imbedded in the code are also options for solving the Boussinesq equations. In this report, an overview of the model is given, user`s guides for using the model are provided, and example problems are presented to illustrate the usage of the model.
Energy Technology Data Exchange (ETDEWEB)
Bouzakis, K.D.; Michailidis, N.; Hadjiyiannis, S.; Skordaris, G. [Mechanical Engineering Dept., Aristoteles Univ. of Thessaloniki (Greece); Erkens, G. [CemeCon AG, Wuerselen (Germany)
2002-09-01
The precise knowledge of materials mechanical properties is always a core issue in every technical application. Through a developed finite elements method (FEM) continuous simulation of the nanoindentation, the applied force course versus the penetration depth is adequately simulated during the loading and unloading phases of this test, and the corresponding material stress-strain curves, as well as the universal hardness, are stepwise defined. Furthermore, the actual tip geometries of various indenters are approached and through equivalent magnitudes described. The results show that the defined material elastoplastic deformation characteristics are independent of the indenter type, as Vickers or Berkovich, since the existing indenter tip form deviations from their ideal geometry are considered. Furthermore, using the developed FEM-based nanoindentation simulation, the influence of the indenter tip geometry on the defined constitutive laws and the universal hardness is sufficiently elucidated. Various materials stress-strain curves and universal hardness courses versus the indentation depth, determined by means of the developed procedure, are presented. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Chung, Y.D., E-mail: ydchung@suwon.ac.kr [Department of Electrical Engineering, Suwon University, Bongdang Eup, Hwaseong Si 445-743 (Korea, Republic of); Lee, C.Y. [Korea Railroad Research Institute, Woram Dong, Uiwang Si 437-757 (Korea, Republic of); Jang, J.Y. [Department of Electrical Engineering, Ansan College of Technology, Choji-Dong, Ansan Si 425-792 (Korea, Republic of); Yoon, Y.S. [Department of Electrical and Electronic Engineering, Yonsei University, Sinchon-dong, Seoul 120-749 (Korea, Republic of); Ko, T.K. [Department of Electrical Engineering, Ansan College of Technology, Choji-Dong, Ansan Si 425-792 (Korea, Republic of)
2011-11-15
We examine levitation and propulsion forces of the proto-type maglev vehicle system based on 3D FEM. The levitation force increases over 15% due to AC current of the guideway. The levitation force by HTS electromagnet (EM) and AC current is larger over 30% than that of only HTS EM. We have been constructed a proto-type electromagnetic suspension (EMS) based maglev vehicle system. The maglev concept utilizes magnetic forces for noncontact suspension, guidance and propulsion. The suspension system with high temperature superconducting (HTS) hybrid electromagnet (EM) is composed of HTS coils and normal coils, which consume little power to keep large suspension gap. The magnetic forces realize to guide the vehicle, propel the vehicle along the guide-way and assist in braking action. The proto-type EMS-based Maglev model is designed to keep the suspension gap of 20 mm. This paper presents the theoretical analysis of the maglev vehicle based on the EMS model to obtain the designing parameters for levitation and propulsion forces. The magnetic field distributions of the electromagnetic forces with hybrid EM and propulsion stator coils are analyzed based on three dimension (3D) finite element method (FEM) analysis. From the simulation results, appropriately design parameters of the suspension, guidance and propulsion were obtained.
Directory of Open Access Journals (Sweden)
M. Schick
2004-01-01
Full Text Available Am Beispiel der Verkopplung von medizinischen Geräten über den menschlichen Körper werden elektromagnetische Störphänomene im Klinikbereich betrachtet. Für die Berechnung dieser komplexen Szenarien wird zum einen die Momentenmethode (MoM verwendet, die sich in besonderem Maße für die Berücksichtigung metallischer Strukturen und offener Streuprobleme eignet, und zum anderen die Methode der Finiten Elemente (FEM, mit der die Eigenschaften des menschlichen Körpers besser berücksichtigt werden können. Mit Hilfe des Äquivalenzprinzips lässt sich das Gesamtproblem in zwei Teile zerlegen, in ein inneres und in ein äußeres. Der Außenraum wird dabei mit der MoM behandelt und das Innere, d.h. der Körper mit der FEM. Die Kopplung der beiden Methoden erfolgt an der Körperoberfläche über äquivalente Oberflächenströme. Durch Lösen des resultierenden linearen Gleichungssystems für das gesamte Problem lassen sich dann die Oberflächenströme und die über die Kontinuitätsgleichung miteinander verknüpften elektromagnetischen Felder bestimmen.
Directory of Open Access Journals (Sweden)
Maciejewska Beata
2017-01-01
Full Text Available The paper presents the methods of heat transfer coefficient determination for boiling research during FC-72 flow in a minichannel. The boundary condition in the form of distributions of temperature on the outer side of the minichannel heated wall was obtained using infrared thermography. It was assumed two-dimensional steady-state heat flow. The local values of the heat transfer coefficients on the surface between the heated foil and boiling liquid, were determined from the Robin boundary condition. Data necessary for the heat transfer coefficient evaluation were obtained from numerical computations using two approaches: calculation procedure based on the Trefftz functions and FEM simulations by ADINA software. The shape functions were linear combinations of the Trefftz functions. Combinations of the Trefftz functions exactly satisfy the differential equation. Coefficients of the linear combination of the shape function in the approximate solution were chosen to minimize residuals on domain boundary and along common edges of adjacent elements. Temperature measurement points were located in boundary nodes. During FEM simulations 4-node FCBI elements were used, fluid flow was assumed to be laminar, incompressible and material constants of the fluid and of the foil were independent on temperature. The results of the comparative analysis were presented and discussed.
Energy Technology Data Exchange (ETDEWEB)
Coppol, R. [ENEA - Casaccia, FPN, CP Roma (Italy); Asserin, O. [CEA Saclay, 91 - Gif sur Yvette (France); Hughes, D.J. [Institut Max von Laue - Paul Langevin, 38 - Grenoble (France)
2007-07-01
Full text of publication follows: A reliable characterization of residual strains and stresses is a crucial step in the development of high quality welds for Helium-Cooled-Lithium-Lead (HCLL) blanket modules for DEMO. This contribution will present the first results of a comparative study, carried out using Finite Element Model (FEM) calculations and neutron diffraction measurements to determine the strain and stress field in an Eurofer97 (9Cr, 0.01C, 1W, 0.2V Fe bal wt%) prototype laser weld. The neutron diffraction measurements were carried out at the SALSA diffractometer at the High Flux Reactor of the Institut Max von Laue-Paul Langevin, Grenoble, France. A diffracting volume of approximately 1 x 1 x 5 mm{sup 3} was defined, giving appropriate neutron counting times and allowing a significant comparison with the material volume sampled by FEM. The measurements were carried out at various distances from the weld and within the Heat Affected Zone (HAZ), where the analysis of the detected diffraction line-widths provides information on the metallurgic phases produced during the heat treatment. The neutron diffraction results are compared with the theoretical calculations in view of providing them with an experimental validation. (authors)
Directory of Open Access Journals (Sweden)
Yue-Ming Gao
2016-04-01
Full Text Available Existing research on human channel modeling of galvanic coupling intra-body communication (IBC is primarily focused on the human body itself. Although galvanic coupling IBC is less disturbed by external influences during signal transmission, there are inevitable factors in real measurement scenarios such as the parasitic impedance of electrodes, impedance matching of the transceiver, etc. which might lead to deviations between the human model and the in vivo measurements. This paper proposes a field-circuit finite element method (FEM model of galvanic coupling IBC in a real measurement environment to estimate the human channel gain. First an anisotropic concentric cylinder model of the electric field intra-body communication for human limbs was developed based on the galvanic method. Then the electric field model was combined with several impedance elements, which were equivalent in terms of parasitic impedance of the electrodes, input and output impedance of the transceiver, establishing a field-circuit FEM model. The results indicated that a circuit module equivalent to external factors can be added to the field-circuit model, which makes this model more complete, and the estimations based on the proposed field-circuit are in better agreement with the corresponding measurement results.
FEM based prediction of phase transformations during Friction Stir Welding of Ti6Al4V titanium alloy
Energy Technology Data Exchange (ETDEWEB)
Buffa, Gianluca, E-mail: gianluca.buffa@unipa.it; Ducato, Antonino, E-mail: antonino.ducato@unipa.it; Fratini, Livan, E-mail: livan.fratini@unipa.it
2013-10-01
Friction Stir Welding (FSW) is a solid state welding process patented in 1991 by TWI; initially adopted to weld aluminum alloys, it is now being successfully used also for high resistant materials. Welding of titanium alloys by traditional fusion welding techniques presents several difficulties due to high material reactivity with oxygen, hydrogen, and nitrogen with consequent embrittlement of the joint. In this way FSW represents a cost effective and high quality solution. The final mechanical properties of the joints are strictly connected to the microstructural evolutions, in terms of phase change, occurring during the process. In the paper a 3D FEM model of the FSW welding process, based on a thermo-mechanical fully coupled analysis, is presented. The model, tuned both for the thermo-mechanical analysis and the phase transformation through experimental data, is able to predict the phase volume fraction in the typical zones of the joints at the varying of the main process parameters. The obtained results permit to assess that the tuned FEM model of the FSW process can be utilized as an effective design tool.
FEM Simulation and Experimental Validation of LBW Under Conduction Regime of Ti6Al4V Alloy
Churiaque, C.; Amaya-Vazquez, M. R.; Botana, F. J.; Sánchez-Amaya, J. M.
2016-08-01
Laser Beam Welding (LBW) is an advanced process to join materials with a laser beam of high energy density. LBW is especially suitable to join titanium alloys, as it allows high localization and low size of the melting pool, reducing considerably the energy of the process, in comparison with other welding technologies. Among the two widely known welding regimes, conduction and keyhole, the former is claimed to be a viable alternative to keyhole, mainly because it is a very stable process, provides high-quality welds free of defects, and involves lower laser cost. In the present work, a Finite Element Method (FEM) has been developed to simulate the LBW of Ti6Al4V alloy under conduction regime. The "Goldak double ellipsoid model" has been taken for the first time to simulate this LBW conduction process. In order to refine and validate the model, experimental conduction welding tests were performed on Ti6Al4V pieces with a high-power diode laser. Microstructural analyses and hardness measurements were also performed on the laser weld beads to identify the generated phases. Distortion and residual stresses were also obtained from the FEM simulations. An excellent agreement between the simulation and experimental results was found regarding the bead morphology and phase transformations.
Gao, Yue-Ming; Wu, Zhu-Mei; Pun, Sio-Hang; Mak, Peng-Un; Vai, Mang-I; Du, Min
2016-04-02
Existing research on human channel modeling of galvanic coupling intra-body communication (IBC) is primarily focused on the human body itself. Although galvanic coupling IBC is less disturbed by external influences during signal transmission, there are inevitable factors in real measurement scenarios such as the parasitic impedance of electrodes, impedance matching of the transceiver, etc. which might lead to deviations between the human model and the in vivo measurements. This paper proposes a field-circuit finite element method (FEM) model of galvanic coupling IBC in a real measurement environment to estimate the human channel gain. First an anisotropic concentric cylinder model of the electric field intra-body communication for human limbs was developed based on the galvanic method. Then the electric field model was combined with several impedance elements, which were equivalent in terms of parasitic impedance of the electrodes, input and output impedance of the transceiver, establishing a field-circuit FEM model. The results indicated that a circuit module equivalent to external factors can be added to the field-circuit model, which makes this model more complete, and the estimations based on the proposed field-circuit are in better agreement with the corresponding measurement results.
Isakari, Hiroshi; Kondo, Toyohiro; Takahashi, Toru; Matsumoto, Toshiro
2017-03-01
This paper presents a structural optimisation method in three-dimensional acoustic-elastic coupled problems. The proposed optimisation method finds an optimal allocation of elastic materials which reduces the sound level on some fixed observation points. In the process of the optimisation, configuration of the elastic materials is expressed with a level set function, and the distribution of the level set function is iteratively updated with the help of the topological derivative. The topological derivative is associated with state and adjoint variables which are the solutions of the acoustic-elastic coupled problems. In this paper, the acoustic-elastic coupled problems are solved by a BEM-FEM coupled solver, in which the fast multipole method (FMM) and a multi-frontal solver for sparse matrices are efficiently combined. Along with the detailed formulations for the topological derivative and the BEM-FEM coupled solver, we present some numerical examples of optimal designs of elastic sound scatterer to manipulate sound waves, from which we confirm the effectiveness of the present method.
Energy Technology Data Exchange (ETDEWEB)
Sarajaervi, U.; Cronvall, O. [VTT (Finland)
2007-03-15
Fatigue is produced by cyclic application of stresses by mechanical or thermal loading. The metal subjected to fluctuating stress will fail at stresses much lower than those required to cause fracture in a single application of load. The key parameters are the range of stress variation and the number of its occurrences. Low-cycle fatigue, usually induced by mechanical and thermal loads, is distinguished from high-cycle fatigue, mainly associated with vibration or high number of small thermal fluctuations. Numerical models describing fatigue behaviour of austenitic stainless piping steels under cyclic loading and their applicability for modelling of low-cycle-fatigue are discussed in this report. In order to describe the cyclic behaviour of the material for analysis with finite element method (FEM) based analysis code ABAQUS, the test data, i.e. stress-strain curves, have to be processed. A code to process the data all through the test duration was developed within this study. A description of this code is given also in this report. Input data for ABAQUS was obtained to describe both kinematic and isotropic hardening properties. Further, by combining the result data for various strain amplitudes a mathematic expression was be created which allows defining a parameter surface for cyclic (i.e. isotropic) hardening. Input data for any strain amplitude within the range of minimum and maximum strain amplitudes of the test data can be assessed with the help of the developed 3D stress-strain surface presentation. The modelling of the fatigue induced initiation and growth of cracks was not considered in this study. On the other hand, a considerable part of the fatigue life of nuclear power plant (NPP) piping components is spent in the phase preceding the initiation and growth of cracks. (au)
Scattering from the Quasi-Optical Ferrite Circulator Using a Coupled Integral Equation/FEM Solution
Epp, L. W.; Hoppe, D. J.; Chinn, G. C.; Lee, J.
1994-01-01
Ferrite materials are used in microwave devices that exploit the property of Faraday rotation to give non-reciprocal behavior. Examples of common waveguide components that use ferrite materials include circulators, isolators and gyrators.
Masterlark, Timothy; Lu, Zhong; Rykhus, Russell P.
2006-01-01
Interferometric synthetic aperture radar (InSAR) imagery documents the consistent subsidence, during the interval 1992–1999, of a pyroclastic flow deposit (PFD) emplaced during the 1986 eruption of Augustine Volcano, Alaska. We construct finite element models (FEMs) that simulate thermoelastic contraction of the PFD to account for the observed subsidence. Three-dimensional problem domains of the FEMs include a thermoelastic PFD embedded in an elastic substrate. The thickness of the PFD is initially determined from the difference between post- and pre-eruption digital elevation models (DEMs). The initial excess temperature of the PFD at the time of deposition, 640 °C, is estimated from FEM predictions and an InSAR image via standard least-squares inverse methods. Although the FEM predicts the major features of the observed transient deformation, systematic prediction errors (RMSE = 2.2 cm) are most likely associated with errors in the a priori PFD thickness distribution estimated from the DEM differences. We combine an InSAR image, FEMs, and an adaptive mesh algorithm to iteratively optimize the geometry of the PFD with respect to a minimized misfit between the predicted thermoelastic deformation and observed deformation. Prediction errors from an FEM, which includes an optimized PFD geometry and the initial excess PFD temperature estimated from the least-squares analysis, are sub-millimeter (RMSE = 0.3 mm). The average thickness (9.3 m), maximum thickness (126 m), and volume (2.1 × 107m3) of the PFD, estimated using the adaptive mesh algorithm, are about twice as large as the respective estimations for the a priori PFD geometry. Sensitivity analyses suggest unrealistic PFD thickness distributions are required for initial excess PFD temperatures outside of the range 500–800 °C.
Design and optimization of the CFRP mirror components
Wei, Lei; Zhang, Lei; Gong, Xiaoxue
2017-09-01
As carbon fiber reinforced polymer (CFRP) material has been developed and demonstrated as an effective material in lightweight telescope reflector manufacturing recently, the authors of this article have extended to apply this material on the lightweight space camera mirror design and fabrication. By CFRP composite laminate design and optimization using finite element method (FEM) analysis, a spherical mirror with φ316 mm diameter whose core cell reinforcement is an isogrid configuration is fabricated. Compared with traditional ways of applying ultra-low-expansion glass (ULE) on the CFRP mirror surface, the method of nickel electroplating on the surface effectively reduces the processing cost and difficulty of the CFRP mirror. Through the FEM analysis, the first order resonance frequency of the CFRP mirror components reaches up to 652.3 Hz. Under gravity affection coupling with +5°C temperature rising, the mirror surface shape root-mean-square values (RMS) at the optical axis horizontal state is 5.74 nm, which meets mechanical and optical requirements of the mirror components on space camera.
La enseñanza del concepto de fem en el contexto de la inducción electromagnética
Oyuela, Diana ; Garzón Isabel ; Zambrano, Tufik
2015-01-01
En el presente trabajo se describe la monografía titulada “La enseñanza del concepto de fem en el contexto de la inducción electromagnética”, en la cual se desarrolló una secuencia de enseñanza; con el propósito de presentar una alternativa para enseñar el concepto de fem inducida, respaldada en un estudio teórico entorno al concepto y una reflexión acerca de los elementos que componen el proceso de enseñanza-aprendizaje; hecha a través del modelo de aprendizaje como invest...
Frakturerede fortænder – behandling med direkte plast
DEFF Research Database (Denmark)
Pallesen, Ulla; van Dijken, Jan WV
2017-01-01
. Klasse IV fyldninger har kortere holdbarhed end fuldkeramiske - og metalkeramikkroner. Holdbarheden er blevet forbedret med nyere materialer og adhæsiver. En plastopbygning af en fraktureret tand er mere konservativ for både tandsubstans, pulpa og det omgivende blødtvæv end en krone. Taget i betragtning...
Alvor og direkte injicerbar livsglæde
DEFF Research Database (Denmark)
Prinds, Christina
2014-01-01
Rejseklumme fra 30th Triennial Congress of International Confederation of Midwives: Improving Womens Health Globally......Rejseklumme fra 30th Triennial Congress of International Confederation of Midwives: Improving Womens Health Globally...
Hvorfor blev Amagerbankens bestyrelse og direktion blankt frifundet?
DEFF Research Database (Denmark)
Werlauff, Erik
2017-01-01
, og i 7 af disse sager blev der indledt erstatningssager mod bankens ledelse eller dele af denne. Det drejer sig om følgende banker (med de påstævnte beløb i parentes): Roskilde Bank (1 mia. kr.), Capinordic Bank (400 mio. kr.), EBH Bank (700 mio. kr.), Amagerbanken (800 mio. kr.), Eik Bank Danmark...... (250 mio. kr.), Eik Bank Færøerne (150 mio. kr.) og Løkken Sparekasse (275 mio. kr.). Med det forbehold, at Højesteret endnu ikke har udtalt sig, ser mønsteret i de hidtil pådømte sager ud som følger, jf. Capinordic-dommen (Østre Landsrets påankede dom af 9. oktober 2015, 13. afdeling nr. B-876-11) og...
Gong, J.; Ozdemir, T.; Volakis, J; Nurnberger, M.
1995-01-01
Year 1 progress can be characterized with four major achievements which are crucial toward the development of robust, easy to use antenna analysis code on doubly conformal platforms. (1) A new FEM code was developed using prismatic meshes. This code is based on a new edge based distorted prism and is particularly attractive for growing meshes associated with printed slot and patch antennas on doubly conformal platforms. It is anticipated that this technology will lead to interactive, simple to use codes for a large class of antenna geometries. Moreover, the codes can be expanded to include modeling of the circuit characteristics. An attached report describes the theory and validation of the new prismatic code using reference calculations and measured data collected at the NASA Langley facilities. The agreement between the measured and calculated data is impressive even for the coated patch configuration. (2) A scheme was developed for improved feed modeling in the context of FEM. A new approach based on the voltage continuity condition was devised and successfully tested in modeling coax cables and aperture fed antennas. An important aspect of this new feed modeling approach is the ability to completely separate the feed and antenna mesh regions. In this manner, different elements can be used in each of the regions leading to substantially improved accuracy and meshing simplicity. (3) A most important development this year has been the introduction of the perfectly matched interface (PMI) layer for truncating finite element meshes. So far the robust boundary integral method has been used for truncating the finite element meshes. However, this approach is not suitable for antennas on nonplanar platforms. The PMI layer is a lossy anisotropic absorber with zero reflection at its interface. (4) We were able to interface our antenna code FEMA_CYL (for antennas on cylindrical platforms) with a standard high frequency code. This interface was achieved by first generating
Energy Technology Data Exchange (ETDEWEB)
Flegr, M.; Koerner, J. (Tuebingen Univ. (Germany, F.R.). Inst. fuer Geologie und Palaeontologie); Monn, L. (Hohenheim Univ., Stuttgart (Germany, F.R.). Inst. fuer Bodenkunde und Standortslehre)
1989-01-01
For four typical sites with beech and/or spruce stands, budgets were established in 1985-1986 for their turnovers of H, Na, Mg, K, Ca, Cl, NO{sub 3}, NH{sub 4}, SO{sub 4}, HCO{sub 3} as well as for Fe, Mn, Zn, Cu, Pb, Cd and Ni from atmospheric uptake with both precipitations in the field and on the site (including stemflow water for beech), and from the dicharges from sites or areas including interflow, leachate, well water and brook water. Investigations regarding the effects deal with nitrogen mineralization in the main rhizospheres of the sites and with the distribution of nutrients and pollutants to plants or parts of plants, leaves, needles, and roots of forest trees and to shoots of herbs as well as to the rhizosphere and soil or soil layers also in sites without tree injury or with moderate to severe tree injury in the Black Forest and the lower ranges of the Swabian Jura. (orig./MG).
