bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Self‐Resonant System ‐ Experimental Investigations of Boundary and Operating Conditions
Authors: Aboulfotoh Noha , Krack Malte , Twiefel Jens , Wallaschek Jörg 
Published: October 2016

AbstractThis contribution introduces the setup of a self‐resonating system consisting of a freely‐sliding mass over a vibrating elastic beam under harmonic excitation. Under specific operating regime, the slider shows tendency to move and adapt its position to where the whole system resonates. The behavior of the slider during that motion is investigated. Experimental observations of the operating regime dependency on some parameters are provided. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Approximation of quasi‐periodic solutions of a rotor in two‐lobe bearings with time‐varying geometry
Authors: Becker Kai , Seemann Wolfgang 
Published: October 2016

AbstractImproving the dynamic behaviour of rotor systems in journal bearings represents an ongoing topic of research. The pressure distribution within journal bearings is described by the Reynolds equation, whereby unwanted oscillations can be caused by the fluid‐solid interaction within the bearings. An approach of a two‐lobe bearing with time‐varying geometry is suggested to suppress or at least to reduce occurring oscillations. In order to systematically analyse the system, a spectral reduction is performed, allowing to handle also quasi‐periodic behaviour by means of numerical continuation algorithms. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the rotordynamic stability of two‐pole synchronous electric machinery considering different load cases
Authors: Boy Felix , Hetzler Hartmut 
Published: October 2016

AbstractThis paper discusses stationary rotordynamics of synchronous electric machinery, considering different load cases. The model comprises the electrical operation in a rigid network and in an isolated condition. The mechanical part is modelled as a Laval Rotor (Jeffcott Rotor) with a noncircular shaft, accounting for both static‐ and dynamic rotor eccentricities. The results show, that the machine's electrical operation may influence the occurence of mechanical vibrations significantly and therefore demonstrate the importance of analysing the electromechanical interaction. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamics of a rotor partially filled with a viscous incompressible fluid
Authors: Kern Dominik , Jehle Georg 
Published: October 2016

AbstractA rotor partially filled with a viscous incompressible fluid is modeled as planar system. Its structural part, i. e. the rotor, is assumed to be rigid, circular, elastically supported and running with a prescribed time‐dependent angular velocity. Both parts, structure and fluid, interact via the no‐slip condition and the pressure. The point of departure for the mathematical formulation of the fluid filling is the Navier‐Stokes equation, which is complemented by an additional equation for the evolution of its free inner boundary. Further, rotor and fluid are subjected to volume forces, namely gravitation. Trial functions are chosen for the fluid velocity field, the pressure field and the moving boundary, which fulfill the incompressibility constraint as well as the boundary conditions. Inserting these trial functions into the partial differential equations of the fluid motion, and applying the method of weighted residuals yields equations with time derivatives only. Finally, in combination with the rotor equations, a nonlinear system of 12 differential‐algebraic equations results, which sufficiently describes solutions near the circular symmetric state and which may indicate the loss of its stability. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sensitivity of Computational Rotor Dynamics Towards the Empirically Estimated Lubrication Gap Clearance of Foil Air Journal Bearings
Authors: Leister Tim , Baum Christoph , Seemann Wolfgang 
Published: October 2016

AbstractThis contribution is concerned with the computational analysis of a rigid rotor supported by means of two self‐acting foil air journal bearings. Even though the overall equation system is thereby typically written in a nondimensional form, prior knowledge about realistic value ranges of occurring dimensionless numbers is required in order to parameterize and interpret such simulations correctly. Unlike all other quantities, the nominal lubrication gap clearance between the rotating journal and the undeformed foil structure is reported to be only poorly known. Thus, even in the light of an advanced understanding of the bearing rotor system's fundamental behavior, the quantitative reproduction and prediction of experimental results by means of computational analysis need to be viewed critically. In this study, the sensitivity of numerical results towards the assumed nominal lubrication gap clearance will be investigated. To this end, the stability of the system is considered and the characteristics of occasionally observed equilibrium points and limit cycles are addressed. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Grenzen numerischer und experimenteller Modelluntersuchungen am Beispiel Regen‐Wind induzierter Schwingungen
Authors: Seidel Christian 
Published: October 2016

