bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deformation and Damage Analysis of a Hybrid‐Forming Tool under Thermal Shock Conditions
Authors: Mahnken R. , Sauerland K.‐H. , Schneidt A. , Gockel F.‐B. 
Published: February 2009

AbstractIn the hybrid–forming process for gradient structures [1] inhomogeneous cyclic thermo–mechanical stresses and strains lead to higher risks of failure of the forming tool. The main topic of this paper is the validation of finite element calculations for a tool–like specimen under complex thermo–mechanical loadings in order to predict the material behaviour [3]. To this end thermal shock experiments of tool–like specimens are performed. Optical measuring systems are used for three–dimensional digitalisation of the specimens to get a sufficient amount of data. Results of experimental optical measurings and results of finite element calculations are compared. Additionally, damage analysis using the eddy current method is performed to characterize the surface state of the cyclically thermal shocked specimens. This damage analysis provides data for lifetime prediction models under thermal shock conditions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
FE‐implementation of plane strain gradient elasticity constitutive equations obtained by homogenization
Authors: Zybell Lutz , Mühlich Uwe , Kuna Meinhard 
Published: February 2009

AbstractThis paper presents a plane strain gradient elasticity model together with a strength criterion based on the maximum hoop stress. It is developed by higher order homogenization based on a cylindrical RVE containing a void and is implemented as mixed–type finite element formulation into the FE–code Abaqus. Numerical simulations are performed in order to study the size effect related to the onset of failure of specimens of porous elastic material. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Towards the analysis of materials with strain gradient effects using ‐Natural Element Method
Authors: Rajagopal A. , Steinmann P. 
Published: February 2009

AbstractThe notion of generalized continua unifies several classes of continuum theories that account for size dependence arising due to the underlying microstructure of the material. In gradient continua, besides the first gradient also the higher gradients of displacements are taken in to account. This results in higher order boundary conditions and C1 continuity requirements. α‐Natural Element Method has been used to this effect for numerical modeling of gradient elasticity. The α‐–Natural Element Method allows the construction of models entirely in terms of nodes and also ensures the linear precision of the interpolant over convex and non convex boundaries. C1 natural neighbor interpolants are achieved by a simple transformation of the Farins interpolant, which are basically obtained by embedding Sibsons natural neighbor coordinates in Bernstein–Bezier surface representation of a cubic simplex. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transient heating of a rotating elastic‐plastic solid shaft
Authors: Arslan E. , Mack W. , Eraslan A. N. 
Published: February 2009

AbstractBased on Tresca's yield criterion and the flow rule associated with it, the transient plasticization in a rotating elastic–plastic solid shaft with temperature dependent yield stress subject to a temperature cycle is studied. Special attention is paid to the residual stresses. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mehrskalenberechnungen nichtlinear elastischer inhomogener Körper
Authors: Bitzenbauer Johann , Schweizerhof Karl 
Published: February 2009

AbstractMehrgittermethoden als besonders schnelle und effiziente Lösungsverfahren für elliptische partielle Differentialgleichungen basieren auf der Diskretisierung des Problems mittels unterschiedlich grober bzw. feiner Netze. Ihre Effizienz leidet jedoch sehr, sobald eine sehr grobe Diskretisierung aufgrund vorhandener komplexer Ränder oder materieller Inhomogenitäten nicht mehr möglich ist. Andererseits führt aber jede klassische FE–Analyse, die komplizierte geometrische Details befriedigend auflöst, zu so vielen Unbekannten, dass nicht multilevelbasierte Gleichungslöser von vorneherein ausscheiden. In [1] werden deshalb Finite–Elemente–Räume entwickelt, deren minimale Dimension nicht mehr mit der Komplexität der Geometrie gekoppelt ist. Diese sogenannte zusammengesetzte Finiten–Elemente–Diskretisierung (CFE) wird über eine Gitterhierarchie definiert. In [2] wird das Konzept auf materiell inhomogene Probleme erweitert. Im Vergleich zu rein algebraisch erzeugten niederdimensionalen Problemen werden bei diesem Vorgehen zusätzliche Geometrieinformationen genutzt. Für einfache eindimensionale Problemklassen besteht kein prinzipieller Unterschied zwischen CFE– und algebraisch motivierten Methoden; dies ändert sich jedoch bei den hier betrachteten zweidimensionalen Problemen der nichtlinearen Elastizitätstheorie. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Non‐linear dynamic contact of thin‐walled structures
Authors: Cichosz Thomas , Bischoff Manfred , Hartmann Stefan , Ramm Ekkehard 
Published: February 2009