FEM Computations Concerning the Effect of Friction in Two LHC Main Dipole Structures
Bajko, M; Perini, D
2000-01-01
The mechanical behaviour of a dipole structure is considered when also friction is taken into account, studying its effect on different components and in different conditions. In particular the difference in behavior between a structure with aluminium collars and one with austenitic steel ones was studied.
Institute of Scientific and Technical Information of China (English)
覃文洁; 张儒华; 左正兴
2004-01-01
The adaptive FEM analysis of the temperature field of the piston in one diesel engine is given by using the ANSYS software. By making full use of the post results provided by the software, the posteriori error estimation and adaptive accuracy meshing algorithm is developed. So the blindness of the mesh design through experiences can be avoided, and the accuracy requirement is adapted to the relative temperature gradient distribution across the entire domain. Therefore the meshes and solutions can be obtained at the same time. Based on the temperature field analysis, the thermal stress and deformation fields are calculated as well. The results show that the stress concentrates on the edge of the piston pin boss and the inside surface of the first ring groove, and the deformation of the head of the piston is greatest. But the difference between the long and short axes of the bottom cross section is greatest.
Zurek, Stan
2017-08-01
The paper introduces a theoretical concept of a shielding for horizontal yokes for measurements of rotational power loss and other rotational and two-dimensional properties. Apart from horizontal parts, the shielding relies on vertical pieces distributed uniformly around the sample circumference, symmetrically on both sides. The simulations in 2D and 3D FEM show significant improvement in reduction of H perpendicular to the sample surface (Hz). The gradient of the tangential H is reduced so that the extrapolation of values towards the surface might be no longer required. There is also an added benefit that the required magnetomotive force is significantly lower (20-70%) for achieving the same B in the sample, as compared to the previously used simple horizontal shields.
Energy Technology Data Exchange (ETDEWEB)
Park, Chan Yuk; Sung, Jin Ho; Jeong, Jong Seob [Dept. of Medical Biotechnology, Dongguk University Biomedi Campus, Goyang (Korea, Republic of)
2015-04-15
In this paper, a linear-array transducer capable of overcoming the faults of a single element and phased array transducers with convex shape for non-destructive ultrasonic testing was designed and fabricated. A 5.5 MHz linear-array transducer was designed using the PiezoCAD program based on the KLM analysis and the PZFlex program based on the FEM analysis. A 2-2 composite structure was employed to achieve broad-band characteristics. A 128 element linear-array transducer was fabricated and its performance was compared with the simulation results. The center frequency of the fabricated transducer was 5.5 Mhzand the -6 dB frequency bandwidth was 70 %. Thus, we expect that the designed transducer can provide an effective inner image of the test material during non-destructive ultrasonic testing.
Directory of Open Access Journals (Sweden)
Ionescu Viorel
2016-01-01
Full Text Available Proton Exchange Membrane Fuel Cells (PEMFC are highly efficient power generators, achieving up to 50–60% conversion efficiency, even in sizes of a few kilowatts. Comsol Multiphysics, a commercial solver based on the Finite Element Method (FEM was used for developing a three dimensional model of a high temperature PEMFC that can deal with both anode and cathode flow field for examining the micro flow channel with electrochemical reaction. Cathode gas flow velocity influence on the cell performance was investigated at first. Polarization curves for three different channel widths (0.8, 1.6 and 2.4 mm and three different channel depths (1, 2 and 3 mm were computed at a cathode inlet flow velocity of 0.06 m/s. Oxygen molar concentration at cathode catalyst layer-GDL channel interface and local current density variation along the cell length were also studied for specific gas channel geometries.
Structural FEM analysis of the strut-to-fuselage joint of a two-seat composite aircraft
Energy Technology Data Exchange (ETDEWEB)
Vargas-Rojas, Erik, E-mail: erikvargasrojas@hotmail.com; Camarena-Arellano, Diego, E-mail: erikvargasrojas@hotmail.com; Hernández-Moreno, Hilario, E-mail: erikvargasrojas@hotmail.com [IPN, ESIME Ticomán, Av. Ticomán 600, Col. San José Ticomán 07340 (Mexico)
2014-05-15
An analysis of a strut-to-fuselage joint is realized in order to evaluate the zones with a high probability of failure by means of a safety factor. The whole section is analyzed using the Finite Element Method (FEM) so as to estimate static resistance behavior, therefore it is necessary a numerical mock-up of the section, the mechanical properties of the Carbon-Epoxy (C-Ep) material, and to evaluate the applied loads. Results of the analysis show that the zones with higher probability of failure are found around the wing strut and the fuselage joint, with a safety factor lower than expected in comparison with the average safety factor used on aircrafts built mostly with metals.
Effect of crack on the impact response of plates by the extended finite element method (X-FEM)
Energy Technology Data Exchange (ETDEWEB)
Tiberkak, Rachid [University of Blida, Soumaa (Algeria); Bachene, Mourad [University of Medea, Medea (Algeria); Rechak, Said [Ecole Nationale Polytechnique, Algiers (Algeria)
2014-06-15
The dynamic response of cracked isotropic plates subjected to impact loading is studied in this paper. The impact properties of cracked plate are compared with the virgin ones to predict the eventual presence of discontinuities in plates. The extended finite element method (X-FEM) is employed in the mathematical modeling of the impact problem, wherein the effects of shear deformation is considered. Conventional finite element without any discontinuity is initially conducted in the numerical implementation. Enriched functions are then added to the nodal displacement field for element nodes that contain cracks. The effects of crack length and crack position on contact force and on plate deflection are analyzed. Results show that the maximal contact force decreases as the deflection increases with increasing crack length a . The effect of crack position on the dynamic response is less pronounced when the crack is near the fixed end.
Directory of Open Access Journals (Sweden)
Maciejewska Beata
2012-04-01
Full Text Available The paper presents the FEM method for determination of boiling heat transfer coefficient in cooling liquid flow in a rectangular minichannel with asymmetric heating. Experimental research has focused on the transition from single phase forced convection to nucleate boiling, i.e. the zone of boiling incipience. The “boiling front” location has been determined from the temperature distribution of the heated wall obtained from liquid crystal thermography. The main part of the test section has been a minichannel of pre-set depth from 0.7 to 2.0 mm, of different spatial orientations. Local values of heat transfer coefficient have been determined following the solution of the two-dimensional inverse heat transfer problem. This problem has been solved with the use of Trefftz functions. Trefftz functions have been used to construct base functions in the finite element method (FEMT.
Enhanced super-radiant emission of FEM near waveguide-cutoff and near zero-slippage conditions
Arbel, M; Pinhasi, Y; Lurie, Y; Abramovich, A; Kleinman, H; Yakover, I M; Gover, A
2002-01-01
We report on super-radiance obtained from the TAU FEM just above waveguide cutoff and near grazing intersection. Grazing intersection (or ''Zero Slippage'') is defined as the point at which the two synchronous frequencies merge to one frequency. In this case, the radiated power frequency can be tuned over a very wide band by change of the pre-modulation frequency. Near the lower synchronous frequency, the super-radiance power is much greater and the spectral width is much narrower than those at the higher synchronous frequency. The super-radiance emission near cutoff (lower synchronous frequency) and near to the upper synchronous frequency was measured and compared to those predicted by an analytical model for a wide range of frequencies.
Directory of Open Access Journals (Sweden)
Muhammad Anwer Solangi
2013-04-01
Full Text Available Inelastic behaviour of blood is predicted by employing Power law and Carreau model along partially blocked capillaries. Numerical results for stream function have been computed for predicting the reattachment length and intensity in the capillaries at various levels of obstacle and inertia. The predicted results obtained by employing FEM (Finite Element Method under semi-implicit Taylor-Galerkin/ pressure-correction scheme. The numerical results have been quantified in terms of reattachment length and intensity, which illustrates that their formation takes place in the downstream of a capillary segment and augment in length as increases inertia or obstacle level. The obtained results are match able with analytical results. This study is accommodating for developing devices related to heart diseases in future
DEFF Research Database (Denmark)
Nakamura, T; Bay, Niels
1998-01-01
A new friction testing method based on combined forward conical can-backward straight can extrusion is proposed in order to evaluate friction characteristics in severe metal forming operations. By this method the friction coefficient along the conical punch surface is determined knowing...... the friction coefficient along the die wall. The latter is determined by a combined forward and backward can extrusion of straight cans. Calibration curves determining the relationship between punch travel, can heights, and friction coefficient for the two rests are calculated based on a rigid-plastic FEM...... analysis. Experimental friction tests are carried out in a mechanical press with aluminium alloy A6061 as the workpiece material and different kinds of lubricants. They confirm that the theoretical analysis results irt reasonable values for the friction coefficient....
Structural FEM analysis of the strut-to-fuselage joint of a two-seat composite aircraft
Vargas-Rojas, Erik; Camarena-Arellano, Diego; Hernández-Moreno, Hilario
2014-05-01
An analysis of a strut-to-fuselage joint is realized in order to evaluate the zones with a high probability of failure by means of a safety factor. The whole section is analyzed using the Finite Element Method (FEM) so as to estimate static resistance behavior, therefore it is necessary a numerical mock-up of the section, the mechanical properties of the Carbon-Epoxy (C-Ep) material, and to evaluate the applied loads. Results of the analysis show that the zones with higher probability of failure are found around the wing strut and the fuselage joint, with a safety factor lower than expected in comparison with the average safety factor used on aircrafts built mostly with metals.
Hartmann, Timo; Tanner, Gregor; Xie, Gang; Chappell, David; Bajars, Janis
2016-09-01
Dynamical Energy Analysis (DEA) combined with the Discrete Flow Mapping technique (DFM) has recently been introduced as a mesh-based high frequency method modelling structure borne sound for complex built-up structures. This has proven to enhance vibro-acoustic simulations considerably by making it possible to work directly on existing finite element meshes circumventing time-consuming and costly re-modelling strategies. In addition, DFM provides detailed spatial information about the vibrational energy distribution within a complex structure in the mid-to-high frequency range. We will present here progress in the development of the DEA method towards handling complex FEM-meshes including Rigid Body Elements. In addition, structure borne transmission paths due to spot welds are considered. We will present applications for a car floor structure.
Gao, Kai; Gibson, Richard L; Chung, Eric T; Efendiev, Yalchin
2014-01-01
It is important to develop fast yet accurate numerical methods for seismic wave propagation to characterize complex geological structures and oil and gas reservoirs. However, the computational cost of conventional numerical modeling methods, such as finite-difference method and finite-element method, becomes prohibitively expensive when applied to very large models. We propose a Generalized Multiscale Generalized Multiscale Finite-Element Method (GMsFEM) for elastic wave propagation in heterogeneous, anisotropic media, where we construct basis functions from multiple local problems for both boundaries and the interior of a coarse node support or coarse element. The application of multiscale basis functions can capture the fine scale medium property variations, and allows us to greatly reduce the degrees of freedom that are required to implement the modeling compared with conventional finite-element method for wave equation, while restricting the error to low values. We formulate the continuous Galerkin and di...
Application of multi-thread computing and domain decomposition to the 3-D neutronics Fem code Cronos
Energy Technology Data Exchange (ETDEWEB)
Ragusa, J.C. [CEA Saclay, Direction de l' Energie Nucleaire, Service d' Etudes des Reacteurs et de Modelisations Avancees (DEN/SERMA), 91 - Gif sur Yvette (France)
2003-07-01
The purpose of this paper is to present the parallelization of the flux solver and the isotopic depletion module of the code, either using Message Passing Interface (MPI) or OpenMP. Thread parallelism using OpenMP was used to parallelize the mixed dual FEM (finite element method) flux solver MINOS. Investigations regarding the opportunity of mixing parallelism paradigms will be discussed. The isotopic depletion module was parallelized using domain decomposition and MPI. An attempt at using OpenMP was unsuccessful and will be explained. This paper is organized as follows: the first section recalls the different types of parallelism. The mixed dual flux solver and its parallelization are then presented. In the third section, we describe the isotopic depletion solver and its parallelization; and finally conclude with some future perspectives. Parallel applications are mandatory for fine mesh 3-dimensional transport and simplified transport multigroup calculations. The MINOS solver of the FEM neutronics code CRONOS2 was parallelized using the directive based standard OpenMP. An efficiency of 80% (resp. 60%) was achieved with 2 (resp. 4) threads. Parallelization of the isotopic depletion solver was obtained using domain decomposition principles and MPI. Efficiencies greater than 90% were reached. These parallel implementations were tested on a shared memory symmetric multiprocessor (SMP) cluster machine. The OpenMP implementation in the solver MINOS is only the first step towards fully using the SMPs cluster potential with a mixed mode parallelism. Mixed mode parallelism can be achieved by combining message passing interface between clusters with OpenMP implicit parallelism within a cluster.
Computer models of steam pipeline components in the evaluation of their local strength
J. Okrajni; W. Essler
2010-01-01
Purpose: The paper discusses the issue of modelling the heating and cooling processes of T-pipes in a power plant pipeline in the start-up conditions of a boiler. The main purpose of this work is the description of the mechanical behaviour of power plant components working under mechanical and thermal loading and validation of the computer modelling methods.Design/methodology/approach: The FEM modelling has been used to describe the local stress-strain behaviour of the chosen component.Findin...
Haufe, Stefan; Huang, Yu; Parra, Lucas C
2015-08-01
In electroencephalographic (EEG) source imaging as well as in transcranial current stimulation (TCS), it is common to model the head using either three-shell boundary element (BEM) or more accurate finite element (FEM) volume conductor models. Since building FEMs is computationally demanding and labor intensive, they are often extensively reused as templates even for subjects with mismatching anatomies. BEMs can in principle be used to efficiently build individual volume conductor models; however, the limiting factor for such individualization are the high acquisition costs of structural magnetic resonance images. Here, we build a highly detailed (0.5mm(3) resolution, 6 tissue type segmentation, 231 electrodes) FEM based on the ICBM152 template, a nonlinear average of 152 adult human heads, which we call ICBM-NY. We show that, through more realistic electrical modeling, our model is similarly accurate as individual BEMs. Moreover, through using an unbiased population average, our model is also more accurate than FEMs built from mismatching individual anatomies. Our model is made available in Matlab format.
The FEM simulation of the thin walled aircraft engine corpus deformation during milling
Matras, A.; Plaza, M.
2016-09-01
This paper discusses the results of the experimental research performed with the support of finite element method. The deformation of the thin walled aircraft engine corpus was analyzed based on a geometric model. Then, the boundary of the outer side of the part was loaded by the components of a cutting force during milling. The material model of the part was also defined in the simulation software. The analysis allowed to optimize feed rate in order to decrease the deformation of the part.
2016-01-01
In vehicle drive shaft is one of the most important component. It transmits torque from the engine to the differential gear of a rear wheel drive vehicle. Generally the drive shaft is made up of steel alloy but the use of conventional steel has disadvantages such as low specific stiffness and strength and high weight. Nowadays this steel drive shaft is replaced by composite material drive shaft. This advanced composite such as graphite, Kevlar, carbon, glass with suitable resin have advantage...
Institute of Scientific and Technical Information of China (English)
王建明; 裴信超; 樊现行; 刘伟; 曹雁超
2013-01-01
为消除有限元法（ finite element method， FEM）处理切屑分离及大变形问题的局限，使用光滑粒子流体动力学法（ smooth particle hydrodynamics， SPH）耦合FEM模拟此类问题。工件使用SPH建模，弹丸使用FEM建模，二者通过接触算法实现耦合，通过仿真实验研究锐边弹丸在不同入射条件下撞击工件时，弹丸的翻转效应对工件表面弹坑深度、切屑堆积高度的影响。结果表明：当前倾角较大时，弹丸向前翻转，对工件表面产生碾压作用，形成尖锐的弹坑，切屑堆积在弹坑前部边缘不与工件分离；当前倾角较小时，弹丸向后翻转，对工件表面产生铲削作用，切屑与工件分离，弹坑横截面光滑而平缓。通过与相关实验及理论数据的比较，验证了仿真模型及结果的正确性，为锐边弹丸侵蚀工件表面的仿真研究提供新的手段。%The smoothed particle hydrodynamics ( SPH) method coupled FEM was applied to eliminate the limitations of finite element method ( FEM) dealing with the chip separation and large deformation of the work piece.The SPH parti-cles were used to model the work piece and the FEM was applied to discrete the angular particle, which were coupled by using the contact algorithm.The influence of particle rotating effects on the crater depths and chips pile-up heights was studied under different simulation incidence conditions.The results showed that the particle would rotate forward when its rake angle bacame large enough.The angular crater would be formed and chips would pile up at the edge of the cra-ter without separating from the work piece.On the other hand, the particle would rotate backward when its rake angle was small.A shallow and smoothed crater would be formed and chips would separate from the work piece.The simula-tion model and results were validated by the existing theoretical and experimental data, which could provide an effective simulation
Generalized Modelling of the Stabilizer Link and Static Simulation Using FEM
Cofaru, Nicolae Florin; Roman, Lucian Ion; Oleksik, Valentin; Pascu, Adrian
2016-12-01
This paper proposes an organological approach of one of the components of front suspension, namely anti-roll power link. There will be realized a CAD 3D modelling of this power link. 3D modelling is generalized and there were used the powers of Catia V5R20 software. Parameterized approach provides a high flexibility in the design, meaning that dimensional and shape changes of the semi-power link are very easy to perform just by changing some parameters. Several new versions are proposed for the anti-roll power link body. At the end of the work, it is made a static analysis of the semi-power link model used in the suspension of vehicles OPEL ASTRA G, ZAFIRA, MERIVA, and constructive optimization of its body.
Directory of Open Access Journals (Sweden)
Srivathsa B.
2015-12-01
Full Text Available Thermal barrier coatings (TBCs are widely used on different hot components of gas turbine engines such as blades and vanes. Although, several mechanisms for the failure of the TBCs have been suggested, it is largely accepted that the durability of these coatings is primarily determined by the residual stresses that are developed during the thermal cycling. In the present study, the residual stress build-up in an electron beam physical vapour deposition (EB-PVD based TBCs on a coupon during thermal cycling has been studied by varying three parameters such as the cooling rate, TBC thickness and substrate thickness. A two-dimensional thermomechanical generalized plane strain finite element simulations have been performed for thousand cycles. It was observed that these variations change the stress profile significantly and the stress severity factor increases non-linearly. Overall, the predictions of the model agree with reported experimental results and help in predicting the failure mechanisms.
Bistacchi, A.; Pisterna, R.; Romano, V.; Rust, D.; Tibaldi, A.
2009-04-01
The plumbing system that connects a sub-volcanic magma reservoir to the surface has been the object of field characterization and mechanical modelling efforts since the pioneering work by Anderson (1936), who produced a detailed account of the spectacular Cullin Cone-sheet Complex (Isle of Skye, UK) and a geometrical and mechanical model aimed at defining the depth to the magma chamber. Since this work, the definition of the stress state in the half space comprised between the magma reservoir and the surface (modelled either as a flat surface or a surface comprising a volcanic edifice) was considered the key point in reconstructing dike propagation paths from the magma chamber. In fact, this process is generally seen as the propagation in an elastic media of purely tensional joints (mode I or opening mode propagation), which follow trajectories perpendicular to the least compressive principal stress axis. Later works generally used different continuum mechanics methodologies (analytic, BEM, FEM) to solve the problem of a pressure source (the magma chamber, either a point source or a finite volume) in an elastic (in some cases heterogeneous) half space (bounded by a flat topography or topped by a "volcano"). All these models (with a few limited exceptions) disregard the effect of the regional stress field, which is caused by tectonic boundary forces and gravitational body load, and consider only the pressure source represented by the magma chamber (review in Gudmundsson, 2006). However, this is only a (sometimes subordinate) component of the total stress field. Grosfils (2007) first introduced the gravitational load (but not tectonic stresses) in an elastic model solved with FEM in a 2D axisymmetric half-space, showing that "failure to incorporate gravitational loading correctly" affect the calculated stress pattern and many of the predictions that can be drawn from the models. In this contribution we report on modelling results that include: 2D axisymmetric or true
Efendiev, Yalchin R.
