bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Construction of Statistically Similar Representative Volume Elements Based on the Lineal‐Path Function
Authors: Brands Dominik , Balzani Daniel , Schröder Jörg 
Published: November 2010

AbstractIn this contribution we propose a method for the construction of statistically similar representative volume elements (SSRVEs) which are characterized by a much less complexity than usual random RVEs and which represent quite accurately the mechanical response of the real material. For the design of such SSRVEs an objective function is minimized taking into account least‐square functionals based on suitable statistical measures, that characterize the inclusion morphology. Here, we find that the incorporation of the lineal‐path function leads to promising results in FE2‐simulations of macroscopically homogeneous boundary value problems as well as inhomogenous ones. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of Homogenization FEM Analysis to Aluminum Honeycomb Core Filled with Polymer Foams
Authors: Burlayenko Vyacheslav N. , Sadowski Tomasz 
Published: November 2010

AbstractThe effect of polyvinyl chloride (PVC) foam filler on elastic properties of a regular hexagonal aluminum honeycomb core is studied. The unit cell strain energy homogenization approach based on the finite element method (FEM) within ABAQUS code is applied for prediction of effective material constants of the foam‐filled honeycomb core. The developed FE model is then used to observe a three‐dimensional stress state over the hexagonal unit cell and, thereby, to assess the influence of the foam‐filling on the distribution of the local interfacial stresses. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development of an elastic‐plastic constitutive model for highly anisotropic materials
Authors: Haasemann Georg , Lux Christian , Ulbricht Volker 
Published: November 2010

AbstractHomogenization methods are used to obtain the effective properties of highly anisotropic materials such like textile reinforced composites. The state of the art is the utilization of this method to compute elastic properties. But the consideration of inelastic and anisotropic properties requires the application of more advanced techniques such as the FE2‐method. Due to the high numerical effort induced by this approach, this paper presents a new method to evaluate inelastic properties of an heterogeneous elastic‐plastic material. The parameters describing the inelastic properties require a modification of the return mapping algorithm which is used for the numerical implementation. Finally, the verification shows the accuracy of the results obtained with this new homogenization method. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new and efficient approach for modeling short fiber reinforced materials within RVEs using an embedded element technique
Authors: Hoffmann S. , André M. , Rodríguez Sańchez A. , Mueller R. 
Published: November 2010

AbstractThis paper focuses on the numerical homogenization by using representative volume elements (RVE method). A new approach is presented that is capable of speeding up the modeling process and reducing the computation time of RVEs significantly. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Homogenization Approach Based on Laminates
Authors: Klusemann Benjamin , Svendsen Bob 
Published: November 2010

AbstractIn this work, a homogenization approach for the modeling of the material behavior of two‐phase composites motivated by modeling a thin‐layer‐type microstructure is presented. The basic idea here is to idealize the thin‐layered microstructure as a first‐order laminate. In particular, a jump in deformation state across the phase interface is modeled constitutively via a rank‐one connection of habit‐plane type. In the material framework, the value for the jump as well as its direction remain as independent constitutive variables. However, in the case of laminates and an ideal plain interface, the direction is given and stays in a first approach constant. We assume that their values are determined by mechanical and configurational equilibrium in the two‐phase composite at the interface. This yields to a set of implicit equations which lead to the corresponding response of the structure. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effective viscous sintering parameters for heterogeneous plate‐like structures using numerical homogenisation
Authors: Schmidt Ingo 
Published: November 2010

AbstractA model to describe the sintering of plate‐like structures and the numerical technique to obtain its ingredients from the analysis of a given heterogeneous structure are described. Finite membrane strains are accounted for and numerical creep tests are used to extract suitably defined macroscopic viscosities and generalised sintering stresses for plate‐like structures. An example is analysed and compared to a full 3D simulation. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Applying Cauchy‐Born rule for converting atomistic model to continuum model
Authors: Shan Wenzhe , Nackenhorst Udo 
Published: November 2010