AbstractIn many areas of mechanical engineering contact problems of thin–walled structures play a crucial role. Car crash tests and incremental sheet metal forming can be named as examples. But also in civil engineering, for instance when determining the moment–rotation characteristics of a bolted beam–column joint, contact occurs. Effective simulation of these and other contact problems, especially in three–dimensional non–linear implicit structural mechanic is still a challenging task. Modelling of those problems needs a robust method, which takes the thin–walled character and dynamic effects into account. We use a segment–to–segment approach for discretization of the contact and introduce Lagrange Multipliers, which physically represent the contact pressure. The geometric impenetrability condition is formulated in a weak, integral sense. Choosing dual shape functions for the interpolation of the Lagrange Multipliers, we obtain decoupled nodal constraint conditions. Combining this with an active set strategy, an elimination of the Lagrange multipliers is easily possible, so that the size of the resulting system of equations remains constant. Discretization in time is done with the implicit Generalized‐α Method and the Generalized Energy–Momentum Method. Using the “Velocity–Update” Method, the total energy is conserved for frictionless contact. Various examples show the performance of the presented strategies. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Seismic response of secondary structures mounted on ductile frames
Authors: Furtmüller Thomas 
Published: February 2009

AbstractThis paper deals with the response of vibration prone non–structural components (or secondary structures) mounted on regular generic plane frames (i.e. primary structures) subjected to ground–accelerations generated by ordinary earthquakes. The response of these multi–degree–of–freedom (MDOF) systems is approximated utilizing constant–ductility floor response spectra of two–degree–of–freedom (2DOF) primary–secondary systems and validated by the response derived by a fully coupled analysis of the entire primary–secondary system. Furthermore, results of coupled and decoupled analyses are set in contrast. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of thin laminated plates by means of the scaled boundary finite element method
Authors: Hebel Jochen , Becker Wilfried 
Published: February 2009

AbstractA new scaled boundary finite element formulation for the static analysis of laminated plates is presented. The problem is formulated in scaled boundary coordinates using a discrete form of the reduction method by Kantorovich. The resulting systems of linear ordinary differential equations for the unknown displacement functions are solved analytically. Element stiffness matrices can be calculated from the appropriate solution subsets for bounded and unbounded domains. From the inherent field expansion in one spatial direction, exponents and coefficients can be extracted efficiently. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Features of an adaptive remeshing strategy in the context of deformation localization and high speed cutting
Authors: Hortig Christian , Gu Xin , Svendsen Bob 
Published: February 2009

AbstractThe purpose of this work is the modeling and simulation of shear banding and chip formation during high–speed cutting. Here, the use of error estimation and adaptive remeshing is of special interest. The current work investigates the application of different refinement strategies on the problem of adiabatic shear banding. As a result the authors will present a combination of a recovery based error estimation and a refinement indicator. Simulation results for the high speed cutting process will be presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of the Lateral Eigenstrains on the Transverse Displacement of Wide Beams
Authors: Huber D. , Krommer M. , Irschik H. 
Published: February 2009

AbstractThe present paper studies the influence of lateral eigenstrains on the transverse deflection of wide beams. We show that in this case a laterally nonuniform transverse displacement becomes notable; moreover, it turns out that the axial variation of the transverse displacement is significantly altered in comparison to the results obtained from beam theory. In order to derive a corrected analytical solution for the transverse displacement of wide beams, the latter are modeled as thin plates with induced eigenstrains in both in–plane directions. A Galerkin method is utilized to solve the plate equations, in which solutions for the transverse displacement resulting from beam theory are used as shape functions for the plate deflection. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An elastodynamic Galerkin Boundary Element Formulation for semi‐infinite domains in time‐domain
Authors: Kielhorn Lars , Schanz Martin 
Published: February 2009

