bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Statistical Descriptors for the Construction of Statistically Similar RVEs
Authors: Scheunemann Lisa , Balzani Daniel , Brands Dominik , Schröder Jörg 
Published: December 2014

AbstractA method for the construction of three‐dimensional statistically similar representative volume elements (SSRVEs) is presented. Since the beneficial material properties of microheterogeneous materials originate in the microstructure, its incorporation in material modeling is desired. The FE2 method is a suitable tool to accomplish this step. Applying this method, a microscopic boundary value problem, given by a representative volume element (RVE) is attached to every integration point of the macroscale. Such RVEs taken from real microstructures exhibit a high level of complexity, thus raise computational costs. The use of a SSRVE with lower complexity is able to decrease these costs. Here, different statistical measures are compared in view of the performance in the SSRVE construction procedure. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Asphalt concrete: From µCT scans towards multiscale modelling of effective properties
Authors: Schüler Thorsten , Jänicke Ralf , Steeb Holger 
Published: December 2014

AbstractThis paper will give a short overview about the geometrical aspects in asphalt concrete and especially the creation of artificial microstructures on the basis of informations taken from µCT scans. Informations such as volume fraction or particle size distribution are the foundation for the artificial microstructures. The generation is executed on the basis of a Voronoi diagram with an option for weighting, shrinking and pseudo‐rotation of the particles. The microstructures are generated in a periodic manner to ensure periodic boundary conditions for all later numerical analyses. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local probabilistic homogenization schemes for assessment of material uncertainties in solid foams
Authors: Hohe Jörg , Paul Hanna , Beckmann Carla 
Published: December 2014

AbstractThe present study is concerned with a probabilistic model for prediction of the uncertainties in the effective material response of long fiber reinforced thermoplastic materials. The model is based on a simple elasticity model using the rules of mixture together with an ensemble averaging procedure. Assuming the scatter band width of local fiber orientation angle and the local fiber density as random variables, a probabilistic model is obtained. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An accelerated simulation method of medium density wood fiber boards
Authors: Sliseris Janis , Andrä Heiko , Kabel Matthias 
Published: December 2014

AbstractAn accelerated micro‐scale simulation method for the prediction of the stiffness of medium density fiber boards is proposed with the aim to increase the speed of the coupled micro‐macro simulation and to study the influence of fiber orientation on material properties. The stiffness is interpolated between loads in a n‐dimensional simplex figure, which is constructed in a macroscopic strain, temperature, moisture, time and other load. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Boundary value driven approach to computational homogenization
Authors: Fleischhauer Robert , Kaliske Michael 
Published: December 2014

AbstractA novel approach to computational homogenization methods for the analysis of heterogeneous structures with large length scale differences between their micro‐ and macroscale is presented. The boundary value driven approach to homogenization (BVDH) is efficient and reliable compared to existing multi‐scale frameworks and the limit cases of homogenization, respectively. Furthermore, the proposed approach is applicable to multi‐physical problems such as thermomechanical analysis. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computation of effective non‐linear inelastic properties of magnetostrictive composites
Authors: Labusch Matthias , Keip Marc‐André , Kiefer Björn , Schröder Jörg 
Published: December 2014

AbstractThe present paper focuses on the determination of effective magneto‐mechanical properties of magnetostrictive composite materials in consideration of their microscopic morphologies. For this purpose, a homogenization procedure involving a two‐scale transition is applied, where representative volume elements (
${\cal RVE}$
s) on the microscopic level are used. In order to obtain characteristic non‐linear and hysteretic magnetization and magnetostrictive strain curves, we implemented a dissipative material model into the homogenization framework. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Guaranteed bounds on homogenized periodic media by FFT‐based Galerkin method
Authors: Vondřejc Jaroslav , Zeman Jan , Marek Ivo 
Published: December 2014

AbstractAn FFT‐based method, introduced by Moulinec and Suquet [1] in 1994, is an effective alternative to conventional Finite Element Method (FEM) for numerical homogenization of periodic media. Here, we summarize the recent variational reformulation and discretizations by Vondřejc et al. [2–6], which are based on conforming Galerkin approximations with trigonometric polynomials as basis functions. This insight, naturally leading to guaranteed bounds on homogenized matrix, opens a wide area of further investigations, which are also briefly discussed here. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Buckling Analysis of Carbon Nanotubes – Application of a concurrent atomistic‐continuum multiscale approach
Authors: Hollerer Stefan 
Published: December 2014