2013-08-21
In this paper, we propose multilevel Monte Carlo (MLMC) methods that use ensemble level mixed multiscale methods in the simulations of multiphase flow and transport. The contribution of this paper is twofold: (1) a design of ensemble level mixed multiscale finite element methods and (2) a novel use of mixed multiscale finite element methods within multilevel Monte Carlo techniques to speed up the computations. The main idea of ensemble level multiscale methods is to construct local multiscale basis functions that can be used for any member of the ensemble. In this paper, we consider two ensemble level mixed multiscale finite element methods: (1) the no-local-solve-online ensemble level method (NLSO); and (2) the local-solve-online ensemble level method (LSO). The first approach was proposed in Aarnes and Efendiev (SIAM J. Sci. Comput. 30(5):2319-2339, 2008) while the second approach is new. Both mixed multiscale methods use a number of snapshots of the permeability media in generating multiscale basis functions. As a result, in the off-line stage, we construct multiple basis functions for each coarse region where basis functions correspond to different realizations. In the no-local-solve-online ensemble level method, one uses the whole set of precomputed basis functions to approximate the solution for an arbitrary realization. In the local-solve-online ensemble level method, one uses the precomputed functions to construct a multiscale basis for a particular realization. With this basis, the solution corresponding to this particular realization is approximated in LSO mixed multiscale finite element method (MsFEM). In both approaches, the accuracy of the method is related to the number of snapshots computed based on different realizations that one uses to precompute a multiscale basis. In this paper, ensemble level multiscale methods are used in multilevel Monte Carlo methods (Giles 2008a, Oper.Res. 56(3):607-617, b). In multilevel Monte Carlo methods, more accurate
Nanda, Kavita; Callahan, Rebecca; Taylor, Douglas; Wang, Meng; Agot, Kawango; Jenkins, David; Van Damme, Lut; Dorflinger, Laneta
2016-07-01
To describe medroxyprogesterone acetate (MPA) levels among Kenyan depot medroxyprogesterone acetate (DMPA) users in the FEM-PrEP HIV prevention trial, and to compare MPA levels between ARV for HIV prevention (treatment) and placebo groups. We measured MPA in previously collected plasma samples from 63 Kenyan trial participants who used DMPA for one or two complete intervals. We separately assessed MPA levels among the nine DMPA users who became pregnant at this site. Mean MPA levels at the end of each 12week injection interval were 0.37ng/ml (95% CI: 0.25, 1.99) and 0.28ng/ml (95% CI: 0.19, 1.22) among participants assigned TDF/FTC and 0.49 (95% CI: 0.40, 1.27) and 0.39 (95% CI: 0.31, 1.17) among those assigned placebo. The difference between groups was not statistically significant overall, or in an analysis which adjusted for the observed low adherence to TDF/FTC. Unanticipated findings of this analysis were low 12-week MPA levels among DMPA users in both study arms. Of 61 women who contributed data for the first DMPA injection interval, 26.2% had MPA levels<0.1ng/ml and 9.8% had levels below the detection level (0.02ng/ml) at 12weeks post-injection. Levels were similar at the end of the second injection interval. Five of nine women who became pregnant had levels below 0.15ng/mL at the time of their last negative pregnancy test. Use of TDF/FTC did not appear to affect serum MPA levels, however we found lower than expected MPA concentrations at the end of the dosing interval among DMPA users in the FEM-PrEP trial, the cause of which are unknown. This study presents some of the few available data on MPA levels among DMPA users in Africa. The low levels among users described here, together with a number of pregnancies among DMPA users, are potentially concerning and require further investigation. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.
3D correction of AIS in braces designed using CAD/CAM and FEM: a randomized controlled trial.
Cobetto, Nikita; Aubin, Carl-Éric; Parent, Stefan; Barchi, Soraya; Turgeon, Isabelle; Labelle, Hubert
2017-01-01
Recent studies showed that finite element model (FEM) combined to CAD/CAM improves the design of braces for the conservative treatment of adolescent idiopathic scoliosis (AIS), using 2D measurements from in-brace radiographs. We aim to assess the immediate effectiveness on curve correction in all three planes of braces designed using CAD/CAM and numerical simulation compared to braces designed with CAD/CAM only. SRS standardized criteria for bracing were followed to recruit 48 AIS patients who were randomized into two groups. For both groups, 3D reconstructions of the spine and patient's torso, respectively built from bi-planar radiographs and surface topography, were obtained and braces were designed using the CAD/CAM approach. For the test group, 3D reconstructions of the spine and patient's torso were additionally used to generate a personalized FEM to simulate and iteratively improve the brace design with the objective of curve correction maximization in three planes and brace material minimization. For the control group (CtrlBraces), average Cobb angle prior to bracing was 29° (thoracic, T) and 25° (lumbar, L) with the planes of maximal curvature (PMC) respectively oriented at 63° and 57° on average with respect to the sagittal plane. Average apical axial rotation prior to bracing was 7° (T) and 9° (L). For the test group (FEMBraces), initial Cobb angles were 33° (T) and 28° (L) with the PMC at 68° (T) and 56° (L) and average apical axial rotation prior to bracing at 9° (T and L). On average, FEMBraces were 50% thinner and had 20% less covering surface than CtrlBraces while reducing T and L curves by 47 and 48%, respectively, compared to 25 and 26% for CtrlBraces. FEMBraces corrected apical axial rotation by 46% compared to 30% for CtrlBraces. The combination of numerical simulation and CAD/CAM approach allowed designing more efficient braces in all three planes, with the advantages of being lighter than standard CAD/CAM braces. Bracing in AIS may
Investigation of Burst Pressures in PWR Primary Pressure Boundary Components
Directory of Open Access Journals (Sweden)
Ihn Namgung
2016-02-01
Full Text Available In a reactor coolant system of a nuclear power plant (NPP, an overpressure protection system keeps pressure in the loop within 110% of design pressure. However if the system does not work properly, pressure in the loop could elevate hugely in a short time. It would be seriously disastrous if a weak point in the pressure boundary component bursts and releases radioactive material within the containment; and it may lead to a leak outside the containment. In this study, a gross deformation that leads to a burst of pressure boundary components was investigated. Major components in the primary pressure boundary that is structurally important were selected based on structural mechanics, then, they were used to study the burst pressure of components by finite element method (FEM analysis and by number of closed forms of theoretical relations. The burst pressure was also used as a metric of design optimization. It revealed which component was the weakest and which component had the highest margin to bursting failure. This information is valuable in severe accident progression prediction. The burst pressures of APR-1400, AP1000 and VVER-1000 reactor coolant systems were evaluated and compared to give relative margins of safety.
Full-scale crash test and FEM simulation of a crashworthy helicopter seat
Institute of Scientific and Technical Information of China (English)
HU Da-yong; ZHANG Xiang
2012-01-01
Crashworthy seat structure with considerable energy absorption capacity is a key component for aircraft to improve its crashworthiness and occupant survivability in emergencies. According to Federal Aviation Administration（FAA） regulations, seat performance must be certified by dynamic crash test which is quite expensive and time-consuming. For this reason, numerical simulation is a more efficient and economical approach to provide the possibility to assess seat performances and predict occupant responses. A numerical simulation of the crashworthy seat structure was presented and the results were also compared with the full-scale crash test data. In the numerical simulation, a full-scale three-dimensional finite element model of the seat/occupant structure was developed using a nonlinear and explicit dynamic finite element code LS-DYNA3D. Emphasis of the numerical simulation was on predicting the dynamic response of seat/occupant system,including the occupant motion which may lead to injuries,the occupant acceleration-time histories, and the energy absorbing behavior of the energy absorbers. The agreement between the simulation and the physical test suggestes that the developed numerical simulation can be a feasible substitute for the dynamic crash test.
Dynamic simulations of geologic materials using combined FEM/DEM/SPH analysis
Energy Technology Data Exchange (ETDEWEB)
Morris, J P; Johnson, S M
2008-03-26
An overview of the Lawrence Discrete Element Code (LDEC) is presented, and results from a study investigating the effect of explosive and impact loading on geologic materials using the Livermore Distinct Element Code (LDEC) are detailed. LDEC was initially developed to simulate tunnels and other structures in jointed rock masses using large numbers of polyhedral blocks. Many geophysical applications, such as projectile penetration into rock, concrete targets, and boulder fields, require a combination of continuum and discrete methods in order to predict the formation and interaction of the fragments produced. In an effort to model this class of problems, LDEC now includes implementations of Cosserat point theory and cohesive elements. This approach directly simulates the transition from continuum to discontinuum behavior, thereby allowing for dynamic fracture within a combined finite element/discrete element framework. In addition, there are many application involving geologic materials where fluid-structure interaction is important. To facilitate solution of this class of problems a Smooth Particle Hydrodynamics (SPH) capability has been incorporated into LDEC to simulate fully coupled systems involving geologic materials and a saturating fluid. We will present results from a study of a broad range of geomechanical problems that exercise the various components of LDEC in isolation and in tandem.
FEM simulation of single beard hair cutting with foil-blade-shaving system.
Fang, Gang; Köppl, Alois
2015-06-01
The performance of dry-shavers depends on the interaction of the shaving components, hair and skin. Finite element models on the ABAQUS/Explicit platform are established to simulate the process of beard hair cutting. The skin is modelled as three-layer structure with a single cylindrical hair inserted into the skin. The material properties of skin are considered as Neo-Hookean hyper-elastic (epidermis) and Prony visco-elastic (dermis and hypodermis) with finite deformations. The hair is modelled as elastic-plastic material with shear damage. The cutting system is composed of a blade and a foil of shaver. The simulation results of cutting processes are analyzed, including the skin compression, hair bending, hair cutting and hair severance. Calculations of cutting loads, skin stress, and hair damage show the impact of clearance, skin bulge height, blade dimension and shape on cutting results. The details show the build-up of finite element models for hair cutting, and highlight the challenges arising during model construction and numerical simulation. Copyright © 2015 Elsevier Ltd. All rights reserved.
Institute of Scientific and Technical Information of China (English)
YU Hai-liang; LIU Xiang-hua; WANG Guo-dong
2008-01-01
Behavior of transversal crack notched on slab comer during vertical-horizontal rolling process was simula-ted by FEM. The crack tip stress in the whole rolling process was obtained. Influences of the friction coefficient, the initial crack size, the edger roll profile, and the groove fillet radii of grooved edger roll on crack tip stress were ana-lyzed. For vertical rolling, the tension stress appears at crack tip near the slab top surface and the compression stress appears at crack tip near the slab side surface for the flat edger roll; however, the compression stress appears at crack tip near the slab top surface and the tension stress appears at crack tip near the slab side surface in the exit stage for the grooved edger roll. For horizontal rolling, the tension stress appears at crack tip just at the exit stage for the flat edger roll, and the tension stress appears in whole rolling stage; the tension stress value near the slab side surface is much larger than that near the slab top surface for the grooved edger roll.
3D FEM numerical simulation and experimental study on symmetric thin-wall tube neck-spinning
Institute of Scientific and Technical Information of China (English)
KUANG Wei-hua; XIA Qin-xiang; RUAN Feng
2006-01-01
A 3D FEM model for symmetric thin-wall tube neck-spinning is established. The spinning process is simulated by means of ANSYS software, and the dynamic boundary and contact problems in simulation are solved. The transient stress distribution of contact area, the transient strain distribution of nodes in typical section and the strain distribution of the whole part at last are attained, and the place and the cause of crack are analyzed. Simulation results show how the strain distribution of typical section, the thickness of some typical nodes, the Z coordinate in typical section and the spinning force of three rollers change with the time. According to study the variation curve, the material flow law along radial, tangential and axial direction is attained and the whole spinning process is studied. The experiment data reflect how the spinning force is influenced by different process parameters, such as feed rate, roundness radius and pass reduction. The simulation and the experiment results supply criteria for optimum design and reasonable parameter selection.
Institute of Scientific and Technical Information of China (English)
Zhu Xinglin; Liu Dong; Yang Yanhui; Hu Yang; Zheng Yong
2016-01-01
During radial–axial ring rolling process, cooperative strategy of the radial–axial feed is critical for dimensional accuracy and thermo mechanical parameters distribution of the formed ring. In order to improve the comprehensive quality of the ring parts, response surface method (RSM) is employed for the first time to optimize the cooperative feed strategy for radial–axial ring rolling process by combining it with an improved and verified 3D coupled thermo-mechanical finite element model. The feed trajectory is put forward to describe cooperative relationship of the radial–axial feed and three variables are designed based on the feed trajectory. In order to achieve multi-objective optimization, four responses including thermo mechanical parameters distribution and rolling force are proposed. Based on the FEM results, RSM is used to establish a response model to depict the function relationship between the objective response and design variables. Through this approximate model, effects of different variables on ring rolling process are analyzed connect-edly and optimal feed strategy is obtained by resorting to the optimal chart specific to a constraint condition.
Directory of Open Access Journals (Sweden)
Guzmán Juan
2015-07-01
Full Text Available There are a lot of applications of the Thomson ring: levitation of superconductor materials, power interrupters (used as actuator and elimination of electric arcs. Therefore, it is important the numerical modeling of Thomson ring. The aim of this work is to model the stationary levitation of the Thomson ring. This Thomson ring consists of a copper coil with ferromagnetic core and an aluminum ring threaded in the core. The coil is fed by a cosine voltage to ensure that the aluminum ring is in a stationary levitated position. In this situation, the state of the electromagnetic field is stable and can be used the phasor equations of the electromagnetic field. These equations are discretized using the Galerkin method in the Lagrange base space (finite element method, FEM. These equations are solved using the COMSOL software. A methodology is also described (which uses the Newton-Raphson method that obtains the separation between coil and aluminum ring. The numerical solutions of this separation are compared with experimental data. The conclusion is that the magnetic coupling of the aluminum ring on the coil can be neglected if the source voltage is high.
Gao, Kai
2015-04-14
It is important to develop fast yet accurate numerical methods for seismic wave propagation to characterize complex geological structures and oil and gas reservoirs. However, the computational cost of conventional numerical modeling methods, such as finite-difference method and finite-element method, becomes prohibitively expensive when applied to very large models. We propose a Generalized Multiscale Generalized Multiscale Finite-Element Method (GMsFEM) for elastic wave propagation in heterogeneous, anisotropic media, where we construct basis functions from multiple local problems for both boundaries and the interior of a coarse node support or coarse element. The application of multiscale basis functions can capture the fine scale medium property variations, and allows us to greatly reduce the degrees of freedom that are required to implement the modeling compared with conventional finite-element method for wave equation, while restricting the error to low values. We formulate the continuous Galerkin and discontinuous Galerkin formulation of the multiscale method, both of which have pros and cons. Applications of the multiscale method to three heterogeneous models show that our multiscale method can effectively model the elastic wave propagation in anisotropic media with a significant reduction in the degrees of freedom in the modeling system.
Directory of Open Access Journals (Sweden)
Zhu Xinglin
2016-06-01
Full Text Available During radial–axial ring rolling process, cooperative strategy of the radial–axial feed is critical for dimensional accuracy and thermo mechanical parameters distribution of the formed ring. In order to improve the comprehensive quality of the ring parts, response surface method (RSM is employed for the first time to optimize the cooperative feed strategy for radial–axial ring rolling process by combining it with an improved and verified 3D coupled thermo-mechanical finite element model. The feed trajectory is put forward to describe cooperative relationship of the radial–axial feed and three variables are designed based on the feed trajectory. In order to achieve multi-objective optimization, four responses including thermo mechanical parameters distribution and rolling force are proposed. Based on the FEM results, RSM is used to establish a response model to depict the function relationship between the objective response and design variables. Through this approximate model, effects of different variables on ring rolling process are analyzed connectedly and optimal feed strategy is obtained by resorting to the optimal chart specific to a constraint condition.
Energy Technology Data Exchange (ETDEWEB)
Bae, Jin Ho; Joo, Young Sang; Ham, Ji Woong; Kim, Jong Bum [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2012-05-15
In-vessel structures of a sodium-cooled fast reactor (SFR) are submerged in opaque liquid sodium in the reactor vessel. The ultrasonic inspection techniques should be applied for observing the in-vessel structures under hot liquid sodium. Ultrasonic sensors such as immersion sensors and rod-type waveguide sensors have developed in order to apply under-sodium viewing of the in-vessel structures of SFR. Recently the novel plate-type ultrasonic waveguide sensor has been developed for the versatile application of under-sodium viewing in SFR. In previous studies, to improve the performance of the ultrasonic waveguide sensor module in the under-sodium application, the dispersion effect due to the 10 m long distance propagation of the A0-mode Lamb wave should be minimized and the longitudinal leaky wave in liquid sodium should be generated within the range of the effective radiation angle. A new concept of ultrasonic waveguide sensors with a layered-structured plate is suggested for the non-dispersive propagation of A0-mode Lamb wave in an ultrasonic waveguide sensor and the effective generation of a leaky wave in liquid sodium. In this work, the propagation and radiation of the leaky Lamb wave in the waveguide sensor coated with Beryllium has been performed by FEM simulations
SIMULATION OF COMPOSITE NON-LINEAR MECHANICAL BEHAVIOR OF CMCS BY FEM-BASED MULTI-SCALE APPROACH
Institute of Scientific and Technical Information of China (English)
高希光; 王绍华; 宋迎东
2013-01-01
The non-linear behavior of continuous fiber reinforced C/SiC ceramic matrix composites (CMCs) under tensile loading is modeled by three-dimensional representative volume element (RVE) models of the composite . The theoretical background of the multi-scale approach solved by the finite element method (FEM ) is recalled first-ly .Then the geometric characters of three kinds of damage mechanisms ,i .e .micro matrix cracks ,fiber/matrix interface debonding and fiber fracture ,are studied .Three kinds of RVE are proposed to model the microstructure of C/SiC with above damage mechanisms respectively .The matrix cracking is modeled by critical matrix strain en-ergy (CMSE) principle while a maximum shear stress criterion is used for modeling fiber/matrix interface debond-ing .The behavior of fiber fracture is modeled by the famous Weibull statistic theory .A numerical example of con-tinuous fiber reinforced C/SiC composite under tensile loading is performed .The results show that the stress/strain curve predicted by the developed model agrees with experimental data .
Institute of Scientific and Technical Information of China (English)
ZHANG Jian; LI HeMing; LUO YingLi; DOU Na; CUI XueShen
2012-01-01
In some control strategies of the direct-rive permanent magnet generator (DDPMG),the mathematics model is excessively simplified and some complex nonlinear characteristics,such as core saturation and cross-saturation,are generally neglected.To solve this problem,this paper utilizes the frozen element permeability method to compute the armature self-and mutual-inductance,permanent magnet d-and q-axis flux varying with d-axis and q-axis current,then an improved model is presented in which the core saturation and cross-saturation between d-axis and q-axis are considered effectively.Based on this model,the method for computing the performance of the generators is also proposed.Taking a 1.5-MW DDPMG as an example,the time-stepping finite element method (T-S FEM) is adopted to analyze the performance with no-load and loaded conditions,the results show a good agreement with the ones obtained by the improved model.Compared with the simplified model,it is demonstrated that the presented model has the high efficiency and reliability and can provide a good reference for optimization design of DDPMG and other PM motors.
Directory of Open Access Journals (Sweden)
Gianluca D’Urso
2016-08-01
Full Text Available The present study was carried out to evaluate how the friction stir spot welding (FSSW process parameters affect the temperature distribution in the welding region, the welding forces and the mechanical properties of the joints. The experimental study was performed by means of a CNC machine tool obtaining FSSW lap joints on AA7050 aluminum alloy plates. Three thermocouples were inserted into the samples to measure the temperatures at different distance from the joint axis during the whole FSSW process. Experiments was repeated varying the process parameters, namely rotational speed, axial feed rate and plunging depth. Axial welding forces were measured during the tests using a piezoelectric load cell, while the mechanical properties of the joints were evaluated by executing shear tests on the specimens. The correlation found between process parameters and joints properties, allowed to identify the best technological window. The data collected during the experiments were used to validate a simulation model of the FSSW process, too. The model was set up using a 2D approach for the simulation of a 3D problem, in order to guarantee a very simple and practical solution for achieving results in a very short time. A specific external routine for the calculation of the thermal energy due to friction acting between pin and sheet was developed. An index for the prediction of the joint mechanical properties using the FEM simulations was finally presented and validated.
Directory of Open Access Journals (Sweden)
Amin Chamani
2013-06-01
Full Text Available The development of yielded or failure zone due to an engineering construction is a subject of study in different disciplines. In Petroleum engineering, depletion from and injection of gas into a porous rock can cause development of a yield zone around the reservoir. Studying this phenomenon requires elasto-plastic analysis of geomaterial, in this case the porous rocks. In this study, which is a continuation of a previous study investigating the elastic behaviour of geomaterial, the elasto-plastic responses of geomaterial were studied. A 3D finite element code (FEM was developed, which can consider different constitutive models. The code features were explained and some case studies were presented to validate the output results of the code. The numerical model was, then, applied to study the development of the plastic zone around a horizontal porous formation subjected to the injection of gas. The model is described in detail and the results are presented. It was observed that by reducing the cohesion of rocks the extension of the plastic zone increased. Comparing to the elastic model, the ability to estimate the extension of the yield and failure zone is the main advantage of an elasto-plastic model.
Directory of Open Access Journals (Sweden)
Bo Wang
2014-01-01
Full Text Available When predicting the nonlinear stability of high-speed spindle system, it is necessary to create an accurate model that reflects the dynamic characteristics of the whole system, including the spindle-bearing joint and spindle-holder-tool joints. In this paper, the distribution spring model of spindle-holder-tool joints was built with the consideration of its dynamic characteristics; the five-DOF dynamic model of the angle contact ball bearing was also established to study the influence of speed and preload on the spindle-bearing joint, both of which were used in the general whole complete spindle system FEM model. The rationality of the model was verified by comparison with the FRF of traditional rigid model and experiments. At last, the influences of speed and cutting force on the nonlinear stability were analyzed by amplitude spectrum, bifurcation, and Poincaré mapping. The results provided a theoretical basis and an evaluating criterion for nonlinear stability prediction and product surface quality improvement.
Mrcarica, Zeljko; Risojevic, Vladimir; Lenczner, Michel; Jakovljevic, Mirko; Litovski, Vanco
1999-03-01
MEMS that exhibit strong coupling between electronics and mechanics need to be described and simulated in a united simulation environment, in order to achieve more flexibility from the description point of view, and to avoid convergence problems. Behavioral simulators and analogue hardware description languages enable modeling of MEMS. Even space- continuous mechanical problems can be described in the hardware description language. That description should and can be automated. Space-discretization commonly leads to very large system of equations. For solving such systems, mechanical FEM simulators usually exploit iterative algorithms that have very low memory demands. However, if the problem at hand contains electronics, as in the case of intelligent materials, iterative methods might be not applicable, since the convergence is not guaranteed anymore. In our behavioral simulator we have implemented a frontal solver, enabling solution of very large sparse matrices with modest main memory resources by storing only part of the matrix at the time. Thermal problems with more than 20000 nodes have been simulated.
