bluuebunny/crossref_metadata_2025_split huggingface dataset:
Towards the simulation of Internal Traverse Grinding – from mesoscale modelling to process simulations
Authors: Holtermann Raphael , Menzel Andreas 
Published: December 2012

AbstractThe present work aims at the modelling and simulation of Internal Traverse Grinding of hardened 100Cr6/AISI 52100 using electro plated cBN grinding wheels. We focus on the thermomechanical behaviour resulting from the interaction of tool and workpiece in the process zone on a mesoscale.Based on topology analyses of the grinding wheel surface, two‐dimensional single‐ and multigrain representative numerical experiments are performed to investigate the resulting load‐displacement‐behaviour as well as the specific heat generation due to friction and plastic dissipation.A thermoelastic‐viscoplastic constitutive model is used to capture thermal softening of the material taken into account. Based on previous work, an adaptive remeshing scheme which uses a combination of error estimation and indicator methods, is applied to overcome mesh dependence. In consequence, the formulation allows to resolve the complex deformation patterns and to predict a realistic thermomechanical state of the resulting workpiece surface. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anisotropic finite strain hyperelasticity based on the multiplicative decomposition of the deformation gradient
Authors: Al‐Kinani Raad , Hartmann Stefan , Netz Torben 
Published: December 2012

AbstractIn this contribution a new constitutive model for transversely isotropic materials is presented. The proposed model is based on the multiplicative decomposition of the deformation gradient into one part containing the deformation only in the direction of anisotropy and another part describing the remaining deformation. This clear assignment leads to a decoupling of the stress‐state. The model is investigated analytically in view of simple tension. Moreover, an inhomogenous deformation is solved using a finite elements simulation. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Zur Abtragssimulation beim Strömungsschleifen
Authors: Schmitt Joachim , Diebels Stefan 
Published: December 2012

AbstractIn dieser Arbeit werden zunächst für eine handelsübliche AFM‐Paste die Parameter eines nicht‐Newtonschen Stoffgesetzes experimentell in Rotationsrheometerversuchen bestimmt und die Ergebnisse an einer weiteren Versuchsreihe (Düsenauspressversuche) mit Hilfr einer FEM‐Simulation überprüft. Danach werden ein einfaches Abtragsmodell vorgestellt und die Funktionsfähigkeit dieses Modells an einem Beispiel demonstriert. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Single‐ and multiscale aspects of the modeling of curing polymers
Authors: Bartels Alexander , Klinge Sandra , Hackl Klaus , Steinmann Paul 
Published: December 2012

AbstractWithin this contribution, the focus is placed on the simulation of the isochoric behavior of polymers during the curing process. To this end, a model based on the assumption of free energy in the form of a convolution integral is applied. Since this allows the implementation of the time‐dependent material parameters, the free energy is interpreted as the total accumulated energy. Different from this, the strain energy is related to the current state of deformation and used to define the temporary stiffness. In order to avoid volume locking effects typical of isochoric materials, the free energy is furthermore split into a volumetric and a deviatoric part. A multifield description depending on the displacements, volume change and hydrostatic pressure is introduced as well. The model is implemented within a single‐ and multiscale FE program and used to simulate the behavior of homogeneous and microheterogeneous polymers. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermoviscoplasticity deduced from enhanced rheological models
Authors: Bröcker Christoph , Matzenmiller Anton 
Published: December 2012

AbstractA new ideal body is proposed for representing isotropic hardening. Hence, a rheological model of thermoviscoplasticity may be assembled with linear isotropic and kinematic hardening and nonlinear strain rate sensitivity. The related constitutive equations including the yield function and the flow rule are directly deduced from the kinematics and the stress equilibrium of the rheological network and result in a well‐known model. Based on the free energy of the rheological network, the equation of heat conduction is obtained with the dissipative heat source term, driven by plastic deformations. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling the finite strain deformation and initial anisotropy of amorphous thermoplastic polymers
Authors: Hempel Philipp , Seelig Thomas 
Published: December 2012

AbstractThis work deals with modeling the mechanical behavior of thermoplastic polymers in the finite strain regime over a wide range of temperatures. Thereby, special emphasis is put on the incorporation of an initial anisotropy in terms of “frozen‐in” molecular orientation which results from a preceding manufacturing process. A computational example is discussed which considers an injection molded plate undergoing inhomogeneous deformation (buckling) during re‐heating. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micromechanical modeling of bainitic phase transformation
Authors: Schneidt Andreas , Antretter Thomas , Mahnken Rolf 
Published: December 2012

