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Element Calculations (element + calculation)
Kinds of Element Calculations Selected AbstractsDer Beitrag von Profilblechdecken zur passiven KühlungBAUPHYSIK, Issue 2 2009Bernd Döring Dr.-Ing. Berechnungsverfahren; Energieeinsparung; Wärme Abstract Die Ausnutzung der thermischen Speichermasse eines Gebäudes zur Beeinflussung der Raumtemperaturen bzw. zur Reduzierung des Energieverbrauchs war in der Vergangenheit Gegenstand zahlreicher Forschungsvorhaben. Um den Einfluss der Speichermasse ermitteln zu können, werden häufig thermische Gebäudesimulationsprogramme eingesetzt, aber auch die aktuelle Fassung von DIN V 18599 berücksichtigt die Wirkung der Wärmekapazität der raumumfassenden Flächen. Sowohl bei Anwendung von DIN V 18599 als auch bei der Gebäudesimulation geht man dabei von einer eindimensionalen Schichtenfolge für Wände und Decken aus. Es gibt jedoch Bauteile, wie z. B. Profilblechdecken, bei denen diese Annahme nicht zutreffend ist. In diesem Bericht werden nun über die Auswertung dynamischer FEM-Berechnungen für inhomogene Deckenaufbauten Ersatzgrößen bestimmt, so dass die Definition einer thermisch äquivalenten Decke als eindimensionales Modell möglich ist. Für ausgewählte Beispiele wird die Wirksamkeit dieser Decken hinsichtlich ihrer Wärmeaufnahme und -abgabe untersucht. The potential of profiled steel sheet deck systems in reference to passive cooling strategies. The use of the thermal inertia of building components to improve the indoor temperature and to reduce the energy consumption was covered in various research projects in the past. Generally, thermal building simulation tools (TRNSYS, TAS, e.g.) are used for the assessment of the effect of thermal inertia, and also the current version of the standard DIN V 18599 takes the effect of the heat capacity of the affected surfaces. Both, DIN V 18599 and thermal building simulation tools, assume a one-dimensional characterization of walls and flooring systems, that means they are assembled based on plane layers. This approach is not valid for inhomogeneous components like profiled steel sheet deck systems. In this report thermal equivalent values for such elements are developed, based on the analysis of transient Finite Element Calculations (FEM), thus the one-dimensional are suitable using these equivalent properties. For a selection of available profiles the effect of such deck systems referring heat-intake and heat-disposal was investigated. [source] The transfer matrix method applied to steel sheet pile wallsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 6 2003D. A. Kort Abstract This paper proposes two subgrade reaction models for the analysis of steel sheet pile walls based on the transfer matrix method. In the first model a plastic hinge is generated when the maximum moment in the retaining structure is exceeded. The second model deals with a beam with an asymmetrical cross-section that can bend in two directions. In the first part of this paper the transfer matrix method is explained on the basis of a simple example. Further the development of two computer models is described: Plaswall and Skewwall. The second part of this paper deals with an application of both models. In the application of Plaswall the effect of four current earth pressure theories to the subgrade reaction method is compared to a finite element calculation. It is shown that the earth pressure theory is of major importance on the calculation result of a sheet pile wall both with and without a plastic hinge. In the application of Skewwall the effectiveness of structural measures to reduce oblique bending is investigated. The results are compared to a 3D finite element calculation. It is shown that with simple structural measures the loss of structural resistance due to oblique bending can be reduced. Copyright © 2003 John Wiley & Sons, Ltd. [source] A note on hinge-free topology design using the special triangulation of design elementsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 12 2005Jae Eun Kim Abstract Hinges, the unrepeated checkerboard cells, may appear in the topology optimization using low-order finite elements, especially for compliant mechanism design. Existing hinge-controlling methods are based on the rectangular element discretization, so slant or curved boundary lines may not be represented satisfactorily. To avoid hinge formation and to represent curved boundary lines better, we consider a macro-design element method which subdivides the design element into eight triangular finite elements; the finite element calculation is carried out with triangular elements, but the design variables are defined at the nodes defining rectangular macro-design elements. For hinge-free results, different stiffness interpolations are suggested depending on whether the triangular element belongs