Coupled RELAP5, 3D CFD and FEM analysis of postulated cracks in RPVs subjected to PTS loading
Energy Technology Data Exchange (ETDEWEB)
González-Albuixech, V.F., E-mail: vicente.gonzalez@psi.ch [Paul Scherrer Institut (PSI), Nuclear Energy and Safety Department, Structural Integrity Group, Villigen CH-5232 (Switzerland); Qian, G., E-mail: guian.qian@psi.ch [Paul Scherrer Institut (PSI), Nuclear Energy and Safety Department, Structural Integrity Group, Villigen CH-5232 (Switzerland); Sharabi, M. [Paul Scherrer Institut (PSI), Nuclear Energy and Safety Department, Structural Integrity Group, Villigen CH-5232 (Switzerland); Mechanical Power Engineering Department, Faculty of Engineering, Mansoura University, 35516 Mansoura (Egypt); Niffenegger, M.; Niceno, B.; Lafferty, N. [Paul Scherrer Institut (PSI), Nuclear Energy and Safety Department, Structural Integrity Group, Villigen CH-5232 (Switzerland)
2016-02-15
Highlights: • RPV fracture mechanics model based on RELAP5. • RPV fracture mechanics model based on CFD. • RPV fracture mechanics analysis. - Abstract: The fracture mechanic analysis of a reactor pressure vessel subjected to pressurized thermal shock loading is one of the most important issues for the assessment of life time extension of a nuclear power plant. The most severe scenario occurs during cold water injection in the cold leg due to a Loss-Of-Coolant Accident (LOCA). In the present study a comprehensive fracture mechanics analysis is performed. Two hypothetical LOCAs are assumed for an adopted reference design of a two-loop Pressurized Water Reactor. Boundary conditions obtained from the RELAP5 code are used as input for Computational Fluid Dynamics (CFD) simulations. For the structural integrity analysis, submodeling technique and the eXtended Finite Element Method (XFEM) based on temperatures calculated by CFD are applied. The results from the 3D FEM calculations are compared to those from a simplified axisymmetric model based on axisymmetric thermal hydraulic model results. The analysis identifies the worst crack orientation and location. It also proves that a complete model is needed for a correct analysis as the simplified model is not conservative and fails to describe accurately the local plume effect.
Institute of Scientific and Technical Information of China (English)
Duc-Toan Nguyen; Duy-Khoe Dinh; Hong-Minh Thi Nguyen; Tien-Long Banh; Young-Suk Kim
2014-01-01
In the current work, to predict and improve the formability of deep drawing process for steel plate cold rolled commercial grade (SPCC) sheets, three parameters including the blanking force, the die and punch corner radius were considered. The experimental plan according to Taguchi’s orthogonal array was coupled with the finite element method (FEM) simulations. Firstly, the data from the test of stress-strain and forming limit curves were used as input into ABAQUS/Explicit finite element code to predict the failure occurrence of deep drawing process. The three parameters were then validated to establish their effects on the press formability. The optimum case found via simulation was finally confirmed through an experiment. In order to obtain the complex curve profile of cup shape after deep drawing, the anisotropic behavior of earring phenomenon was modeled and implemented into FEM. After such phenomenon was correctly predicted, an error metric compared with design curve was then measured.
Sidorenko, Irina; Bauer, Jan; Monetti, Roberto; Mueller, Dirk; Rummeny, Ernst; Eckstein, Felix; Raeth, Christoph
2010-03-01
The assessment of trabecular bone microarchitecture by numerical analysis of high resolution magnetic resonance (HRMR) images provides global and local structural characteristics, which improve the understanding of the progression of osteoporosis and its diagnosis. In the present work we apply the finite elements method (FEM), which models the biomechanical behaviour of the bone, the scaling index method (SIM), which describes the topology of the structure on a local level, and Minkowski Functionals (MF), which are global topological characteristics, for analysing 3D HRMR images of 48 distal radius specimens in vitro. Diagnostic performance of texture measures derived from the numerical methods is compared with regard to the prevalence of vertebral fractures. Both topological methods show significantly better results than those obtained using bone mineral density (BMD) measurement and the failure load estimated by FEM. The receiver operating characteristic analysis for differentiating subjects with and without fractures reveals area under the curve of 0.63 for BMD, 0.66 for maximum compressive strength as determined in a biomechanical test, 0.72 for critical load estimated by FEM, 0.79 for MF4 and 0.86 for SIM, i.e. local topological characteristics derived by SIM suit best for diagnosing osteoporosis. The combination of FEM and SIM on tissue level shows that in both weak and strong bones the plate-like substructure of the trabecular network are the main load bearing part of the inner bone and that the relative amount of plates to rods is the most important characteristic for the prediction of bone strength.
Institute of Scientific and Technical Information of China (English)
时红; 郝友进; 陈斌; 司凤玲; 王鹏; 何正波
2013-01-01
Thefem-1 gene plays a key role in sex determination in Caenorhabditis elegans.In this study,three homologs of the C.elegansfem-1 gene were cloned and characterized from a transcriptome database of the oriental migratory locust,Locusta migratoria manilensis,based on bioinformatical analysis.They were named Lmfem-1a,Lmfem-1b and Lmfem-1c,with the Genbank accession numbers of AB698670,AB698671 and AB698672,respectively.The cDNAs of the three genes are 2 233,2 625 and 2 142 bp in length,encoding proteins with 662,642 and 638 amino acids,respectively.Bioinformatical analysis revealed that Lmfem-1a,Lmfem-1b and Lmfem-1c contain 6,8 and 8 typical ankyrin repeat motifs,respectively.Gene expression analysis showed that Lmfem-1 a,Lmfem-1 b and Lmfem-1c were expressed in all tested tissues with significantly different transcript level,suggesting that Lmfem-1a,Lmfem-1b and Lmfem-1c are tightly regulated and might be involved in multiple physiological processes.Lmfem-1a,Lmfem-1b and Lmfem-1c had the highest expression level in testis,and their expression increased gradually with the development of testis.These findings strongly suggest that Lmfem-1a,Lmfem-1b and Lmfem-1c may be involved in the spermatogenesis of the locust.Further functional analysis is required to clarify the roles of these genes in sex determination in the locust.%秀丽隐杆线虫Caenorhabditis elegans fem-1基因是性别决定的关键基因.本研究基于生物信息学方法从东亚飞蝗Locusta migratoria manilensis的转录组数据库中克隆出了线虫fem-1的3个同源基因,将其分别命名为Lmfem-1a,Lmfem-1b和Lmfem-1c(GenBank登录号分别为AB698670,AB698671和AB698672).其cDNA序列长度分别为2 233,2 625和2 142 bp,分别编码662,642和638个氨基酸.生物信息学分析显示,Lmfem-1a,Lmfem-1b和Lmfem-1c分别含有6,8和8个典型的锚蛋白重复序列模体.组织表达谱分析发现,Lmfem-1a,Lmfem-1b和Lmfem-1c基因在检测的所有组织中都有表达,但均在精巢
Rubber Piston Membrane Model for Pneumatic Braking based on ANN-FEM%基于FEM-ANN法的气动刹车橡胶活塞膜设计模型
Institute of Scientific and Technical Information of China (English)
陈培文
2015-01-01
In this paper,artificial neural network(ANN)-finite element metho (FEM) model of rubber piston membrane to work out a pneumatic braking device based on Traincgf algorithm were established.In this model,the thickness of the rubber piston membrane of the pneumatic braking device was T,radius of the central ring was R,the fillet radius was R1 and fillet radius was R2,the output was stress analysis for the rubber piston membrane of the pneumatic braking device and network framework was considered to be 4-6-1.The final relative errors (RE) was 9.225%. As for optimal parameters for the rubber piston membrane of the pneumatic braking device the thickness was 8 mm,R1 was 6 mm,R2 was 18 mm and the greatest tolerant pressure was 4.83 MPa.%基于Traincgf算法建立了建立气动刹车装置橡胶活塞膜的神经网络（ANN）-有限元（FEM）设计模型。气动刹车装置橡胶活塞膜的厚度T，中心环半径R，倒圆角半径R1，倒圆角半径R2；输出层为气动刹车装置橡胶活塞膜应力分析。网络模型结构为4-6-1。最终测试相对误差（RE）为9.225%。气动刹车橡胶活塞膜设计的最佳参数为厚度T为8mm，倒角R1为6mm，倒角R2为18mm，可承受的压力最大为4.83MPa。
Directory of Open Access Journals (Sweden)
Kikinis Ron
2006-03-01
Full Text Available Abstract Introduction Mitral Valve (MV 3D structural data can be easily obtained using standard transesophageal echocardiography (TEE devices but quantitative pre- and intraoperative volume analysis of the MV is presently not feasible in the cardiac operation room (OR. Finite element method (FEM modelling is necessary to carry out precise and individual volume analysis and in the future will form the basis for simulation of cardiac interventions. Method With the present retrospective pilot study we describe a method to transfer MV geometric data to 3D Slicer 2 software, an open-source medical visualization and analysis software package. A newly developed software program (ROIExtract allowed selection of a region-of-interest (ROI from the TEE data and data transformation for use in 3D Slicer. FEM models for quantitative volumetric studies were generated. Results ROI selection permitted the visualization and calculations required to create a sequence of volume rendered models of the MV allowing time-based visualization of regional deformation. Quantitation of tissue volume, especially important in myxomatous degeneration can be carried out. Rendered volumes are shown in 3D as well as in time-resolved 4D animations. Conclusion The visualization of the segmented MV may significantly enhance clinical interpretation. This method provides an infrastructure for the study of image guided assessment of clinical findings and surgical planning. For complete pre- and intraoperative 3D MV FEM analysis, three input elements are necessary: 1. time-gated, reality-based structural information, 2. continuous MV pressure and 3. instantaneous tissue elastance. The present process makes the first of these elements available. Volume defect analysis is essential to fully understand functional and geometrical dysfunction of but not limited to the valve. 3D Slicer was used for semi-automatic valve border detection and volume-rendering of clinical 3D echocardiographic
Variability and component composition
Storm, T. van der
2004-01-01
In component-based product populations, feature models have to be described at the component level to be able to benefit from a product family approach. As a consequence, composition of components becomes very complex. We describe how component-level variability can be managed in the face of compone
A Flexible Method for Producing F.E.M. Analysis of Bone Using Open-Source Software
Boppana, Abhishektha; Sefcik, Ryan; Meyers, Jerry G.; Lewandowski, Beth E.
2016-01-01
This project, performed in support of the NASA GRC Space Academy summer program, sought to develop an open-source workflow methodology that segmented medical image data, created a 3D model from the segmented data, and prepared the model for finite-element analysis. In an initial step, a technological survey evaluated the performance of various existing open-source software that claim to perform these tasks. However, the survey concluded that no single software exhibited the wide array of functionality required for the potential NASA application in the area of bone, muscle and bio fluidic studies. As a result, development of a series of Python scripts provided the bridging mechanism to address the shortcomings of the available open source tools. The implementation of the VTK library provided the most quick and effective means of segmenting regions of interest from the medical images; it allowed for the export of a 3D model by using the marching cubes algorithm to build a surface mesh. To facilitate the development of the model domain from this extracted information required a surface mesh to be processed in the open-source software packages Blender and Gmsh. The Preview program of the FEBio suite proved to be sufficient for volume filling the model with an unstructured mesh and preparing boundaries specifications for finite element analysis. To fully allow FEM modeling, an in house developed Python script allowed assignment of material properties on an element by element basis by performing a weighted interpolation of voxel intensity of the parent medical image correlated to published information of image intensity to material properties, such as ash density. A graphical user interface combined the Python scripts and other software into a user friendly interface. The work using Python scripts provides a potential alternative to expensive commercial software and inadequate, limited open-source freeware programs for the creation of 3D computational models. More work
Directory of Open Access Journals (Sweden)
Monica Namburi
2017-01-01
Full Text Available Abstract Background Extraction of premolars and retracting the anterior teeth using mini-implants and anterior retraction hooks became advent now a day. In such treatments, consolidation of arches is not done in regular practice. So, the present study is concentrated on effects of consolidation in two implant and three implant combinations of retraction and intrusion. Methods A three-dimensional FEM model of maxillary teeth and periodontal ligament housed in the alveolar bone with the first premolars extracted is generated with appropriate number of elements and nodes. The models were broadly divided into two groups according to the no. of implants. Mini-implants were placed bilaterally between the second premolar and molar at varying heights (7, 10, 13 mm in group I, and along with bilateral implants, an additional mid-implant is placed between the central incisors as group II. Brackets with 0.022 slot were placed on the teeth, 19 × 25 SS wire is placed in the brackets, an anterior retraction hook was placed at 9 mm height, and analysis was done to evaluate the stresses and displacement patterns in consolidation and non-consolidation models. Results The results showed that consolidation of the anterior teeth during intrusion and retraction shows various advantages such as less stresses on the bone, PDL, implant, teeth, and no labial flaring of the anterior teeth and three implant system, i.e., two bilateral implant at 10 mm and a mid-implant at 12 mm between the centrals has shown to be better than other models as bodily movement is observed. Conclusion Consolidation is better than non consolidation during enmasse retraction and intrusion.
Free vibration analysis of civil engineering structures by component-wise models
Carrera, Erasmo; Pagani, Alfonso
2014-09-01
Higher-order beam models are used in this paper to carry out free vibration analysis of civil engineering structures. Refined kinematic fields are developed using the Carrera Unified Formulation (CUF), which allows for the implementation of any-order theory without the need for ad hoc formulations. The principle of virtual displacements in conjunction with the finite element method (FEM) is used to formulate stiffness and mass matrices in terms of fundamental nuclei. The nuclei depend neither on the adopted class of beam theory nor on the FEM approximation along the beam axis. This paper focuses on a particular class of CUF models that makes use of Lagrange polynomials to discretize cross-sectional displacement variables. This class of models are referred to as component-wise (CW) in recent works. According to the CW approach, each structural component (e.g. columns, walls, frame members, and floors) can be modeled by means of the same 1D formulation. A number of typical civil engineering structures (e.g. simple beams, arches, truss structures, and complete industrial and civil buildings) are analyzed and CW results are compared to classical beam theories (Euler-Bernoulli and Timoshenko), refined beam models based on Taylor-like expansions of the displacements on the cross-section, and classical solid/shell FEM solutions from the commercial code MSC Nastran. The results highlight the enhanced capabilities of the proposed formulation. It is in fact demonstrated that CW models are able to replicate 3D solid results with very low computational efforts.
National Aeronautics and Space Administration — Model with Tetrahedral elements includes wing, balance, exciter and modelcart Some files were too large and had to be split into parts. To combine the parts, use cat...
Livtag med fem flygtningemyter
DEFF Research Database (Denmark)
Booss-Bavnbek, Bernhelm; Hansen, Ali
2015-01-01
Fejlagtige myter i den danske flygtningedebat er sejlivede, skriver formand for aftenskolen Grobund Ali Hansen og matematiker Bernhelm Booß-Bavnbek. De er ligesom vabler - de skal punkteres, før de kan hele...
Fem landskabsstrategiske principper
DEFF Research Database (Denmark)
Bach, Rune Christian; Juel Clemmensen, Thomas
2005-01-01
The question whether the traditional distinction between city and countryside is still adequate in describing and understanding the physical environment, is brought into focus as a new urban-rural landscape emerges. A phenomenon characterised by an increasing dissolving of the boundaries between ...
Fem landskabsstrategiske principper
DEFF Research Database (Denmark)
Bach, Rune Christian; Juel Clemmensen, Thomas
2005-01-01
to the unbuilt can be seen as a trend within the more recent urban research and planning practice, where the development of new urban concepts uses landscape as a theoretical and methodical basis. This article highlights this current trend and tries to explain how the landscape is operationalized strategically...... urban structures and rural elements, a gradual dissolving of conventional hierarchies and a mutual penetration of built form and open space. (Sieverts) What premises does this development set for the planning as a discipline; to what extent can urban planning in its traditional form provide qualitative...... influence on the physical environment in the new urban-rural landscape? Global market economy and the withdrawal of public authority create a situation where urban development is increasingly influenced by fluctuations on the real estate market and where buildings are considered more in respect...
Manogharan, Prabhakaran; Rajagopal, Prabhu; Balasubramaniam, Krishnan
2015-03-01
Composite structures are used in a wide variety of applications. The use of stiffened composites is common in aerospace box-like components and provides the additional stiffness required. Examples of such stiffened structural geometries include airfoils, fuselage, wing box, tail section, etc. The inspection of the radius filler "Noodle" that fills the interface between skin and stiffener has been of great concern to the aerospace composites industry. This paper describes the 3D FEM models of the ultrasonic axially propagating guided wave modes. Additionally, the models were used for understanding their confinement in the Noodle region, their leakage to the remaining sections of the component and their interaction with defects of different types, sizes and their locations along Noodle region. The ultrasonic guided wave modes that propagate along the length of the Noodle were identified using the 3D finite element model. These simulations were validated using graphite-epoxy test coupons and components from aerospace industry.
Study on the Application of FEM Technology to Design of Truck Door%FEM技术用于车门设计的研究
Institute of Scientific and Technical Information of China (English)
叶德涛
2006-01-01
介绍了解决有限元FEM(finite element method)技术用于某小型运输车车门设行加强的车门进行了下沉工况静力分析和自由状态的模态分析,得到了车门的固有频率及其相应振型,对车门的静刚度和动刚度做出了评价,为进一步设计提供了参考.
Acevedo, Pedro; Vázquez, Mónica; Durán, Joel; Petrearce, Rodolfo
A simulation case is presented using the Finite Element Method (FEM) to simulate the performance of PVDF arrays to measure temperature gradients through the determination of phase shifts, i.e. time shifts of the waveform of the echo due to a change in the speed of propagation of ultrasound as a result of a change in temperature, they can be interpreted as phase shifts in the frequency domain. Making it possible to determine the change in temperature from the phase shifts; in a medium of propagation previously characterized.
Institute of Scientific and Technical Information of China (English)
H.L. Yang; D.C. Kang; Z.L. Zhang; X.H. Piao; Z.D. Shi
2001-01-01
Shear-extrusion process and its forming parameters are proposed, whilst its laborsae ing characteristic is utilized to forge large-size shutoff valve body on middle-due pre ss.This new process is intended for the manufacture of large-size forged tubular components with branches on middle-due press. Experiments are carried out and proeessing parameters are obtained regarding the shear-extrusion process of a large-size shutoff valve body. Deformation and metal flow in the shear-extrnsion process are investigated. In order to verify the laborsaving characteristic of this new procss some contrastive experiments of extrusion foree are performed between shear-extrusion and upsetting-extrusion for forming tubular components with branches. Based on rigidplastic FEM a plane-strain model is established to analyze shear-extrusion process of tubular components with branches. The analysis results by 2-dimensions FEM are comparatively quite well consistent with those of experiments. Both simulated anl etperimental results show that this new forming process is feasible for forging large-size tubular components with branches on middle-due press.
U.S. Environmental Protection Agency — The Reusable Component Services (RCS) is a super-catalog of components, services, solutions and technologies that facilitates search, discovery and collaboration in...
Bro, R.; Smilde, A.K.
2014-01-01
Principal component analysis is one of the most important and powerful methods in chemometrics as well as in a wealth of other areas. This paper provides a description of how to understand, use, and interpret principal component analysis. The paper focuses on the use of principal component analysis
Grain alignment and microstructure of (Nd,Dy){sub 12.8}(Fe,M) {sub 80.7}B{sub 6.5} by strip casting
Energy Technology Data Exchange (ETDEWEB)
Liu, H.Q. [Physics Department, School of Physics and Microelectronics, Shandong University, Ji' nan, 250100 (China)]. E-mail: liuhq168@163.com; Wang, B. [Physics Department, School of Physics and Microelectronics, Shandong University, Ji' nan, 250100 (China); Han, G.B. [Physics Department, School of Physics and Microelectronics, Shandong University, Ji' nan, 250100 (China); Gao, R.W. [Physics Department, School of Physics and Microelectronics, Shandong University, Ji' nan, 250100 (China)]. E-mail: gaorwbox@sdu.edu.cn
2005-01-01
The alignment of Nd2Fe14B grains (T{sub 1}) and the microstructure of (Nd,Dy){sub 12.8}(Fe,M) {sub 80.7}B{sub 6.5} strip cast ribbons are reported in this paper. In the strips there is a pronounced texture of the tetragonal T{sub 1} phase and the columnar grains exhibit apparent alignment along [00L]. The alignment coefficient {phi} changes with the wheel speed V and is highest at V=1.5-2m/s. The Nd-rich phase is well segregated and widely distributed enclosing the fine columnar grains of the main phase in the strips prepared at V=2m/s. The magnetic properties of sintered magnets prepared from this kind of (Nd,Dy){sub 12.8}(Fe,M) {sub 80.7}B{sub 6.5} strip cast ribbons are as follows: B{sub r}=1.457T(14.57kG), H{sub cj}=1048kA/m (BH){sub max}=408kJ/m{sup 3} (51.3MGOe)
Energy Technology Data Exchange (ETDEWEB)
Wang, Peng-yi; Wang, Zhong-jin, E-mail: wangzj@hit.edu.cn
2016-12-01
Magnetorheological fluid (MR fluid), a kind of smart material, has been used as a new pressure-carrying medium in magnetorheological pressure forming (MRPF). The mechanical property of MR fluid under the pressure significantly affects the sheet formability. However, there is little knowledge on the deformation behavior of MR fluid under three-dimensional stress states. In this paper, a new procedure via a combination of extrusion test and FEM simulation has been proposed to determine the flow stress of MR fluids. The experimental device for extrusion test of MR fluids was designed. The flow stresses of a MR fluid (MRF-J01T) under four different magnetic fields were determined through the proposed procedure. In addition, the obtained flow stresses were used in the following FEM simulations to verify the accuracy by comparing with the experimental results. The simulation results were in good agreement with the experimental data, which supports the correctness and practicability of the proposed method. - Highlights: • An effective procedure is proposed to determine the flow stress of MR fluids. • The rheological behaviour of a MR fluid during extrusion tests is studied. • Flow stress curves of a MR fluid under different magnetic fields are obtained.
