bluuebunny/crossref_metadata_2025_split huggingface dataset:
Damage Detection by Wave Propagation Observation with Laser SpeckleInterferometry
Authors: Schmidt Alexander , Lammering Rolf , Plenge Michael 
Published: December 2005

AbstractFor quality insurance and fault detection, one and three dimensional ESPI (Electronic Speckle Pattern Interferometry) technique is applied to various structures. These experiments are an extension of previous experiments with Holographic Interferometry [4], a related measurement technique. ESPI is a non contact, high resolution Laser measurement technique. It facilitates transient full field vibration measurements that deliver absolute deflections, either one dimensional out‐of‐plane or three dimensional in and out‐of‐plane.Experiments have been performed with a full scale concrete embedded track segment. Different known artificial defects represent various flaws and voids due to the fabrication process and operation. Wave propagation due to impact is observed and allows for damage detection. ESPI measurements are in good accordance with expectations. An in‐situ measurement setup for quality management of concrete embedded railway tracks has been built. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Re‐entrant corner problems for isotropic materials and layered composites
Authors: Schnack E. , Dimitrov A. , Langhoff T.‐A. , Tsotsova R. 
Published: December 2005

AbstractModern materials like composites in different types require new methods in computational fracture mechanics. Besides of classical fracture mechanics we have to solve the asymptotic solution around crack tips. This can be done on the basis of the Kondratievs theorem with the Pietrov‐Galerkin method to solve the unknown eigenvalues for those problems. Additionally, we have to de.ne instead classical modes I, II and III, mode I* up to mode IV* to interpret the computational results for the unknown eigenvalues. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On Well Posedness in Continuum Interface Problems
Authors: Utzinger Johannes , Menzel Andreas , Kuhl Ellen , Steinmann Paul 
Published: December 2005

AbstractBy considering continuum interface problems like e.g. the modeling of composites, the possible loss of well posedness of the resulting Boundary Value Problem has to be considered, dependent on the choice of material laws in the bulk and in the interface. In this contribution, the problem is discussed for a bulk material connected to a rigid substrate by an interface layer. The isotropic bulk material is linear elastic while for the interface elasticity and elasticity with damage is investigated. A complex surface acoustic tensor is introduced by applying a decaying surface wave ansatz to the incremental boundary value problem. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison of a biphasic and a multicomponent model describing viscoelastic swelling phenomena
Authors: Acartürk A. , Ehlers W. , Karajan N. , Markert B. 
Published: December 2005

AbstractBiological soft tissues like articular cartilage and their artificial replacement hydrogel have a multicomponent microstructure, consisting of a charged viscoelastic solid matrix saturated by a fluid, which is composed of the liquid solvent and the dissolved anions and cations. Such charged multiphasic materials exhibit a swelling behaviour under varying chemical conditions.These materials are best described by a macroscopic approach like the Theory of Porous Media (TPM). Starting from this point, a standard two‐phase model is extended by dividing the fluid into the above mentioned components. Therein, the chemical relations describing the behaviour of the ions and their interaction with the other mixture constituents are incorporated. The resulting model covers mechanical as well as osmotic and electrostatic effects. For numerical and simplicity reasons, it is possible to describe the swelling phenomena by a simplified biphasic model, where the ions as a third degree of freedom and their time‐dependent diffusion are neglected. Furthermore, the viscoelastic solid matrix can be replaced by an elastic material.Note that using the multicomponent model generally results in numerical problems, since the boundary conditions depend on the internal fixed charge density. It is shown that this problem can be solved by including the boundary conditions into the weak formulation. Finally, to compare the different behaviour of the above mentioned models by means of an swelling example, they are implemented into the FE tool PANDAS using stable Taylor‐Hood elements for the spatial discretization. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Adaption des Morph‐Stoffgesetzes an die Abaqus‐Benutzerschnittstelle
Authors: Besdo D. , Ihlemann J. 
Published: December 2005

AbstractDas Morph‐Stoffgesetz dient der Nachbildung des mechanischen Verhaltens inelastischer Gummiwerkstoffe unter großen Verformungen und enthält neben Spannungs‐ und Verzerrungstensoren auch deren Zeitableitungen. Für die Implementierung in das Fem‐Programmpaket Abaqus müssen Eulersche Varianten der aktuellen Spannungen und der Materialsteifigkeit bereitgestellt werden.Während sich die Verformungsgröße, nach der die Spannungen abzuleiten sind, als pfadabhängig erweist, entspricht deren Zaremba‐Jaumann‐Zeitableitung dem Tensor der Formänderungsgeschwindigkeiten. Für die Zeitintegration der Eulerschen Zeitableitungen im Stoffgesetz ist ein diesbezüglich geeignetes Beobachtersystem zu identifizieren. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Geometrically exact shells for multibody dynamics
Authors: Betsch Peter 
Published: December 2005