to a master group or a slave group. The performance of the proposed method was checked with compliant mechanism design problems from the viewpoint of hinge suppression and the possibility of generating slant boundary lines. Copyright © 2005 John Wiley & Sons, Ltd. [source] Adaptive mesh technique for thermal,metallurgical numerical simulation of arc welding processesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2008M. Hamide Abstract A major problem arising in finite element analysis of welding is the long computer times required for a complete three-dimensional analysis. In this study, an adaptative strategy for coupled thermometallurgical analysis of welding is proposed and applied in order to provide accurate results in a minimum computer time. The anisotropic adaptation procedure is controlled by a directional error estimator based on local interpolation error and recovery of the second derivatives of different fields involved in the finite element calculation. The methodology is applied to the simulation of a gas,tungsten-arc fusion line processed on a steel plate. The temperature field and the phase distributions during the welding process are analyzed by the FEM method showing the benefits of dynamic mesh adaptation. A significant increase in accuracy is obtained with a reduced computational effort. Copyright © 2007 John Wiley & Sons, Ltd. [source] Fatigue crack initiation in naval welded joints: experimental and numerical approachesPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2008D. Thevenet This work deals with the fatigue behavior of welded joints. The proposed strategy can be split into two stages: the structure shakedown study and the fatigue crack initiation study. Firstly, stabilized elastic stress,strain cycles are obtained in any point of the welded joint by a finite element analysis, taking constant or variable amplitude loadings into account. The second part of this work is the calculation of the fatigue crack initiation period. Under the assumption of a fast elastic shakedown, a recent approach, proposed by Lemaitre et al., based on damage mechanics, can be used to predict the fatigue crack initiation life in a structure subjected to variable and complex loadings. This strategy is used as a post,treatment of the shakedown finite element calculation for the studied welded specimen. As a validation, four,point bending fatigue tests under constant amplitude loading were carried out on welded specimens provided by DCNS group. Good correlations between experimental and calculated fatigue crack initiation lives have been established. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Prediction of the Elastic Properties of Polycrystalline Microcomponents by Numerical HomogenizationADVANCED ENGINEERING MATERIALS, Issue 3 2009Katja Jöchen Polycrystalline microcomponents made of Stabilor®G, a dental alloy mainly consisting of gold, are examined in terms of their elastic properties. Finite element calculations of uniaxial tensile tests are carried out with ABAQUS so as to identify the characteristic parameters of the distribution of Young's modulus. It is shown that the statistics of mechanical properties observed experimentally can be estimated by using the finite element method. The findings are generalized to microcomponents consisting of crystals with a cubic symmetry. [source] Incrementalization of a single hardening constitutive model for frictional materialsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 7 2002P. V. Lade Abstract The governing equations for an elasto-plastic constitutive model for frictional materials such as soil, rock, and concrete are presented, and the incremental form is indicated in preparation for implementation of the model in a user-defined module for finite element calculations. This isotropic, work-hardening and -softening model employs a single yield surface, it incorporates non-associated plastic flow, and its capability of capturing the behaviour of different types of frictional materials under various three-dimensional conditions has been demonstrated by comparison with measured behaviour, as presented in the literature. The incrementalization procedure is indicated and the resulting equations for the single hardening model are presented together with parameters for a dense sand. Following the implementation of the model, these parameters are used for evaluation of different integration schemes as presented in a companion paper by Jakobsen and Lade (Int. J. Numer. Anal. Meth. Geomech. 