AbstractThe present work focuses on the problem of modelling wave propagation phenomena within a 3–d elastodynamic halfspace by use of a symmetric Galerkin Boundary Element formulation. Unfortunately, this formulation requires the evaluation of hypersingular integral kernels which are regularized by integration by parts.In Boundary Element Methods semi–infinite domains are commonly approximated in space by considering just a sufficiently large enough region. Applying this simple discretization to the symmetric formulation implies the evaluation of the hypersingular bilinear form on a truncated mesh which will fail due to the regularization approach. To overcome this drawback a methodology based on infinite elements is presented. The numerical tests show that this approach is promising for treating semi–infinite domains with a symmetric Galerkin scheme. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of dynamic loads acting on carrying cable in operating ropeway
Authors: Knawa Marta , Bryja Danuta 
Published: February 2009

AbstractThe model of a carrying rope under in–service loads is developed to analyze dynamic response of the cable during ropeway operation including: start conditions while carriers leave the station, steady ride, an emergency stop of a system. The pendulum model of a moving passenger carrier is formulated to define loads acting on the cable. Equations of motion of the cable loaded by moving pendulums are derived by applying Ritz approximate method and Lagrangian description of motion. Some numerical results are presented to illustrate applicability of proposed method in an investigation of carrying cable vibrations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Geometrical covariant approach for contact between curves representing beam and cable type structures
Authors: Konyukhov Alexander , Schweizerhof Karl 
Published: February 2009

AbstractThe geometrical approach for curve–to–curve interaction is considered in a specially defined local coordinate system related to the contacting curve. This coordinate system is defined following the closest point projection (CPP) procedure in which two nearest contact points are defined correspondingly on both curves. The iterative numerical algorithm is then formulated in this coordinate system and all necessary parameters are derived in a covariant form. This leads to a contact description which is applicable for contact between curved beams and cables as well as for contact between surface edges. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Variational analysis in dynamical problems of linear elasticity
Authors: Kostin Georgy , Saurin Vasily 
Published: February 2009

AbstractThe initial–boundary value problems in the linear theory of elasticity is considered. Based on the method of integrodifferential relations (MIDR) two dynamical variational principles is proposed and discussed. It is shown that the Hamilton principle as well as the corresponding complementary principle stated for dynamic boundary value problems follow out the variational formulations proposed. To minimize the nonnegative functional under algebraic and differential constraints a regular finite element algorithm is worked out. The algorithm allows us to estimate explicitly the local and integral quality of numerical solutions obtained. A 3D problem of lateral motions of a rectilinear elastic prism with a rectangular cross section are considered. The numerical results are presented and discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Adaptive Cross Approximation in an elastodynamic Boundary Element formulation
Authors: Messner Matthias , Schanz Martin 
Published: February 2009

AbstractElastodynamic phenomena can be effectively analyzed by using the Boundary Element Method (BEM), especially in unbounded media. However, for the simulation of such problems, beside others, two difficulties restrict the BEM to rather small or medium–sized problems. Firstly, one has to deal with dense matrices and secondly the treatment of the kernel functions is very costly. Several approaches have been developed to overcome these drawbacks. Approaches, such as Fast Multipole and Panel Clustering etc. gain their efficiency basically from an analytic kernel approximation. The main difficulty of these methods is that the so called degenerate kernel has to be known explicitly.Hence, the present work focuses on a purely algebraic approach, the adaptive cross approximation (ACA). By means of a geometrical clustering and a reliable admissibility condition, first, a so called hierarchical matrix structure is set up. Then each admissible block can be represented by a low–rank approximation. The advantage of the ACA is based on the fact that only a few of the original matrix entries have to be generated.As will be shown numerically, the presented approach is suitable for an efficient simulation of elastodynamic problems. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Explicit Buckling Analysis and Design Equations for Composite Plates under Compression with Free Reinforced Edges
Authors: Mittelstedt Christian , Schager Martin 
Published: February 2009

