bluuebunny/crossref_metadata_2025_split huggingface dataset:
Realisation and Modelling of Geotechnical Experiments
Authors: Avci O. , Ehlers W. 
Published: February 2009

AbstractThe realistic description of slope failure due to critical superimposed loads or heavy rainfall events remains a challenging research topic in soil mechanics. Here, the investigations concern granular materials, such as sand, which undergo a highly complex deformation behaviour that can be characterised via homogeneous triaxial experiments. Within this contribution, benchmark tests of base and slope failure situations will be presented, which are simulated by using the FE–tool PANDAS. The solid skeleton is described within the Theory of Porous Media (TPM) as a linear elasto–plastic material exhibiting an isotropic hardening–softening effect and a non–associated plastic flow behaviour.On the basis of triaxial experiments, the material parameters of the elastic as well as the plastic constitutive equations are determined using a gradient–based optimisation method, which is coupled with PANDAS. Finally, the simulations of the benchmark experiments and the localisation of the shear bands are carried out using either a biphasic model including a deformable solid skeleton and pore air or a triphasic model with an additional water phase (pore water) depending on the type of experiment. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Multi‐phase‐field model including inelastic deformation for solid state transformations
Authors: Benke Stefan 
Published: February 2009

AbstractA multi phase field model is presented in order to take the plastic deformation during a solid state transformation into account and to investigate its effect on the transformation kinetics and morphology in a multi phase material. The model is formulated consistently with the multi phase field model for diffusional and surface driven phase transformations [1]. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effiziente FEM‐Adaption des Konzepts repräsentativer Raumrichtungen
Authors: Freund M. , Ihlemann J. 
Published: February 2009

AbstractDas Konzept repräsentativer Raumrichtungen dient der Verallgemeinerung eindimensionaler Stoffgesetze zu vollständigen dreidimensionalen Materialmodellen für die Finite–Elemente–Methode und basiert auf der numerischen Integration einachsiger Spannungszustände über diskret verteilte Raumrichtungen. Zur Reduzierung der Programmlaufzeit einer FE–Simulation ist eine möglichst geringe Anzahl dieser Richtungen anzustreben, was jedoch aufgrund des Diskretisierungsfehlers zu einer entsprechenden Richtungsabhängigkeit des Spannungs–Dehnungs–Verhaltens des resultierenden Stoffgesetzes führt. Ziel ist es, die Effizienz der numerischen Integration derart zu steigern, dass sich für eine hinreichend genaue FE–Simulation ähnliche Berechnungszeiten wie bei herkömmlichen Stoffgesetzen ergeben. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental Investigations on and Modelling of the Transient Phenomena of the Payne‐Effect.
Authors: Höfer Philipp , Lion Alexander 
Published: February 2009

AbstractThe wide majority of industrially–used rubber is filled with a considerable amount of active fillers like carbon black or silica. Due to this, the material is strengthend and mechanical key features like stiffness and strength are significantly increased. In contrast to unfilled rubber, filled elastomers show a pronounced amplitude dependence, which is widely known as Fletcher–Gent or Payne effect. Besides that, some recently published works show a significant history dependence of this effect with distinctive relaxation phenomena.In the present work, some experiments on typical tyre rubber compounds with focus on these amplitude dependent phenomena are presented. On this basis, an appropriate thermodynamic consistent phenomenological material model of finite viscoelasticity is introduced. In order to incorporate the history dependent phenomena of the amplitude dependence, this model is generalized with intrinsic time scales on the basis of inner structure variables, which are a measure of the materials microstructure. The performance of the model is critically demonstrated by a few simulation results. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Plastic deformation of bicrystals within continuum dislocation theory
Authors: Kochmann D. M. , Le K. C. 
Published: February 2009

AbstractWe analyze the evolution of the plastic distortion and the nucleation and accumulation of dislocations within a model bicrystal with one active slip system in each single crystal (symmetric with respect to the interface), which is subject to prescribed displacements of plane–strain shear and extension, and we present closed–form analytical solutions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Elastomeric materials: Theoretical investigation and experiments
Authors: Koprowski Nadine , Diebels Stefan , Johlitz Michael 
Published: February 2009

AbstractIn this contribution we investigate an incompressible carbon–filled rubber experimentally and theoretically. On the experimental side we perform uniaxial tension tests and theoretically we use two different constitutive models, the Arruda–Boyce–Model and the Yeoh–Model, to describe the experimental observed behaviour. The model parameters are identified by a comercial fitting tool Origin Pro from National Instruments. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A fully variational algorithmic formulation for wrinkling at finite strains
Authors: Mosler J. 
Published: February 2009