AbstractAn schlanken, geneigten Zylinderstrukturen wie Kabeln von Schrägkabelbrücken und Hängebrücken, Hängern von Bogenbrücken oder an Abspannseilen kann bei gleichzeitigem Auftreten von Regen und Wind das hydroaeroelastische Phänomen der Regen‐Wind induzierten Schwingungen beobachtet werden. Die komplexen Strömungsvorgänge des Phänomens bedingen die Entwicklung eines hybriden Modells. Diese halbanalytischen/halbnumerischen und halbexperimentellen Verfahren zeigen Grenzbereiche zwischen Numerik und Experiment, deren physikalisch sinnvolle Beschreibung und Erklärung nur mit Hilfe der Kombination von numerischen und experimentellen Untersuchungen gelingt. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Minimization‐ and Saddle‐Point‐Based Modeling of Diffusion‐Deformation‐Processes in Hydrogels
Authors: Böger Lukas , Nateghi Aref , Miehe Christian 
Published: October 2016

AbstractHydrogels have gained importance during the last years due to their wide range of synthetically fabricable elastic properties as well their increasing meaning in biomedical applications. Future exploitation of the vast prospects of hydrogels is however only feasible by establishing reliable material models that precisely capture their behavior in different environments. To this end, we propose a consistent variational framework for deformation‐diffusion processes, offering a canonically compact approach to the chemo‐mechanical coupling of hydrogels via a saddle‐point as well as a new minimization formulation. The work depicts the construction of rate‐type potentials for the chemo‐mechanical evolution problem and their transformation into time‐discrete incremental potentials. In terms of spatial discretization, the finite element method is employed, benefiting from the intrinsic symmetric structure of the variational foundation. While the saddle‐point formulation yields the well‐known LBB condition as a constraint for finite element interpolations, on the part of its minimizing counterpart H(Div, ℬ︁)‐conforming elements have to be chosen. We illustrate appropriate solutions to both challenges, using mixed Taylor‐Hood for the saddle‐point and Raviart‐Thomas elements for the minimization formulation and discuss advantages of the new approach. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A numerical framework for rheological models based on the decomposition of the deformation rate tensor
Authors: Donner Hendrik , Ihlemann Jörn 
Published: October 2016

AbstractIn this contribution, the rheological models based on the decomposition of the deformation rate tensor, as proposed by Palmow (1984), is combined with the numerical solution of objective tensorial ODEs as published by Rashid (1993). The resulting framework is suitable to model the complex inelastic properties of many materials at large strains. As an example, the Schwedoff model, which is appropriate for the simulation of metal forming processes, is analyzed within a cyclic simple shear test. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Some Basic Ideas for the Simulation of Wave Propagation in Microstructures using Proper Orthogonal Decomposition
Authors: Fangye Yannick F. , Weber Wolfgang E. , Zastrau Bernd W. , Balzani Daniel 
Published: October 2016

AbstractFor the modeling of micro‐heterogeneous materials, models are required that take into account the microstructure. More and more, computational homogenization is used to quantify the effective macroscopic response. The large number of resulting microscopic boundary value problems need to be solved efficiently. To reduce the computational effort and simulation time, model reduction methods may be applied. In this contribution the performance of the proper orthogonal decomposition is analyzed for the wave propagation in fiber reinforced materials. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of a chassis bushing with regard to strain induced softening of filled rubber
Authors: Gelke Sören , Ihlemann Jörn 
Published: October 2016

