bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anisotropic damage for higher order continuum models
Authors: Ebinger Tobias , Steeb Holger , Diebels Stefan 
Published: December 2005

AbstractA continuum model for the description of the deformation behavior of foam‐like structures with open cells is presented. On the microlevel the struts can be modeled by beam elements. The macroscopic model, which is derived by homogenization of microscopic quantities, is extended towards anisotropic damage. Thereby, it is considered that not only the normal and shear forces transduced by the microstructural beam elements cause damage but also the bending moments. Thus, on the macroscale a standard continuum theory in conjunction with first order homogenization is not sufficient because the effects of the bending moments would be neglected. An extended continuum theory is chosen on the macroscale considering the bending moments on the microscale requiring a second order homogenization procedure. The idea of including microstructural information by homogenization without formulation of macroscopic constitutive and evolution equations is known from literature as FE2 model. The capability of the presented model is demonstrated in a numerical example. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Deformation Driven Homogenization of Fracturing Solids
Authors: Gürses Ercan , Birkle Manuel , Miehe Christian 
Published: December 2005

AbstractThe paper discusses numerical formulations of the homogenization for solids with discrete crack development. We focus on multi–phase microstructures of heterogeneous materials, where fracture occurs in the form of debonding mechanisms as well as matrix cracking. The definition of overall properties critically depends on the developing discontinuities. To this end, we extend continuous formulations [1] to microstructures with discontinuities [2]. The basic underlying structure is a canonical variational formulation in the fully nonlinear range based on incremental energy minimization. We develop algorithms for numerical homogenization of fracturing solids in a deformation–driven context with non–trivial formulations of boundary conditions for (i) linear deformation and (ii) uniform tractions. The overall response of composite materials with fracturing microstructures are investigated. As a key result, we show the significance of the proposed non–trivial formulation of a traction–type boundary condition in the deformation–driven context. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Formulation of the material force approach for elastic and inelastic materials
Authors: Näser Bastian , Kaliske Michael , André Markus 
Published: December 2005

AbstractFracture mechanical investigations are important for the durability of fracture sensitive products. Fracture mechanical simulations help to shorten the product development cycle and to decrease product costs. The so‐called material force approach as an efficient tool is used to determine fracture mechanical parameters for elastic and inelastic materials. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the macroscopic material behaviour of textile reinforced concrete undertensile loading
Authors: Richter Mike 
Published: December 2005

AbstractThis paper concerns with the development of the macroscopic material behaviour of textile reinforced concrete (TRC) using an analytical approach. Therefore the heterogeneous structure of TRC is modelled on the mesoscopic level. The overall material behaviour on the macroscopic level is obtained by means of the homogenisation technique. The analytical approach is based on the micro mechanical solution for a single inclusion according to Eshelby. In extension of this solution for multidirectional reinforced concrete an effective field approximation is used. This approach considers the interactions between the different orientated rovings and the micro cracks in an average sense. For the mechanical modelling of the bond behaviour between roving and matrix after initiating of the macro cracking a slip based bond model with a multiple linear shear stress‐slip relation is used. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Direct FEM Simulation and Replacement Crack Approach for Mixed Mode Crack Growth in a Unit Cell
Authors: Sch?tte Henning , Molla‐Abbasi Kianoush 
Published: December 2005

AbstractA whole class of continuum damage models uses microcracks as the main source of reduction of stiffness. For the growth of these cracks mostly only mode I is considered. We want to present a method to describe mixed mode crack growth inside a unit cell with a crack, without the need of a direct FEM simulation of crack growth per integration point. We replace the infinitesimal grown and kinked crack with the help of a replacement crack model. This replacement method is mainly based on the equivalence of the dissipation of the original kinking and the replacement crack. The resulting evolution of the stiffness of the unit cell is compared to a direct FEM simulation of mixed mode crack growth. The crack growth criterion used is the principle of maximum energy release rate, which has shown to be a direct consequence of a variational principle of a body with a crack [1]. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A consistent theory for poroelastic plates
Authors: Busse Anke , Schanz Martin 
Published: December 2005