AbstractIn this work, a concurrent atomistic‐continuum multiscale approach is applied in order to analyse the buckling behaviour of carbon nanotubes. In particular, the bridging domain method that is grounded on an overlapping domain partitioning scheme with an energy‐based blending of the subdomains is used. The atomistic subdomain is modelled by means of a molecular statics approach and the continuum subdomain is handled using the finite element method. Outcomes of numerical simulations of defective single‐walled carbon nanotubes under bending load are presented. More specifically, the impact of variably located Stone‐Wales defects on the buckling behaviour of a nanotube is studied using the concurrent multiscale approach. The results of the multiscale model are validated against a full atomistic molecular statics simulation. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Molecular dynamics and finite elements: an approach to couple different worlds
Authors: Pfaller Sebastian , Possart Gunnar , Steinmann Paul 
Published: December 2014

AbstractThe procedure proposed here couples a continuum with a particle region by introducing an overlapping bridging domain where both regions exchange information. Beyond existing methods, the particle region is computed by Molecular Dynamics (MD) at finite temperature, using a code that has been developed by our co‐workers of the Theoretical Physical Chemistry Group at TU Darmstadt. It is also used in the wide field of physical chemistry for various approaches. In contrast to MD procedures employing periodic boundary conditions (PBC), stochastic boundary conditions (SBC) allow for the definition of static anchor points. These additional artificial particles are coupled to the continuum part and serve as information transmitter. The continuum is treated classically by the Finite Element Method (FEM) which has been adapted based on the Arlequin and the bridging domain method. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Localisation in granular media: Particle approach, homogenisation and continuum modelling
Authors: Bidier Sami , Ehlers Wolfgang 
Published: December 2014

AbstractThe individual motion of grains in granular material has a strong influence on the macroscopic material behaviour, which is in particular the case for the phenomena of strain localisation in shear zones and justifies the need for techniques that incorporate a micro‐macro transition. In this contribution, granular media are investigated in three steps. Firstly, a microscopic particle‐based modelling is set up, where individual grains are considered as rigid uncrushable particles while their motion is obtained through Newton's equations of state. The inter‐particle contact forces are thereby determined via constitutive contact‐force formulations, which have to account for the envisaged material behaviour. The second step is the homogenisation of the obtained particle's displacements and contact forces through a particle‐centre‐based strategy towards continuum quantities. Therefore, Representative Elementary Volumes (REV) are introduced on the mesoscale and the specific construction of the REV boundary leads to the understanding of granular media as a micropolar continuum. Finally, in order to verify the homogenisation strategy, a continuum based micropolar model is applied to model localisation phenomena and a comparative study of the results is carried out in a qualitative way. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A non‐affine micro‐sphere formulation for electroactive polymers
Authors: Thylander Sara , Menzel Andreas , Ristinmaa Matti 
Published: December 2014

AbstractWith the capability to convert electrical energy into mechanical energy, electroactive polymers (EAP) continuously find new and more advanced applications. Their ability to considerably change in size and shape together with low cost and weight makes them suitable for technological applications in robotics and biomimetics as actuators and sensors. A dielectric actuator, one of the most common applications of EAP, consists of a soft elastomer sandwiched between two electrodes. Common for elastomeric material is a viscous response and associated time dependence on both electric and mechanical behaviour. In this work, an electromechanically coupled micro‐sphere formulation for nonlinear electroelasticity formerly proposed by the authors is further extended and includes non‐affine deformation measurements as well as viscous effects. Also, a finite element simulation of a cylindrical specimen and calibration of mechanical parameters have been performed. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling advanced high‐strength steels based on direct micro‐macro calculations
Authors: Gandhi Ashutosh , Balzani Daniel , Schröder Jörg 
Published: December 2014

AbstractAdvanced high strength steels have immense commercial applicability today owing to the good combination of strength and ductility they offer. These properties mainly result from interactions of micro‐heterogeneities leading to a complex macroscopic material behavior. One of these steels is the Dual Phase (DP) steel which has a microstructure consisting of two phases: ferrite (matrix material) and martensite (inclusion material). This paper proposes a technique to model the post‐production situation of these steels, which is characterized by distributed material properties as well as eigenstresses. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental and numerical investigation of paperboard creasing
Authors: Li Yujun , Simon Jaan‐Willem , Reese Stefanie 
Published: December 2014

AbstractLaminated paperboard is widely used in packaging products. It usually consists of multiple layers bonded to each other by starch or adhesion. The indentation of fold lines (creasing) plays a crucial role during the whole converting process. It is important to control delamination and other damage effects to arrive at commercial cartons with high quality. Thus, the aim of this study is to describe the material behavior of a laminated paperboard during the creasing process. The paperboard was considered as a laminate of three different layers, and each was modeled separately with an anisotropic elastic‐plastic material model while a cohesive zone approach described the opening behavior in between. The initial yielding was given by the Hill's 48 yield criterion, while the isotropic strain hardening was described by a power law hardening function. To calibrate the material parameters, a sequence of tensile and compression tests was conducted for each layer in different directions to account for the material's anisotropy. Finally, the creasing process was investigated using a two‐dimensional plane strain finite element model. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Patterned turbulence and relaminarization in MHD pipe and duct flows
Authors: Krasnov Dmitry , Zikanov Oleg , Boeck Thomas 
Published: December 2014