AbstractIn the present work we extend the unified framework for the computational treatment of rigid bodies and nonlinear beams developed by Betsch & Steinmann [1] to the realm of nonlinear shells. In particular, a specific constrained formulation of shells is proposed which leads to the semi‐discrete equations of motion characterized by a set of differential‐algebraic equations (DAEs). The DAEs provide a uniform description for rigid bodies, semi‐discrete beams and shells and, consequently, flexible multibody systems. The DAEs are further discretized by means of an energy‐consistent mechanical integrator. The use of rotational parameters is completely circumvented throughout the whole discretization process. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A finite element formulation based on the theory of a Cosserat point
Authors: Boerner Eiris F. I. , Wriggers Peter , Rubin Miles B. 
Published: December 2005

AbstractThe theory of Cosserat points is the basis of a 3D finite element formulation allowing for large deformations in structural mechanics, that recently was presented by [1]. First attempts have revealed, that this formulation is free of showing undesired locking or hourglassing‐phenomena. It additionally shows excellent behaviour for any type of incompressible material, for large deformations and sensitive structures such as plates or shells. Within the theory of Cosserat points, the position vectors X and x, are described through director vectorsDi and di by use of trilinear shape functions Ni for an 8‐node brick element.The special choice of shape functions Ni allows for director vectors with which the deformation can be split into a homogeneous and an inhomogeneous part. This split enables the use of stiffnesses that correspond to different deformation modes. Analytical solutions to the inhomogeneous deformation modes are incorporated in the formulation and avoid the undesired phenomena. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Space‐time DG Method for Porous Media
Authors: Chen Zhiyun , Steeb Holger , Diebels Stefan 
Published: December 2005

AbstractIn this work we present a new coupled space‐time discontinuous Galerkin method for the dynamical analysis of fully‐saturated porous media. The method consists of a finite element discretization in space and time simultaneously. The numerical solution is solved on every time‐slab (Qn = Ω × ℐn), which is in analogy to classical finite difference methods in time. The method is stable and efficient. The computational accuracy can be easily raised by increasing the order of the ansatz functions. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Simulation of the Application of NiTi Alloys in Medical Technologies
Authors: Christ Daniel , Reese Stefanie 
Published: December 2005

AbstractShape memory alloys are nowadays already established as a material which is able to solve exceptional tasks in practical applications. Particularly, its utilization in the field of medical technologies increases steadily. For example micro tools (staple, catheters) and implants (coronary stents) are made out of Nickel‐Titanium well known as a basic shape memory alloy. Apart from the advantages like the avoidance of auxiliary components and joints in the system and to utilize the high volume specific work of shape memory alloys, NiTi alloys exhibit a good biocompatibility. This property is necessary with regard to either permanent or temporary implants. To optimize the use of NiTi alloys in the scope of medical technologies, the support of the development of applicable tools by numerical simulations is highly recommended. However the complex material behaviour containing a profoundly thermomechanical coupling poses indeed a big challenge to the material modeling and its implementation into a finite element code. Particularly, the material model proposed by Helm [1] proves to be a firm model containing the most common properties of shape memory alloys, as the pseudoelasticity, the shape memory effect and the two‐way effect. In the present contribution the FE modelling of a medical staple used in foot surgery is presented by considering the model of Helm which was investigated by the authors to improve its performance in the finite element method [2]. The foot staple, produced by a group of members of the SFB 459 which is funded by the DFG, avails the shape memory effect to excite the desired clamping effect [3]. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Analysis of a Cyclical Loaded Construction under Corrosion Degradation
Authors: Dudda W. , Badur J. 
Published: December 2005

AbstractA contribution for analytical and numerical tools that permits of a deterministic evaluation of structure behavior in external conditions, under multiparameter and/or cyclic mechanical, thermal and chemical loads, is the aim of this paper. Particular structure elements undergo the plastic and corrosion degradation and they dissipate energy, which consists of irreversible contributions, like a work on the inelastic strains. The construction and its unit lifetime are estimated according to a dissipated energy criterion. The paper emphasizes the modeling and numerical implementation of degradation effects, such as cyclic plasticity, generated by mechanical and thermal loads, stress corrosion, electrochemical corrosion and low‐cyclic corrosion. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Delaminationsberechnung von Faserverbundstrukturen
Authors: Fiolka M. , Matzenmiller A. 
Published: December 2005