AbstractA material model is presented, which describes the material behavior of rubbery materials in the case of uniaxial tension/compression. It includes the characteristic nonlinearity of rubber at large strains as well as strain induced softening called Mullins effect. The generalization to arbitrary deformations is done with the concept of representative directions, published by Freund & Ihlemann [2] utilizing a numerical integration on a unit sphere. An FE simulation of a chassis bushing shows that the Mullins effect is reproduced appropriately, verifying the preceding material characterization. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Loss of ellipticity in additive logarithmic finite strain plasticity and related results on Hencky‐type energies
Authors: Ghiba Ionel‐Dumitrel , Neff Patrizio , Martin Robert J. 
Published: October 2016

AbstractThe aim of this paper is to present some results regarding the Legendre‐Hadamard ellipticity and loss of ellipticity of some energies depending on the logarithmic strain tensor. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the composites consisting of randomly distributed fibers
Authors: Ilie Ruxandra 
Published: October 2016

AbstractThe results highlight and interpret the testing and properties of natural fibre composites including, non‐destructive and high strain rate testing. The potential of this material for noise enclosures is investigated by using a coupled method cnoidal – Extended Finite Element Method (XFEM). XFEM enables the accurate approximation of solutions with jumps, discontinuities or general high gradients across interfaces. The dissipation of the sound power into a plate/cavity system shows the efficiency of this composite to achieve noise reduction better to that obtained at low and higher frequencies with traditional foams. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A general modelling framework and specific mechanical approaches to simulate curing phenomena in polymers
Authors: Landgraf Ralf , Ihlemann Jörn 
Published: October 2016

AbstractPolymers are employed as adhesives, filling or sealing materials, among others. Within these applications, a chemical reaction (e.g. polymerization) leads the materials to cure from a liquid to a solid. In this contribution, first a general continuum mechanical modelling framework for the simulation of curing phenomena is highlighted. It takes into account the main chemical, thermal and mechanical phenomena of polymeric curing processes. Secondly, different mechanical models to capture the mechanical behaviour of polymeric curing processes are regarded. It is shown that elastic, viscoelastic and viscoplastic models at large deformations can be employed. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computational Excavation Analysis of a Single Cutting Tool using a Hypoplastic Constitutive Model
Authors: Leon Abdiel Ramon , Dang Thai Son , Meschke Günther 
Published: October 2016

AbstractWe propose a computational model for the numerical analysis of the dynamic interaction between a single excavation tool and the surrounding soil. An incremental non‐linear (hypoplastic) constitutive model is employed to capture the complex response of soft soils. Large displacements and deformations are handled by an Updated Lagrangian formulation, the particle finite element method (PFEM). (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Localized modes at defects in sonic composites
Authors: Moşneguţu Valerica 
Published: October 2016

AbstractThe paper discusses a sonic composite consisting of an array of silicone rubber coated hollow steel cylinders embedded in an epoxy matrix, with linear defects. Such structures allow localization of modes in the vicinity of the line defect with propagation along this line. The material in the vicinity of the line behaves like frequency‐specific mirrors. The mirrors localize waves within a finite region of the line defect, and modes are quantized into discrete frequencies. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the non‐periodic multilayer films
Authors: Munteanu Ligia 
Published: October 2016

AbstractThe non‐periodic multilayer film is studied in order to discern some of the most important features of periodic sonic composites, such as the full band‐gaps and modes that are localized around defects. The band‐gap for different number of Cantor elements into the film is analysed by taken into account the role of the fracton and phonon vibration regimes in the wave propagation. The film can prohibit the propagation of Lamb waves in the Ox1 direction. The band‐gap is generated in the band structure of the structure, meaning that the surface waves are forbidden to propagate with certain frequencies in the Ox1 direction. The structure of the band‐gaps for different number of Cantor elements into the film is analysed. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Extended balance of linear momentum from higher gradient stress field theory
Authors: Münch Ingo , Wöhler Franziska 
Published: October 2016