AbstractIn the present contribution, the buckling problem of compressively loaded symmetrically laminated orthotropic composite plates with free reinforced edges is studied [1]. Starting from the exact transcendental elasticity solution of the problem, a straightforward criterion for the determination of the minimum bending stiffness EImin of the edge stiffeners is presented that allows for the determination of EI such that no global buckling of the plate and flange occurs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Excitation of Rolling Tires from the Road Surface Texture
Authors: Brinkmeier M. , Nackenhorst U. , Suwannachit A. 
Published: February 2009

AbstractRolling tires are excited from the contact with the rough road surface to vibrations, which cause rolling noise. A two scale approach is suggested, where at the macro–scale the vibration of the rolling tire structure is modeled by quite detailed finite element methods. The road surface is described using measured textures. A fine resolution finite element discretization of the tread rubber is performed in order to resolve the asperity contact. The material properties are described by a non–linear viscoelastic rubber model. The tread patch is enforced to approach the rough surface in a transient dynamics manner. From these investigations an enveloping surface profile is reconstructed to be used for the excitation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An exact sinusoidal beam finite element
Authors: Pawlak Zdzislaw , Rakowski Jerzy 
Published: February 2009

AbstractThe purpose of the paper is to derive an efficient sinusoidal thick beam finite element for the static analysis of 2D structures. A two–node, 6–DOF curved, sine–shape element of a constant cross–section is considered. Effects of flexural, axial and shear deformations are taken into account. Contrary to commonly used curvilinear co–ordinates, a rectangular co–ordinates system is used in the present analysis. First, an auxiliary problem is solved: a symmetric clamped–clamped sinusoidal arch subjected to unit nodal displacements of both supports is considered using the flexibility method. The exact stiffness matrix for the shear–flexible and compressible element is derived. Introduction of two parameters “n” and “t” enables the identification of shear and membrane influences in the element stiffness matrix. Basing on the principle of virtual work a full set of 18 shape functions related to unit support displacements is derived (total rotations of cross–sections, tangential and normal displacements along the element). The functions are found analytically in the closed form. They are functions of one linear dimensionless coordinate of x–axis and depend on one geometrical parameter of sinusoidal arch, height/span ratio “c” and on physical and geometrical properties of the element cross–section. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Plateau regularization method for structural shape optimization and geometric mesh control
Authors: Wüchner R. , Firl M. , Linhard J. , Bletzinger K.‐U. 
Published: February 2009

AbstractWithin this contribution the algorithmic treatment of the inverse problem of finding mechanically motivated membrane shapes is discussed and the key point, that the corresponding numerical methods have a broader spectrum of applications which enables their adoption to similar problems from other disciplines, is highlighted. The presented adaptive scheme is the Updated Reference Strategy (URS) enhanced by a newly derived “element distortion control”. The key feature is the ability of the proposed stabilized scheme to overcome the singular problem of finding equilibrium shapes of prestressed membranes which is due to the non–uniqueness of nodal positions in the finite element mesh and the purposeful adjustment of the underlying stress state based on a local geometrical criterion in case of incompatible stress states. Therefore, the derived methodology is –beside the mere computation of equilibrium configurations– able to distribute (probably very local) deformations of the mesh in a smooth way to the whole domain by at the same time conserving specific mesh characteristics which guarantees regular meshes with high quality concerning the element shape. This results in robust computations even for complex and problematic geometrical situations. Due to the effective mesh control of this approach a transfer of the developed methodology to other fields of application like e.g. mesh smoothing, large displacement mesh moving problems and stabilized CAD–free shape optimization of shells is promising and therefore accomplished. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural vibration control by means of nonlinear pendulum dampers
Authors: Yousefi Seyed Mehdi , Heuer Rudolf 
Published: February 2009