AbstractIn many fields of engineering thin porous components are used, e.g. as damping elements for noise insulation in cars or walls in buildings. Today these elements are often calculated using a numerical 3‐D model. Because of numerical problems which occur using a 3‐D model for thin transversly loaded structures a plate theory is advantageous. To take into account the porous structure as well as the damping effect of the porosity of these components a poroelastic plate theory is necessary.Several posibilities exist to establish plate theories. Generally, methods to derive a plate theory require a priory assumptions motivated by engineering intuition (like the classical Kirchhoff normal hypothesis).In this contribution a priori assumptions are not used. Plate theories of different orders are derived from the 3‐D poroelastic theory using series expansion. For elastic plates this idea was introduced in [3]. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Finite Element Formulation for the Nonlinear Analysis of Piezoelectric Three‐Dimensional Beam Structures
Authors: Butz Alexander , Klinkel Sven 
Published: December 2005

AbstractA finite element formulation for a three‐dimensional piezoelectric beam which includes geometrical and material nonlinearities is presented. To account for the piezoelectric effect, the coupling between the mechanical stress and the electrical displacement is considered. Based on the Timoshenko theory, an eccentric beam formulation is introduced which provides an efficient model to analyze piezoelectric structures. The geometrically nonlinear assumption allows the calculation of large deformations including buckling analysis. A quadratic approximation of the electric potential through the cross section of the beam ensures the fulfilment of the charge conservation law exactly. This assumption leads to a finite element formulation with six mechanical and five electrical degrees of freedom per node. To take into account the typical ferroelectric hysteresis phenomena, a nonlinear material model is essential. For this purpose, the phenomenological Preisach model is implemented into the beam formulation which provides an efficient determination of the remanent part of the polarization. The applicability of the introduced beam formulation is discussed with respect to available data from literature. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Second order homogenization method based on higher order finite elements
Authors: D?ster A. , Rank E. , Diebels S. , Ebinger T. , Steeb H. 
Published: December 2005

AbstractModeling materials with lattice‐like microstructures like open‐cell foams requires an extended continuum mechanical setting on the macroscopic scale, e. g. a micropolar or micromorphic theory. In order to avoid the formulation of constitutive equations a higher order numerical homogenization scheme (FE2) is proposed. Therefore, each integration point possesses its own microstructure which, in the present case, consists of beam‐like elements representing the cell walls. In this paper, the microstructures are discretized by continuum‐based higher order locking free finite elements with high aspect ratios, leading to a numerically efficient treatment of a local displacement‐driven boundary value problem according to the macroscopic strain and curvature. The resulting stress distributions in the microstructures are homogenized to macroscopic stresses and couple stresses. The approach is demonstrated by a numerical example. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerische Aufbereitung der Stoffgesetze spezieller thermoplastischer Festigkeitsträger zur Berechnung von Elastomer‐Faserverbunde
Authors: Jacob H.‐G. , Besdo D. , Oehmen K. H. 
Published: December 2005

AbstractIm Bereich der gummiartigen Werkstoffe wird derzeitig sehr emsig geforscht. Hier werden Arbeiten vorgestellt, die phänomenologisch und physikalisch basiert sind. Mit den entwickelten Materialgesetzen, lassen sich die wesentlichen physikalischen Eigenschaften des Elastomers schon in befriedigendem Maße wiedergeben. Um jedoch Berechnungen an einem Gummi‐Faser‐Verbundsystem durchführen zu können, benötigt man noch eine Materialbeschreibung des Festigkeitsträgers. Ein thermoplastischer Festigkeitsträger verhält sich, ebenso wie Gummimaterial, stark nichtlinear, erleidet große Deformationen und zeigt deutliche Hystereseerscheinungen während eines Belastungszyklus. Dieses Verhalten muss in einem das Fadenmaterial beschreibenden Stoffgesetz ebenso enthalten sein, wie der strukturelle Aufbau des Fadens in den Deformationsmaßen. Die Berücksichtigung des Aufbaus des Festigkeitsträgers macht es erst möglich, dass wesentliche physikalische Effekte im Verbund berechnet und dann visualisiert werden können. Die Berechnung von Luftfedern und Fahrzeugreifen ist unter diesen Umständen sehr schwierig. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A model‐adaptive coupling strategy of non‐linear and model‐reduced linear subsystems
Authors: Rickelt Christian , Reese Stefanie 
Published: December 2005

