bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling and simulation of magnetorheological elastomers: A comparison of continuum and dipole approaches
Authors: Metsch Philipp , Romeis Dirk , Saphiannikova Marina , Kästner Markus 
Published: March 2018

AbstractIn the present work, a comparison of the results of a microscale continuum and a dipolar mean‐field approach with regard to their predictions for the magnetostrictive response of magnetorheological elastomers is presented. It turns out that – for random, isotropic microstructures – there is a very good agreement between both modeling strategies. This is in contrast to former comparisons of continuum and other dipole approaches, which have shown considerable deviations. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computational Multi‐Scale Stability Analysis of Periodic Electroactive Polymer Composites at Finite Strains
Authors: Polukhov Elten , Vallicotti Daniel , Keip Marc‐André 
Published: March 2018

AbstractThis work is dedicated to multi‐scale stability analysis, especially macroscopic and microscopic stability analysis of periodic electroactive polymer (EAP) composites with embedded fibers. Computational homogenization is considered to determine the response of materials at macro‐scale depending on the selected representative volume element (RVE) at micro‐scale [4, 5]. The quasi‐incompressibility condition is considered by implementing a four‐field variational formulation on the RVE, see [7]. Based on the works [1–3, 6, 8] the macroscopic instabilities are determined by the loss of strong ellipticity of homogenized moduli. On the other hand, the bifurcation type microscopic instabilities are treated exploiting the Bloch‐Floquet wave analysis in context of finite element discretization, which allows to detect the changed critical size of periodicity of the microstructure and critical macroscopic loading points. Finally, representative numerical examples are given which demonstrate the onset of instability surfaces, the stable macroscopic loading ranges, and further a periodic buckling mode at a microscopic instability point is presented. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Derivation of an n‐layered composite sphere model for thermo‐chemo‐mechanical effective properties
Authors: Dammann Christian , Mahnken Rolf , Lenz Peter 
Published: March 2018

AbstractOur work presents extensions of multi layered composite sphere models known from the literature to temperature‐dependent elastic effects accompanied by curing. In particular, volumetric effective properties are obtained by homogenization for a representative unit cell (micro‐RVE) on the heterogeneous microscale for thermo‐chemo‐mechanical coupling within linear elasticity. To this end, an analytical solution for an n‐layered composite sphere model is derived. In a numerical study for a (3)‐phase matrix it is demonstrated that the effective elastic and thermal properties lie within Voigt and Reuss bounds, whilst for the chemical part of the model an analogous result is obtained for the effective strains. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Homogenization of periodic micro‐structures with FFT‐based higher order schemes
Authors: Dietrich Felix , Merkert Dennis 
Published: March 2018

AbstractA matrix‐free homogenization method making use of the fast Fourier transform (FFT) to work on structured grids was introduced by Moulinec and Suquet in 1994. Due to its simplicity and computational advantages, this so‐called Basic Scheme has provided the basis for many works in the past two decades. An extension presented by Tran, Monchiet and Bonnet allows for the quasi‐static equations of linear elasticity to include effects from higher‐order derivatives by expanding the strain and the displacement as asymptotic series. To compute the solution hierarchically, we derive generalized Lippmann Schwinger‐type equations. Furthermore, we show how existing algorithms have to be adapted for these problems. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Two‐Scale Simulation of a Disc With a Crack by X‐FEM and Cell Model
Authors: Donhauser Michael , Schmerbauch Mario , Matzenmiller Anton 
Published: March 2018

AbstractThe two‐scale simulation of a linear‐elastic orthotropic disc with a central crack under mode‐I loading may be used to verify the extended finite element method implementation of orthotropic enrichment functions into finite element codes such as FEAP. The stress distribution on the finer scale is simultaneously resolved by the high fidelity generalized method of cells called at each integration point of the macro elements. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient Simulation of Short Fibre Reinforced Composites
Authors: Springer Rolf , Meyer Arnd 
Published: March 2018

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 stationary 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. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stochastic Modeling of Turbulent Scalar Transport at Very High Schmidt Numbers
Authors: Klein Marten , Schmidt Heiko 
Published: March 2018

AbstractA stochastic modeling approach, the so‐called One‐Dimensional Turbulence (ODT), is used to study passive scalar transport in incompressible, fully‐developed, turbulent channel flows up to very high Schmidt numbers Sc = ν/Γ ∼ 104 (kinematic viscosity ν, scalar diffusivity Γ). Good agreement is obtained between ODT and Direct Numerical Simulation (DNS) results with respect to the mean, the fluctuation statistics, and the dimensionless mass transfer coefficient K+. ODT yields the mass transfer coefficient to become independent of the Reynolds number at high Schmidt numbers, which is similar to reference laboratory measurements and DNS. The present ODT results exhibit the power law K+ ∝ Sc−0.65 with a scaling exponent that is only slightly larger than in the reference laboratory measurements and DNS. The results obtained suggests that ODT can be a versatile tool for turbulent transport modeling in a wide range of physical parameters. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of ODT to constant volume autoignition problems
Authors: Medina Méndez Juan A. , Schmidt Heiko 
Published: March 2018

