bluuebunny/crossref_metadata_2025_split huggingface dataset:
An anisotropic phase‐field model for transversely isotropic barium titanate with bounded moduli
Authors: Nadgir Omkar , Keip Marc‐André , Miehe Christian 
Published: October 2016

AbstractThis contribution presents a phase‐field model for transversely isotropic barium titanate, which allows for the adjustment of the full set of anisotropic material parameters. It is a direct extension of the work by Schrade et al. [1] who proposed a phase‐field model for ferroelectrics in the framework of invariant theory. In the present contribution, the loss of positive definiteness is avoided by formulating energetic terms that provide upper and lower bounds for all material moduli involved. We show the characteristics of the formulation by a set of numerical examples in two and three dimensions. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A thermodynamical consistent model for modeling of ionic electroactive polymers (EAPs) within the framework of the Theory of Porous Media
Authors: Serdas Serdar , Bluhm Joachim , Schröder Jörg 
Published: October 2016

AbstractIonic electroactive polymers are widely used in many engineering fields. These kind of materials can be stimulated to change their shape and size, see [1]. Since, the material under consideration has a complex multiphasic microstructure, such multiphasic materials are best described by a continuum mechanical approach. Thus, the presented model is based on the Theory of Porous Media (TPM), cf. [2]. In this contribution, we consider the Ionic Polymer Metal Composites (IPMCs). Stimulating by an electrical voltage, a structural deformation will be caused. Responsible for this deformation are the mobile ions. The focus of the presented model is to capture this material behavior, e.g. the distribution of the mobile cations. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical simulation of fluid‐structure interaction problems by a coupled SPH‐FEM approach
Authors: Stasch Jessica , Avci Bircan , Wriggers Peter 
Published: October 2016

AbstractIn scientific computing there is a great interest in numerical simulation of fluid‐structure interaction (FSI) problems. Within this work a numerical approach to simulate fluid‐structure interactions between elastic structures and weakly incompressible fluids is developed. For the fluid part and the solid part the Smoothed Particle Hydrodynamics method (SPH) and the Finite Element Method (FEM) are used, respectively. To transfer the resulting reaction forces from the fluid particles onto the structure's surface two methods are implemented, investigated and compared. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling thermoplastic material behaviour of dual‐phase steels on a microscopic length scale ‐ numerical treatment
Authors: Zeller Sebastian , Löhnert Stefan , Wriggers Peter 
Published: October 2016

AbstractOn a microscopic length scale dual‐phase steels exhibit a polycrystalline microstructure consisting of ferrite and martensite. In this work it is assumed that the martensitic phase behaves purely thermoelastic while for the ferritic phase a thermoplastic material model was developed based on the assumption that the driving mechanism for persistent deformation is the movement of dislocations on preferred planes in preferred directions. The necessary shear stress to move dislocations at a certain temperature and deformation rate is assumed to possess contributions from the atomic lattice, alloying atoms and the dislocation structure. To consider the influence of the dislocation structure, dislocation densities are introduced as state variables for which temperature and deformation rate dependent evolution equations are formulated. Since for general loading histories the model equations cannot be integrated analytically, a time discretized form of the model equations with an appropriate solution algorithm is presented. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of effective properties for CFRP curing coupled to viscoleasticity based on a three‐scale framework
Authors: Dammann Christian , Mahnken Rolf 
Published: October 2016

AbstractOur work presents a three‐scale model for temperature‐dependent visco‐elastic effects accompanied by curing, which are important phenomena in a resin transfer molding (RTM) process. The effective bulk quantities in dependence on the degree of cure are obtained by homogenization for a representative unit cell (micro‐RVE) on the heterogeneous microscale. To this end, an analytic solution is derived by extension of the composite spheres model [1]. Voigt and Reuss bounds resulting from the assumption of a homogeneous matrix proposed in [2] are compared to the effective quantities. During curing, the periodic mesostructure defined by a visco‐elastic polymeric matrix and linear‐thermo‐elastic fibres is taken into account as a representative unit cell (meso‐RVE) subjected to thermo‐mechanical loading on the mesoscale. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Surface Wetting by Droplets Using a Phase Field Model
Authors: Diewald Felix , Kuhn Charlotte , Blauwhoff Ricardo , Heier Michaela , Becker Stefan , Werth Stephan , Horsch Martin , Hasse Hans , Müller Ralf 
Published: October 2016