AbstractThis paper discusses the application of a nonlinear Pendulum Tuned Mass Damper (PTMD) for the reduction of structural vibrations. Pendulum dynamic absorbers are used extensively to reduce the vibration level of slender elastic structures such as towers. A PTMD is a device consisting of a suspended mass, and a damper that is attached to the tower in order to reduce its dynamic response. The primary eigenfrequency of the nonlinear damper is tuned to a particular structural frequency. Energy is dissipated by the damping force acting on the structure. Here, the PTMD is applied to a tower as a continuous system consisting of distributed mass and elasticity. The optimum values of PTMD parameters are found based on minimization of the response of the tower tip–point. Time history and frequency domain responses for the tower with PTMD in linear and nonlinear condition are compared. In addition, the equations of motion of active pendulum control are intruduced. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wechselwirkung bewegter Temperaturfelder mit Zellulären Automaten
Authors: Bode K.H. , Ostermeyer G.‐P. 
Published: February 2009

AbstractDie Reibung in Bremsen und Kupplungen unterliegt einer Dynamik, die durch eine Vielzahl komplexer Vorgänge, insbesondere durch eine Wechselwirkung der Größen “Reibwert” und “Verschleiß”, bedingt ist [1]. Diese Erkenntnis motiviert die Entwicklung diskreter Modelle, mit denen die lastabhängige Ausbildung der Grenzschicht erfassbar ist [2].Eine Einbeziehung tribochemischer Reaktionen, denen bei einer material– bzw. mischungssensitiven Simulation der Reibung eine erhebliche Bedeutung zukommt, erfordert eine genaue Kenntnis der Temperaturen in der Grenzschicht. Vor diesem Hintergrund wird ein bestehender Algorithmus nach der Methode der Zellulären Automaten [3] verwendet und hier vertiefend betrachtet.Im Einzelnen widmet sich dieses Paper der Anwendung auf das dreidimensionale Problem einer über die Oberfläche eines raumfesten Körpers bewegten Wärmequelle. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
First‐trimester maternal serum matrix metalloproteinase‐9 (MMP‐9) and adverse pregnancy outcome
Authors: Poon Leona C. Y. , Nekrasova Ekaterina , Anastassopoulos Panagiotis , Livanos Panagiotis , Nicolaides Kypros H. 
Published: February 2009

AbstractObjectiveTo investigate the potential value of maternal serum matrix metalloproteinase‐9 (MMP‐9) in first‐trimester screening for preeclampsia and spontaneous early preterm delivery.MethodsThe concentrations of MMP‐9, tumour necrosis factor soluble receptor‐1 (TNF‐R1), pregnancy‐associated plasma protein‐A (PAPP‐A) and uterine artery pulsatility index (UA‐PI) were measured at 11+0 − 13+6 weeks in cases of preeclampsia (n = 128), gestational hypertension (n = 88), small for gestational age (n = 296), spontaneous early preterm delivery (n = 57) and controls (n = 569). The distributions of measured metabolites and UA‐PI in the control and adverse outcome groups were compared. Logistic regression analysis was used to determine the significant contributors in the prediction of adverse outcomes.ResultsThe median MMP‐9 was higher than controls in the preeclampsia (1.190 MoM) and preterm delivery (1.187 MoM) groups. In the preeclampsia group there was a significant association between serum MMP‐9 and TNF‐R1 (r = 0.523, P < 0.0001). Significant prediction of preeclampsia was provided by history and UA‐PI, and prediction of preterm delivery was provided by history and neither was improved by the addition of MMP‐9.ConclusionIn pregnancies developing preeclampsia, the increased level of MMP‐9 and the good correlation with TNF‐R1 suggest the presence of an underlying inflammatory process. In the pregnancies resulting in spontaneous preterm delivery the small increase in MMP‐9 is not useful in the prediction of preterm delivery. Copyright © 2009 John Wiley & Sons, Ltd.