AbstractThis contribution is concerned with an efficient novel algorithmic formulation for wrinkling at finite strains. In contrast to previously published numerical implementations, the advocated method is fully variational. More precisely, the parameters describing wrinkles or slacks, together with the unknown deformation mapping, are computed jointly by minimizing the potential energy of the considered mechanical system. Furthermore, the wrinkling criteria are naturally included within the presented variational framework. The presented approach allows to employ three–dimensional constitutive models directly, i.e., plane stress conditions characterizing membranes are variationally enforced by minimizing the potential energy with respect to the transversal strains. Since the proposed formulation for wrinkling in membranes is fully variational, it can be conveniently combined with other variational methods (based on energy minimization). As an example, a variationally consistent framework for finite strain plasticity theory is considered. More precisely, the minimization principle characterizing wrinkling in elastic membranes and that describing plasticity in inelastic solids are coupled leading to a novel variational approach for inelastic membranes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiscale modelling and structural characterization of Fe enriched Al alloy
Authors: Parashkevova Ludmila , Bontcheva Nikolina 
Published: February 2009

AbstractScale dependent modelling of inelastic behaviour of rapidly solidified Al Fe enriched powders subjected to cold compaction and subsequent hot extrusion is provided. The alloy is considered as a ductile “in situ” composite. The average elastic end plastic properties of bulk material depend on density evolution, temperature and matrix hardening. The model assumptions are based on microstructural observations. The microstructure characterization was carried out using Scanning Electro Microscopy (SEM) and Energy Dispersive X–ray (EDX) analysis. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Asymmetric effects of polymers in finite thermoviscoplasticity
Authors: Shaban Ahmed , Mahnken Rolf 
Published: February 2009

AbstractGlassy polymers such as polycarbonate exhibit different behaviours in different loading scenarios, such as tension and compression. For the simulation of these asymmetric effects we present a framework for thermoviscoplastic modelling of polymers at large strains. To this end a flow rule is postulated within a thermodynamic consistent framework in a mixed variant formulation which is decomposed into a sum of weighted stress mode related quantities. The different stress modes are chosen such that they are accessible to individual examination in the laboratory, where tension and compression are typical examples. The characterisation of the stress modes is obtained in the octahedral plane of the deviatoric stress space in terms of the Lode angle, such that stress mode dependent scalar weighting functions can be constructed. Furthermore the numerical implementation of the resulting set of constitutive equations is used in the finite element program ABAQUS to simulate the laser transmission welding process. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Frequency characteristics of flexibly vibration discrete‐continuous mechatronic system
Authors: Buchacz A. 
Published: February 2009

AbstractThe purpose of this paper is formulating of problem of flexibly vibrating mechatronic system. The main approach of the subject was to formulate the problem in the form of set of differential equation of motion and state equation of considered mechatronic model of object. The considered flexibly vibrating mechanical system is a continuous beam, clamped at one of its end. Integral part of mechatronic system is a transducer, extorted by harmonic voltage. In the paper the linear mechanical subsystem and linear electric subsystem of mechatronic system has been considered. The methods of analysis and obtained results can be base on design and investigation for this type of mechatronic systems. The mechatronic system formed from mechanical and electric subsystems with electromechanical bondage has been considered. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Lp‐Lq time decay estimate to the solution of the Cauchy problem of the system of equations for nonlocal model of hyperbolic thermoelasticity theory
Authors: Gawinecki Jerzy , Lazuka Jaroslaw , Rafa Jozef 
Published: February 2009

AbstractThe aim of this paper is to present a new system of equations describing nonlocal model of hyperbolic thermoelasticity theory. We used the Papkin and Gurtin approach based on the constitutive relations for internal energy e(x), and heat flux q(x), with integral terms. Such system of equations describes the propagation of thermal perturbation with finite velocity. Using the modified Cagniard–de Hoop's method we constructed the matrix of fundamental solutions for this system of equations in three–dimensional space. Basing on the constructed matrix of fundamental solutions in the explicit formula we represent the solution of the Cauchy problem to this system of equations in the form of some kind of convolutions. Next, applying the method of Sobolev spaces, we obtain the Lp−Lq time decay estimate to the solution of the Cauchy problem. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of macroscopical transient frost processes and microscopical driving forces
Authors: Kruschwitz Jens , Setzer Max J. 
Published: February 2009