AbstractIn the proposed phase field model a continuous order parameter indicates the phase distribution (liquid/gas). An energy density functional which is dependent on the surface tensions and defined by three contributions yields the total energy of the system. An equilibrium state is then computed by minimizing this energy of the system using an evolution equation. Details of the algorithmic implementation are discussed by illustrative examples. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effective plastic properties of laminates
Authors: Glüge Rainer 
Published: October 2016

AbstractIn this contribution, we make use of the fact homogenization of elastic properties of laminates [1] can be extended relatively easy to the plastic case [2] to derive exact expressions for the effective yield limit and the ultimate loading in monotonic tension test. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of failure in rough interfaces
Authors: Hirsch Franz , Kästner Markus 
Published: October 2016

AbstractIn this contribution a multiscale description of the inelastic behavior of bi‐material interfaces is considered. We study different local properties , e.g. the surface roughness, and their effects on the overall interface characteristics. Since there is a large separation of length scales between the microstructure and the macroscopic joint, we employ a numerical homogenization approach to extract effective interface properties. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Solution of Contact Problems using Level Set Methods on Voxel Discretizations
Authors: Leichner Alexander , Andrä Heiko , Simeon Bernd 
Published: October 2016

AbstractFast solvers performing on a regular grid are often used for problems in elasticity, in order to avoid expensive mesh generations. However, if overlaps between solid materials occur without any interactions, these might deteriorate the results, especially for the stresses. Therefore, we want to present an approach for developing numerical methods for contact problems on a regular mesh with the help of signed distance data and multi‐material voxels. In this contribution we will focus on problems in linear elastostatics with contact between several different bodies. Finally, we present the results from a numerical test for the two dimensional Hertz problem, solved on a triangular regular mesh. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A micromechanics model for FRC composites
Authors: Timothy Jithender J. , Zhan Yijian , Meschke Günther 
Published: October 2016

AbstractA multiscale model for FRC composite structures taking into consideration the complex interactions at the scales of the fiber and microcracks is proposed. At the scale of the single fiber, a semi‐analytical model characterizes the microslip behavior at the interface between the matrix and the fiber in terms of the overall composite stresses. The influence of fiber bundles on microcrack bridging and arrest is taken into account within the framework of linear elastic fracture mechanics. Upscaling to the macroscopic level using continuum micromechanics shows that the macroscopic deformation of the FRC composite is governed by a ’TERZAGHI’ like effective stress. For the finite element analyses of failure behavior at the scale of the composite structure, an ’interface solid element’ technique is used to consider localized cracking. Selected numerical and semi‐analytical results together with experimental validations are provided. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
About an analytical approach to a quasicontinuum method via Γ‐convergence
Authors: Schäffner Mathias , Schlömerkemper Anja 
Published: October 2016

AbstractWe report on an analytical study of a quasicontinuum method in the context of fracture mechanics in a one‐dimensional setting. To this end, we compare the asymptotic behaviour of a discrete model with pairwise interactions of Lennard‐Jones type and its quasicontinuum approximation via Γ‐convergence. In an elastic regime the limiting behavior of the orginal model and its quasicontinuum approximation coincide. In the case of fracture it turns out that it is necessary to coarse grain the quasicontinuum approximation in the continuum region and at the atomistic/continuum interface in order to capture the same behavior as the atomistic model. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Assembly and Solution of the High‐Fidelity Generalized Method of Cells with Interface Damage
Authors: Schmerbauch Mario , Matzenmiller Anton 
Published: October 2016

AbstractThe assembly of the system of equations and its solution are presented for the High‐Fidelity Generalized Method of Cells (HFGMC) with interface damage. The direct stiffness assembly, which is used in the Finite Element Method with its unknown nodal displacements, is applied to the HGFMC. The nonlinear set of equations due to damage is solved with Newton's Method for the microscopic surface‐averaged displacements, which are the unknowns in the efficient version of the HFGMC. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient Simulation of Short Fibre Reinforced Composites
Authors: Springer Rolf , Meyer Arnd 
Published: October 2016

AbstractIn this paper we present a way how short fibre reinforced composites, produced by injection moulding, can be simulated in a linear thermoelastic setting, with an instationary heat equation. The main problem is the unknown stochastic fibre orientation. The only information known about this orientation field are the first moments of its distribution. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of the string method to compute minimum energy paths for a chain of bi‐stable elements using the finite element method and molecular dynamics
Authors: Ulz Manfred 
Published: October 2016