FEM Modelling and Oscillation Analysis of Solid Propellant Rocket Motor%固体火箭发动机柔性喷管有限元建模及摆动分析
Institute of Scientific and Technical Information of China (English)
王成林; 刘勇; 文立华
2012-01-01
The methods of FEM Modelling and Oscillation Analysis of Solid Propellant Rocket Motor were explores. The FEM model of flexible nozzle using the equivalent model of flexible joint based on the three-direction custom spring elements is build; modify the FEM model of the flexible joint according to the experiment data; and carry out the oscillation analysis of solid propellant rocket motor.%研究了固态火箭发动机柔性喷管有限元建模及摆动分析方法.利用基于自定义三向弹簧单元的柔性接头线性等效模型,建立了发动机柔性喷管有限元模型.根据试验数据对柔性接头模型进行修正,并对发动机柔性喷管进行了摆动分析.
SPH-FEM接触算法在冲击动力学数值计算中的应用%APPLICATION OF SPH-FEM CONTACT ALGORITHM IN IMPACT DYNAMICS SIMULATION
Institute of Scientific and Technical Information of China (English)
张志春; 强洪夫; 高巍然
2011-01-01
Coupling of Smoothed Particle Hydrodynamics (SPH) and Finite Element Method (FEM) can make full use of the superiority of SPH in dealing with large deformation and the high accuracy and efficiency of FEM. This paper calculates the contact between SPH particles and finite elements using meshless particle contact method, and background particles are assigned in the position of FE nodes. The oblique impact between spheral-nosed projectile and steel target and the normal impact between blunt-nosed projectile and steel target are calculated using the SPH-FEM contact algorithm. The fully variable smoothing lengths algorithm is used in SPH and the EBE algorithm is used in FEM. The numerical results of LS-DYNA and the experimental observations validate the accuracy of the SPH-FEM contact algorithm.%为了充分发挥光滑粒子流体动力学方法(Smoothed Particle Hydrodynamics,SPH)易于处理大变形以及有限元(Finite Element Method,FEM)计算精度和效率高的优势,论文基于无网格粒子接触算法,在有限元节点处设置背景粒子,通过接触力的方式计算SPH粒子和有限单元之间的接触问题.使用SPH-FEM接触算法分别对球头钢弹斜冲击钢板和平头钢弹正冲击钢板的情况进行了三维数值计算,SPH采用完全变光滑长度算法,FEM采用矩阵向量积的EBE(Element-By-Element)算法.将SPH-FEM接触算法的计算结果与LS-DYNA的计算结果以及实验结果进行了对比验证.
Directory of Open Access Journals (Sweden)
Vieraşu, T.
2011-01-01
Full Text Available In this article I will go through three main logistics components, which are represented by: transportation, inventory and facilities, and the three secondary logistical components: information, production location, price and how they determine performance of any supply chain. I will discuss then how these components are used in the design, planning and operation of a supply chain. I will also talk about some obstacles a supply chain manager may encounter.
Energy Technology Data Exchange (ETDEWEB)
Lacy, Benjamin Paul; Kottilingam, Srikanth Chandrudu; Porter, Christopher Donald; Schick, David Edward
2017-09-12
Various embodiments of the disclosure include a turbomachine component. and methods of forming such a component. Some embodiments include a turbomachine component including: a first portion including at least one of a stainless steel or an alloy steel; and a second portion joined with the first portion, the second portion including a nickel alloy including an arced cooling feature extending therethrough, the second portion having a thermal expansion coefficient substantially similar to a thermal expansion coefficient of the first portion, wherein the arced cooling feature is located within the second portion to direct a portion of a coolant to a leakage area of the turbomachine component.
Psychological Component of Infertility
... Home FAQs Frequently Asked Questions Quick Facts About Infertility FAQs About Infertility FAQs About the Psychological Component of Infertility FAQs About Cloning and Stem Cell Research SART's ...
Directory of Open Access Journals (Sweden)
Mack N
2013-10-01
Full Text Available Natasha Mack,1 Stella Kirkendale,1 Paul Omullo,2 Jacob Odhiambo,2 Malebo Ratlhagana,3 Martha Masaki,4 Phumzile Siguntu,5 Kawango Agot,2 Khatija Ahmed,3 Saidi Kapiga,4 Johan Lombaard,5 Lut Van Damme,1 Amy Corneli1 1FHI 360, Durham, NC, USA; 2Impact Research and Development Organization, Bondo, Kenya; 3Setshaba Research Centre, Soshanguve, South Africa; 4Kilimanjaro Christian Medical Center, Moshi, Tanzania; 5Josha Research, Bloemfontein, South Africa Abstract: Biomedical HIV-prevention research is most likely to succeed when researchers actively engage with community stakeholders. To this effect, the Joint United Nations Programme on HIV/AIDS and the AIDS Vaccine Advocacy Coalition developed good participatory practice guidelines for biomedical HIV-prevention trials in 2007 and updated them in 2011. The Preexposure Prophylaxis Trial for HIV Prevention among African Women (FEM-PrEP clinical trial, testing once-daily Truvada as preexposure prophylaxis among women at higher risk of HIV in Kenya, South Africa, and Tanzania, included a community program to engage with local stakeholders. Following the trial, we revisited the community program to situate activities in the context of the 2011 guidelines. In the paper, we describe implementation of the six guidelines relevant to local stakeholder engagement – stakeholder advisory mechanisms, stakeholder engagement plan, stakeholder education plan, communications plan, issues management plan, trial closure, and results dissemination – in light of on-the-ground realities of the trial. We then identify two cross-cutting themes from our considerations: (1 stakeholder education beyond the good participatory practice recommendation to increase research literacy about the specific trial is needed; education efforts should also communicate a base of information on HIV transmission and prevention; and (2 anticipatory preparation is useful in communications planning, issues management, and trial closure and
Timmerman, M.E.
2006-01-01
A general framework for the exploratory component analysis of multilevel data (MLCA) is proposed. In this framework, a separate component model is specified for each group of objects at a certain level. The similarities between the groups of objects at a given level can be expressed by imposing cons
Hendricks, Robert C.; Zaretsky, Erwin V.
2001-01-01
Critical component design is based on minimizing product failures that results in loss of life. Potential catastrophic failures are reduced to secondary failures where components removed for cause or operating time in the system. Issues of liability and cost of component removal become of paramount importance. Deterministic design with factors of safety and probabilistic design address but lack the essential characteristics for the design of critical components. In deterministic design and fabrication there are heuristic rules and safety factors developed over time for large sets of structural/material components. These factors did not come without cost. Many designs failed and many rules (codes) have standing committees to oversee their proper usage and enforcement. In probabilistic design, not only are failures a given, the failures are calculated; an element of risk is assumed based on empirical failure data for large classes of component operations. Failure of a class of components can be predicted, yet one can not predict when a specific component will fail. The analogy is to the life insurance industry where very careful statistics are book-kept on classes of individuals. For a specific class, life span can be predicted within statistical limits, yet life-span of a specific element of that class can not be predicted.
Directory of Open Access Journals (Sweden)
Roberto Di Cosmo
2011-08-01
Full Text Available Modern software systems, like GNU/Linux distributions or Eclipse-based development environment, are often deployed by selecting components out of large component repositories. Maintaining such software systems by performing component upgrades is a complex task, and the users need to have an expressive preferences language at their disposal to specify the kind of upgrades they are interested in. Recent research has shown that it is possible to develop solvers that handle preferences expressed as a combination of a few basic criteria used in the MISC competition, ranging from the number of new components to the freshness of the final configuration. In this work we introduce a set of new criteria that allow the users to specify their preferences for solutions with components aligned to the same upstream sources, provide an efficient encoding and report on the experimental results that prove that optimising these alignment criteria is a tractable problem in practice.
Di Cosmo, Roberto; Michel, Claude; 10.4204/EPTCS.65.1
2011-01-01
Modern software systems, like GNU/Linux distributions or Eclipse-based development environment, are often deployed by selecting components out of large component repositories. Maintaining such software systems by performing component upgrades is a complex task, and the users need to have an expressive preferences language at their disposal to specify the kind of upgrades they are interested in. Recent research has shown that it is possible to develop solvers that handle preferences expressed as a combination of a few basic criteria used in the MISC competition, ranging from the number of new components to the freshness of the final configuration. In this work we introduce a set of new criteria that allow the users to specify their preferences for solutions with components aligned to the same upstream sources, provide an efficient encoding and report on the experimental results that prove that optimising these alignment criteria is a tractable problem in practice.
Institute of Scientific and Technical Information of China (English)
Jiahe Ai; Huiju Gao; Tongchun Zhao; Xishan Xie; Yu Liu
2004-01-01
The 3-D thermo-mechanical coupled elasto-plastic finite element method (FEM) was used for the simulation of the twopass continuous hot rolling process of 60SiMnA spring steel bars and rods using MARC/AutoForge3.1 software. The simulated results visualize the metal flow and the dynamic evolutions of the strain, stress and temperature during the continuous hot rolling, especially inside the work-piece. It is shown that the non-uniform distributions of the strain, stress and temperature on the longitudinal and transverse sections are a distinct characteristic of the continuous hot rolling, which can be used as basic data for improving the tool design, predicting and controlling the micro-structural evolution of a bar and rod.
Energy Technology Data Exchange (ETDEWEB)
Conde, J.C.; Chiussi, S.; Gontad, F.; Gonzalez, P. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, 36310 Vigo (Spain); Martin, E. [Dpto. de Mecanica, Maquinas, Motores Termicos y Fluidos, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, 36310 Vigo (Spain)
2011-03-15
Research on epitaxial crystalline silicon (c-Si) and silicon-germanium (Si{sub 1-x}Ge{sub x}) alloys growth and annealing for microelectronic purposes, such as Micro- or Nano-Electro-Mechanical Systems (MEMS or NEMS) and Silicon-On-Nothing (SON) devices is continuously in progress. Laser assisted annealing techniques using commercial ArF Excimer Laser sources are based on ultra-rapid heating and cooling cycles induced by the 193 nm pulses of 20 ns, which are absorbed in the near surface region of the heterostructures. During and after the absorption of these laser pulses, complex physical processes appear that strongly depend on sample structure and applied laser pulse energy densities. The control of the experimental parameters is therefore a key task for obtaining high quality alloys. The Finite ElementsMethod (FEM) is a powerful tool for the optimization of such treatments, because it provides the spatial and temporal temperature fields that are produced by the laser pulses. In this work, we have used a FEM commercial software, to predict the temperatures gradients induced by ArF excimer laser over a wide energy densities range, 0.1<{phi}<0.4 J/cm{sup 2}, on different SiO{sub 2}/Si/Si{sub (1-x)}Ge{sub (x)} thin films deposited on SOI substrate. These numerical results allow us to predict the threshold energies needed to reach the melting point (MP) of the Si and SiGe alloy without oxidation of the thin films system. Therefore, it is possible to optimize the conditions to achieve high quality epitaxy films. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Qiu, Chen; Kershner, Aaron; Wang, Yeming; Holley, Cynthia P; Wilinski, Daniel; Keles, Sunduz; Kimble, Judith; Wickens, Marvin; Hall, Traci M Tanaka
2012-02-24
mRNA control networks depend on recognition of specific RNA sequences. Pumilio-fem-3 mRNA binding factor (PUF) RNA-binding proteins achieve that specificity through variations on a conserved scaffold. Saccharomyces cerevisiae Puf3p achieves specificity through an additional binding pocket for a cytosine base upstream of the core RNA recognition site. Here we demonstrate that this chemically simple adaptation is prevalent and contributes to the diversity of RNA specificities among PUF proteins. Bioinformatics analysis shows that mRNAs associated with Caenorhabditis elegans fem-3 mRNA binding factor (FBF)-2 in vivo contain an upstream cytosine required for biological regulation. Crystal structures of FBF-2 and C. elegans PUF-6 reveal binding pockets structurally similar to that of Puf3p, whereas sequence alignments predict a pocket in PUF-11. For Puf3p, FBF-2, PUF-6, and PUF-11, the upstream pockets and a cytosine are required for maximal binding to RNA, but the quantitative impact on binding affinity varies. Furthermore, the position of the upstream cytosine relative to the core PUF recognition site can differ, which in the case of FBF-2 originally masked the identification of this consensus sequence feature. Importantly, other PUF proteins lack the pocket and so do not discriminate upstream bases. A structure-based alignment reveals that these proteins lack key residues that would contact the cytosine, and in some instances, they also present amino acid side chains that interfere with binding. Loss of the pocket requires only substitution of one serine, as appears to have occurred during the evolution of certain fungal species.
GCS component development cycle
Rodríguez, Jose A.; Macias, Rosa; Molgo, Jordi; Guerra, Dailos; Pi, Marti
2012-09-01
The GTC1 is an optical-infrared 10-meter segmented mirror telescope at the ORM observatory in Canary Islands (Spain). First light was at 13/07/2007 and since them it is in the operation phase. The GTC control system (GCS) is a distributed object & component oriented system based on RT-CORBA8 and it is responsible for the management and operation of the telescope, including its instrumentation. GCS has used the Rational Unified process (RUP9) in its development. RUP is an iterative software development process framework. After analysing (use cases) and designing (UML10) any of GCS subsystems, an initial component description of its interface is obtained and from that information a component specification is written. In order to improve the code productivity, GCS has adopted the code generation to transform this component specification into the skeleton of component classes based on a software framework, called Device Component Framework. Using the GCS development tools, based on javadoc and gcc, in only one step, the component is generated, compiled and deployed to be tested for the first time through our GUI inspector. The main advantages of this approach are the following: It reduces the learning curve of new developers and the development error rate, allows a systematic use of design patterns in the development and software reuse, speeds up the deliverables of the software product and massively increase the timescale, design consistency and design quality, and eliminates the future refactoring process required for the code.
Robust Principal Component Analysis?
Candes, Emmanuel J; Ma, Yi; Wright, John
2009-01-01
This paper is about a curious phenomenon. Suppose we have a data matrix, which is the superposition of a low-rank component and a sparse component. Can we recover each component individually? We prove that under some suitable assumptions, it is possible to recover both the low-rank and the sparse components exactly by solving a very convenient convex program called Principal Component Pursuit; among all feasible decompositions, simply minimize a weighted combination of the nuclear norm and of the L1 norm. This suggests the possibility of a principled approach to robust principal component analysis since our methodology and results assert that one can recover the principal components of a data matrix even though a positive fraction of its entries are arbitrarily corrupted. This extends to the situation where a fraction of the entries are missing as well. We discuss an algorithm for solving this optimization problem, and present applications in the area of video surveillance, where our methodology allows for th...
Discriminant Incoherent Component Analysis.
Georgakis, Christos; Panagakis, Yannis; Pantic, Maja
2016-05-01
Face images convey rich information which can be perceived as a superposition of low-complexity components associated with attributes, such as facial identity, expressions, and activation of facial action units (AUs). For instance, low-rank components characterizing neutral facial images are associated with identity, while sparse components capturing non-rigid deformations occurring in certain face regions reveal expressions and AU activations. In this paper, the discriminant incoherent component analysis (DICA) is proposed in order to extract low-complexity components, corresponding to facial attributes, which are mutually incoherent among different classes (e.g., identity, expression, and AU activation) from training data, even in the presence of gross sparse errors. To this end, a suitable optimization problem, involving the minimization of nuclear-and l1 -norm, is solved. Having found an ensemble of class-specific incoherent components by the DICA, an unseen (test) image is expressed as a group-sparse linear combination of these components, where the non-zero coefficients reveal the class(es) of the respective facial attribute(s) that it belongs to. The performance of the DICA is experimentally assessed on both synthetic and real-world data. Emphasis is placed on face analysis tasks, namely, joint face and expression recognition, face recognition under varying percentages of training data corruption, subject-independent expression recognition, and AU detection by conducting experiments on four data sets. The proposed method outperforms all the methods that are compared with all the tasks and experimental settings.
Scientific Software Component Technology
Energy Technology Data Exchange (ETDEWEB)
Kohn, S.; Dykman, N.; Kumfert, G.; Smolinski, B.
2000-02-16
We are developing new software component technology for high-performance parallel scientific computing to address issues of complexity, re-use, and interoperability for laboratory software. Component technology enables cross-project code re-use, reduces software development costs, and provides additional simulation capabilities for massively parallel laboratory application codes. The success of our approach will be measured by its impact on DOE mathematical and scientific software efforts. Thus, we are collaborating closely with library developers and application scientists in the Common Component Architecture forum, the Equation Solver Interface forum, and other DOE mathematical software groups to gather requirements, write and adopt a variety of design specifications, and develop demonstration projects to validate our approach. Numerical simulation is essential to the science mission at the laboratory. However, it is becoming increasingly difficult to manage the complexity of modern simulation software. Computational scientists develop complex, three-dimensional, massively parallel, full-physics simulations that require the integration of diverse software packages written by outside development teams. Currently, the integration of a new software package, such as a new linear solver library, can require several months of effort. Current industry component technologies such as CORBA, JavaBeans, and COM have all been used successfully in the business domain to reduce software development costs and increase software quality. However, these existing industry component infrastructures will not scale to support massively parallel applications in science and engineering. In particular, they do not address issues related to high-performance parallel computing on ASCI-class machines, such as fast in-process connections between components, language interoperability for scientific languages such as Fortran, parallel data redistribution between components, and massively
Components in Chemical Thermodynamics
Alberty, Robert A.
1995-09-01
Chemical equations are actually matrix equations, and this has important implications for their thermodynamic treatment. The fundamental equation for chemical thermodynamics for a chemical reaction system can be written in terms of species, but at chemical equilibrium, it has to be written in terms of components. The number of components is equal to the number of species minus the number of independent chemical reactions. The fundamental equation for the Gibbs energy of a system containing ethylene, methane, ethane, and propane is discussed. At chemical equilibrium there are two components, which can be taken to be carbon and hydrogen or ethylene and methane. There are advantages in using matrix notation.
Federal Laboratory Consortium — The 98,000 square foot Explosive Components Facility (ECF) is a state-of-the-art facility that provides a full-range of chemical, material, and performance analysis...
Directory of Open Access Journals (Sweden)
Carla J Hale
1997-01-01
Full Text Available BACKGROUND: Current definitions of pain suggest that emotion is an essential component of pain, however, the presumed relationship between emotion and pain, and the specific emotions that are involved in pain experiences have yet to be clarified.
Fracture criteria for automobile crashworthiness simulation of wrought aluminium alloy components
Energy Technology Data Exchange (ETDEWEB)
El-Magd, E. [RWTH Aachen (Germany); Gese, H. [MATFEM, Munich (Germany); Tham, R. [Fraunhofer Inst. fuer Kurzzeitdynamik, Freiburg (Germany); Hooputra, H.; Werner, H. [BMW Group, Munich (Germany)
2001-09-01
In automobile crashworthiness simulation, the prediction of plastic deformation and fracture of each significant, single component is critical to correctly represent the transient energy absorption through the car structure. There is currently a need, in the commercial FEM community, for validated material fracture models which adequately represent this phenomenon. The aim of this paper is to compare and to validate existing numerical approaches to predict failure with test data. All studies presented in this paper were carried out on aluminium wrought alloys: AlMgSi1.F31 and AlMgSiCu-T6. A viscoplastic material law, whose parameters are derived from uniaxial tensile and compression tests at various strain rates, is developed and presented herein. Fundamental ductile fracture mechanisms such as void nucleation, void growth, and void coalescence as well as shear band fracture are present in the tested samples and taken into consideration in the development of the fracture model. Two approaches to the prediction of fracture initiation are compared. The first is based on failure curves expressed by instantaneous macroscopic stresses and strains (i.e. maximum equivalent plastic strain vs. stress triaxiality). The second approach is based on the modified Gurson model and uses state variables at the mesoscopic scale (i.e. critical void volume fraction). Notched tensile specimens with varying notch radii and axisymmetric shear specimens were used to produce ductile fractures and shear band fractures at different stress states. The critical macroscopic and mesoscopic damage values at the fracture initiation locations were evaluated using FEM simulations of the different specimens. The derived fracture criteria (macroscopic and mesoscopic) were applied to crashworthiness experiments with real components. The quality of the prediction on component level is discussed for both types of criteria. (orig.)
Ensey, Tyler S.