AbstractThe artificial saturation phenomenon due to freeze–thaw cycles is described by a multi–phase and multiscale model [1,2,3] formulated within the Theory of Porous Media, [4]. It represents partially saturated concrete as a mixture of 5 interacting constituents φα, namely the solid skeleton φs, the bulk water φl, the pore volume occupied by vapour φv, the ice φi and the gel water phase φp. Most relevant for the model is the distinction between two length scales and their characteristic time scales. The boundary is marked where macroscopic bulk conditions change to surface physics and chemistry. Surface physics and chemistry acting on the nano–scale affect fundamental properties of concrete and consequently the durability of concrete against freeze–thaw.At the macroscopic scale the model describes transient conditions (i.e. water–uptake, heat transport, volume dilatation of 9%, phase change of first order considering hysteresis) which are characterized by a relatively long time period to reach equilibrium in contrast to the processes modelled on the microstructure. At the microscopic scale the model represents the nanoscopic CSH–gel system consisting of solid CSH and water as a linked system of both components basing on the concept of the “Solid–Liquid Gel System” [5]. In the constribution the numerical results of the model are presented with focus on the evaluation of the process zone during the penetration of the melting front into the matrix. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Error estimates for mixed finite element discretization of the Richards equation
Authors: Radu Florin A. 
Published: February 2009

AbstractWe present a numerical scheme based on the mixed finite element method (MFEM) for the Richards equation, a nonlinear, degenerate parabolic equation. Due to the degeneracy, the solution of the equation has low regularity and therefore only lower order finite elements are recommended. We review the main posibilities for proving the convergence of the scheme. Especially for the case without using the Kirchhoff transformation a new result is given. We also briefly discuss how to solve the nonlinear fully discrete problems appearing at each time step and refer to papers where the convergence of these methods is rigurously studied. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of powder metallurgical coating by radial axial ring rolling
Authors: Frischkorn J. , Reese S. 
Published: February 2009

AbstractThe process integrated powder coating by radial axial rolling of rings is expected to provide a new hybrid production technique to apply different kinds of powder metallurgical functional surfaces to ring–shaped work pieces. The main advantages compared with conventional manufacturing processes in this field can be found in lower costs, shorter process cycles and larger producible work pieces. In order to meet the requirements for an industrial application of this new process it is important to proof its capability particularly with regard to reproducibility and to investigate its boundaries. A reliable process simulation will provide a deeper insight into the governing parameters and reduce the money and time consuming experimental tests. Considering a numerical simulation using the FE method two challenges can be named. First one requires a material model to describe the compaction of metal powder at different elevated temperatures. As second the simulation of the ring rolling process itself is still very time consuming. A fine spatial discretization due to large deformations in the rolling gap and contact interaction between workpiece and rollers are the most prevailing factors in this context. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interpretation of parameters in phase field models for ferroelectrics
Authors: Schrade D. , Müller R. , Gross D. 
Published: February 2009

AbstractFerroelectric ceramics have a complex micro–structure which is responsible for their non–linear behavior on the macroscopic scale. The presented model treats the spontaneous polarization as an order parameter, for which a Ginzburg–Landau type evolution is postulated. Contrary to sharp interface models this allows for the simulation of evolving domain structures. The equations are solved via the Finite Element Method, employing an implicit time integration scheme. Numerical simulations show the physical interpretability of the phase field parameters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pyramidal indentation into fcc single crystals and quasi‐isotropic polycrystals: similar phenomena, different driving mechanisms
Authors: Eidel Bernhard , Schürg Marco 
Published: February 2009

AbstractPyramidal microindentation into the (001) surface of an fcc single crystal made of the Ni–base superalloy CMSX‐4 has shown indent shapes which strongly depend on the azimuthal orientation of the pyramid. This observation is experimentally elucidated by digital surface models obtained from high resolution electron back–scatter diffraction (EBSD) technique along with digital image processing. Predictions of crystal plasticity finite element simulations agree with the experimental observations; the observed surface deformation patterns are due to pile–up formation, which is invariantly maximum in <110> directions thus being independent of the azimuthal orientation of the pyramid. The material pile–up is locally accommodated to the indenter faces leading to a convex, a concave contact rim at the faces of the indenter depending on the orientation. The result of maximum pile–up in <110> directions suggests that the driving mechanism for pile–up is purely crystallographic in that the influence of stress concentrations due to different indenter orientations and indenter shapes is negligible. The present findings for fcc single crystals are contrasted to well known observations for quasi–isotropic polycrystals. The different driving mechanisms resulting in phenomenologically similar material response are identified for both materials. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase‐field‐based modeling and simulation of solidification and deformation behavior of technological alloys
Authors: Gladkov Svyatoslav , Stiemer Marcus , Svendsen Bob 
Published: February 2009

AbstractThe purpose of this work is the formulation and application of a continuum field approach to the phenomenological modeling of the behavior of technological alloys undergoing phase transitions and attendant inelastic deformation. To describe the phase transition, a phase–field approach is utilized. For the fully coupled system, an algorithmic formulation is derived based on efficient finite element techniques. Applications will be discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Multi‐Scale Analysis of Textile Reinforced Concrete Structures
Authors: Lepenies Ingolf G. , Richter Mike , Zastrau Bernd W. 
Published: February 2009