AbstractThis article introduces a new three‐level discretisation strategy in which the entire structure is divided into subsystems according to the required modelling accuracy(continuum, structural and substituted model level). This note especially focuses on the transition between the structural and the substituted model level. The principle idea is to separate the structure strictly into linear and non‐linear substructures by the concept of coupling forces. Additionally the linear parts are reduced by modal reduction. The method is verified by a transient analysis of a bridge arch having regard to the evolution of damage. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interlaminar Stresses at Corners of Laminate Reinforcements
Authors: Wigger Hubertus Michael , Becker Wilfried 
Published: December 2005

AbstractFor inplane loaded plates the use of two laminate patches which are attached symmetrically to a base laminate with respect to the out‐of‐plane direction is a possibility to reinforce a highly stressed region. But corners at the patches' boundaries constitute a source for stress localizations. The expedient knowledge of the local mechanical inplane fields at such corners can be obtained with the boundary finite element method (BFEM). In order to investigate the intrinsically three‐dimensional nature of the laminate corner setup the gradients of the inplane fields are readily evaluated since they are provided by the BFEM in a semi‐analytical way. The interlaminar stresses inside the plate are retrieved by equilibrium considerations on a ply‐by‐ply basis. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solving plasticity problems by a perturbation technique
Authors: Zahrouni H. , Braikat B. , Damil N. , Potier‐Ferry M. 
Published: December 2005

AbstractThe present work deals with a new technique to regularize the elastoplastic constitutive laws in the framework of the asymptotic numerical method. In this contribution, we limit ourselves to uniaxial stress train relation but the procedure is implemented also in a finite element code for plain stress case and for different work hardening laws. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Incompressible Flows with Coupled FEM/EFG shape functions
Authors: Fries Thomas‐Peter , Matthies Hermann G. 
Published: December 2005

AbstractA method for the simulation of incompressible flows is described which is able to handle geometrically complex situations, such as those including moving and rotating objects in the flow field. In these situations, standard meshbased methods such as the finite element method (FEM) may fail if a suitable mesh can not be maintained at reasonable cost throughout the simulation. The proposed method introduces the desirable features of meshfree methods in parts of the domain where the mesh generates problems. This is realized by coupling FEM and element‐free Galerkin (EFG) shape functions. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Towards High Order Numerical Simulation of Aeolian Tones
Authors: Müller Bernhard 
Published: December 2005

AbstractStrictly stable high order finite difference operators have been applied to the compressible Navier‐Stokes equations in perturbation form for low Mach number computational aeroacoustics. Aeolian tones generated by vortex shedding from a circular cylinder have been simulated. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerische Berechnungen der Bewegungsvorgänge während des Gärungsprozesses in einem Modell eines zylindrokonischen Gärtanks
Authors: Szymczyk J. A. , Meironke H. , Nurzynski M. 
Published: December 2005