2013-01-01
During my internship at NASA, I was a model developer for Ground Support Equipment (GSE). The purpose of a model developer is to develop and unit test model component libraries (fluid, electrical, gas, etc.). The models are designed to simulate software for GSE (Ground Special Power, Crew Access Arm, Cryo, Fire and Leak Detection System, Environmental Control System (ECS), etc. .) before they are implemented into hardware. These models support verifying local control and remote software for End-Item Software Under Test (SUT). The model simulates the physical behavior (function, state, limits and 110) of each end-item and it's dependencies as defined in the Subsystem Interface Table, Software Requirements & Design Specification (SRDS), Ground Integrated Schematic (GIS), and System Mechanical Schematic.(SMS). The software of each specific model component is simulated through MATLAB's Simulink program. The intensiv model development life cycle is a.s follows: Identify source documents; identify model scope; update schedule; preliminary design review; develop model requirements; update model.. scope; update schedule; detailed design review; create/modify library component; implement library components reference; implement subsystem components; develop a test script; run the test script; develop users guide; send model out for peer review; the model is sent out for verifictionlvalidation; if there is empirical data, a validation data package is generated; if there is not empirical data, a verification package is generated; the test results are then reviewed; and finally, the user. requests accreditation, and a statement of accreditation is prepared. Once each component model is reviewed and approved, they are intertwined together into one integrated model. This integrated model is then tested itself, through a test script and autotest, so that it can be concluded that all models work conjointly, for a single purpose. The component I was assigned, specifically, was a
Component fragility research program
Energy Technology Data Exchange (ETDEWEB)
Tsai, N.C.; Mochizuki, G.L.; Holman, G.S. (NCT Engineering, Inc., Lafayette, CA (USA); Lawrence Livermore National Lab., CA (USA))
1989-11-01
To demonstrate how high-level'' qualification test data can be used to estimate the ultimate seismic capacity of nuclear power plant equipment, we assessed in detail various electrical components tested by the Pacific Gas Electric Company for its Diablo Canyon plant. As part of our Phase I Component Fragility Research Program, we evaluated seismic fragility for five Diablo Canyon components: medium-voltage (4kV) switchgear; safeguard relay board; emergency light battery pack; potential transformer; and station battery and racks. This report discusses our Phase II fragility evaluation of a single Westinghouse Type W motor control center column, a fan cooler motor controller, and three local starters at the Diablo Canyon nuclear power plant. These components were seismically qualified by means of biaxial random motion tests on a shaker table, and the test response spectra formed the basis for the estimate of the seismic capacity of the components. The seismic capacity of each component is referenced to the zero period acceleration (ZPA) and, in our Phase II study only, to the average spectral acceleration (ASA) of the motion at its base. For the motor control center, the seismic capacity was compared to the capacity of a Westinghouse Five-Star MCC subjected to actual fragility tests by LLNL during the Phase I Component Fragility Research Program, and to generic capacities developed by the Brookhaven National Laboratory for motor control center. Except for the medium-voltage switchgear, all of the components considered in both our Phase I and Phase II evaluations were qualified in their standard commercial configurations or with only relatively minor modifications such as top bracing of cabinets. 8 refs., 67 figs., 7 tabs.
Peng, Xuan
The standard procedure of the fabrication of low temperature superconductor precursors is the co-extrusion of composite materials followed by co-drawing. Defects including wire breakage and poor bonding between core and sleeve as well as between individual filaments are the main manufacturing problems. Understanding of interfacial bonding during the co-extrusion and co-drawing of the composites including the distributions of deformation, stress and temperature, and the generation process of interfacial bonding under different conditions will be helpful for the selection of parameters in the manufacture. First, the bonding created during the extrusion of subelements was examined and characterized using a focused ion beam (FIB) technique together with scanning transmission electronic microscopic (STEM) and the results confirmed that perfectly bonded subelements could be obtained by proper assembly, HIP, and subsequent extrusion. The second part of the work was aimed at the bonding generation during co-drawing process. Finite Element Method (FEM) was used to simulate the co-deformation process in order to investigate the effects of die angle, area reduction, core ratio, and the variation of bonding between components on the deformed geometry, and stress distribution in the product. The FEM simulation incorporated with a Pressure Bonding Model to study the generation process of interfacial bonding between components during the drawing process. This work starts with the multiple-pass drawing of a simple cylindrical monocore arrangement consisting of a Nb7.5%Ta core inside a Cu sleeve and a six-around-one restack of the monocores. The effect of the drawing pass, area reductions, die angles and core ratio on the deformation and bonding generation was investigated. On the experimental side, Cu-clad Nb7.5%Ta monocore "billet" was drawn to certain size, restacked into a Cu can to form a 7 restack multifilamentary billet, and then drawn to small size. High resolution scanning
Energy Technology Data Exchange (ETDEWEB)
Schlecht, Berthold; Rosenloecher, Thomas; Schulze, Thomas [Technische Univ. Dresden (Germany). Inst. fuer Maschinenelemente und Maschinenkonstruktion
2009-07-01
An exact knowledge of the dynamic characteristics and the additional demands resulting from these already enables a recognizing of damages (in particular damages of interlocking and bearing) of wind power plants during the development of products. The method of many-body simulation offers extensive possibilities in the solving of this problem. Since 2001, the many-body simulation successfully has been used at the Institute of Machine Elements and Machine Design at the Technical University of Dresden (Federal Republic of Germany). On the basis of many-body systems, the method of flexible many-body systems developed. Thus, individual components and complex construction units can be modelled as flexible structures in the simulation model. Taking finite element structures as a basis enables the flexible modelling of shafts, casings of bearings and supporting structures. Apart from the determination of the dynamic characteristics and the relative motions of rigid bodies, additionally the inherent frequencies and deformations of individual flexible bodies can be examined.
Scientific Component Technology Initiative
Energy Technology Data Exchange (ETDEWEB)
Kohn, S; Bosl, B; Dahlgren, T; Kumfert, G; Smith, S
2003-02-07
The laboratory has invested a significant amount of resources towards the development of high-performance scientific simulation software, including numerical libraries, visualization, steering, software frameworks, and physics packages. Unfortunately, because this software was not designed for interoperability and re-use, it is often difficult to share these sophisticated software packages among applications due to differences in implementation language, programming style, or calling interfaces. This LDRD Strategic Initiative investigated and developed software component technology for high-performance parallel scientific computing to address problems of complexity, re-use, and interoperability for laboratory software. Component technology is an extension of scripting and object-oriented software development techniques that specifically focuses on the needs of software interoperability. Component approaches based on CORBA, COM, and Java technologies are widely used in industry; however, they do not support massively parallel applications in science and engineering. Our research focused on the unique requirements of scientific computing on ASCI-class machines, such as fast in-process connections among components, language interoperability for scientific languages, and data distribution support for massively parallel SPMD components.
Spacecraft Component Adaptive Layout Environment (SCALE): An efficient optimization tool
Fakoor, Mahdi; Ghoreishi, Seyed Mohammad Navid; Sabaghzadeh, Hossein
2016-11-01
For finding the optimum layout of spacecraft subsystems, important factors such as the center of gravity, moments of inertia, thermal distribution, natural frequencies, etc. should be taken into account. This large number of effective parameters makes the optimum layout process of spacecraft subsystems complex and time consuming. In this paper, an automatic tool, based on multi-objective optimization methods, is proposed for a three dimensional layout of spacecraft subsystems. In this regard, an efficient Spacecraft Component Adaptive Layout Environment (SCALE) is produced by integration of some modeling, FEM, and optimization software. SCALE automatically provides optimal solutions for a three dimensional layout of spacecraft subsystems with considering important constraints such as center of gravity, moment of inertia, thermal distribution, natural frequencies and structural strength. In order to show the superiority and efficiency of SCALE, layout of a telecommunication spacecraft and a remote sensing spacecraft are performed. The results show that, the objective functions values for obtained layouts by using SCALE are in a much better condition than traditional one i.e. Reference Baseline Solution (RBS) which is proposed by the engineering system team. This indicates the good performance and ability of SCALE for finding the optimal layout of spacecraft subsystems.
DEFF Research Database (Denmark)
Feng, Ling
2008-01-01
of audio contexts along with pattern recognition methods to map components to known contexts. It also involves looking for the right representations for auditory inputs, i.e. the data analytic processing pipelines invoked by human brains. The main ideas refer to Cognitive Component Analysis, defined......This dissertation concerns the investigation of the consistency of statistical regularities in a signaling ecology and human cognition, while inferring appropriate actions for a speech-based perceptual task. It is based on unsupervised Independent Component Analysis providing a rich spectrum...... as the process of unsupervised grouping of generic data such that the ensuing group structure is well-aligned with that resulting from human cognitive activity. Its hypothesis runs ecologically: features which are essentially independent in a context defined ensemble, can be efficiently coded as sparse...
Adaptable component frameworks
DEFF Research Database (Denmark)
Katajainen, Jyrki; Simonsen, Bo
2009-01-01
The CPH STL is a special edition of the STL, the containers and algorithms part of the C++ standard library. The specification of the generic components of the STL is given in the C++ standard. Any implementation of the STL, e.g. the one that ships with your standard-compliant C++ compiler, should...... provide at least one realization for each container that has the specified characteristics with respect to performance and safety. In the CPH STL project, our goal is to provide several alternative realizations for each STL container. For example, for associative containers we can provide almost any kind...... of balanced search tree. Also, we do provide safe and compact versions of each container. To ease the maintenance of this large collection of implementations, we have developed component frameworks for the STL containers. In this paper, we describe the design and implementation of a component framework...
An integrated magnetics component
DEFF Research Database (Denmark)
2013-01-01
The present invention relates to an integrated magnetics component comprising a magnetically permeable core comprising a base member extending in a horizontal plane and first, second, third and fourth legs protruding substantially perpendicularly from the base member. First, second, third...... extending substantially orthogonally to the first flux path. Another aspect of the invention relates to a multiple-input isolated power converter comprising the integrated magnetics component....... and fourth output inductor windings are wound around the first, second, third and fourth legs, respectively. A first input conductor of the integrated magnetics component has a first conductor axis and extends in-between the first, second, third and fourth legs to induce a first magnetic flux through a first...
Electronic components and systems
Dennis, W H
2013-01-01
Electronic Components and Systems focuses on the principles and processes in the field of electronics and the integrated circuit. Covered in the book are basic aspects and physical fundamentals; different types of materials involved in the field; and passive and active electronic components such as capacitors, inductors, diodes, and transistors. Also covered in the book are topics such as the fabrication of semiconductors and integrated circuits; analog circuitry; digital logic technology; and microprocessors. The monograph is recommended for beginning electrical engineers who would like to kn
Towards Cognitive Component Analysis
DEFF Research Database (Denmark)
Hansen, Lars Kai; Ahrendt, Peter; Larsen, Jan
2005-01-01
Cognitive component analysis (COCA) is here defined as the process of unsupervised grouping of data such that the ensuing group structure is well-aligned with that resulting from human cognitive activity. We have earlier demonstrated that independent components analysis is relevant for representing...... semantics, not only in text, but also in dynamic text (chat), images, and combinations of text and images. Here we further expand on the relevance of the ICA model for representing context, including two new analyzes of abstract data: social networks and musical features....
Web-Based Synthetic Optimization Design System of Micro-Components
Institute of Scientific and Technical Information of China (English)
GONG Xiao-yan; JIANG Ping-yu
2005-01-01
In order to meet the requirement of network synthesis optimization design for a micro component, a three-level information frame and functional module based on web was proposed. Firstly, the finite element method (FEM) was used to analyze the dynamic property of coupled-energy-domain of virtual prototype instances and to obtain some optimal information data. Secondly, the rough set theory (RST) and the genetic algorithm (GA) were used to work out the reduction of attributes and the acquisition of principle of optimality and to confirm key variable and restriction condition in the synthesis optimization design. Finally, the regression analysis (RA) and GA were used to establish the synthesis optimization design model and carry on the optimization design. A corresponding prototype system was also developed and the synthesis optimization design of a thermal actuated micro-pump was carried out as a demonstration in this paper.
Multimode geodesic branching components
Schulz, D.; Voges, E.
1983-01-01
Geodesic branching components are investigated for multimode guided wave optics. Geodesic structures with particular properties, e.g. focussing star couplers, are derived by a synthesis technique based on a theorem of Toraldo di Francia. Experimentally, the geodesic surfaces are printed on acrylic glass and are spin-coated with organic film waveguides.
Component School Construction Program.
New Brunswick Dept. of Economic Growth, Fredericton.
In 1968, the Province of New Brunswick initiated a three-phase program to provide for elementary school facilities, employing a component systems approach to their construction. This booklet describes briefly the planning and construction of these schools, and provides graphic and photographic records of the construction in progress as well as of…
Autonomous component carrier selection
DEFF Research Database (Denmark)
Garcia, Luis Guilherme Uzeda; Pedersen, Klaus; Mogensen, Preben
2009-01-01
in local areas, basing our study case on LTE-Advanced. We present extensive network simulation results to demonstrate that a simple and robust interference management scheme, called autonomous component carrier selection allows each cell to select the most attractive frequency configuration; improving...
Energy Technology Data Exchange (ETDEWEB)
Conde, J.C., E-mail: jconde@uvigo.es [Dpto. Fisica Aplicada, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain); Martin, E. [Dpto. Mecanica, Maquinas, Motores Termicos y Fluidos, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain); Stefanov, S. [Dpto. Fisica Aplicada, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain); Alpuim, P. [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Chiussi, S. [Dpto. Fisica Aplicada, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain)
2012-09-15
Highlights: Black-Right-Pointing-Pointer nc-Si:H is a material with growing importance for a large-area of nano-electronic, photovoltaic or biomedical devices. Black-Right-Pointing-Pointer UV-ELA technique causes a rapid heating that provokes the H{sub 2} desorption from the Si surface and bulk material. Black-Right-Pointing-Pointer Next, diffusion of P doped nc-Si films and eventually, for high energy densities would be possible to reach the melting point. Black-Right-Pointing-Pointer These multilayer structures consisting of thin alternating a-Si:H(10 nm) and n-doped nc-Si:H(60 nm) films deposited on SiO{sub 2}. Black-Right-Pointing-Pointer To optimize parameters involved in this processing, FEM numerical analysis of multilayer structures have been performed. Black-Right-Pointing-Pointer The numerical results are compared with exhaustive characterization of the experimental results. - Abstract: UV excimer laser annealing (UV-ELA) is an alternative annealing process that, during the last few years, has gained enormous importance for the CMOS nano-electronic technologies, with the ability to provide films and alloys with electrical and optical properties to fit the desired device performance. The UV-ELA of amorphous (a-) and/or doped nano-crystalline (nc-) silicon films is based on the rapid (nanoseconds) formation of temperature profiles caused by laser radiation that is absorbed in the material and lead to crystallisation, diffusion in solid or even in liquid phase. To achieve the desired temperature profiles and to optimize the parameters involved in the processing of hydrogenated nanocrystalline silicon (nc-Si:H) films with the UV-ELA, a numerical analysis by finite element method (FEM) of a multilayer structure has been performed. The multilayer structures, consisting of thin alternating a-Si:H(10 nm) and n-doped nc-Si:H(60 nm) layers, deposited on a glass substrate, has also been experimentally analyzed. Temperature profiles caused by 193 nm radiation with 25
Simulation of Electromagnetic Scattering of Chopped Carbon Fiber Based on FEM%短切碳纤维电磁散射特性仿真研究
Institute of Scientific and Technical Information of China (English)
黎炎图; 王超英; 杜作娟; 黄小忠
2011-01-01
研究单根碳纤维的电磁散射特性,如何改善碳纤维的吸波性能,是碳纤维复合吸波材料的难点问题.为上述问题,提出用圆柱体模型模拟碳纤维,根据三维电磁场有限元(FEM)算法,当平面波激励时,采用四面体棱边元网格划分及辐射边界条件以及矩阵方程组的自适应迭代算法,在Ansoft HFSS仿真平台上模拟了碳纤维的电场散射特性,获得了单根碳纤维的电场散射图.结果表明,在合适的长径比范围内,碳纤维与人射波产生强烈的谐振,碳纤维的电导率、轴向和入射波频率对其电磁波散射均有重要影响.仿真结果对设计具有强吸波性能的短切碳纤维复合吸波材料具有参考价值.%In the research of absorbing composite materials, the diffcult problem is how to study the scattering of electromagnetic wave for single carbon fiber.To solve this problem, the single carbon fiber is simulated with the cylinder model.According to three-dimensional finite element (FEM) algorithm, during plane waves excitation, tetrahedral edge element mesh, radiation boundary conditions and the adaptive iterative algorithm of matrix equations are used to simulate the scattering of electric field of short carbon fiber based on Ansoft HFSS simulation platform, and the maps of electric field scattering are visible.The results show that carbon fibers have strong resonance with the incident wave at appropriate aspect ratio, and its orientation, electrical conductivity and the frequency of the incident wave have an important effect on its electromagnetic scattering.Simulation results have great significance for the preparation of carbon fiber composite absorbing material with strong absorbing properties.
Directory of Open Access Journals (Sweden)
Hendri Yanda
2010-11-01
Full Text Available Demand for higher productivity and good quality for machining parts has encourage many researchers to study the effects of machining parameters using FEM simulation using either two or three dimensions version. These are due to advantages such as software package and computational times are required. Experimental work is very costly, time consuming and labor intensive. The present work aims to simulate a three-dimensional orthogonal cutting operations using FEM software (Deform-3D to study the effects of rake angle on the cutting force, effective stress, strain and temperature on the edge of carbide cutting tool. There were seven runs of simulations. All simulations were performed for various rake angles of -15 deg, -10 deg, -5 deg, 0 deg, +5 deg, +10 deg, and +15 deg. The cutting speed, feed rate and depth of cut (DOC were kept constant at 100 m/min, 0.35 mm/rev and 0.3 mm respectively. The work piece used was ductile cast iron FCD500 grade and the cutting tool was DNMA432 series (tungsten, uncoated carbide tool, SCEA = 0; and radius angle 55 deg. The analysis of results show that, the increase in the rake angle from negative to positive angle, causing the decrease in cutting force, effective stress and total Von Misses strain. The minimum of the cutting force, effective stress and total Von Misses strain were obtained at rake angle of +15 deg. Increasing the rake caused higher temperature generated on the edge of carbide cutting tool and resulted in bigger contact area between the clearance face and the workpiece, consequently caused more friction and wear. The biggest deformation was occurred in the primary deformation zone, followed by the secondary deformation zone. The highest stress was also occurred in the primary deformation zone. But the highest temperature on the chip usually occurs in secondary deformation zone, especially in the sliding region, because the heat that was generated in the sticking region increased as the workpiece was
Lin, G.; Chang, W. L.; Chang, C. P.
2015-12-01
Postseismic deformation following large earthquakes can persist from years to decades. Since the 1999 Chi-Chi earthquake (Mw=7.6), more than a decade of GPS records reveal postseismic deformation across Taiwan and have been used for afterslip and lithospheric rheology studies. Previous researches show that this earthquake has experienced rapid afterslip on deeper part of Chelungpu fault with slip rates decreased within years [Hsu et al., 2002 and 2007]. Other postseismic deformation signals were modeled by assumed Maxwell viscoelastic relaxation with heterogeneous lower crust and upper mantle [Rousset et al., 2012; Tang et al., 2015], which suggest that the pattern of vertical displacements is more sensitive to the geometry of heterogeneous viscoelastic lithospheric structure. To improve the spatial coverage of observation, this study processed both ERS and Envisat SAR images from 1999-2008 with PSInSAR techniques, and the result provide a better illustration of Line-Of-Sight (LOS) deformation field which is near to vertical. Both GPS and PSInSAR results reveal that the surface displacement rates (horizontal or vertical?) of eastern Taiwan are higher than interseismic rates after a decade, and this feature may reveal the importance of low viscosity zone beneath central range of Taiwan. With the benefits from GPS and PSInSAR data, we intend to test other posssible viscosity and the geometry of viscoelastic structure. We adopt coseismic fault geometry and slip distribution of the Chi-Chi earthquake based on previous studies, and build a set of 2D rheological models with an elastic upper-crust layer overlain a viscoelastic lower-crust layer and a viscoelastic upper mantle. The depths of the two layer boundaries are determined according to subsurface tectonic and velocity structures inferred by previous literatures. We employ the finite element method (FEM), Pylith, to estimate the postseismic surface deformation corresponding to different viscosities. Benefit from the
Katagi, T.; Hashimoto, M.; Hashizume, M.; Choosakul, N.; Takemoto, S.; Fukuda, Y.; Fujimori, K.; Satomura, M.; Wu, P.; Otsuka, Y.; Takiguchi, H.; Saito, S.; Maruyama, T.; Kato, T.
2007-12-01
We have studied postseismic displacement following the Sumatra-Andaman earthquake of December 26, 2004 in Thailand and other Southeast Asian countries using continuous GPS observation. We will report the results of our GPS analysis from the beginning of 2001 to the end of October 2007. We have also constructed 3D-FEM to evaluate the effect of viscoelastic relaxation following the earthquake. We will also report this result. We used continuous GPS data from 6 sites operated by Chulalongkorn Univ. and Kyoto Univ. or JAMSTEC, 2 sites by Shizuoka Univ. and JAMSTEC, 3 sites by NICT in Thailand and Myanmar, 1 site by STE-Lab, Nagoya Univ., and IGS sites which are located in countries surrounding the Indian Ocean include Japan, China and Australia. Bernese 5.0 was used for the processing of 30 sec. sampling data to obtain static solutions. From our analysis, no significant motions were detected at each site until the day of the earthquake. Although postseismic displacements still have been detected at CHMI and SIS2 in northern Thailand, far from the epicenter, they seem to be decelerated. On the other hand, at SAMP and PHKT, close to the epicenter, where postseismic displacements also became smaller, but still may take a time to stop. An about 29 cm SW-ward motion was detected at PHKT from just after the Sumatra-Andaman earthquake to June 2007, which is larger than its coseismic displacement, about 26 cm. We have constructed 3D-FEM model to estimate how much viscoelastic relaxation affects postseismic displacements after the earthquake. We adopted a Maxwell viscoelastic body as well as Katagi et al. (2006), and modeled around the Andaman-Sea area using isoparametric hexahedral elements with 8 nodes (Zienkiewicz and Cheng, 1967). The Andaman-Sea is well known as a back arc basins, and its ocean floor is still spreading. Therefore, the mantle viscosity under the Sunda-plate may be smaller because of upwelling warm mantle. We are going to investigate and report the
Fields, Christina M.