AbstractWe develop a micromechanical material model for phase transformation from austenite to bainite for a polycrystalline low alloys steel. In this material (e.g. 51CrV4) the phase changes from austenite to perlite‐ferrite, bainite or martensite, respectively. This work is concerned with phase transformation between austenite and n‐bainite variants in differently orientated grains. The characteristic features of bainite formation are the combination of time‐dependent transformation kinetics and lattice shearing in the microstructure. These effects are considered on the microscale and transferred to the polycrystalline macroscale by means of homogenisation of stochastically orientated grains. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A model for martensitic microstructure, its geometry and interface effects
Authors: Goodarzi Mehdi , Hackl Klaus 
Published: December 2012

AbstractIn line with our formerly presented continuum micromechanical model [4,5] of the laminate microstructure of martensite, we here modify and reformulate the model to further its simplicity and clarity. The basic postulates are slightly altered. However, the approach remains the same, namely the kinematic assumption of nearly‐planar laminate geometry put into an energy minimization framework with proper ansatzes of twin‐interface and boundary energies. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On consistent tangent operator derivation and comparative study of rubber‐like material models at finite strains
Authors: Hossain Mokarram , Steinmann Paul 
Published: December 2012

AbstractRubber‐like materials can deform largely and non‐linearly upon loading and return to the initial configuration when the load is removed. Such rubber elasticity is achieved due to very flexible long chain molecules and a three‐dimensional network structure that is formed via cross‐linking or entanglements between molecules. Over the years, to model the mechanical behaviour of such randomly‐oriented micro‐structure, several phenomenological and micro‐mechanically motivated network models for nearly incompressible hyperelastic polymeric materials have been proposed in the literature. For comparison of all selected models in reproducing the well‐known Treloar data, the analytical expressions for the three homogeneous defomation modes, i.e. uniaxial tension, equibiaxial tension and pure shear have been derived and the performances of the models are analysed. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
All‐electron calculations with finite elements
Authors: Schauer Volker , Linder Christian 
Published: December 2012

AbstractThe Kohn‐Sham equations resemble a nonlinear eigenvalue problem for the determination of the electronic structure of an atomic system, where the electrons are exposed to an effective potential, accounting for the Coulomb and quantum mechanical interactions between the particles. The effectiveness of the potential requires an iterative solution procedure, until self‐consistency is reached. This work illustrates the implementation of the self consistent field algorithm based on nested finite elements spaces and analyzes its properties in the case of all‐electron calculations on atoms as large as the noble gas Xenon. All‐electron calculations have maximal requirements onto the numerical basis, as it must be able to represent all the orthogonal electronic wavefunctions simultaneously together with the electrostatic potential, showing singularities at the positions of the atoms. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear dynamics of the dielectric elastomer actuator
Authors: Xu Bai‐Xiang , Mueller Ralf , Klassen Markus , Gross Dietmar 
Published: December 2012

AbstractAs potential material for artificial muscles and haptic displays, dielectric elastomer provides large deformations with lower cost and high efficiency. The material behaves nonlinearly in both the kinematics and the constitutive relation. In this work, the nonlinear equation of motion for a dielectric elastomer actuator with a sandwich structure under constant electric potential is derived from the energy conservation condition. The equation of motion is numerically solved, and the results are discussed. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A flexible multi‐physics coupling interface for partitioned solution approaches
Authors: Brändli Silvan , Düster Alexander 
Published: December 2012

AbstractA common way of solving multi‐physics problems is the use of a partitioned approach. To this end specialized solvers are utilized for the different subproblems and linked via a common communication interface. In this paper a communication interface is presented, which is capable of dealing with different kind of coupled problems. The subproblems may be discretized separately and linked either through a common boundary or by a common volume region.In order to stabilize and to accelerate the implicit coupling iteration different relaxation techniques and predictor methods are implemented. Finally, the coupling interface is applied to a well‐known fluid‐structure interaction (FSI) benchmark. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Freezing and Thawing Processes with Capillary Effects in fluid filled porous media
Authors: Bloßfeld Wolfgang Moritz , Bluhm Joachim , Ricken Tim 
Published: December 2012

AbstractIn this contribution, a macroscopic quadruple model for the simulation of freezing and thawing processes in fluid filled porous media is presented. The main focus lies on the description of the distribution of fluid and ice pressure as well as solid deformation before, during and after the ice formation in consideration of energetic and capillary effects. Furthermore, the porosity change of the porous material is considered, i.e., the variation of permeability during ice formation will be simulated. The illustrated results of numerical examples will be presented to demonstrate the practical application of the model. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Acceleration of partitioned coupling schemes for problems of thermoelasticity
Authors: Erbts Patrick , Düster Alexander 
Published: December 2012