2002; 26:661). Copyright © 2002 John Wiley & Sons, Ltd. [source] Microstructure development in concentrated suspensions in a spinning ball rheometer,INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 3 2006Anne M. Grillet Abstract The spinning ball rheometer has been proposed as a method to measure the microstructure effect on the bulk rheological properties of concentrated suspensions. Recent experiments have shown that the measured extra torque on the spinning ball decreases as the radius of the spinning ball becomes comparable to the size of the suspended particle. We have performed a series of three-dimensional boundary element calculations of the rheometer geometry to probe the microstructure effects that contribute to that apparent slip. We present a series of quasi-static results based on random initial configurations as well as fully three-dimensional transient calculations, both of which are compared to the available experimental data. For the two cases, the apparent viscosity decreased as the size of the spinning ball decreased relative to the suspended particle. Comparison of the quasi-static and transient simulations indicates that the microstructure development is critical even at short times. In the transient calculations, the viscosity was observed to increase substantially relative to the torque based on the random initial configuration. Published in 2005 by John Wiley & Sons, Ltd. [source] The behaviour of the periodontal ligament is influencing the use of new treatment toolsJOURNAL OF ORAL REHABILITATION, Issue 9 2006CH. SANDER summary, Orthodontic treatment can cause resorptions on teeth. Factors causing resorptions are forces and moments. Other factors that cause resorptions are less influenced by an orthodontic treatment. By carrying out experiments and finite element calculations, it was possible to demonstrate that forces and moments will produce stress in certain parts of the periodontal ligament and the root. This stress reaches or exceeds the blood pressure in some areas. To avoid high pressure in those areas, new treatment devices were constructed consisting of NiTi wires or a combination of NiTi and stainless steel. In the levelling phase, the acting forces remained below 0·5 N using NiTi wire with a diameter of 0·012, (using elastic ligatures). With a NiTi stainless steel spring molars can be uprighted. The orthodontist can easily choose between an intrusive force, a very low intrusive force and an extrusive force. Because of the use of NiTi elements, there was acting an almost constant moment. [source] The role of suture complexity in diminishing strain and stress in ammonoid phragmoconesLETHAIA, Issue 1 2008FABIO VITTORIO DE BLASIO Several hypotheses have been put forward to explain the sinuosity and complexity of suture lines in Ammonoidea. At present, the two principal opponent views maintain either that high complexity was a requisite to reinforce the shell in response to hydrostatic pressure, or that complexity augmented the attachment area for muscles. By using finite element calculations and analytical estimates of simplified ammonoid shell geometries, it is shown that complex suture lines reduced dramatically the strain and the stress in the phragmocone. The calculations lend support to the hypothesis that high sinuosity is an evolutionary response to external pressure. Additionally, it is found that without complex septa, the inward deformation of an ammonoid with thin shell would cause it to shrink in response to pressure and to lose buoyancy by a non-negligible amount. [source] Piezoelectric effects in sidewall quantum wires grown on patterned (311)A GaAs substratePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2003D. Alderighi Abstract Time-resolved photoluminescence measurements have been performed on sidewall InGaAs/AlGaAs quantum wires and quantum wells. Experimental data show a band filling of quantum wells and quantum wires that is dominant in the first 400 ps after the excitation pulse, then a dynamical screening of the built-in piezoelectric field (Fp) by means of fast injection of photo-generated charges is observed allowing an efficient radiative recombination. At longer time delay, during the regime when the Fp unscreened value is recovered, a strong quantum confined Stark effect is observed. A good agreement is obtained for the energy shift and the overlap integrals of electrons and heavy holes by means of discrete element calculations. [source] Effect of silicon reinforcement on load-capacity of porous nanofiltersPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2008Ádám Kovács Square,form microfilters consisting of a two,layer porous membrane with nano,size pores and reinforced by silicon columns have been investigated. The change of layer thicknesses and reinforcement geometry modify the load,capacity of the device through the variation of strength properties. A simple thin plate model was constructed by substituting the effect of silicon columns by an equivalent third layer. Estimates for the load,capacity were made by finite element calculations. These estimates have been verified by experimental results. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||