2013-01-01
The Spaceport Command and Control System (SCCS) Simulation Computer Software Configuration Item (CSCI) is responsible for providing simulations to support test and verification of SCCS hardware and software. The Universal Coolant Transporter System (UCTS) was a Space Shuttle Orbiter support piece of the Ground Servicing Equipment (GSE). The initial purpose of the UCTS was to provide two support services to the Space Shuttle Orbiter immediately after landing at the Shuttle Landing Facility. The UCTS is designed with the capability of servicing future space vehicles; including all Space Station Requirements necessary for the MPLM Modules. The Simulation uses GSE Models to stand in for the actual systems to support testing of SCCS systems during their development. As an intern at Kennedy Space Center (KSC), my assignment was to develop a model component for the UCTS. I was given a fluid component (dryer) to model in Simulink. I completed training for UNIX and Simulink. The dryer is a Catch All replaceable core type filter-dryer. The filter-dryer provides maximum protection for the thermostatic expansion valve and solenoid valve from dirt that may be in the system. The filter-dryer also protects the valves from freezing up. I researched fluid dynamics to understand the function of my component. The filter-dryer was modeled by determining affects it has on the pressure and velocity of the system. I used Bernoulli's Equation to calculate the pressure and velocity differential through the dryer. I created my filter-dryer model in Simulink and wrote the test script to test the component. I completed component testing and captured test data. The finalized model was sent for peer review for any improvements. I participated in Simulation meetings and was involved in the subsystem design process and team collaborations. I gained valuable work experience and insight into a career path as an engineer.
Institute of Scientific and Technical Information of China (English)
肖毅华; 胡德安; 韩旭; 杨刚
2012-01-01
为了准确、高效地模拟高速冲击问题,提出了一种自适应轴对称有限元(FEM)-光滑粒子流体动力学(SPH)耦合算法.该算法在初始时刻全部采用FEM计算,在动态变形过程中自动将畸变单元转化为粒子,采用SPH计算.该算法采用一种新的耦合算法实现单元与粒子间的高精度耦合,并应用最小内角转化准则和单元分组转化方式实现单元向粒子的自动转化.计算了几个典型的高速冲击问题:首先,通过计算应力波传播测试了新的单元-粒子耦合算法的精度;然后,通过计算泰勒杆问题验证了自适应耦合算法及相应程序的正确性;最后,计算了弹体侵彻铝板和混凝土板.结果表明:自适应耦合算法计算精度好且效率高,适合模拟高速冲击问题.%An adaptive axisymmetric finite element method (FEM) - smoothed particle hydrodynamics (SPH) coupling algorithm is proposed to accurately and efficiently simulate high velocity impact problems. It uses FEM to calculate at the beginning. During the deformation process, it automatically converts distorted elements to particles and uses SPH for calculation at these regions where distorted elements appear. In the adaptive coupling algorithm, a new coupling algorithm is applied to link elements and particles accurately, and a minimum interior angle criterion combined with a group-based conversion manner is adopted to convert elements to particles. Several typical high velocity impact problems are calculated. Firstly, the stress wave propagation is calculated to test the accuracy of the new element-particle coupling algorithm. Then, the Taylor test is calculated to validate the adaptive coupling algorithm and the corresponding code. Finally, the simulation of projectiles penetrating aluminum and concrete plates is presented. The results show that the adaptive coupling algorithm is accurate and efficient and it is very suitable for the simulation of high velocity impact.
Component-Based Reduced Basis for Eigenproblems
2013-07-17
Timoshenko model [18], global FEM and SCRBE with and without port reduction (in which the beam is constructed as the concatenation of eight beam...not taken into account in Euler Bernoulli and Timoshenko models which consider only bending displacement. Note that for a beam with a square section...and/or slender beams; Timoshenko is better for shorter wavelength and/or shorter beams. Not surprisingly, the FE (and SCRBE) eigenvalues are closer to
Compressive Principal Component Pursuit
Wright, John; Min, Kerui; Ma, Yi
2012-01-01
We consider the problem of recovering a target matrix that is a superposition of low-rank and sparse components, from a small set of linear measurements. This problem arises in compressed sensing of structured high-dimensional signals such as videos and hyperspectral images, as well as in the analysis of transformation invariant low-rank recovery. We analyze the performance of the natural convex heuristic for solving this problem, under the assumption that measurements are chosen uniformly at random. We prove that this heuristic exactly recovers low-rank and sparse terms, provided the number of observations exceeds the number of intrinsic degrees of freedom of the component signals by a polylogarithmic factor. Our analysis introduces several ideas that may be of independent interest for the more general problem of compressed sensing and decomposing superpositions of multiple structured signals.
Directory of Open Access Journals (Sweden)
S. Wittig
1998-01-01
Full Text Available Cooling of high speed rotating components is a typical situation found in turbomachinery as well as in automobile engines. Accurate knowledge of discharge coefficients and heat transfer of related components is essential for the high performance of the whole engine. This can be achieved by minimized cooling air flows and avoidance of hot spots. In high speed rotating clutches for example aerodynamic investigations improving heat transfer have not been considered in the past. Advanced concepts of modern plate design try to reduce thermal loads by convective cooling methods. Therefore, secondary cooling air flows have to be enhanced by an appropriate design of the rotor stator system with orifices. CFD modelling is used to improve the basic understanding of the flow field in typical geometries used in these systems.
Food Components and Supplements
DEFF Research Database (Denmark)
Parlesak, Alexandr
2012-01-01
The major part of food consists of chemical compounds that can be used for energy production, biological synthesis, or maintenance of metabolic processes by the host. These components are defined as nutrients, and can be categorized into macronutrients (proteins, carbohydrates, triglycerides.......g., secondary plant metabolites such as flavonoids), or as contaminants that enter the food chain at different stages or during the food production process. For these components, a wide spectrum of biological effects was observed that ranges from health-threatening impacts (e.g., polycyclic aromatic amines...... the growth of these bacteria (prebiotics) are added to food to achieve health effects exceeding its pure nutritional function. Several of these effects are mediated by enzyme systems involved in xenobiotic and drug metabolism, and in some cases this might lead to undesired interactions with medication...
Food Components and Supplements
DEFF Research Database (Denmark)
Parlesak, Alexandr
2012-01-01
.g., secondary plant metabolites such as flavonoids), or as contaminants that enter the food chain at different stages or during the food production process. For these components, a wide spectrum of biological effects was observed that ranges from health-threatening impacts (e.g., polycyclic aromatic amines...... the growth of these bacteria (prebiotics) are added to food to achieve health effects exceeding its pure nutritional function. Several of these effects are mediated by enzyme systems involved in xenobiotic and drug metabolism, and in some cases this might lead to undesired interactions with medication...... cases, nutrients, food contaminants, and secondary plant metabolites can themselves become substrates for xenobiotic-metabolizing enzymes, resulting in health-promoting or health-threatening products. This chapter focuses on how important components of our daily nutrition and supplements can interfere...
Bayesian Independent Component Analysis
DEFF Research Database (Denmark)
Winther, Ole; Petersen, Kaare Brandt
2007-01-01
In this paper we present an empirical Bayesian framework for independent component analysis. The framework provides estimates of the sources, the mixing matrix and the noise parameters, and is flexible with respect to choice of source prior and the number of sources and sensors. Inside the engine...... in a Matlab toolbox, is demonstrated for non-negative decompositions and compared with non-negative matrix factorization....
Analysis of Dynamic Response of Gearbox Based on FEM%基于有限元方法的齿轮箱动态响应分析
Institute of Scientific and Technical Information of China (English)
荆焕亮; 吴鹏翔; 王洪福; 段海华; 岳晓露
2015-01-01
In this paper, the numerical simulation of gearbox is carried out by FEM, and the three-dimensional finite element model for the gearbox is constructed, and then the gearbox modal analysis is also completed by the Lancozs method, its natural frequency and principal modal are obtained.In order to analyze the dynamic response, modal frequency response of gearbox is established, its vibration velocity, displacement and vibration acceleration are calculated.It could provide a theoretical basis for the post-structural optimization and noise reduction of gearbox.%运用结构有限元法对某齿轮箱进行数值仿真分析。建立齿轮箱三维有限元模型，基于分块Lancozs完成齿轮箱模态分析，提取其固有频率及振型，分析齿轮啮合动态激励，完成齿轮箱频率响应分析，得到了振动速度、振动位移及振动加速度，分析了动态响应规律，这为后期齿轮箱结构优化及降噪提供理论依据。
Kujawińska, M.; Łapka, P.; Malesa, M.; Malowany, K.; Prasek, M.; Marczak, J.
2016-12-01
The paper presents the new approach to the analysis of interaction between a high power laser beam and matter. The method relies on the combined experimental-numerical spatio-temporal analysis of temperature, displacement and strain maps which are generated at a surface of an object illuminated by a high power laser beam. Transient heat transfer numerical simulations were carried out applying the FVM, while the quasi-transient structural analyses were performed with the aid of the FEM. The displacement maps were captured by means of 3D Digital Image Correlation method, and temperature maps were provided by a high speed IR camera. The experimental data are compared to the initial model of laser induced heat transfer in an object and resulting displacements/strains. The first approach to hybrid experimental-numerical method which aims in indirect determination of laser beam profile is described. The monitoring of displacement/strain maps directly at an illuminated object may be also used for a structural integrity analysis of a target. In the paper at first the numerical simulations applied to model laser beam thermal interaction with solid bodies are presented. Next the laboratory experimental stand is described and the results of the initial tests performed at aluminum and bronze samples are shown and compared with numerical simulations. The advantages and disadvantages of the proposed methodology are discussed in relation to the two applications mentioned above.
Directory of Open Access Journals (Sweden)
Yu-Jun Zhang
2012-01-01
Full Text Available The models of stress corrosion and pressure solution established by Yasuhara et al. were introduced into the 2D FEM code of thermo-hydro-mechanical-migratory coupling analysis for dual-porosity medium developed by the authors. Aiming at a hypothetical model for geological disposal of nuclear waste in an unsaturated rock mass from which there is a nuclide leak, two computation conditions were designed. Then the corresponding two-dimensional numerical simulation for the coupled thermo-hydro-mechanical-migratory processes were carried out, and the states of temperatures, rates and magnitudes of aperture closure, pore and fracture pressures, flow velocities, nuclide concentrations and stresses in the rock mass were investigated. The results show: the aperture closure rates caused by stress corrosion are almost six orders higher than those caused by pressure solution, and the two kinds of closure rates climb up and then decline, furthermore tend towards stability; when the effects of stress corrosion and pressure solution are considered, the negative fracture pressures in near field rise very highly; the fracture aperture and porosity are decreases in the case 1, so the relative permeability coefficients reduce, therefore the nuclide concentrations in pore and fracture in this case are higher than those in case 2.
L形管件弯曲成形有限元分析%FEM analysis of bending process for L-shaped tube
Institute of Scientific and Technical Information of China (English)
李福涛; 葛位维; 张召春; 李玮
2012-01-01
采用有限元软件Deform-3D建立了L形管件三维有限元模型,并对其弯曲过程运动仿真.模拟分析了管件的等效应力、金属流动速度、材料损伤分布以及模具间隙和芯棒对弯管质量的影响.对成形缺陷进行了分析,通过优化得到满足要求的弯曲管件.%The FEM model for L-shaped tube has been built by use of 3D finite element analysis (FEA) software Deform-3D. The motion simulation of the bending process has been carried on. The influence of tube equivalent stress, velocity, and the material damage distribution on the tube quality has been simulated and analyzed, as well as the influence of die clearance and mandrel. The forming faults have been analyzed. The bending tube which meets the requirement after optimization has been obtained.
Directory of Open Access Journals (Sweden)
Xiaoguang Lin
2013-01-01
Full Text Available For this study, we conducted a numerical simulation on co-seismic displacement for a dip-slip fault in a half-space medium based upon a finite element method (FEM. After investigating technical problems of modeling, source and boundary treatment, we calculated co-seismic deformation with consideration to topography. To verify the numerical simulation results, the simulated co-seismic displacement was compared with that calculated using a dislocation theory. As a case study, considering the seismic parameters of the 2008 Wenchuan earthquake (M 8.0 as a source model, we calculate the co-seismic displacements with or without consideration of the terrain model in the finite element model to observe terrain effects on co-seismic deformation. Results show that topography has a non-negligible effect on co-seismic displacement, reaching from -11.59 to 4.0 cm in horizontal displacement, and from -3.28 to 3.28 cm in vertical displacement. The relative effects are 9.05 and 2.95% for horizontal and vertical displacement, respectively. Such a terrain effect is sufficiently large and can be detected by modern geodetic measurements such as GPS. Therefore, we conclude that the topography should be considered in applying dislocation theory to calculate co-seismic deformations.
Wang, Yugang; Wu, Xinjun; Sun, Pengfei; Li, Jian
2015-02-03
Electromagnetic acoustic transducers (EMATs) can generate non-dispersive T(0,1) mode guided waves in a metallic pipe for nondestructive testing (NDT) by using a periodic permanent magnet (PPM) EMAT circular array. In order to enhance the excitation efficiency of the sensor, the effects of varying the number of elements of the array on the excitation efficiency is studied in this paper. The transduction process of the PPM EMAT array is studied based on 3-D finite element method (FEM). The passing signal amplitude of the torsional wave is obtained to represent the excitation efficiency of the sensor. Models with different numbers of elements are established and the results are compared to obtain an optimal element number. The simulation result is verified by experiments. It is shown that after optimization, the amplitudes of both the passing signal and defect signal with the optimal element number are increased by 29%, which verifies the feasibility of this optimal method. The essence of the optimization is to find the best match between the static magnetic field and the eddy current field in a limited circumferential space to obtain the maximum circumferential Lorentz force.
声表面波换能器激励的有限元仿真%FEM simulation of SAW transducer excitation
Institute of Scientific and Technical Information of China (English)
张永刚
2009-01-01
采用有限元法分析了声表面波换能器电极上的激励问题.从声场波动方程、麦克斯韦方程以及压电本构方程出发,利用哈密顿原理,推导了在压电介质中声表而波有限元方程,然后采用Newmark法对有限元方程进行时域变换.分析了换能器电极上的静态电荷分布和动态电荷分布.对压电介质中声表面波振动振幅进行计算并分析了质点振动振幅随深度的变化情况.%The relationship between surface acoustic wave (SAW) and voltage excitation is analyzed with the finite element method (FEM). Starting from the acoustic field wave equations, Maxwell equations and piezoelectric constitu-tive equations, the finite element equations for interdigital transducers are established with Hamilton principle, and then transformed into time-domain with Newmark method. The static charge distribution and the dynamic charge dis-tribution on electrodes are analyzed. The SAW vibration amplitude of the interdigital transducers is calculated and its variation with depth is also analyzed.
Directory of Open Access Journals (Sweden)
Marcin Krzeszowiec
2015-03-01
Full Text Available Computer simulations of physical phenomena are at the moment common both in science and industry. The possibility of finding approximate solutions for complicated systems of differential equations, mathematically describing issues in the fields of mechanics, physics or chemistry, allows for shorten design and research time, often significantly reducing the need for expensive experimental studies or costly production of prototypes. However, the mentioned prevalence of these methods, particularly the Finite Element Method, resulted in analysis outcomes to be often in advance regarded as accurate ones. The purpose of the article is to showcase, on a simple stress analysis problem, how parameters such as the density of the finite element mesh, finite element formulation or integration scheme significantly influence on the simulation results and how easy it is to end up with the results that do not hold any physical sense, despite the fact that all the basic assumptions of correct analysis (suitable boundary conditions, total system energy stored etc. have been met. The results of this study can serve as a warning against premature conclusion drawing from calculations carried out by means of FEM simulation.[b]Keywords[/b]: computational mechanics, finite element method, shell elements, numerical integration
Directory of Open Access Journals (Sweden)
José Ángel López Campos
2015-10-01
Full Text Available Current knowledge of the behavior of heavy quadricycles under impact is still very poor. One of the most significant causes is the lack of energy absorption in the vehicle frame or its steel chassis structure. For this reason, special steels (with yield stresses equal to or greater than 350 MPa are commonly used in the automotive industry due to their great strain hardening properties along the plastic zone, which allows good energy absorption under impact. This paper presents a proposal for a steel quadricycle energy absorption system which meets the percentages of energy absorption for conventional vehicles systems. This proposal is validated by explicit dynamics simulation, which will define the whole problem mathematically and verify behavior under impact at speeds of 40 km/h and 56 km/h using the finite element method (FEM. One of the main consequences of this study is that this FEM–based methodology can tackle high nonlinear problems like this one with success, avoiding the need to carry out experimental tests, with consequent economical savings since experimental tests are very expensive. Finally, the conclusions from this innovative research work are given.
Energy Technology Data Exchange (ETDEWEB)
West, O.R.; Toran, L.E.
1994-04-01
Modeling the movement of hazardous waste in groundwater was identified by the US Department of Energy (DOE) as one of the grand challenges in scientific computation. In recognition of this need, DOE has provided support for a group of scientists from several national laboratories and universities to conduct research and development in groundwater flow and contaminant transport modeling. This group is part of a larger consortium of researchers, collectively referred to as the Partnership in Computational Science (PICS), that has been charged with the task of applying high-performance computational tools and techniques to grand challenge areas identified by DOE. One of the goals of the PICS Groundwater Group is to develop a new three-dimensional groundwater flow and transport code that is optimized for massively parallel computers. An existing groundwater flow code, 3DFEMWATER, was parallelized in order to serve as a benchmark for these new models. The application of P-FEM, the parallelized version of 3DFEMWATER, to a real field site is the subject of this report.
Rossi, Francesca; Zingoni, Tiziano; Di Cicco, Emiliano; Manetti, Leonardo; Pini, Roberto; Fortuna, Damiano
2011-07-01
Laser light is nowadays routinely used in the aesthetic treatments of facial skin, such as in laser rejuvenation, scar removal etc. The induced thermal damage may be varied by setting different laser parameters, in order to obtain a particular aesthetic result. In this work, it is proposed a theoretical study on the induced thermal damage in the deep tissue, by considering different laser pulse duration. The study is based on the Finite Element Method (FEM): a bidimensional model of the facial skin is depicted in axial symmetry, considering the different skin structures and their different optical and thermal parameters; the conversion of laser light into thermal energy is modeled by the bio-heat equation. The light source is a CO2 laser, with different pulse durations. The model enabled to study the thermal damage induced into the skin, by calculating the Arrhenius integral. The post-processing results enabled to study in space and time the temperature dynamics induced in the facial skin, to study the eventual cumulative effects of subsequent laser pulses and to optimize the procedure for applications in dermatological surgery. The calculated data where then validated in an experimental measurement session, performed in a sheep animal model. Histological analyses were performed on the treated tissues, evidencing the spatial distribution and the entity of the thermal damage in the collageneous tissue. Modeling and experimental results were in good agreement, and they were used to design a new optimized laser based skin resurfacing procedure.
Optimized Kernel Entropy Components.
Izquierdo-Verdiguier, Emma; Laparra, Valero; Jenssen, Robert; Gomez-Chova, Luis; Camps-Valls, Gustau
2016-02-25
This brief addresses two main issues of the standard kernel entropy component analysis (KECA) algorithm: the optimization of the kernel decomposition and the optimization of the Gaussian kernel parameter. KECA roughly reduces to a sorting of the importance of kernel eigenvectors by entropy instead of variance, as in the kernel principal components analysis. In this brief, we propose an extension of the KECA method, named optimized KECA (OKECA), that directly extracts the optimal features retaining most of the data entropy by means of compacting the information in very few features (often in just one or two). The proposed method produces features which have higher expressive power. In particular, it is based on the independent component analysis framework, and introduces an extra rotation to the eigen decomposition, which is optimized via gradient-ascent search. This maximum entropy preservation suggests that OKECA features are more efficient than KECA features for density estimation. In addition, a critical issue in both the methods is the selection of the kernel parameter, since it critically affects the resulting performance. Here, we analyze the most common kernel length-scale selection criteria. The results of both the methods are illustrated in different synthetic and real problems. Results show that OKECA returns projections with more expressive power than KECA, the most successful rule for estimating the kernel parameter is based on maximum likelihood, and OKECA is more robust to the selection of the length-scale parameter in kernel density estimation.
Stable Principal Component Pursuit
Zhou, Zihan; Wright, John; Candes, Emmanuel; Ma, Yi
2010-01-01
In this paper, we study the problem of recovering a low-rank matrix (the principal components) from a high-dimensional data matrix despite both small entry-wise noise and gross sparse errors. Recently, it has been shown that a convex program, named Principal Component Pursuit (PCP), can recover the low-rank matrix when the data matrix is corrupted by gross sparse errors. We further prove that the solution to a related convex program (a relaxed PCP) gives an estimate of the low-rank matrix that is simultaneously stable to small entrywise noise and robust to gross sparse errors. More precisely, our result shows that the proposed convex program recovers the low-rank matrix even though a positive fraction of its entries are arbitrarily corrupted, with an error bound proportional to the noise level. We present simulation results to support our result and demonstrate that the new convex program accurately recovers the principal components (the low-rank matrix) under quite broad conditions. To our knowledge, this is...
Inkjet deposited circuit components
Bidoki, S. M.; Nouri, J.; Heidari, A. A.
2010-05-01
All-printed electronics as a means of achieving ultra-low-cost electronic circuits has attracted great interest in recent years. Inkjet printing is one of the most promising techniques by which the circuit components can be ultimately drawn (i.e. printed) onto the substrate in one step. Here, the inkjet printing technique was used to chemically deposit silver nanoparticles (10-200 nm) simply by ejection of silver nitrate and reducing solutions onto different substrates such as paper, PET plastic film and textile fabrics. The silver patterns were tested for their functionality to work as circuit components like conductor, resistor, capacitor and inductor. Different levels of conductivity were achieved simply by changing the printing sequence, inks ratio and concentration. The highest level of conductivity achieved by an office thermal inkjet printer (300 dpi) was 5.54 × 105 S m-1 on paper. Inkjet deposited capacitors could exhibit a capacitance of more than 1.5 nF (parallel plate 45 × 45 mm2) and induction coils displayed an inductance of around 400 µH (planar coil 10 cm in diameter). Comparison of electronic performance of inkjet deposited components to the performance of conventionally etched items makes the technique highly promising for fabricating different printed electronic devices.