AbstractThe One‐Dimensional Turbulence (ODT) model is applied to a constant volume configuration by means of a periodic, one‐dimensional domain subject to randomized ensemble members with initial inhomogeneous temperature fields and homogeneous mass fraction profiles. The multidimensional turbulent interactions in the flow are modeled by the separate implementation of turbulent advection and the diffusion‐reaction processes, neglecting the mean advection of the system. On one hand, turbulent advection is modeled by means of the eddy events defined within the framework of ODT; on the other hand, the diffusion‐reaction system is solved by means of the Zero‐Mach limit conservation equations discretized with a 1D Finite Volume Method (FVM). The treatment is specialized in this work to constant volume systems. Due to the inherent stiffness of the diffusion‐reaction system, an operator splitting approach is also included in the formulation. Results for n‐Heptane chemistry comprising the temporal evolution of the heat release rate, pressure and normalized density‐weighted displacement speed are shown and compared to DNS results from Yoo et al. [Combust. Flame 158 (2011) 1727‐1741], in terms of individual ensemble members and mean ensemble behavior. The results show that it is possible to obtain reasonably good results in comparison to the DNS if an appropriate set of initial conditions is used. Furthermore, it is shown that the model uncertainty is negligible in comparison to the ensemble standard deviation introduced by randomized initial conditions. Overall, this work introduces the framework for constant volume autoignition in ODT and shows its efficiency for complex chemistry simulations. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Laws of the wall for velocity and temperature in supersonic turbulent boundary layers
Authors: Vigdorovich Igor 
Published: March 2018

AbstractScaling laws for velocity and temperature profiles in the near‐wall region of sub‐ and supersonic turbulent boundary layers have been developed, which allow us to represent velocity and temperature profiles in compressible gas stream in terms of those in an incompressible boundary layer. They are obtained as asymptotic expansions of the solutions to the Reynolds equations in a small parameter — the Mach number based on the friction velocity and gas enthalpy on the wall. The leading term of the expansion for velocity corresponds to known Van Driest's formula. However, the obtained solution contains additional terms of order unity, which explains the contradiction between Van Driest's formula and experimental data. The law of the wall for temperature, which has been formulated for the first time, has an analogous structure. Besides the von Kármán constant and the turbulent Prandtl number in the logarithmic region, known for incompressible flow, the obtained relations contain three new universal constants, which do not depend on gas molecular properties and the specific heat ratio. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling the filling process of lithium‐ion batteries
Authors: Neumann Tim , Boettcher Konrad , Ehrhard Peter 
Published: March 2018

AbstractLithium‐ion batteries are composed of several single cells, each consisting of conductive, impermeable electrodes made of aluminum and copper. Both are coated with a thin, porous layer on both sides (collectors) and a thin, non‐conductive and permeable layer is separating them. As the layers are stacked, the liquid enters the battery at all front edges, while the gas is trapped inside. To estimate the filling process of these batteries with the viscous suspensions containing the electrolyte, a model for the flow of a well‐wetting liquid displacing a gas in a single cell is established. This can be modeled as a stack of three porous layers with heterogeneous characteristics (cf. figure 2). The porous structure of the electrode coatings is approximated as a packed bed of spheres. Considering the small ratio of layer thickness to particle diameter, the influence of the wall effect onto the relevant forces has to be taken into account. These models according to the hydrodynamics of this multi‐phase flow are implemented into the commercial CFD‐software Ansys CFX. Derived from the numerical results, a 1D description is developed to specify the whole filling process. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of the Stochastic Field Method to two phase flow
Authors: Raquet Martin , Class Andreas , Edelbauer Wilfried 
Published: March 2018

