bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the vibrations due to thermal deflection of the drum in the coiling process
Authors: Holl Helmut J. , Hammelmüller Franz 
Published: December 2011

AbstractThe modelling of the coiling process involves a mechanical model of the dynamic system that consists of the rotating coiling drum and the axially and transversally moving strip. Due to the coiling a change of mass in the system takes place. For such a variable mass system a control volume concept has to be introduced in order to get the equations of motion of the dynamic system with variable parameters. A Runge Kutta time integration algorithm is applied to compute the solution. It is assumed that the outer radius of the coiling drum increases linear with the rotation angle. The bending deflection of the shaft results from an inhomogeneous temperature distribution within the coiled material on the coiling drum. Two different boundary conditions of the moving strip have been considered and it is demonstrated that the thermal deflection of the drum has a high influence upon the fluctuation of the strip force. For a given geometry and strip speed we obtain a critical thermal deflection where the minimum strip tension force is zero. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Jumping and hopping motion on sports surfaces – Energetic aspects vs. risk of injury
Authors: Körner Claudia , Seemann Wolfgang 
Published: December 2011

AbstractThe aim in high‐performance sports activities is reaching the optimum between high efficiency and low risk of injuries during workout. The goal of this contribution is to increase the understanding of these two facts while interaction between athletes and sports surfaces. A typical movement in sports activities is human hopping. Several studies on this topic have already been done, but to the best of our knowledge any of them uses a continuous model of the sports surface. Therefore, an Euler‐Bernoulli beam with visco‐elastic foundation is analysed. The human modelling is represented by a one‐dof‐oscillator. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the complexity of hydromount‐models in full vehicle simulation
Authors: Vilsecker Johannes , Mack Werner , Falkner Anton , Hanfstingl Robert 
Published: December 2011

AbstractThe influence of the complexity of hydromount‐models on the results in full vehicle simulation is studied. In particular, a Kelvin‐Voigt model, a linear lever model and a non‐linear model are assessed with respect to their predictive capabilities as compared to the necessary parameterization and computation efforts. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of dynamic brake pad properties on automotive disk brake squeal
Authors: Hornig Sylwia , Gräbner Nils , von Wagner Utz 
Published: December 2011

AbstractComparing different methods of characterizing dynamic properties of brake pad materials clearly shows, that those properties strongly depend on the boundary conditions as well as on amplitude and frequency in the excitation. Actually simulations of brake squeal suffer on the missing of correct material parameters identified under conditions relevant for squeal. The present paper gives inside into a method for the measurement and identification of linear and nonlinear brake pad material parameters identified under correct boundary conditions. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Longer time steps in explicit dynamics subject to small nonlinearities
Authors: Wolff Sebastian 
Published: December 2011

AbstractAn approach that increases the critical time step in explicit time integration is presented. By derivation as a variational integrator, symplecticity and momentum preservation are ensured. The linear response is assumed to be dominant and is integrated implicitly, while the nonlinear forces are explicitly integrated. MOLLY filters the high‐frequent portions of the nonlinear forces and increases the critical time step. An SDOF example and a structural example using modal reduction verify the improved stability. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A thermodynamically consistent model of shape‐memory alloys
Authors: Benešová Barbora 
Published: December 2011

AbstractThis contribution presents a non‐isothermal mesoscopic model of single‐crystalline shape‐memory alloys within the framework of continuum mechanics. We briefly recall static mesoscopic modeling concepts as presented in e.g. [4, 5] and propose a thermomechanically consistent model featuring the heat equation and thermo‐mechanical coupling. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micro‐mechanical study of interactions between polymers and filler aggregates
Authors: Dargazany Roozbeh , Itskov Mikhail 
Published: December 2011

AbstractFilled rubber‐like materials exhibit a complex, history‐dependent hysteretic behavior which is mostly due to damage of micro‐structures inside the rubber matrix. In this paper, we study the contribution of filler aggregates inside the elastomer to this damage behavior. To this end, a recently proposed multi‐scale model of single aggregates [1] is applied. The network decomposition concept adopted there is further extended here to an additional network [1] which takes into account elasticity of filler aggregates and polymer chains in their vicinity. This network is described by means of a 3D statistical volume element (SVE) obtained by homogenization over the aggregate size distribution within the rubber matrix. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface energies in microstructure of martensite
Authors: Goodarzi Mehdi , Hackl Klaus 
Published: December 2011

AbstractA continuum model for laminate geometry in microstructure of martensite, employing energy minimization, is presented. Ansatzes for twin interface energies as well as grain boundary energy are proposed. The model is applied to predict scale properties and geometrical characteristics of refinement and accommodation of microstructure. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Creep‐fatigue analysis of the steel AISI type 316 component failure
Authors: Gorash Yevgen , Altenbach Holm 
Published: December 2011