Ronchin, Erika; Masterlark, Timothy; Dawson, John; Saunders, Steve; Martí Molist, Joan
2015-04-01
In this study, we present a method to fully integrate a family of finite element models (FEMs) into the regularized linear inversion of InSAR data collected at Rabaul caldera (PNG) between February 2007 and December 2010. During this period the caldera experienced a long-term steady subsidence that characterized surface movement both inside the caldera and outside, on its western side. The inversion is based on an array of FEM sources in the sense that the Green's function matrix is a library of forward numerical displacement solutions generated by the sources of an array common to all FEMs. Each entry of the library is the LOS surface displacement generated by injecting a unity mass of fluid, of known density and bulk modulus, into a different source cavity of the array for each FEM. By using FEMs, we are taking advantage of their capability of including topography and heterogeneous distribution of elastic material properties. All FEMs of the family share the same mesh in which only one source is activated at the time by removing the corresponding elements and applying the unity fluid flux. The domain therefore only needs to be discretized once. This precludes remeshing for each activated source, thus reducing computational requirements, often a downside of FEM-based inversions. Without imposing an a-priori source, the method allows us to identify, from a least-squares standpoint, a complex distribution of fluid flux (or change in pressure) with a 3D free geometry within the source array, as dictated by the data. The results of applying the proposed inversion to Rabaul InSAR data show a shallow magmatic system under the caldera made of two interconnected lobes located at the two opposite sides of the caldera. These lobes could be consistent with feeding reservoirs of the ongoing Tavuvur volcano eruption of andesitic products, on the eastern side, and of the past Vulcan volcano eruptions of more evolved materials, on the western side. The interconnection and
Institute of Scientific and Technical Information of China (English)
袁竹根; 李卓棠; 吴佩芳
2001-01-01
自ThMn12型结构的富铁稀土-过渡元素间化合物及其氮化物90年代初被北京大学杨应昌教授发现以来,一直没有实用化.作者用Nd0.9Dy0.1(Fe,M)12Nx磁粉制作粘结永磁体,发现其(BH)max=38.56 kJ/m3,达到实用化的标准.然后用自制的装置测定其温度系数,发现其可逆温度系数比SmCo5高,要用于仪器仪表还要进一步改进.
Optical system components for navigation grade fiber optic gyroscopes
Heimann, Marcus; Liesegang, Maximilian; Arndt-Staufenbiel, Norbert; Schröder, Henning; Lang, Klaus-Dieter
2013-10-01
Interferometric fiber optic gyroscopes belong to the class of inertial sensors. Due to their high accuracy they are used for absolute position and rotation measurement in manned/unmanned vehicles, e.g. submarines, ground vehicles, aircraft or satellites. The important system components are the light source, the electro optical phase modulator, the optical fiber coil and the photodetector. This paper is focused on approaches to realize a stable light source and fiber coil. Superluminescent diode and erbium doped fiber laser were studied to realize an accurate and stable light source. Therefor the influence of the polarization grade of the source and the effects due to back reflections to the source were studied. During operation thermal working conditions severely affect accuracy and stability of the optical fiber coil, which is the sensor element. Thermal gradients that are applied to the fiber coil have large negative effects on the achievable system accuracy of the optic gyroscope. Therefore a way of calculating and compensating the rotation rate error of a fiber coil due to thermal change is introduced. A simplified 3 dimensional FEM of a quadrupole wound fiber coil is used to determine the build-up of thermal fields in the polarization maintaining fiber due to outside heating sources. The rotation rate error due to these sources is then calculated and compared to measurement data. A simple regression model is used to compensate the rotation rate error with temperature measurement at the outside of the fiber coil. To realize a compact and robust optical package for some of the relevant optical system components an approach based on ion exchanged waveguides in thin glass was developed. This waveguides are used to realize 1x2 and 1x4 splitter with fiber coupling interface or direct photodiode coupling.
Recursive principal components analysis.
Voegtlin, Thomas
2005-10-01
A recurrent linear network can be trained with Oja's constrained Hebbian learning rule. As a result, the network learns to represent the temporal context associated to its input sequence. The operation performed by the network is a generalization of Principal Components Analysis (PCA) to time-series, called Recursive PCA. The representations learned by the network are adapted to the temporal statistics of the input. Moreover, sequences stored in the network may be retrieved explicitly, in the reverse order of presentation, thus providing a straight-forward neural implementation of a logical stack.
Institute of Scientific and Technical Information of China (English)
ZHANG Hong; WANG Xin; LI Junwei; CAO Xianguang
2006-01-01
A new unsupervised feature extraction method called similar component analysis (SCA) is proposed in this paper. SCA method has a self-aggregation property that the data objects will move towards each other to form clusters through SCA theoretically,which can reveal the inherent pattern of similarity hidden in the dataset. The inputs of SCA are just the pairwise similarities of the dataset,which makes it easier for time series analysis due to the variable length of the time series. Our experimental results on many problems have verified the effectiveness of SCA on some engineering application.
Analysis Components Investigation Report
2014-10-01
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Electronic components and technology
Sangwine, Stephen
2007-01-01
Most introductory textbooks in electronics focus on the theory while leaving the practical aspects to be covered in laboratory courses. However, the sooner such matters are introduced, the better able students will be to include such important concerns as parasitic effects and reliability at the very earliest stages of design. This philosophy has kept Electronic Components and Technology thriving for two decades, and this completely updated third edition continues the approach with a more international outlook.Not only does this textbook introduce the properties, behavior, fabrication, and use
Impedance of accelerator components
Energy Technology Data Exchange (ETDEWEB)
Corlett, J.N. [Center for Beam Physics, Lawrence Berkeley National Laboratory, I Cyclotron Road, Berkeley, California 94720 (United States)
1997-01-01
As demands for high luminosity and low emittance particle beams increase, an understanding of the electromagnetic interaction of these beams with their vacuum chamber environment becomes more important in order to maintain the quality of the beam. This interaction is described in terms of the wake field in time domain, and the beam impedance in frequency domain. These concepts are introduced, and related quantities such as the loss factor are presented. The broadband Q=1 resonator impedance model is discussed. Perturbation and coaxial wire methods of measurement of real components are reviewed. {copyright} {ital 1997 American Institute of Physics.}
CSIR Research Space (South Africa)
Heyes, AM
1998-06-01
Full Text Available be expected[ 023 A[ M[ HEYES Fig[ 6[ Low magni_cation fractograph showing the seam defect "S#\\ fatigue area "F# and the brittle fracture area "B#[ Fig[ 7[ Fracture surface marked F in Fig[ 6\\ typical of a fatigue fracture surface in a high strength steel... Ltd[ All rights reserved[ Keywords] Accident investigation\\ automotive failures\\ decarburization\\ fatigue\\ weld fatigue[ 0[ INTRODUCTION Failure of automotive components is an occurrence which a}ects the life of almost every person at one stage...
Component Interaction Graph: A new approach to test component composition
Acharya, Arup Abhinna
2010-01-01
The key factor of component based software development is component composition technology. A Component interaction graph is used to describe the interrelation of components. Drawing a complete component interaction graph (CIG) provides an objective basis and technical means for making the testing outline. Although many researches have focused on this subject, the quality of system that is composed of components has not been guaranteed. In this paper, a CIG is constructed from a state chart diagram and new test cases are generated to test the component composition.
Interactions between photodegradation components
Directory of Open Access Journals (Sweden)
Abdollahi Yadollah
2012-09-01
Full Text Available Abstract Background The interactions of p-cresol photocatalytic degradation components were studied by response surface methodology. The study was designed by central composite design using the irradiation time, pH, the amount of photocatalyst and the p-cresol concentration as variables. The design was performed to obtain photodegradation % as actual responses. The actual responses were fitted with linear, two factor interactions, cubic and quadratic model to select an appropriate model. The selected model was validated by analysis of variance which provided evidences such as high F-value (845.09, very low P-value (2 = 0.999, adjusted R-squared (Radj2 = 0.998, predicted R-squared (Rpred2 = 0.994 and the adequate precision (95.94. Results From the validated model demonstrated that the component had interaction with irradiation time under 180 min of the time while the interaction with pH was above pH 9. Moreover, photocatalyst and p-cresol had interaction at minimal amount of photocatalyst (p-cresol. Conclusion These variables are interdependent and should be simultaneously considered during the photodegradation process, which is one of the advantages of the response surface methodology over the traditional laboratory method.
Su, Hao; Koo, Jin Mo; Cui, Honggang
2015-12-10
One-component nanomedicine (OCN) represents an emerging class of therapeutic nanostructures that contain only one type of chemical substance. This one-component feature allows for fine-tuning and optimization of the drug loading and physicochemical properties of nanomedicine in a precise manner through molecular engineering of the underlying building blocks. Using a precipitation procedure or effective molecular assembly strategies, molecularly crafted therapeutic agents (e.g. polymer-drug conjugates, small molecule prodrugs, or drug amphiphiles) could involuntarily aggregate, or self-assemble into nanoscale objects of well-defined sizes and shapes. Unlike traditional carrier-based nanomedicines that are inherently multicomponent systems, an OCN does not require the use of additional carriers and could itself possess desired physicochemical features for preferential accumulation at target sites. We review here recent progress in the molecular design, conjugation methods, and fabrication strategies of OCN, and analyze the opportunities that this emerging platform could open for the new and improved treatment of devastating diseases such as cancer.
Laser generating metallic components
McLean, Marc A.; Shannon, G. J.; Steen, William M.
1997-04-01
Recent developments in rapid prototyping have led to the concept of laser generating, the first additive manufacturing technology. This paper presents an innovative process of depositing multi-layer tracks, by fusing successive powder tracks, to generate three dimensional components, thereby offering an alternative to casting for small metal component manufacture. A coaxial nozzle assembly has been designed and manufactured enabling consistent omni-directional multi-layer deposition. In conjunction with this the software route from a CAD drawing to machine code generation has been established. The part is manufactured on a six axes machining center incorporating a 1.8 kW carbon-dioxide laser, providing an integrated opto-mechanical workstation. The part build-up program is controlled by a P150 host computer, linked directly to the DNC machining center. The direct manufacturing route is shown, including initial examples of simple objects (primitives -- cube, cylinder, cone) leading to more complex turbine blade generation, incorporating build-up techniques and the associated mechanical properties.
Advanced Power Electronics Components
Schwarze, Gene E.
2004-01-01
This paper will give a description and status of the Advanced Power Electronics Materials and Components Technology program being conducted by the NASA Glenn Research Center for future aerospace power applications. The focus of this research program is on the following: 1) New and/or significantly improved dielectric materials for the development of power capacitors with increased volumetric efficiency, energy density, and operating temperature. Materials being investigated include nanocrystalline and composite ceramic dielectrics and diamond-like carbon films; 2) New and/or significantly improved high frequency, high temperature, low loss soft magnetic materials for the development of transformers/inductors with increased power/energy density, electrical efficiency, and operating temperature. Materials being investigated include nanocrystalline and nanocomposite soft magnetic materials; 3) Packaged high temperature, high power density, high voltage, and low loss SiC diodes and switches. Development of high quality 4H- and 6H- SiC atomically smooth substrates to significantly improve device performance is a major emphasis of the SiC materials program; 4) Demonstration of high temperature (> 200 C) circuits using the components developed above.
Prognostics for Microgrid Components
Saxena, Abhinav
2012-01-01
Prognostics is the science of predicting future performance and potential failures based on targeted condition monitoring. Moving away from the traditional reliability centric view, prognostics aims at detecting and quantifying the time to impending failures. This advance warning provides the opportunity to take actions that can preserve uptime, reduce cost of damage, or extend the life of the component. The talk will focus on the concepts and basics of prognostics from the viewpoint of condition-based systems health management. Differences with other techniques used in systems health management and philosophies of prognostics used in other domains will be shown. Examples relevant to micro grid systems and subsystems will be used to illustrate various types of prediction scenarios and the resources it take to set up a desired prognostic system. Specifically, the implementation results for power storage and power semiconductor components will demonstrate specific solution approaches of prognostics. The role of constituent elements of prognostics, such as model, prediction algorithms, failure threshold, run-to-failure data, requirements and specifications, and post-prognostic reasoning will be explained. A discussion on performance evaluation and performance metrics will conclude the technical discussion followed by general comments on open research problems and challenges in prognostics.
Component Based Testing with ioco
van der Bijl, H.M.; Rensink, Arend; Tretmans, G.J.
Component based testing concerns the integration of components which have already been tested separately. We show that, with certain restrictions, the ioco-test theory for conformance testing is suitable for component based testing, in the sense that the integration of fully conformant components is
Food Components and Supplements
DEFF Research Database (Denmark)
Parlesak, Alexandr
2012-01-01
The major part of food consists of chemical compounds that can be used for energy production, biological synthesis, or maintenance of metabolic processes by the host. These components are defined as nutrients, and can be categorized into macronutrients (proteins, carbohydrates, triglycerides......, and alcohol), minerals, and micronutrients. The latter category comprises 13 vitamins and a hand full of trace elements. Many micronutrients are used as food supplements and are ingested at doses exceeding the amounts that can be consumed along with food by a factor of 10–100. Both macro- and micronutrients....... The supplements and contaminants can compete directly with drug oxidation, induce or suppress the expression of xenobiotic-metabolizing enzymes, change the bioavailability of drugs, and, in the case of live bacteria, bring in their own xenobiotic metabolism, including cytochrome P450 (CYP) activity. In numerous...
Impedance and component heating
Métral, E; Mounet, N; Pieloni, T; Salvant, B
2015-01-01
The impedance is a complex function of frequency, which represents, for the plane under consideration (longitudinal, horizontal or vertical), the force integrated over the length of an element, from a “source” to a “test” wave, normalized by their charges. In general, the impedance in a given plane is a nonlinear function of the test and source transverse coordinates, but it is most of the time sufficient to consider only the first few linear terms. Impedances can influence the motion of trailing particles, in the longitudinal and in one or both transverse directions, leading to energy loss, beam instabilities, or producing undesirable secondary effects such as excessive heating of sensitive components at or near the chamber wall, called beam-induced RF heating. The LHC performance limitations linked to impedances encountered during the 2010-2012 run are reviewed and the currently expected situation during the HL-LHC era is discussed.
Sprayed skin turbine component
Allen, David B
2013-06-04
Fabricating a turbine component (50) by casting a core structure (30), forming an array of pits (24) in an outer surface (32) of the core structure, depositing a transient liquid phase (TLP) material (40) on the outer surface of the core structure, the TLP containing a melting-point depressant, depositing a skin (42) on the outer surface of the core structure over the TLP material, and heating the assembly, thus forming both a diffusion bond and a mechanical interlock between the skin and the core structure. The heating diffuses the melting-point depressant away from the interface. Subsurface cooling channels (35) may be formed by forming grooves (34) in the outer surface of the core structure, filling the grooves with a fugitive filler (36), depositing and bonding the skin (42), then removing the fugitive material.
Distributed and Parallel Component Library
Institute of Scientific and Technical Information of China (English)
XU Zheng-quan; XU Yang; YAN Ai-ping
2005-01-01
Software component library is the essential part of reuse-based software development. It is shown that making use of a single component library to store all kinds of components and from which components are searched is very inefficient. We construct multi-libraries to support software reuse and use PVM as development environments to imitate largescale computer, which is expected to fulfill distributed storage and parallel search of components efficiently and improve software reuse.
Sensitivity Analysis of Component Reliability
Institute of Scientific and Technical Information of China (English)
ZhenhuaGe
2004-01-01
In a system, Every component has its unique position within system and its unique failure characteristics. When a component's reliability is changed, its effect on system reliability is not equal. Component reliability sensitivity is a measure of effect on system reliability while a component's reliability is changed. In this paper, the definition and relative matrix of component reliability sensitivity is proposed, and some of their characteristics are analyzed. All these will help us to analyse or improve the system reliability.
Optical communication components
Eldada, Louay
2004-03-01
We review and contrast key technologies developed to address the optical components market for communication applications. We first review the component requirements from a network perspective. We then look at different material systems, compare their properties, and describe the functions achieved to date in each of them. The material systems reviewed include silica fiber, silica on silicon, silicon on insulator, silicon oxynitride, sol-gels, polymers, thin-film dielectrics, lithium niobate, indium phosphide, gallium arsenide, magneto-optic materials, and birefringent crystals. We then describe the most commonly used classes of optical device technology and present their pros and cons as well as the functions achieved to date in each of them. The technologies reviewed include passive, actuation, and active technologies. The passive technologies described include fused fibers, dispersion-compensating fiber, beam steering, Bragg gratings, diffraction gratings, holographic elements, thin-film filters, photonic crystals, microrings, and birefringent elements. The actuation technologies include thermo-optics, electro-optics, acousto-optics, magneto-optics, electroabsorption, liquid crystals, total internal reflection technologies, and mechanical actuation. The active technologies include heterostructures, quantum wells, rare-earth doping, dye doping, Raman amplification, and semiconductor amplification. We also investigate the use of different material systems and device technologies to achieve building-block functions, including lasers, amplifiers, detectors, modulators, polarization controllers, couplers, filters, switches, attenuators, isolators, circulators, wavelength converters, chromatic dispersion compensators, and polarization mode dispersion compensators. Some of the technologies presented are well established in the industry and in some cases have reached the commodity stage, others have recently become ready for commercial introduction, while some others
Post, J.; Huétink, J.; Geijselaers, H. J. M.; Voncken, R. M. J.
2003-10-01
Sandvik steel IRK91 combines good corrosion resistance with high strength. The steel has good deformability in austenitic conditions. This material belongs to the group of metastable austenites, so during deformation a strain-induced transformation into martensite takes place. After deformation, transformation ccontinues as a resuit of internai stresses. Depending on the heat treatment, this stress-assisted transformation is more or less atitocatalytic. Both transformations are stress-state and temperature dependent. This article presents a constitutive model for this steel, based on the macroscopic material behaviour measured by inductive measurements. Both the stress-assisted and the strain-induced transformation to martensite are incorpomted in this model. Path-dependent work hardening is also taken into account. The model is implemented in the commercial FEM code MARC for doing simulations. In the simulations thé tools are treated as rigid bodies, friction is taken into account beeause it inflnences the stress state during metal forming. The material properties after a calculation step are mapped to the next step to incorporate the cumulative effect of the transformation and work hardening during the different steps. A multi-stage metal-forming process is simulated. The process consists of different forming steps with intervals between them to simulate the waiting time between the different metal-forming steps. Results of the transformation behaviour are presented together with the shape of the product during and after metal forming. Finally, this article shows the results of the calculation in which the material transforms autocatalytic, as a resuit of a specific heat treatment.
有限元评估中人孔模拟方法合理性的研究%Rationality of manholes modelling in FEM analysis
Institute of Scientific and Technical Information of China (English)
刘寅华; 吴嘉蒙
2015-01-01
有限元评估中，对主要支撑构件腹板上的人孔，协调版共同结构规范（CSR-H）要求删除适宜的单元进行模拟。而针对与人孔无本质差异的开口，规范允许采用不模拟开口但修正剪应力的方法。不同的模拟方法会引起人孔周围不同的应力水平。文章分析应力差异产生的原因，并比较各方法下人孔周围的应力集中系数。最后从单元屈服利用率的角度评估不同人孔模拟方法的合理性。%According to Harmonised Common Structural Rules (CSR-H), for manholes on primary supporting members (PSM), adequate elements should be removed during FEM analysis; while for the openings which are similar to manholes, shear stress should be modiifed without simulation of the openings. Different modeling methods will cause different stress levels around the manholes. It analyzes the reason causing stress differences, and compares the stress concentration factors around the manholes induced by different methods. Finally a conclusion is drawn to evaluate the rationality of different simulation methods from the viewpoint of yielding utilization factor.
Directory of Open Access Journals (Sweden)
Kiryanto Kiryanto
2012-02-01
Full Text Available Crack defect on main deck plate is source of failure ship structure. Small intensity of crack in the future canbe to large influence lateral force and bending moment. Crack defect characteristics can be to know shearintensity factor (SIF on main deck is used mathematics simulation model based on fracture mechanics (FMand finite element method (FEM. Goal of this research know characteristics main deck plate get a crack withload forces while deck plate start is loading until to crack propagation good stability.The MT Klawotong is chose in this research . Main deck plate is location as the sample. It is number 3 oncargo oil. Any analysis of data that is to counting of profile constructions, length strength, modeling withANSYS Version 9.0 and counting of shear intensity factor (SIF.Research on this structure failure result any substance that is, Sagging condition plate shears 50.34 MPa withsafety factor 8,939 crack long maximum is 0.02 m, value of shear intensity factor (SIF KI WD. Pilkey = 12.615MPa m , KII WD. Pilkey = 0 MPa m , KI ANSYS = 13.,451 MPa m , KII ANSYS = 0.693 MPa m . Prosentaso oferror counting programe KI = 0.062 %, KII = 1% . The ather hand Hoging condition plate shears 15.08 MPawith safety factor 29.841 crack long maximum is 0 .3 m , value of shear intensity factor (SIF KI WD. Pilkey=14.,645 MPa m , KII WD. Pilkey = 0 MPa m , KI ANSYS = 15.585 MPa m , KII ANSYS = 0.352 MPa m ,Prosentaso of error counting programe KI = 0.062 %, KII = 1%.