AbstractThe Stochastic Field Method was introduced in the field of combustion and represents a Eulerian Monte‐Carlo technique. It was first transfered to the field of multiphase flow in [1] facing a problem in nuclear technology. Within this work it is applied to cavitating flows in the automotive sector. Both phases, the continuous and the dispersed phase, are observed using a Eulerian perspective which fits the architecture of CFD solvers resulting in efficient computations. Instead of solving the behaviour of individual bubbles, as in Lagrangian Particle Methods, variations of volume fractions of the dispersed phase in each computational mesh cell are considered. A stochastic term is introduced into the transport equations for the volume fractions of the dispersed phase via a Wiener process. Thus sampling over several time steps provides the probability density function of volume fraction in each mesh cell. The implementation is carried out by compiling user‐functions to a commercial CFD code. A test case representing an injection system in an automotive application is presented. Moreover strategies to implement the effect of coalescence are shown. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Linear forced sloshing for a baffled rectangular fuel tank
Authors: Buck Fabian , Hetzler Hartmut , Fruend Eckhard , Oexl Stefan 
Published: March 2018

AbstractSloshing in a fuel tank of a commercial vehicle, which is subdivided by a perforated plate as baffle, is investigated to predict occuring forces. Using linear potential theory and a two‐dimensional modal description, the eigenmodes and eigenfrequencies are determined for the baffled tank and compared to experimental results. Damping due to viscous boundary layers and the pressure drop at the baffle is examined and discussed with regard to experimental findings. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental investigation of the effect of aircraft trailing vortices on roofs
Authors: Uhl Anna , Braun Sebastian , Hille Sebastian , Hörnschemeyer Ralf , Stumpf Eike 
Published: March 2018

AbstractRoofs of buildings in the vicinity of airports can be damaged by trailing vortices of aircraft during take‐off and landing. Preliminary experimental investigations have been conducted in a water towing tank in order to examine a discrepancy between damage probability assumptions and actual roof damage frequency. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison of parametric and non‐parametric methods for bladed disks with random geometric mistuning
Authors: Koebele Maxime , Proppe Carsten 
Published: March 2018

AbstractThis paper presents different strategies to quantify the influence of random geometric mistuning on the dynamic behavior of bladed disk. These strategies are compared for different correlation lengths of the random field describing the blade geometry. The results allow to determine the kind of random geometric mistuning for which these strategies are appropriate. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal Expansion Planning for an Electric Distribution Network with the NLP Solver WORHP
Authors: Berger Arne , Jung Francesca , Echim Mitja , Büskens Christof , Schollmeyer Michael 
Published: March 2018

AbstractThis paper shows how an electrical distribution network can be modeled as constraints of a continuous nonlinear optimization problem. The objective is to minimize the deviation from a given nominal voltage. We explain how this setup can be used to optimize wire diameters within the network. Thus we find the optimal expansion of the network by identifying wires which should be enforced. The results are shown by applying the functionality to a real world example. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Localized and efficient estimators for obstacle problems in the context of standard residual estimators
Authors: Walloth Mirjam 
Published: March 2018

AbstractIn order to localize the estimator contributions with respect to the active set of constraints special error measures and residual‐type estimators have been derived for different variational inequalities [2–4]. Considering the classical obstacle problem, we summarize the basic ideas and draw a relation to estimators for linear elliptic problems without constraints. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Implementing an image based control algorithm for an optomechanical image derotator
Authors: Altmann Bettina , Pape Christian , Reithmeier Eduard 
Published: March 2018

AbstractIn this paper an image‐based control for an optomechanical image derotator is implemented. A derotator is an optical system to support measurements on rotating components by tracking their rotational movement. As a consequence, the position and rotational velocity of the measurement object has to be known continuously. In general this would be accomplished by measuring these variables using a rotary encoder. However, not all measuring objects are equipped for this task. As a solution universally applicable to a wide range of measuring objects, an image‐based approach is developed in the scope of this work. The object is captured with a high‐speed camera to determine its position and velocity by image processing algorithms. To proof the applicability of this concept, a controller using the data acquired with the camera and a controller using data of the rotary encoder are compared. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Approximation and implementation of transformation based feedback laws for distributed parameter systems
Authors: Ecklebe Stefan , Riesmeier Marcus , Woittennek Frank 
Published: March 2018

AbstractA novel approach to the efficient numerical approximation and implementation of transformation based state feedback originating from backstepping or flatness based approaches is applied to a flatness based feedback law for the so called heavy rope system. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient and accurate two‐scale simulation of non‐linear heterogeneous microstructures
Authors: Kochmann Julian , Wulfinghoff Stephan , Svendsen Bob , Reese Stefanie 
Published: March 2018

AbstractThis work is concerned with the development of an efficient two‐scale numerical scheme for the prediction of the local and effective mechanical response of heterogeneous materials with non‐linear constitutive behavior. In order to ensure both, accurate micromechanical fields and feasible overall CPU‐times, an efficient but rather simple solution scheme is proposed. Its capabilities are demonstrated using the FE‐FFT method [2,3] for the solution of simple two‐scale problems. As an example, two‐dimensional polycrystalline microstructures with an elasto‐viscoplastic constitutive law are considered. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Active Impedance Matching in Slender Continua via a Special PID Controller
Authors: Krumm Ludwig , Kreuzer Edwin 
Published: March 2018