AbstractWe present results of a numerical analysis of relaminarization processes in MHD duct and pipe flows. It is motivated by Julius Hartmann's classical experiments on flows of mercury in pipes and ducts under the influence of magnetic fields. The simulations, conducted both in periodic and non‐periodic settings, provide a first detailed view of flow structures that have not been experimentally accessible. The main novelty of the analysis is very long (tens to hundreds of hydraulic diameters) computational domains that allows to discover new flow regimes with localized turbulent spots near the side walls parallel to the magnetic field. The computed critical parameters for transition as well as the friction coefficients are in good agreement with Hartmann's data. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Examples of the Re‐number effect on the transitional flat plate boundary layers
Authors: Antoš Pavel , Jonáš Pavel , Procházka Pavel , Uruba Václav 
Published: December 2014

AbstractDimensionless mean flow characteristics and the location of the transitional region were investigated of flat plate boundary layers (smooth surface or covered by sandpaper 60 grit) at the external flow velocities about 5 m/s, 10 m/s and 14 m/s and with turbulence levels either natural (less than 0.003) or gained by a grid across the flow (FST level 0.03 at the leading edge). Preliminary comparison of the received results with those previously published [1] is presented. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A study of truly incompressible and weakly compressible Smoothed Particle Hydrodynamics methods to model incompressible flows with free surfaces
Authors: Beck Florian , Hirschler Manuel , Niecken Ulrich , Eberhard Peter 
Published: December 2014

AbstractThe Smoothed Particle Hydrodynamics (SPH) method is a meshless discretization method for solving, e.g., the Navier‐Stokes equations. By now, it is used for hydraulic problems as well as for solid bodies. In general, there are two distinguishable approaches for incompressible fluid flows. One is called weakly compressible SPH (WCSPH) and the other is called truly incompressible SPH (ISPH). The main difference between these two approaches is the way of pressure evaluation. In WCSPH, a state equation is used, while in ISPH the pressure Poisson equation is solved. Each approach has its advantages as well as its disadvantages, for example the complexity of the numerical algorithm for WCSPH is smaller than for ISPH, but the pressure field is more accurate for ISPH.In this work, two representative examples are studied. The simulations were performed with two different codes, one developed at the Institute of Engineering and Computational Mechanics and one at the Institute of Chemical Process Engineering. It is the aim of this work to show some properties of WCSPH and ISPH as well as to compare two different implementations that, in detail, are very complex. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Variational Formulations for Viscous Flow
Authors: Scholle Markus 
Published: December 2014

AbstractFor physical systems, the dynamics of which is formulated within the framework of Lagrange formalism the dynamics is completely defined by only one function, namely the Lagrangian. As well‐known the whole conservative Newtonian mechanics has been successfully embedded into this methodical concept. Different from this, in continuum theories many open questions remain up to date, especially when considering dissipative processes. The viscous flow of a fluid, given by the Navier‐Stokes equations is a typical example for this. In this contribution a special approach for finding a Lagrangian for viscous flow is suggested and discussed. The equations of motion resulting from the respective Lagrangian are compared to the Navier‐Stokes equations and differences are discussed. For a simple flow example their solution is compared to the one resulting from Navier‐Stokes equations. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micro diffuser flow modeling for cold gas propulsion systems
Authors: Groll Rodion 
Published: December 2014

AbstractThe use of highly diluted and hypersonic gas flow is in the scope of application of cold gas thrusters for space applications. Satellites and small spacecrafts are navigated to their orbital trajectory with these nozzles. Inside these propulsion systems high density gradients are dominating the efficiency and the thrust steering behavior of the propulsion systems.Micro flows in the transient regime between free molecular flow and continuous flow are not able to be computed with trustworthy results by using a continuous model with no‐slip boundary conditions. Therefore boundary slip‐velocity models are used for modeling the reduced wall shear stress. Molecular shear stresses decrease the molecular mean velocity near the wall. With a Knudsen number depending slip‐velocity model the effective shear stress is computed by the mean gradient of the velocity profile near the wall.In the present study a trans‐sonic nozzle flow is computed by using a calibrated velocity slip model what depends on the Knudsen number. The Knudsen numbers are lower the Kn=1 at the nozzle neck of the propulsion system. The results are compared with simulation results of a uniform channel flow and computations of the corresponding no‐slip approach. The differences in the hypersonic region are following discussed. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Premixed Turbulent Combustion in a Gas Engine using the Immersed Boundary Method and a Level Set Flame Model
Authors: Bruzzese Christian , Class Andreas , Bruder Ingmar , Bronner Yvan 
Published: December 2014