AbstractWe present the equation of linear momentum considering higher gradients for stress and body force. Both are approximated via Taylor series expansion within a finite Cauchy cube of dimensions Lc. Whereas linear terms of the series expansion result to the classical balance of linear momentum, terms up to third order yield an extended balance equation. The extension includes an internal length scale L2c caused by surface integrals on the cube. The approach makes use of Cauchy's theorem and standard Newtonian mechanics but constitutive assumptions are not applied. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Constitutive modeling of ferromagnetic and ferroelectric behaviors and application to multiferroic composites
Authors: Avakian Artjom , Ricoeur Andreas 
Published: October 2016

AbstractIn this paper, the constitutive modeling of nonlinear multifield behavior as well as the finite element implementation are presented. Nonlinear material models describing the magneto‐ferroelectric or electro‐ferromagnetic behaviors are presented. Both physically and phenomenologically motivated constitutive models have been developed for the numerical calculation of principally different nonlinear magnetostrictive behaviors. Further, the nonlinear ferroelectric behavior is based on a physically motivated constitutive model. On this basis, the polarization in the ferroelectric and magnetization in the ferromagnetic and magnetostrictive phases, respectively, are simulated and the resulting effects analyzed. Numerical simulations focus on the calculation of magnetoelectric coupling and on the prediction of local domain orientations going along with the poling process, thus supplying information on favorable electric‐magnetic loading sequences. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Time‐adaptive non‐linear finite‐element computations for thermo‐mechanically coupled analysis in inelastic dynamical systems
Authors: Grafenhorst Matthias , Hartmann Stefan , Rang Joachim 
Published: October 2016

AbstractIn structural dynamics the initial boundary‐value problem has to be solved in the space and time domain. The spatial discretization is done using finite elements yielding systems of differential equations of second‐order. Incorporating inelastic material properties, thermo‐mechanical coupling and particular Dirichlet boundary conditions essentially changes the underlying mathematical problem. The main goal is to provide higher‐order time integration schemes using diagonally‐implicit Runge‐Kutta methods (DIRK) and the Generalized α‐method consistently applied to the semi‐discretized ODE‐system comprising the semi‐discretized equations of motion, the unsteady semi‐discrete heat equation and constitutive equations of evolutionary‐type. Furthermore, we want to show the applicability of time‐adaptivity by embedded schemes so that step‐sizes are chosen automatically. The inelastic constitutive equations are given by a thermo‐viscoplasticity model of Perzyna/Chaboche‐type with non‐linear kinematic hardening. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magneto‐Structural analysis of rotating electrical machines
Authors: Haas Stefan , Mair Mathias , Ellermann Katrin 
Published: October 2016

AbstractThe vibrations of the stator core of a rotating electrical machine induce acoustic noise. These oscillations of the stator yoke are excited of the force density due to the magnetic field in the air gap. This requires a transient magnetic field analysis coupled with a dynamic mechanical analysis. Coupling these two different physical fields results in a high numerical effort and usually one direction of the interaction is disregarded. This paper presents a method to calculate the vibrations of a stator core under design operating conditions. For this purpose, harmonic electromagnetic excitation forces have been calculated in a linear magnetic field analyses using the finite element method. The resulting forces have been applied to a linear structural dynamic FE model in the frequency domain. The results of the calculations are harmonic velocities specified by amplitude and phase from the structural surface of the stator core. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A ternary phase bi‐scale FE‐model for diffusion‐driven dendritic alloy solidification processes
Authors: Henning Carla , Moj Lukas , Ricken Tim 
Published: October 2016