AbstractThe purpose of this work is to extend a typical creep‐damage model in order to describe material behavior under variable thermal and mechanical loading in wide stress range. The model basis is creep constitutive law in form of hyperbolic sine stress response function proposed by Nadai. The constitutive law is extended to assume the damage process under creep and fatigue by the introduction of scalar damage parameters and appropriate evolution equations according to Kachanov‐Rabotnov concept. The material constants for model are identified by fitting the experimental creep and low‐cycle fatigue data for the steel AISI type 316 at the range of temperatures 500°C – 750°C. The development of such model is motivated by the well described failure case study of high‐temperature components at unit 1 of Eddystone power plant, which have operated during 130520 hours under creep‐fatigue interaction conditions. The main steam piping (MSP) from this power plant is selected for thermo‐mechanical creep‐fatigue analysis applying the proposed material model. The estimated values of damage parameters comply with the real location of the component failure and a scatter of experimental data on creep‐fatigue interaction diagram. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Softening in Nanocrystalline Metals: Modeling of Grain Growth Induced Creep and Relaxation
Authors: Gürses Ercan , El Sayed Tamer 
Published: December 2011

AbstractA variational multiscale model is presented for grain growth in face‐centered cubic nanocrystalline (nc) metals. In particular, grain‐growth‐induced stress softening and the resulting relaxation and creep phenomena are addressed. The behavior of the polycrystal is described by a conventional Taylor‐type averaging scheme in which the grains are treated as two‐phase composites consisting of a grain interior phase and a grain boundary affected zone. Furthermore, a grain growth law that captures the experimentally observed characteristics of the grain coarsening phenomena is proposed. The model is shown to provide a good description of the experimentally observed grain‐growth‐induced relaxation in nc‐copper. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Regularized Sharp Interface Model for Martensitic Phase Transformations at Large Strains
Authors: Hildebrand Felix , Miehe Christian 
Published: December 2011

AbstractThe macroscopic mechanical behavior of many functional materials crucially depends on the formation and evolution of their microstructure. When considering martensitic shape memory alloys, this microstructure typically consists of laminates with coherent twin boundaries. We suggest a variational‐based phase field model for the dissipative evolution of microstructure with coherence‐dependent interface energy and construct a suitable gradient‐extended incremental variational framework for the proposed dissipative material. We use our model to predict laminate microstructure in martensitic CuAlNi. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effect of deposition in a model for quantum dot self‐arrangement
Authors: Maciek D. Korzec  
Published: December 2011

AbstractIn a recently derived thin‐film model that describes the self‐assembly of quantum dots, an atom deposition flux is added and its influence on the evolution of the nano‐crystals is analyzed. A qualitative agreement to experiments is achieved: A realistic Stranski‐Krastanov growth mode can be simulated, where the dot density grows with increased rates as it can be observed in experiments. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computational Homogenisation of Polycrystalline Elastoplastic Microstructures at Finite Deformation
Authors: Lehmann Eva , Loehnert Stefan , Wriggers Peter 
Published: December 2011

AbstractDuring sheet bulk metal forming processes both, flat geometries and three‐dimensional structures change their shape significantly while undergoing large plastic deformations. As for forming processes, FE‐simulations are often done before in situ experiments, a very accurate material model is required, performing well for a huge variety of different geometrical characteristics.Because of the crystalline nature of metals, anisotropies have to be taken into account. Macroscopically observable plastic deformation is traced back to dislocations within considered slip systems in the crystals causing plastic anisotropy on the microscopic and the macroscopic level. A finite crystal plasticity model is used to model the behaviour of polycrystalline materials in representative volume elements (RVEs) of the microstructure. A multiplicative decomposition of the deformation gradient into elastic and plastic parts is performed, as well as a volumetric‐deviatoric split of the elastic contribution. In order to circumvent singularities stemming from the linear dependency of the slip system vectors, a viscoplastic power‐law is introduced providing the evolution of the plastic slips and slip resistances.The model is validated with experimental microstructural data under deformation. Through homogenisation and optimisation techniques, effective stress‐strain curves are determined and can be compared to results from real forming processes leading to a suitable effective material model. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Damping Behaviour of Vibrating Shape Memory Alloy Rods Investigated by a Novel Constitutive Model
Authors: Leindl Mario , Fischlschweiger Michael , Oberaigner Eduard Roman 
Published: December 2011