AbstractThe concept of impedance matching is well known in electrical engineering and can be applied in mechanical engineering as well. Slender systems, which have a relatively low stiffness and should not be treated as a rigid body are typical candidates for the application of impedance matching.Impedance matching imposes a special boundary condition. In general, at the boundary of a slender mechanical system, waves are partially reflected. The goal of impedance matching is to minimize those wave reflections and to transmit the wave motion to the vicinity. In this paper, it is shown that the impedance matching approach has a great potential of damping vibrations and that a simple PID controller can be used to implement an active version. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Screw Theory – A forgotten Tool in Multibody Dynamics
Authors: Müller Andreas 
Published: March 2018

AbstractMechanism theory, synthesis and control of robots, rigid body dynamics, geometrically exact formulations of the kinematics of continua, structure preserving numerical integration methods, and in part geometric mechanics – they all have a common denominator, namely the theory of screws, for which Lie group theory forms the mathematical foundation. This paper is an attempt to provide a short survey identifying several scientific areas where screw theory is already (sometimes implicitly) used and such where its systematic application could lead to new formulations and computational algorithms. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On quadratic stage costs for mobile robots in model predictive control
Authors: Müller Matthias A. , Worthmann Karl 
Published: March 2018

AbstractWe consider nonholonomic mobile robots. Since the system is finite time controllable, it is stabilizable by a receding horizon control scheme with purely quadratic stage costs if an infinite optimization horizon is employed. However, due to the so called short‐sightedness of model predictive control, these stability properties are not preserved if the control problem is only optimized on a truncated and, thus, finite prediction horizon — even if an arbitrarily large terminal weight is added. Hence, it is necessary to either incorporate structurally different terminal costs or use non‐quadratic stage costs to appropriately penalize the deviation from the desired set point. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An Efficient Thermo‐Kinematic (ETK) Model for Long‐Time Simulation of High Speed Railway Brake Dynamics
Authors: Srisupattarawanit T. , Ostermeyer G.‐P. , Schiefer F. 
Published: March 2018

AbstractHigh speed railway brakes transfer a large amount of kinetic energy into heat during the brake operation. Due to its design one major problem is tapered wear, which could significantly reduce brake performance and safety as well as increase aftermarket costs. Modeling and simulation of these brake systems is rather complicated with respect to the coupled multiphysics, multiscaled phenomena, friction and wear, especially on long time scale. Here, we present the so‐called Efficient Thermo‐Kinematic (ETK) model, which include the complexities of the multiphysics of the brake process in the efficient way. Using this model, we are able to proceed the simulation of the brake dynamics in long‐time scale. The partial differential equations are derived based on the coupled manner. The simulation with ETK model shows reasonable results with very fast computational time. The ratio of computing time to real time can reach 1:2000 (with a standard personal computer). Thus, investigations on tapered wear can be performed not only in one brake operation but in many times of brake operations. The simulation results will support the development process of railway brakes in order to mitigate tapered wear of the brake pads. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Constitutive model error and uncertainty quantification
Authors: Franck Isabell M. , Koutsourelakis P.S. 
Published: March 2018

AbstractThis paper proposes a novel Bayesian strategy for high‐dimensional inverse problems in the context of elastostatics. Apart from parametric uncertainties, model inadequacies and, particularly, constitutive model errors, are also addressed. This is especially important in biomedical settings when the inferred material properties will be used to make decisions/diagnoses. Traditional approaches use an additional regression model (e.g., Gaussian process), added to the model output or within a submodel to account, for an underlying model error. This can violate physical constraints and becomes impractical in high dimensions.In this work we unfold conservation and constitutive laws to estimate model discrepancies. In addition, efficient Bayesian strategies are employed. In elastography, the accurate identification of the unknown mechanical properties of a tissue as well as the associated uncertainty, can greatly assist noninvasive, medical diagnosis. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stochastic upscaling of random microstructures
Authors: Rosić Bojana , Sarfaraz Muhammad Sadiq , Matthies Hermann G. , Ibrahimbegović Adnan 
Published: March 2018

AbstractIn this work we present an upscaling technique for multi‐scale computations based on random microstructures modelled as realisations of lognormally distributed random fields, or described by randomly distributed inclusions in a homogeneous matrix. Their corresponding coarse‐scale model parameters are considered as uncertain, and are approximated by random variables, the distributions of which are obtained via polynomial chaos based Bayesian procedures in which the fine‐scale energy is used as an observation. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)