AbstractThe Cauchy‐Born rule has been applied in the Quasicontinuum method to derive continuum material properties based on underlying atomistic model in a physically consistent way. In this short work, the procedure is demonstrated, where the resulted materials constants are compared with experimental data found in literature. Moreover, the condition for applying the Cauchy‐Born rule is discussed, with an intuitive explanation for why it can be only applied to crystalline materials with perfect structure. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micromechanically based stress and strain‐rate flow potentials for anisotropic polycrystals
Authors: Tsotsova Rumena , Böhlke Thomas 
Published: November 2010

AbstractThe dissipation of rigid‐viscoplastic material behaviour is related to the stress flow potential and its Legendre‐Fenchel conjugated strain‐rate flow potential. In this paper micromechanically based approximation of these flow potentials, expressed in terms of the deviatoric stresses and strain‐rates, is derived from texture measurements. The dual potentials for single face‐centered cubic crystals are approximated in terms of Fourier expansion with tensorial texture coefficients. The macroscopic flow stress and strain‐rate potentials for an aggregate of polycrystals can be deduced from those of single crystal under the assumption of either homogeneous strain‐rate, or homogeneous stress field from the codf measurements. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Turbulent Poiseuille flow with near‐critical wall transpiration
Authors: Vigdorovich Igor , Oberlack Martin 
Published: November 2010

AbstractAn incompressible, pressure‐driven, fully developed turbulent flow between two parallel walls, with an extra constant transverse velocity component, is considered. A closure condition is formulated, which relates the shear stress with the first and the second derivatives of the longitudinal mean velocity. The closure condition is derived without invoking any special hypotheses on the nature of turbulent motion, only taking advantage of the fact that the flow depends on a finite number of governing parameters. By virtue of the closure condition, the momentum equation is reduced to the boundary‐value problem for a second‐order differential equation, which is solved by the method of matched asymptotic expansions at high values of the logarithm of the Reynolds number based on the friction velocity. The case of near‐critical transpiration, when the shear stress at the injection wall vanishes, is considered. It is shown that the maximum point on the mean velocity profile lies in a thin sublayer near the suction wall in this case. A formula for the position of the maximum point as a function of the transpiration factor is obtained. The mean velocity profiles near the suction wall are calculated. A friction law for Poiseuille flow with near‐critical transpiration is found, which makes it possible to describe the relation between the shear stress at the wall, the Reynolds number, and the transpiration velocity by a single function of one variable. Direct numerical simulation of the flow for some transpiration factors is performed. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A hybrid model for electroosmotic flows in microchannels induced by internal electrodes
Authors: Stieglitz Ina , Ehrhard Peter 
Published: November 2010

AbstractInternal electrodes, adjacent to insulating walls at defined zeta potential, lead to a non‐continuous potential distribution at the wall. Hence, simplified treatment appears problematic due to the singularity of the electrical field strength. To avoid this difficulty, we develop a hybrid model, which solves the electrical problem, including a resolution of the EDL, while the flow problem is solved in the fluid bulk only. We apply this hybrid model to investigate the position of internal electrodes with regard to their influence onto the flow field, driven by electroosmosis in a modular rectangular microchannel. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Stokesian Dynamics Method and the Settling behaviour of Particle‐Fibre‐Mixtures
Authors: Feist Markus , Keller Florian , Dörfler Willy , Nirschl Hermann 
Published: November 2010

AbstractSedimentation of fibres and particles can be observed manifold in industrial application. In waste water treatment, the water is clarified from solid particles and fibres utilizing sedimentation. Some filtration processes use fibres as an aid to improve the filtration quality. Finally, in the paper recycling process, one tries to separate cellulose fibres from inorganic particles used as filling material or in printing colours. For all these applications, it is necessary to understand the hydrodynamic interactions between single particles as well as particle and fibre collectives.In the present paper, the sedimentation behaviour of fibres and particles is considered in detail. Mathematic modelling is used to investigate inter particle influences in detail. In particular, a method called Stokesian Dynamics is used to simulate the settling of fibres and particles. The main challenge of the modelling is the dependence of the direction of each fibre on its sedimentation velocity and the different sizes of the particles in a poly‐modal particle size distribution. Additionally fibres, particles and the fluid are influencing each other in a significant manner and in a long range. Therefore, while calculating the force on a particle, one has to take into account the influences of many particles. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling and Numerical Simulation of Breaking Waves on Structures
Authors: Fuchs Vilmar , Wünsch Olaf 
Published: November 2010