AbstractDie Kenntnis der Konvektionsvorgänge in den heute fast ausschließlich verwendeten zylindrokonischen Gär‐ und Lagertanks stellt eine notwendige Voraussetzung dar, wenn man den Prozess der Bierherstellung, insbesondere der Gärung, optimieren will. Im Rahmen der Untersuchungen der konvektiven Transportvorgänge in Gär‐ und Lagertanks werden in der folgenden Arbeit die Ergebnisse der numerischen Simulation der Strömungsvorgänge auf Basis eines Finite‐Volumen‐Verfahrens präsentiert. Grundlage der Berechnungen stellt ein spezieller Gär‐ und Lagertank (270 Liter) dar, der den realen Gärungs‐ und Lagerungsprozess realisieren kann und in einer weiteren Betriebsart in der Lage ist, eine simulierte experimentelle Gärung mittels definierter Steuerung von Heizungs‐ und Kühlungsrandbedingungen durchzuführen. Ein wesentlicher Schwerpunkt dieser Arbeit ist die Erstellung eines Modells, das dem realen Strömungsverhalten, in der experimentell simulierten Gärung in dem 270 Liter Tank, nahezu entspricht. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Applications of Wavelet Packets in System Identification
Authors: Brehm Maik , Zabel Volkmar , Markwardt Klaus 
Published: December 2005

AbstractAs existing facilities / structures are modi.ed, as engineering knowledge advances and as the requirements to extend life increase, industries must demonstrate that operations can continue safely and economically. This is one objective of the Thematic Network SAFERELNET [1], where reassessment strategies are covered. One possibility to enhance the knowledge is an experimental assessment. This study aims to identify system parameters like mass, damping and stiffness of a dynamical system using wavelet packets. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification of material parameters in extended contiuum mechanicalmodels
Authors: Chatzouridou Anthippi , Diebels Stefan 
Published: December 2005

AbstractA method for the identification of material parameters of constitutive models describing foamed materials is discussed in the present work. One can model foamed materials in two ways: using a lattice‐like micro‐model or alternatively a continuum mechanical approach. A beam model is used for the description of foams on a microscopic scale and alternatively an extended continuum model based on the Cosserat theory is employed on the macroscopic scale. By performing numerical shear tests at specimens of different sizes, we can observe the following effect on both models: The distribution of the rotations shows a strong boundary layer character at the top and bottom boundary of the specimen, whereas at the inner part it takes a constant value. These boundary layer effects do not scale with the size of the specimen, as a result specimens occur to be stiffer, see [1]. The goal is to perform a fitting of the Cosserat parameters by comparing the results of the macroscopic model to these of the microscopic one. The parameter fitting concerns an inverse problem which is treated within the framework of stochastic optimization methods. An evolutionary algorithm is used in combination with a response surface method for the identification of the material parameters. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Design and Control of a Pneumatic Hybrid Actuator
Authors: Dhanu Singh M. , Liem K. , Kecskeméthy A. , Neumann R. 
Published: December 2005

AbstractTo simulate arbitrary force/displacement relationships, a hybrid actuator consisting of a .uidic muscle and a linear pressure spring is presented. Fluidic Muscles are interesting in their use as actuators in robotics, since they have a high power/weight ratio, a slip‐stick free motion and a long durability. The operating point is de.ned as the half contracted‐stroke of the muscle. The present paper describes a procedure to simulate virtual stiffness of a linear actuator by choosing an operating point of the pre‐stressed muscle and applying PID Control to produce desired forces as function of state. The results are presented for a testbed. It is shown how the aforementioned control scheme produces a rapid and .exible stiffnes simulation. The device can be employed for later use in general environments such as motion simulations. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Monitoring of the Nonlinear Dynamics of Railway Wheelsets
Authors: Glösmann Philipp , Kreuzer Edwin 
Published: December 2005

AbstractThis paper focuses on the identification of dominant coherent structures in the nonlinear dynamic behavior of railway wheelsets by Karhunen‐Loève‐Transform (KLT). The ultimate goal is the characterization of the rolling quality of railway wheelsets. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Konstitutive Charakterisierung von Kautschukmischungen mit dem Hochdruckkapillarviskosimeter
Authors: Müllner Herbert Wolfgang , Eberhardsteiner Josef , Wieczorek André 
Published: December 2005