AbstractActivated processes are frequently found in solid state mechanics. The energy landscape of such processes show a non‐convex behaviour, and therefore the computation of energy barriers between two stable minima is of importance. Such barriers are revealed by computing minimum energy paths. The string method is a simple and efficient algorithm to move curves over an energy landscape and to identify minimum energy paths.A hierarchical two‐scale model recently introduced to the literature (molecular dynamics coupled with the finite element method) is used in this paper to investigate the string method in a model phase transition in a copper single crystal. To do so, bi‐stable elements are constructed and the energetic behaviour of a two‐elements chain is investigated. We identify successfully the minimum energy path between two local stable minima of the chain and demonstrate thereby the performance of the string method applied to a complex multiscale model. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Double Grid Integration with Projection (DoGIP): Application to numerical homogenization by Fourier‐Galerkin method
Authors: Vondřejc Jaroslav 
Published: October 2016

AbstractIn this contribution, the DoGIP approach is introduced as a method for decomposition of a linear system into a (block) diagonal matrix based on a double grid integration and an interpolation/projection operator that is never assembled but optimised for fast matrix‐vector multiplication. The method reduces memory requirements, especially when higher order basis functions are used for discretisations. The method is explained for Fourier‐Galerkin method within a numerical homogenisation. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Relating DEM contact parameters to macroscopic material parameters
Authors: Wessels Nicola , Hackl Klaus 
Published: October 2016

AbstractAlthough the Discrete Element Method (DEM) is already widely applied in several fields of applications, one main challenge remains to define contact parameters that lead to realistic material behaviour. Here, it is shown how potentials can be defined on the contact level and from these a correlation to the macroscopic continuum parameters can be established. The analytically formed predictions are then compared to the results of discrete element simulations. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Calibrating microfluidic pressure correction functions in Laval nozzle flow by eliminating production accuracy influences
Authors: Groll Rodion , Gomez Juan 
Published: October 2016

AbstractThe investigated case is a micronozzle flow with Knudsen numbers in the slip‐flow regime near the nozzle throat in vacuum environment. Compared gases are neon, argon, krypton and xenon. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear instability of a viscous liquid jet
Authors: Renoult Marie‐Charlotte , Brenn Günter , Mutabazi Innocent 
Published: October 2016

AbstractWe investigate the weakly nonlinear temporal instability of an axisymmetric Newtonian liquid jet. Early nonlinear studies on the capillary instability of inviscid liquid jets were carried up to the third order contributions to the jet deformation and showed the nonlinear interaction between different modes. A recent study on the weakly nonlinear instability of planar Newtonian liquid sheets revealed the role of the liquid viscosity in the sheet stability behavior and showed a complicated influence [1]. Here, the instability of a liquid jet is examined as the axisymmetric counterpart of the sheet, in search for corresponding insight into the role of the liquid viscosity in the jet instability mechanism. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Jungebad apparatus for the production of oil‐dispersion baths
Authors: Höffmann Ann Kathrin , Lakshmanan Peter , Ehrhard Peter , Ostermann Thomas 
Published: October 2016

AbstractThe Jungebad apparatus is used to generate oil‐dispersion baths in medical applications. The oil‐water dispersion is produced by dispersing medically‐effective oil while filling the bathtub. The aim is to produce smaller droplets in comparison to conventionally produced oil‐dispersion baths to generate a high surface‐to‐volume ratio of the oil. Additionally, the oil should be dispersed homogenously in the bath. Due to the greater surface of the oil, a better admission through the skin of the patient is achieved.Experimental investigations with regard to the functionality of the Jungebad apparatus are presented. The analysis of the functionality and the oil‐water dispersion generation is accomplished by observations with a high‐speed camera. Results are discussed with respect to the required characteristics of the dispersion. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transport of Mass, Momentum and Energy through Periodic Open Cell Metal Foams Applied in Catalysis
Authors: Horneber Tobias , Rauh Cornelia , Delgado Antonio 
Published: October 2016

AbstractAn ODE model to predict the temperature field of periodic open cell metal foams applied in catalysis as carrier structures is presented. The catalytic and highly endothermic reaction takes place in a porous layer which surround the struts of the foam and releases gas from a fluid. The one‐dimensional model includes dependencies of the foam structure (strut radius, shape of strut), process conditions (surrounding velocity, surrounding fluid: liquid and/or gas), chemical conditions (reaction enthalpy, activation energy) and material parameters (thermal conductivity, density, viscosity). This makes it possible to estimate optimal parameters, that are able to provide sufficient heat to the reaction. The advantage of this model is the substantial time saving in contrary to three dimensional finite volume simulations. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical investigation into a liquid displacing a gas in thin porous layers
Authors: Neumann Tim , Boettcher Konrad , Ehrhard Peter 
Published: October 2016