AbstractA partitioned coupling scheme for problems of thermo‐elasticity at finite strains is presented. The coupling between the mechanical and thermal field is one of the most important multi‐physics problem. Typically two different strategies are used to find an accurate solution for both fields: Partitioned or staggered coupling schemes, in which the mechanics and heat transfer is treated as a single field problem, or a monolithic solution of the full problem. Monolithic formulations have the drawback of a non‐symmetric system which may lead to extremely large computational costs. Because partitioned schemes avoid this problem and allow for numerical formulations which are more flexible, we consider a staggered coupling algorithm which decouples the mechanical and the thermal field into partitioned symmetric sub‐problems by means of an isothermal operator‐split. In order to stabilize and to accelerate the convergence of the partitioned scheme, two different methods are employed: dynamic relaxation and a reduced order model quasi‐Newton method. A numerical simulation of a quasi‐static problem is presented investigating the performance of accelerated coupling schemes. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantifying diffusion for an ultrasonic wire bonding process by applying the theory of material forces
Authors: Sbeiti Mohamad , Müller Wolfgang H. , Schneider‐Ramelow Martin , Geissler Ute , Schmitz Stefan 
Published: December 2012

AbstractUltrasonic wire bonding is a method applied in electronic packaging to fabricate interconnections between two devices at ambient temperature. In order to investigate the material diffusion during this process, the occurring thermal and mechanical mechanisms at and around the interface of the formed bond were studied by means of coupled thermo‐mechanical FE simulations. Within the framework of material forces the local jump of the Eshelby tensor was compared with the thickness of the formed intermetallic phase for various bonding parameters. This allows us to predict an effective diffusion constant which takes temperature and mechanical driving forces into account. After this relation has been established a subsequent objective of our investigations is to optimize the growth of the Au8Al3 intermetallic phase in terms of bonding parameters. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase transition in methane oxidation layers – a coupled FE multiphase description
Authors: Sindern Andrea , Ricken Tim , Bluhm Joachim , Denecke Martin , Schmidt Torsten C. 
Published: December 2012

AbstractWorldwide, the most common sites of waste disposal are landfills. After solid waste is deposited in a landfill, physical, chemical, and biological processes ensue and modify the waste. Due to these reactions, landfill gas is produced inside the landfill body and effuses into the atmosphere at the outer layer. These processes create environmentally harmful landfill pollutants (methane (CH4)) and carbon dioxide (CO2)). The impact of methane on the greenhouse effect is about 20 times higher than that of carbon dioxide.WorldwideIn order to estimate potential environmental risk of the landfill, a second important phenomenon has to be taken into account: the bacterial methane conversion in the porous cover layer which significantly reduces the amount of methane emitted into the atmosphere. Subsequently, the metabolism of different methanotrophic bacteria converts methane and oxygen into carbon dioxide, water, and biomass.WorldwideTo model this highly complex and coupled problem we used the well‐known theory of porous media to obtain a thermodynamically consistent description which in turn leads to a fully‐coupled finite element (FE) calculation concept. The theoretical and numerical framework will be presented in order to describe the coupled processes occurring during the phase transition by bacterial activity in the methane oxidation layer. The model analyzes the relevant gas concentrations of methane, carbon dioxide, oxygen, and nitrogen as well as the driving phenomena of production, diffusion, and convection. Based on a model predicting gas production in landfills, see [1], a multiphase continuum approach for landfill cover layers is presented. In order to validate the model, we compare numerical simulations with experimental data. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Domain Decomposition Solvers for Some Fluid‐Structure Interaction Problems
Authors: Langer Ulrich , Yang Huidong 
Published: December 2012

AbstractIn this note, we present some of our recent work on domain decomposition solvers for the fluid‐structure interaction problems with nearly incompressible and anisotropic elasticity models. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Macroscopic modelling of the selective beam melting process
Authors: Riedlbauer Daniel , Mergheim Julia , McBride Andrew , Steinmann Paul 
Published: December 2012

AbstractThe present contribution is concerned with the macroscopic modelling of the selective beam melting process by using finite elements. In this context the objective is to detail a continuum model to describe the process. Furthermore two different solution approaches are applied to the model and compared in terms of performance. An adaptive mesh refinement strategy is also demonstrated to increase the quality of the solution in the vicinity of the beam. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Modeling and Simulations of Dielectric Elastomer Actuators for Thin Structures
Authors: Zwecker Sandro , Klinkel Sven 
Published: December 2012