AbstractThis work deals with the analytical and numerical simulation of the loads on cylindrical offshore structures due to breaking waves. We investigate breaking waves impact on a cylindrical structure on the surface of the water by using a multiphase flow model of immiscible fluids based on the Volume of Fluid (VOF) method. Different numerical schemes are applied to identify the sharp interface between water and gas. The results are compared as well with the already existing experimental, analytical and numerical studies by [1‐3]. The agreement shows that the analytical and numerical models are suited to describe the experimental results. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Weakly 3D Transonic Flows in Narrow Channels
Authors: Kornfeld M. , Kluwick A. 
Published: November 2010

AbstractSteady transonic flows through channels so slender that the classical boundary layer approach fails are considered. The resulting viscous inviscid interaction problem for weakly three‐dimensional laminar flows is formulated for perfect gases under the requirement that the channel is sufficiently narrow so that the flow outside the viscous wall layers becomes two‐dimensional in the leading order approximation. The behavior of the flow upstream of a surface mounted three‐dimensional obstacle will be demonstrated. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Heat Transfer through the Boundary Layer on a Moving Cylindrical Fibre
Authors: Redmond Brendan , McDonnell David 
Published: November 2010

AbstractThis paper applies boundary layer theory to the process of manufacturing polymer fibres known as the melt spinning process. The rate of heat loss of the fibre during this process, characterised by the local Nusselt number, is evaluated by means of a Pohlhausen integral method. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fluid‐Structure Interactions in ALE and Fully Eulerian Coordinates
Authors: Richter Thomas , Wick Thomas 
Published: November 2010

AbstractWe present a novel approach to treat fluid‐structure interactions in a closed variational setting. The standard model is the so‐called ‘arbitrary Lagrangian‐Eulerian’ (ALE) framework. Here, the fluid is transformed into an artificial coordinate system, which fits with the Lagrangian structure system. In the fully Eulerian framework, which is the reverse to ALE, the fluid is left in its natural coordinates while structure is transformed. With this approach, very large deformations, change of topology as well as free movement of the structure can be computed. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crystallization waves in thin amorphous layers on heat conducting substrates
Authors: Buchner Christoph , Schneider Wilhelm 
Published: November 2010

AbstractA crystallization process in thin films is considered, where, driven by the release of the latent heat of fusion, the transformation from an amorphous state to the crystalline state takes place in a progressing wave of invariant shape. The crystallization rate is determined by a rate equation. The influence of the heat loss due to heat conduction into the substrate is taken into account. The resulting system of an ordinary differential equation and an integro‐differential equation is solved numerically using a collocation method. The propagation speed of the wave in dependence on a non‐dimensional heat loss parameter is determined. It turns out that the existence of a self‐sustaining crystallization wave requires the heat loss parameter to be smaller than a certain critical value. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of Sound Radiated by Axisymmetric Vortex Ring
Authors: Alexandru Dumitrache , Horia Dumitrescu , Florin Frunzulica 
Published: November 2010

AbstractA theoretical and numerical study using the unsteady, 3D Navier‐Stokes equations to generate axisymmetric vortex rings is reported. Increasing the vorticity, the vortex ring transition to a turbulent state are analyzed. After transition to a turbulent stage, the self‐similarity of the temporal evolution of the flow is observed. Then we can compare sound radiated by the vortex ring to jet noise, at similar Reynolds number and low Mach number. The agreement between the simulation results and the simplified model is good. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic Wave Propagation in Porous Media Semi‐Infinite Domains
Authors: Heider Yousef , Markert Bernd , Ehlers Wolfgang 
Published: November 2010