AbstractTo examine the filling process in a lithium‐ion battery, a numerical model to characterize the displacing flow of a liquid in air‐filled pores of thin heterogeneous porous materials is elaborated. The investigation is based on the volume‐averaged Navier‐Stokes equations for small Reynolds numbers, using a volume‐of‐fluid method to cover the multiphase flow. The flow is investigated with respect to the wall effect and to capillary action within the porous matrix. On the one hand, model experiments with similar particle‐size distributions as in the battery layers are conducted to extract the porosity as function of the wall distance. On the other hand, experiments with the three different porous layers of the battery are performed to receive mean values for the most important properties related to the two‐phase flow. Results for the displacement flow in parts of the battery are presented and discussed, showing a considerable influence of the modeled effects onto the flow characteristics. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulations of Particle‐laden Flows with the Lattice Boltzmann Method
Authors: Rettinger Christoph , Rüde Ulrich 
Published: October 2016

AbstractA lattice Boltzmann method is presented which enables the direct numerical simulation of particle‐laden flows. It applies a fluid‐solid coupling technique based on the momentum exchange method to represent geometrically fully resolved particles of arbitrary shape. The test case of a single moving sphere allows an in‐depth evaluation of the algorithm. The method is fully parallelizable and yields results with an accuracy comparable to classical CFD simulations. This forms the basis for simulations of complex systems involving several thousand particles like the sediment transport in river beds. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the predictive capabilities of a multiphase SPH model for hydrodynamic spreading dynamics
Authors: Sivanesapillai Rakulan , Steeb Holger 
Published: October 2016

AbstractWe assess the predictive capabilities of a multiphase Smoothed‐Particle Hydrodynamics (SPH) model to simulate two‐phase flow processes that are decisively governed by the dynamics of hydrodynamically moving contact lines. The spreading of a liquid droplet on a completely wettable, smooth and flat substrate serves as prototype validation problem. Our simulation results reproduce the main features of hydrodynamic spreading in the quasi‐static limit, i. e. when the balance of viscous and capillary forces near the contact line governs the dynamics. The exponential spreading rate is consistent with Tanner's law. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The excitation mechanism of a shear stress induced rotary wave
Authors: Steinrück Herbert , Gusner Lorenz 
Published: October 2016

AbstractThe free surface flow in a vertical, cylindrical, rotating container will be considered when axis‐symmetric angular and radial shear stress distributions are applied on the free surface. It is well known that in the inviscid case a rotary wave which can be described by a flow potential exists. We want to determine the stability limit of the axis‐symmetric base state with respect to the rotary wave for small Ekman and Froude numbers. Under the above assumption, the critical flow conditions can be determined analytically. The results can be verified experimentally using a vertical, cylindrical container partially filled with water where the top lid rotates with a given angular velocity. Thus, the induced air flow will exert shear stresses in the angular and radial direction onto the water surface. Above a certain threshold, rotary waves can be observed. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computational magneto‐hydrodynamic modeling of hypersonic flows with resolved shock wave diffusion
Authors: Chelem Mayigue Charles , Groll Rodion 
Published: October 2016

AbstractThe present model describes magneto‐hydrodynamic (MHD) effects on diffusing shock waves in compressible flows. The accurateness and the robustness of these new density‐based numerical algorithm in his ideal form was tested on a series of benchmark numerical experiments like the present MHD shock tube [1]. Interpolation schemes are used for interpolation of density, temperature, velocity and the magnetic field. For the discretization of laplacian terms with diffusion coefficient for polyhedral meshes, we make use of the Gauss linear uncorrected schemes to deal with the case that the consecutive cell faces are non‐orthogonal. The approach described above and developed in the present project has been coupled with semi‐discrete central schemes (e.g. Greenshields et al. [2]). All computational results are validated with verified data and analytical results. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A strategy to implement volume sources into Galbrun equation
Authors: Retka Stefanie 
Published: October 2016

AbstractWhen considering noise propagation in flow in frequency domain computations, the standard Helmholtz equation is not sufficient to describe these effects. Therefore, using the linearized Euler equations (LEE) is common practice to describe sound propagation based on displacement perturbation. Galbrun reformulated the LEE in terms of an arbitrary Eulerian‐Lagrangian description, which resulted in the displacement based Galbrun equation. This equation can also be formulated in terms of pressure and displacements.We want to include sources (monopoles, dipoles and quadrupoles) in the harmonic analysis of Galbrun equation when a volume flow is present. In a first step we will solve Galbrun equation considering a volume flow. The velocity field is obtained in a CFD computation. Afterwards, the sources will be included in the acoustic computations as well.Preliminary computational results are discussed and implications for future directions of research are addressed. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)