AbstractIt is of high interest to describe alloy solidification processes with numerical simulations. In order to predict the material behavior as precisely as possible, a ternary phase, bi‐scale numerical model will be presented. This paper is based on a coupled thermo‐mechanical, two‐phase, two‐scale finite element model developed by Moj et al. [2], where the theory of porous media (TPM) [1] has been used. Finite plasticity extended by secondary power‐law creep is utilized to describe the solid phase and linear visco‐elasticity with Darcy's law of permeability for the liquid phase, respectively. Here, the microscopic, temperature‐driven phase transition approach is replaced by the diffusion‐driven 0D model according to Wang and Beckermann [3]. The decisive material properties during solidification are captured by phenomenological formulations for dendritic growth and solute diffusion processes. A columnar as well as an equiaxial solidification example will be shown to demonstrate the principal performance of the presented model. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of Multifield Processes Regarding the Life‐Cycle of Concrete Structures
Authors: Kowalsky Ursula , Cramer Friedhelm , Dinkler Dieter 
Published: October 2016

AbstractThe presented model allows for the description of the most important coupled processes in porous media, whereby focus is laid on concrete structures. It can be employed for a consistent numerical analysis within a monolithic solution algorithm. Mechanical processes are coupled with transport processes, e.g. of energy and humidity, as well as with chemical processes like depassivation due to chloride penetration, carbonation or dehydration. The coupled model enables the predictive analysis of the behaviour of concrete structures over their whole life cycle. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Smoothed Particle Hydrodynamics modelling of poroelastic media
Authors: Osorno Maria , Steeb Holger 
Published: October 2016

AbstractNumerical modelling of poroelastic properties in porous media allows widely varied investigations at low costs and relatively short times. The study of porous media is of high interest at different scales, in this case we focus our analysis at meso‐ and macroscale which is highly relevant e.g. in geothermal explorations. We model a biphasic poroelastic media assuming incompressible fluid and solid grains and a large solid‐fluid density ratio.Meshfree methods are nowadays more widely used due to the advantages that present in the simulation of large deformations. In this case we choose to employ the Smoothed Particle Hydrodynamics method (SPH), a Lagrangian method where the domain is discretized in particles. The solution is computed in parallel, which allows to simulate large domains more representative of the scale of our study cases.We validate our implementation with a classical consolidation problem and compare the simulated diffusion process with Terzaghi's analytical solution. Future work includes simulation of fractures initiation and propagation in the porous media at reservoir scale. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Continuum modeling of the swelling behavior of concrete when modified through superabsorbent polymers
Authors: Sauerwein Malte , Jänicke Ralf , Steeb Holger 
Published: October 2016

AbstractThe main purpose of our investigation is to model the physical solidification process of a concrete mixture, involving water absorbing constituents, i. e. Superabsorbent Polymers (SAP). In order to model the chemo‐mechanical swelling process, the system is described within the framework of the Theory of Porous Media (TPM). The swelling process is accounted for by including mass exchange terms between free and absorbed water. The chemo‐mechanical driving forces are deduced from non‐equilibrium thermodynamics while constitutive relations are motivated by appropriate micro‐models of the swelling process. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical investigation of vacuum‐assisted resin transfer moulding (VARTM) within deformable fibre fabrics
Authors: Schenke Maik , Ehlers Wolfgang 
Published: October 2016

AbstractThe VARTM procedure is a manufacturing step in the production line when building parts made of fibre‐reinforced plastics (FRP), such as glass‐ or carbon fibre‐reinforced plastics acronymed GFRP or CFRP, respectively. In the VARTM process, an initially dry (gas‐saturated) fibre‐fabric is gradually impregnated by resin, where the flow process is, besides the driving injection pressure, governed by the mutual interactions between the fabric, the resin and the ambient air. To predict the mechanical properties of the manufactured structure, simulations are vital.Within the present contribution, the simulation model proceeds from the macroscopic Theory of Porous Media (TPM), which intrinsically accounts for the interplay between the individual components, in particular, the fibre‐network, the ambient air and the resin, where the latter two simultaneously percolate through inter‐fibrous pore space. The underlying holistic modelling approach allows, on the one hand, for a continuous transition from the fully gas‐saturated towards the fully resin‐saturated state and, on the other hand, the consideration of the so‐called spring‐back effect. The presented simulation example investigates the model behaviour within a practically relevant application scenario. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)