AbstractDas Ablösen der Einzelschichten unidirektional verstärkter Faserverbundlaminate voneinander ‐ die Delamination ‐ ist eine der gefährlichsten Versagensarten, da sie zum globalen Kollaps der Struktur führen kann. Statische, interlaminare Bruchtests, die zur Ermittlung der Bruchzähigkeit und des Rissfortschrittes dienen, werden mit der Methode der finiten Elemente simuliert. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of multiphasic flow phenomena in deformable porous materials under consideration of thermal effects
Authors: Graf T. , Ehlers W. 
Published: December 2005

AbstractThe consideration of thermal effects in the description of multiphasic flow processes and their interaction with a deformable solid skeleton plays a significant role in a big field of engineering applications, as for example in the modelling of carbon dioxide storage in the subsurface or the remediation of contaminated partially saturated soil by in‐situ‐methods. In this contribution, a continuum mechanical approach based on a multiphasic formulation embedded in the well‐founded framework of the Theory of Porous Media (TPM) is presented to describe the non‐isothermal material behaviour of partially saturated soil. The single constituents are an elasto‐viscoplastic solid skeleton, a materially incompressible pore‐liquid and a materially compressible pore‐gas. The resulting system of strongly coupled differential‐algebraic equations is solved by the FE tool PANDAS that has been designed for the computation of strongly coupled solid‐.uid problems. As a numerical example, the injection process of heated gas in a partially saturated soil is discussed, whereby the capability of the presented model to describe the behaviour of unsaturated soil under non‐isothermal conditions is pointed out. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Galerkin methods in time for semi‐discrete viscoelastodynamics
Authors: Groß Michael , Betsch Peter 
Published: December 2005

AbstractIn semi‐discrete nonlinear elastodynamics, higher order energy and momentum conserving time stepping schemes turned out to be well suited for computing long time motions [1]. In comparison to standard ODE integrators, conserving schemes exhibit superior stability properties which are of utmost importance in a nonlinear .nite element framework. We show that conserving schemes are particularly well suited as starting point for the development of energy consistent schemes for dissipative dynamical systems. In particular, viscoelastic material behaviour is considered. A key advantage of energy consistent schemes lies in the fact that the equilibrium state of viscoelastic systems can be de.nitely reached, independent of the material parameters. In the paper, we compare two Galerkin methods for the temporal discretisation of semi‐discrete nonlinear viscoelastodynamics: the standard continuous Galerkin (cG) method and an enhanced continuous Galerkin (eG) method which ful.ls the total energy balance exactly. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transient dynamic investigation of nonlinear 3D soil–structure interaction problems using an iterative coupling approach
Authors: Hagen Christian , von Estorff Otto 
Published: December 2005

AbstractA domain decomposition approach for the transient analysis of arbitrary three‐dimensional soil–structure interaction problems is presented. The coupling of the subdomains is performed in an iterative manner. For this purpose, a sequential as well as a parallel interface relaxation algorithm have been developed, where the coupling iterations are performed very effectively together with the iterations which are required to solve the nonlinear FEM system of equations. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulating the Microstructure of cement‐based Construction Materials
Authors: Hain Michael , Wriggers Peter 
Published: December 2005

AbstractFor a better understanding of material phenomena, it is reasonable to take a deeper look into the microstructure of the material under consideration. In this contribution we focus on hardened cement paste with the goal to determine the effective material properties through simulations of the microstructure and numerical homogenization. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Hydroforming of Metal Sheets with an Efficient FE‐Formulation Based on an Analytical Meshfree Description of a Compressible Fluid
Authors: Haßler Marc , Schweizerhof Karl 
Published: December 2005

AbstractHydroforming is very interesting for the automotive industry, as it offers a great variety to efficiently manufacture thin walled structures. In order to simulate such static large deformation processes under hydraulic or pneumatic pressure, an analytical meshfree description of a compressible heavy or weightless fluid is presented. Thus a fully nonlinear formulation of the fluid‐structure‐interaction only based on the surface of the wetted membrane structure and the constitutive equations for the fluid can be derived. Considering physically realistic boundary conditions this formulation finally leads for all combinations of fluids and gas to a symmetric tangential stiffness matrix including several dyadic rank updates, which can be cast into a very efficient solution procedure by sequential applications of the Sherman‐Morrison formula. Furthermore other algorithms such as mesh refinements and structural contact can be restricted to the models for the work piece and the matrix. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Follower loads for high order finite elements
Authors: Heisserer Ulrich , Düster Alexander , Rank Ernst 
Published: December 2005