AbstractThe contribution is concerned with a finite element formulation that deals with thin structures made from dielectric elastomer material. For that a special solid shell formulation, which uses eight nodes per element and four degrees of freedom (three displacements and one for the electric potential) per node, is presented. It is based on a Hu‐Washizu mixed variational principle using six independent fields: displacements, electric potential, strains, electric field, mechanical stresses, and dielectric displacements. In recent years structures made from dielectric elastomers have been investigated by many researchers. This interest is caused by the ability of such devices to efficiently transform electric energy into mechanical work at inexpensive cost of production. The efficiency increases with a higher area to thickness ratio, thus the need to accurately simulate thin structures is well‐founded. On the other hand a 3d description of the constitutive behavior is necessary to capture all nonlinear effects arising from the material. Thus a 3d constitutive law with respect to the electro‐mechanical coupling incorporated in a finite element solid shell formulation is presented. Some examples demonstrate how it deals with finite strains and large deformations of thin structures by applying electrical loading conditions. The analyzed devices respond with elongation, bending, or buckling, depending on the mode of activation. The electrically induced buckling can be utilized to obtain large deformations. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical simulation of dense fluid‐particle flows using computational fluid dynamics (CFD) and discrete element method (DEM)
Authors: Iqbal Naveed , Rauh Cornelia , Delgado Antonio 
Published: December 2012

AbstractDiscrete Element Method (DEM) has been successfully coupled with Computational Fluid Dynamics (CFD) in the framework of OpenFOAM an open source CFD simulation code. In the current study, at first the model is validated with the simple test case of spherical particle comparing the results with the analytical solution. Then the simulation of a gaseous fluidized bed is considered. The coupled mass and momentum balance equations are used to calculate the flow behavior, particle fluidization and bubble formation. The dimensions of the simulation domain are similar to Link et al. (2005) but with different stiffness of particles. The higher velocity of gaseous fluid relative to particles entering through a jet causes the particles to fluidize. The particles behavior, fluidization, bubble formation and the velocity vectors of particles show a good agreement with the literature. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical simulation of organic binder decomposition and combined seepage‐ and diffusive transport of the gaseous reaction products through a porous green body during thermal debinding of ceramic parts.
Authors: Schmidt Ingo , Riedel Hermann , Svoboda Jiři 
Published: December 2012

AbstractThis article presents a model which describes the chemical decomposition of organic binders, the combined Maxwell‐Stefan and Knudsen diffusion and the seepage flow of multiple gaseous reaction products through a porous body and the implementation of the model into a finite element framework. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Finite element methods for problems with solid‐liquid‐solid phase transitions and free melt surface
Authors: Jahn Mischa , Luttmann Andreas , Schmidt Alfred , Paul Jordi 
Published: December 2012

AbstractModeling and computation of a process with solid‐liquid‐solid phase transitions and a free capillary surface is discussed. The main components of the model are heat conduction, a free melt surface, a moving phase boundary, and its coupling with the Navier‐Stokes equations. We present two different approaches for handling the phase transitions by applying in a FE method, namely an energy conservation based approach, and a sharp interface approach with moving mesh. By combining both methods, we benefit from the advantages of the respective approach. The methods are applied to a problem where material is accumulated by melting the tip of thin steel wires using laser heating. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Modeling Aspects of Dielectric Elastomer Actuators
Authors: Müller Ralf , Klassen Markus , Xu Baixiang 
Published: December 2012

AbstractIn modern actuator technology dielectric elastomers are considered as new materials to realize smart actuators which are known as dielectric elastomer actuators (DEAs). In comparison to piezoceramics actuators, DEAs offer the possibility to achieve large deformations with low actuation forces. This property motivates the implementation as artificial muscles since the deformation‐force behavior is similar. Other application fields are pumps, deformable surfaces in aerospace, robotics and haptic feedback.The present work introduces the fundamental concepts to describe the electromechanical coupling in the concept of continuum mechanics for finite deformations.As a benchmark a 3D sandwich actuator setup is taken into account to analyze the mechanical compression stability of the elastomer structure, see [1, 2]. This structure is also considered to study the influence of inhomogeneities in the deformation behavior. For this purpose piezoceramic and air inclusions are considered in the finite element mesh.As a last numerical example an elastomer tube with three pairs of electrodes is simulated numerically to motivate the use of dielectric elastomers as peristaltic pumps. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Invariance of Parrinello‐Rahman molecular dynamics and its relation to continuum mechanics
Authors: Ulz Manfred H. 
Published: December 2012

AbstractParrinello‐Rahman molecular dynamics has proved to be a reliable technique for the investigation of phase transitions in solids. This type of molecular dynamics may lead to a proper description of the atomistic scale in multi‐scale analysis of engineering problems. However, the employed Lagrangian is proposed without a derivation and lacks invariance under modular transformations. A re‐interpretation of the Lagrangian in terms of continuum mechanics was recently developed. The new formulation is derived in a consistent physical manner and only quantities native to continuum mechanics are incorporated into this Lagrangian. Based on this recent continuum‐related derivation, the invariance of the new Lagrangian under modular transformations is investigated. The implication that the obtained dynamics is invariant to the chosen unit cell corroborates with results in solid state physics and is a mandatory requirement for the suitability of multi‐scale analysis. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)