AbstractThe problem of dynamic wave propagation in semi‐infinite domains is of great importance, especially, in subjects of applied mechanics and geomechanics, such as the issues of earthquake wave propagation in an infinite half‐space and soil‐structure interaction under seismic loading. In such problems, the elastic waves are supposed to propagate to infinity, which requires a special treatment of the boundaries in initial boundary‐value problems (IBVP).Saturated porous materials, e. g. soil, basically represent volumetrically coupled solid‐fluid aggregates. Based on the continuum‐mechanical principles and the established macroscopic Theory of Porous Media (TPM) [1, 2], the governing balance equations yield a coupled system of partial differential equations (PDE). Restricting the discussion to the isothermal and geometrically linear case, this system comprises the solid and fluid momentum balances and the overall volume balance, and can be conveniently treated numerically following an implicit monolithic approach [3]. Therefore, the equations are firstly discretised in space using the mixed Finite Element Method (FEM) together with quasi‐static Infinite Elements (IE) at the boundaries that represent the extension of the domain to infinity [4], and secondly in time using an appropriate implicit time‐integration scheme. Additionally, a stable implementation of the Viscous Damping Boundary (VDB) method [5] for the simulation of transient waves at infinity is presented, which implicitly treats the damping boundary terms in a weakly imposed sense. The proposed algorithm is implemented into the FE tool PANDAS and tested on a two‐dimensional IBVP. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Receptor clustering on cell membranes
Authors: Daub Markus 
Published: November 2010

AbstractApoptosis is an important physiological process since it enables organisms to remove unwanted or damaged cells. The stimulus of the extrinsic signalling pathway of apoptosis is the clustering of TNF‐receptors on the cell membrane. We introduce a mathematical model for the clustering of TNF‐receptors on the cell membrane. Numerical simulations yield a time evolution of the receptor clusters. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the viscoelastodynamic problem with Signorini boundary conditions
Authors: Petrov Adrien , Schatzman Michelle 
Published: November 2010

AbstractThis note focuses on a viscoelastodynamic problem being subject to unilateral boundary conditions. Under appropriate regularity assumptions on the initial data, the problem can be reduced to the pseudo‐differential linear complementarity problem through Fourier analysis. We prove that this problem possesses a solution, which is obtained as the limit of a sequence of solutions of penalized problems and we establish that the energy losses are purely viscous. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Γ‐convergence for one‐dimensional Ginzburg‐Landau functional with generalized Lipschitz penalizing term
Authors: Raguž Andrija 
Published: November 2010

AbstractWe use the approach developed in the paper G. Alberti, S. Muller: A new approach to variational problems with multiple scales, Comm. Pure Appl. Math. 54, 761‐825 (2001) to obtain Γ‐convergence for a class of Ginzburg‐Landau functionals Iε(v), where v = v(s) is appropriate Sobolev function. We generalize results from the paper A. Raguž: Relaxation of Ginzburg‐Landau functional with 1‐Lipschitz penalizing term in one dimension by Young measures on micropatterns, Asymptotic Anal. 41(3,4), 331‐361 (2005), where original functional was penalized by 1‐Lipschitz function g = g(s). In this note we prove Γ‐convergence when g = g(s, v(s), v′(s)) under suitable growth conditions imposed on g. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of Nonlinear Stochastic Ship Dynamics Under Extended Wave Modeling
Authors: Dostal Leo , Kreuzer Edwin 
Published: November 2010

AbstractAnalytical criteria for risk assessment of ships in random seas are important for the development of new intact stability criteria and also for the first design stage, where many ship designs have to be compared. The analysis is performed by Stochastic Averaging. The results are compared to those obtained by Monte Carlo simulations. We use extended wave modeling by means of two independent stochastic processes realizing a traveling wave with random phase and amplitude corresponding to a prescribed sea spectral density. The righting lever curve in waves is approximated by a polynomial, while quasistatic equilibrium of the analyzed ship in waves is assumed. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Approximate Gauss‐Newton Method for Robust Parameter Estimation
Authors: Binder Tanja , Kostina Ekaterina 
Published: November 2010