AbstractAn efficient simulation approach for turbulent flame brush propagation is a level set formulation closed by the turbulent flame speed. A formulation of the level set equation with the corresponding treatment of the turbulent mass burning rate that is compatible with standard Finite Volume discretization schemes available in computational fluid dynamics codes is employed. In order to simplify and to speed up the meshing process in complicated geometries (here in gas engines) the immersed boundary method in a continuous formulation, where the forces replacing the boundaries are introduced in the momentum conservation equations before discretization, is employed. In our contribution, aspects of the numerical implementation of the level set flame model combined with the immersed boundary formulation in OpenFOAM are presented. First representative simulation results of a homogeneous methane/air mixture combustion in a simplified engine geometry are shown. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of a multi‐component Eulerian approach to capture interface evolution and vorticity generation in compressible multiphase flow
Authors: Nowakowski Andrzej F. , Nicolleau Franck C.G.A. 
Published: December 2014

AbstractThe hyperbolic Eularian model is used as a mathematical framework for compressible multiphase flows. The formulation was obtained after an averaging process of the single phase Navier‐Stokes equations. The closure of multi‐component system leads to the volume fraction equation containing a non‐conservative term and a pressure equilibrium condition. As a result the model equations cannot be written in a conservative form. To solve the equations a finite volume Godunov type computational approach is developed which uses an approximate Riemann solver combined with a numerical scheme to tackle the non‐conservative terms. The approach accounts for pressure non‐equilibrium. It enables resolving interfaces separating compressible fluids and captures the baroclinic source of vorticity generation. The computations are performed for various initial conditions and compared with theoretical and experimental data for a shock‐bubble interaction problem. The investigated cases include acoustic wave transmission through isolated bubbles of helium and krypton. The numerical results illustrate the characteristic features of the evolving interfaces. The impulsively generated flow perturbations are dominated by the reflection and refraction of the shock and by the vorticity generation within the media. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experiments on the spreading of silicone oil droplets on horizontal rotating plates
Authors: Blank Mirja , Ehrhard Peter 
Published: December 2014

AbstractThe spreading of liquid films is involved in many coating processes, e.g. in the spin‐coating process. To achieve a high quality of the coating, the spreading liquid layer should be thin and homogeneous. Instabilities at the wetting front may lead to an inhomogeneous thickness of the coating layer and to uncoated areas. In this article the spreading of perfectly‐wetting silicone oil droplets with viscosity of 100 mPa s on rotating glass plates is discussed. A Schlieren system is set up to observe the wetted area and a traversed chromatic confocal distance sensor is used to measure the contour of the droplet. The experimental data are presented and compared to an analytical model which is derived from lubrication theory and valid for thin liquid layers. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Investigation of the Free‐Surface Flow within an Annulus
Authors: Gundlach Janto , Lübke Martin , Wünsch Olaf 
Published: December 2014

AbstractThis study describes the free‐surface flow of a highly viscous liquid between two concentric cylinders. In the process the morphology of the phase boundary is determined using a straight volume of fluid approach. Due to large differences in viscosity the gaseous phase is considered as vacuum. The numerical results of free‐surface flow measures are compared to previous calculations and experimental values. The investigation shows that the used two‐phase method is well‐suited to predict the location and shape of the interface. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The flow of vapors through porous ceramic membranes consisting of several layers
Authors: Loimer Thomas , Uchytil Petr , Reznickova Jirina 
Published: December 2014

AbstractThe flow of a vapor through a porous ceramic membrane is investigated. The membrane consists of several layers and is asymmetric with respect to the flow direction. The flow process is modeled accounting for capillary condensation, for the capillary pressure at liquid menisci, and for the temperature difference between the upstream and the downstream side of the membrane due to the Joule‐Thomson effect, which induces a transfer of heat in downstream direction. Condensation may occur in various parts of the membrane. Condensation has a large influence on the mass flux through the membrane. The mass flux in one flow direction through the membrane may be a few times larger than the mass flux in the other flow direction. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the sonic composites subjected to severe acoustic loads
Authors: Ilie Ruxandra , Ioan Rodica , Brişan Cornel 
Published: December 2014

AbstractTransformation acoustics opens a new avenue towards the fabrication of a new class of sonic composites with scatterers made of auxetic materials embedded in the epoxy matrix. The design of the acoustic scatterers is based on the property of Helmoltz equations to be invariant under coordinate transformations, i.e. a specific spatial compression is equivalent to a variation of the material parameters in the original space. In this paper, the noise suppression for a wide full band‐gap of frequencies is discussed for spherical shell scatterers made of auxetic materials. (© 2014 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)