AbstractIn diesem Beitrag wird über eine Parameteridentifikation für die Bestimmung der viskosen Eigenschaften von Kautschukmischungen berichtet. Bisher wurde die Kopplung der Zustandsgrößen durch die Anwendung von Korrekturverfahren berücksichtigt. Mit Hilfe eines Iterationsverfahrens werden die Materialparameter nun direkt ermittelt. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Shear Modulus Identification in Soft Tissue‐like Materials
Authors: Reichling Stefan , Timme Bruhns Otto , Khaled Walaa , Ermert Helmut 
Published: December 2005

AbstractElastography is a method motivated by the observation that changes in tissue elasticity are generally correlated with pathological phenomena. By applying quasi‐static compression to the considered tissue‐like object, components of the internal displacement field can be determined with an ultrasound‐elastography system. Based on the assumption that the investigated material is elastic, isotropic, and nearly incompressible, the stiffness distribution can be calculated from the displacement field in the framework of inverse problems. In this paper, existing procedures for calculating the shear modulus distribution with knowledge of internal displacement field are presented. The methods are compared with respect to the stability of algorithms using numerical simulations and ultrasound measurements. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental Observations on Superelastic NiTi‐Shape Memory Alloys and Suggestions for Modelling
Authors: Schmidt Ina , Vishnevsky Andrey , Lammering Rolf 
Published: December 2005

AbstractDuring stress‐induced transformation NiTi shows a distinct generation of transformation bands. A simple one‐dimensional model for superelastic NiTi wires has been developed to show exemplarily methods to account for these bands in plasticitybased models. To clarify the dependence of the transformation bands on the distribution of latent heat and therefore on the mechanical behaviour, optical and thermographical experiments have been performed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On Boundary Conditions Modelling of the Fluid‐Structure Interaction at Wind Tunnel Testing
Authors: Rašuo Boško 
Published: December 2005

AbstractThe present paper discusses some newer developments, but concentrates mainly on the specification of the wall boundary conditions that are of importance for the calculation of the wind tunnel wall interference. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fully–coupled model for electrokinetic flow and transport in microchannels
Authors: Barz Dominik P. J. , Ehrhard Peter 
Published: December 2005

AbstractWe investigate the electrokinetic flow and mass transport in microchannels. Therefore, mathematical models of the electrical, fluid‐mechanical and chemical processes are established. Within the electrical double layer (EDL), approximative analytical solutions can be found and matched asymptotically to the numerical (FEM) solution of the channel core. The results of the simulations show a strong coupling between the processes. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anisotropy Invariant Reynolds Stress Model and Its Application to Fully Developed Channel Flows
Authors: Breuer M. , Ray S. , Kumar V. , Jovanović J. , Durst F. 
Published: December 2005

AbstractThe paper is concerned with a second‐moment closure for the Reynolds‐averaged Navier‐Stokes equations which relies on the anisotropy invariant theory. It is shown how the anisotropy invariant map can be used to derive reasonable closure assumptions for turbulent flows. Furthermore, a first highly encouraging application for an inhomogeneous flow is discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Das instationäre Strömungsfeld hinter einer arteriellen Stenose
Authors: Chen Xueming , Böhme Gert 
Published: December 2005

AbstractIn der vorliegen Arbeit geht es darum, ein grundsätzliches Verständnis für die komplexe instationäre Durchströmung eines pathologischen Blutgefäßes zu entwickeln. Zur Analyse der Strömungsprozesse wird eine modellhafte Untersuchung mit Hilfe der Particle Image Velocimetry (PIV) durchgeführt. Ausgehend von der Reynoldsschen und der Strouhalschen Ähnlichkeit wurde ein Versuchsstand aufgebaut, der aus dem optisch zugänglichen Modell der arteriellen Stenose mit einer im Längsschnitt cosinusförmigen Einschnürung und einem System zur Realisierung der pulsierenden Blutströmung besteht. Mit dem PIV‐System wurde das Geschwindigkeitsfeld im Längsschnitt hinter der Stenose zu verschiedenen Zeitpunkten des Pulszyklus gemessen. Auf diese Weise werden die Strömungsvorgänge während der Beschleunigungsphase, der Verzögerungsphase und der Konstantphase experimentell charakterisiert. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)