AbstractWe consider robust parameter estimation problems in which either the l1 norm or the Huber function of a measurement error vector used as cost functionals. In order to avoid high computational effort of computing exact derivatives needed for the solution of these problems with the Gauss‐Newton method, we suggest to use approximations of the derivatives in the occurring linearized subproblems. We show how the error introduced by using only approximated derivatives can be compensated by adding a correction term to the objective function of the linearized problems. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Model reduction in topology optimisation analysing the inner structure of sensitivity matrices
Authors: Gerzen Nikolai , Barthold Franz‐Joseph 
Published: November 2010

AbstractTopology optimisation models usually contain a great number of design variables and correspondingly lead to large matrices (pseudo load matrixandsensitivity matrix) which appear in sensitivity analysis. We applysingular value decomposition(SVD) to these matrices to analyse their inner structure. Based on the obtained information, we perform model reduction by transformation of the design variables into a lower‐dimensional space. Numerical examples illustrate the advocated theoretical concept. Reasonable results are obtained, based on only a fraction of all design variables. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimierungsstrategien im Bereich der Formoptimierung bei Massivumformverfahren
Authors: Schellenberg Dirk , Kreißig Reiner , Ihlemann Jörn 
Published: November 2010

AbstractZur Lösung von Formoptimierungsproblemen und der Identifikation von Materialparametern wurde an der TU Chemnitz das Programm SPC‐Opt (Scientific Programming and Optimization) entwickelt. Darin werden moderne Aspekte der nichtlinearen FEM und Optimierung umgesetzt. So können beispielsweise die Vorteile paralleler Rechnerarchitekturen genutzt und außer der hauseigenen FEM‐Software auch kommerzielle Programme zur Lösung der notwendigen Anfangs‐Randwert‐Probleme verwendet werden. In der Annahme hinreichend glatter Zielfunktionen werden die Optimierungsprobleme mittels gradientenbasierter Methoden gelöst. Zu diesem Zweck wurden mehrere Trust‐Region‐ und Line‐Search‐Verfahren implementiert. Da diese jedoch lediglich das nächstgelegene lokale Minimum finden, stehen auch verschiedene Verfahren zur Startparametervariation zur Verfügung.Ein wichtiger Punkt bei der Lösung von Formoptimierungsproblemen stellt die durch die Variation der Designvariablen erforderliche Neuvernetzung des FEM‐Netzes dar. Durch die Nutzung von Bezugskurven konnte ein Verfahren entwickelt werden, welches die bestehende Netztopologie beibehält und eine direkte Neuberechnung der Knotenkoordinaten zulässt. Speziell bei Problemen, welche die Beibehaltung der Knotenanzahl erfordern, können so verfahrensbedingte Diskretisierungsunterschiede bei der Neuvernetzung vermieden werden. Gegenüber anderen auf Formbasisvektoren basierenden Verfahren behalten diese FEM‐Netze auch bei deutlicher Variation ihrer Randkonturen eine gute Qualität. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An alternative way of solving large Lyapunov equations
Authors: Eppler André K. , Bollhöfer Matthias 
Published: November 2010

AbstractSystem reduction has become an essential tool in simulating large electrical circuits. Among such methods balanced truncation is in particular popular since it preserves properties like passivity of the underlying descriptor system. One of the main tasks therein consists of solving large scale Lyapunov equations efficiently. In this setting one is looking for a symmetric low rank solution. For this purpose we discuss Krylov‐subspace methods such as the General‐Minimal‐Residual method. To speed up convergence the method is combined with the Low Rank Cholesky‐Factor‐Alternating‐Direct‐Implicit‐Iteration as a structure preserving preconditioner. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)