AbstractFinite element modelling of hydrostatic compaction where the applied pressure acts normal to the deformed surface requires a geometric nonlinear formulation and follower load terms [1, 5, 7]. These concepts are applied to high order [6] (p‐FEM) elements with hierarchic shape functions. Applying the blending function method allows to precisely describe curved boundaries on coarse meshes. High order elements exhibit good performance even for high aspect ratios and strong distortion and therefore allow an efficient discretization of thin‐walled structures. Since high order finite elements are less prone to locking effects a pure displacement‐based formulation can be chosen.After introducing the basic concept of the p‐version the application of follower loads to geometrically nonlinear high order elements is presented. For the numerical solution the displacement based formulation is linearized yielding the basis for a Newton‐Raphson iteration. The accuracy and performance of the high order finite element scheme is demonstrated by a numerical example. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of Electromechanical Contact on a Microscopic Lengthscale
Authors: Helmich Tobias , Nackenhorst Udo 
Published: December 2005

AbstractThis paper treats the simulation of the contact mode of an atomic force microscope (AFM). The contact forces between the tip and the sample surface is calculated via the van derWaals force in a Finite Element approach, the integration of the contact force a FEM environment is discussed and numerical examples are presented. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ein Vergleich numerischer Methoden zur Beschreibung von Kontaktvorgängen
Authors: Hesch Christian , Betsch Peter 
Published: December 2005

AbstractDie am häufigsten zum Einsatz kommende Methode zur Beschreibung eines Kontaktvorgangs ist das sog. NTS‐ (node‐tosegment‐) Element (vgl. [3]). Die NTS‐Methode bewirkt eine punktweise Erfüllung der Kontaktbedingung. Demgegenüber steht die Mortar Methode (vgl. [1]), die eine variationell konsistente Beschreibung des Kontaktvorgangs ermöglicht. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of the EAS‐concept to a p‐version of the finite shell formulation to avoid volumetric locking
Authors: Hommel Jan‐Hendrik , Meschke Günther 
Published: December 2005

AbstractA modification of the enhanced assumed strain concept is proposed to avoid volumetric locking phenomena in finite elements using higher‐order p‐shell element formulations based on Lagrangean polynomials and a linear finite shell kinematics. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New modelling approach for damped mutilayed composites
Authors: Hu Heng , Belouettar Salim , Daya El Mostafa , Potier‐Ferry Michel 
Published: December 2005

AbstractThe aim of this paper is to get a good approximation of damping properties of viscoelastic damped sandwich structures. Firstly we will compare the classical models based on the kinematics of Kirchhoff‐Love, Mindlin, Reddy or Touratier. In the second stage these models are used to establish the zig‐zag models which describe a piecewise continuous displacement field. These models are compared in the static and the dynamic fields. In all cases the Finite‐Element‐based solution is considered as reference. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of thin polymer films
Authors: Johlitz Michael , Steeb Holger , Diebels Stefan 
Published: December 2005

AbstractIf we bond substrates like metal sheets by a thin polymer film we know about the existence of a boundary layer between the polymer and the substrate. The properties of this boundary layer differ from the bulk properties and influence the overall behavior of the bond. Here we present a mechanical theory based on a scalar‐valued order parameter that allows us to describe these effects. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Density gradient based regularization of topology optimization problems
Authors: Kotucha Gregor , Hackl Klaus 
Published: December 2005

AbstractIn the present paper we focus on the regularization of topology design problems with regard to numerical instabilities such as the occurrence of optimal designs characterized by oscillating material density distributions, for example in the form of the well–known “checkerboard–like” patterns, as well as the dependence of the obtained designs on the used finite–element–mesh. In this context we discuss a regularization approach penalizing spatial oscillations of the material density by means of a penalty functional reflecting the global distribution of the density gradient. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Mixed Finite Element Formulation for Piezoelectric Materials
Authors: Linnemann Konrad , Klinkel Sven 
Published: December 2005

AbstractA geometrically nonlinear finite element formulation to analyze multi‐field problems as they arise e.g. in piezoelectric or magnetostrictive materials is presented. Here we focus on piezoelectric problems. The formulation is based on a Hu‐Washizu functional considering six independent fields. These are displacements u, electric potential ϕ, strains E, stresses S, electric field $\vec E$, and the electric flux density $\vec D$. The finite element approximation leads to an 8‐node hexahedral element with uand ϕ as nodal degrees of freedom. The fields E, S, $\vec E$, and $\vec D$ are interpolated on element level by employing some internal degrees of freedom. These fields do not require continuity across the element boundaries, thus the internal degree of freedoms are eliminated on element level by a static condensation. The geometrically non‐linear theory allows large deformations and accounts for stability problems. To fulfill the charge conservation law in bending dominated situations exactly a quadratic approximation of the electric potential is necessary. This leads in general to additional nodal degrees of freedom, which is circumvented by the presented formulation by employing appropriate interpolations of $\vec E$ and $\vec D$. Numerical examples show that the locking effect which arise in low order elements are significantly reduced and that the element provides good accuracy with respect to experimental data. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)