AbstractTextile reinforced concrete (TRC) is a composite of rovings (multi filament yarns) and fine grained concrete which is used in civil engineering to fabricate new structural elements and to strengthen existing constructions. The proposed multi–scale approach is based on a hierarchical material description on the micro, the meso and the macro scale. The paper deals with structural models of the macro scale, using the detailed information of the micro– and the mesoscopic models to simulate the behavior of typical structural members made of reinforced concrete. Due to the textile reinforcement in TRC the crack opening displacements are very small. This leads to the major influence of the post cracking behavior of concrete on the overall response of the structural member. In the case of a steel and textile reinforced concrete plate the simulated crack width of the meso model is used to capture this effect within the framework of a multi–scale analysis. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Sachs bound in stress‐induced phase transformations in polycrystalline scalar shape‐memory alloys
Authors: Schlömerkemper Anja , Bhattacharya Kaushik 
Published: February 2009

AbstractWe consider stress–induced transformations of polycrystalline shape–memory alloys which are so–called scalar materials. In this case the Sachs bound on the phase transformation yield stress turns out to be sharp. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Approaches to Model Nanotube‐Reinforced Polymers using Micromechanics and Finite Elements
Authors: Schmidt Ina 
Published: February 2009

AbstractIn this work, the applicability of new analytical methods for modeling polymer nanocomposites is examined. The influence of an interphase between nanotube and matrix could be captured by this modeling strategy. However, it is shown that there are some difficulties in calculation of composites including extremely weak fibers with stiff coatings. Furthermore, finite element calculations are shown for comparison. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiscale Coupling through Locally Enriched Finite Elements
Authors: Shan Wenzhe , Nackenhorst Udo 
Published: February 2009

AbstractMultiscale modeling helps us to focus our limited computational power into those special places where traditional models based on continuum mechanics will fail while not losing the big picture of the macro scale behavior. An hourglass shaped development can be observed in today's simulation technologies. Simulation tools in the macroscale category and that for the micro phenomenons are both relatively well developed. Many algorithms and methods have been proposed in recent years to fill the gap between them. However, rather than trying to bridging different techniques, many tend to replace them completely and become independent simulation tools. Since many single–scale models have already been widely adopted by both the industry and the academy, it would be more beneficial to concentrate just on coupling techniques which can be applied without significant modifications of the original simulation framework. In this work, we present a multiscale idea of coupling the fine–scale model with the coarse–scale model through local enrichment within the elements at the coupling boundary. Higher order shape functions have been used to ‘enrich’ the coarse–scale model, allowing softer transition of the displacement field from the fine–scale model to the coarse–scale model. A least–square process has been used to fit the displacement gradients of different models at the coupling region. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Computation of the Macroscopic Tangent for Multiscale Volumetric Homogenization Problems
Authors: Temizer İlker , Wriggers Peter 
Published: February 2009

Abstract For the computation of the macroscopic tangent that is required in multiscale volumetric homogenization techniques, two methods are summarized. First, a condensation approach is followed where the linearity of variational terms associated with the penalty enforcement of boundary conditions is explored in order to extract a macroscopic tangent at any stage of the Newton–Raphson iterations of a microstructural testing procedure. As an alternative approach, a second method is explored that requires only the knowledge of infinitesimally close macroscopic deformation states. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A study of effects of wall‐normal rotation on the turbulent channel flow
Authors: Mehdizadeh A. , Oberlack M. 
Published: February 2009

AbstractThe effects of the wall–normal rotation on the turbulence channel flow have been studied. A series of direct numerical simulations have been performed with various rotation rates for Reynolds number 180 based on the friction velocity in the non–rotating case. All remarkable changes are discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental in‐situ investigations on fluid flow during High Pressure Processing by means of LDA and HWA
Authors: Song K. , Rauh C. , A.  
Published: February 2009

AbstractIn a tube injection system for High Pressure Processing (HPP) of foods and biomaterials, pressure transmitting medium is injected into the vessel to increase the pressure up to 1000 MPa generating a submerged liquid jet. The presence of a turbulent free jet during pressurizing and its positive influence on the homogeneity of the product treatment have already been examined by computational fluid dynamics investigations. However, up to now there is no experimental evidence, supporting the existence and properties of turbulence of a free jet during HPP due to difficulties in gaining in–situ insight into the high pressure vessel and the lack of high pressure withstanding probes. Hence, we developed two experimental setups: (1) HP–Laser Doppler Anemometry (HP–LDA), and (2) HP–Hot Wire Anemometry (HP–HWA). This paper presents first results of velocity profiles measured by LDA and HWA under high pressure conditions up to 300 MPa. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)