AbstractHysteretic behaviour of shape memory alloys (SMAs) is highly important for design and applicability of these materials in active structural elements like rods. Especially the damping performance of SMAs depend strongly on their hysteretic characteristics. Experimental investigations show the influences of stress on the hysteretic cycle. The current study shows some computational results of a constitutive model which is capable to investigate the effect of an external applied stress field on the hysteretic cycle according to a recently developed method on the basis of statistical mechanics method. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A one‐dimensional approach to the chemical and thermo‐mechanical coupled modeling of curing adhesives including plasticity
Authors: Liebl Christoph , Lion Alexander 
Published: December 2011

AbstractThe modeling and simulation of curing adhesives is of great importance for industrial applications, mainly for the automotive industry. The one‐dimensional model proposed here combines known viscoelastic models for curing material with effects of plasticity. To describe these plasticity effects, a yield stress with isotropic hardening is formulated as an equation of temperature and degree of cure. The proposed model therefore includes viscoelastic properties, thermo‐chemical shrinkage and the aforementioned plasticity characteristics, all as functions of temperature and degree of cure. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantification of the degree of irreversibility in terms of material parameters by using Ziegler's non‐linear constitutive relation for the stress‐velocity gradient relationship
Authors: Müller Wolfgang H. , Emek Abali B. 
Published: December 2011

AbstractThe non‐trivial task of an engineer is to derive or at least to use a constitutive relation which leads to a solvable equation but still expresses the system behavior adequately, so that the solution for the motion is accurate. Often the system has solid‐like or fluid‐like behavior, and an appropriate relation is chosen. In the so‐called Bingham‐Ilyushin matter both regimes occur simultaneously. This can be expressed by using a tensor‐linear constitutive relation with a nonlinear (viscosity) term and even be solved in a specific case of material parameters (b = 0). The analytical solution for the velocity distribution in a channel with moving walls is presented here. The velocity gradients lead to an increase in temperature. The internal friction due to the (nonlinear) viscosity contributes to the entropy production and accounts for the irreversibility of the process. The aim is to analyze the role of each material parameter in the entropy production which might be used as a measure of irreversibility of the process. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling the material behaviour of magnetorheological fluids under shear deformation
Authors: Obst Martin , Kästner Markus , Adam Frank , Brummund Jörg , Ulbricht Volker 
Published: December 2011

AbstractIn recent years the interest in materials with specific adjustable properties has increased due to higher requirements on the material performance. Here a smart composite material is to be developed, whose stiffness can be varied subjected to a magnetic field. To realise this aim a magnetorheological fluid (MRF) embedded in a polymeric matrix material is considered. To model the material behaviour of the composite a homogenisation method will be applied. Amongst others this requires the knowledge of the multiaxial material behaviour of each constituent. The modelling of the material behaviour of MRF under shear deformation, which is the aim of this work, represents the first step in this process. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interaction of phase‐transformations and plasticity – a multi‐phase micro‐sphere approach
Authors: Ostwald Richard , Bartel Thorsten , Menzel Andreas 
Published: December 2011

AbstractWe present an efficient model for the simulation of solid to solid phase‐transformations in polycrystalline materials. As a basis, we implement a scalar‐valued Gibbs‐energy‐barrier‐based phase‐transformation model making use of statistical physics. In this work, we particularly adopt the model for the simulation of phase‐transformations between an austenitic parent phase and a martensitic tension and compression phase. The incorporation of plasticity phenomena is established by enhancing the Helmholtz free energy functions of the material phases considered, where the plastic driving forces acting in each phase are derived from the overall free energy potential. The coupled model is embedded into a micro‐sphere formulation in order to simulate three‐dimensional boundary value problems—a technique well‐established in the context of computational inelasticity at small strains. It is shown that the model is capable of reflecting experimentally observed behaviour. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling the hydrogen material interaction as parametric instability of the continuum
Authors: Polyanskiy Vladimir , Yakovlev Yuriy 
Published: December 2011

AbstractThe hydrogen is contained in any material. Its concentration inside the materials leads to mechanical properties degradation. The two‐continuum model of solid allows one to describe the influence of small concentration of hydrogen on the mechanical properties of materials in terms of changing the bonding energy of the second continuum, the latter being responsible for the hydrogen concentration. The application of this model to fatigue task give the hydrogen concentration that are critical for material destruction. Such fatigue destruction has a nature of parametric instability during the cyclic redistribution of the hydrogen under the cyclic loading. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase Field Modeling of Crack Propagation at Large Strains with Application to Rubbery Polymers
Authors: Schänzel Lisa , Hofacker Martina , Miehe Christian 
Published: December 2011

AbstractThe computational modeling of failure mechanisms in solids due to fracture based on sharp crack discontinuities exhibits drawbacks in situations with complex crack topologies. This drawback is overcome by diffusive crack modeling based on the introduction of a fracture phase field characterizing via an auxiliary variable the crack topology. In the following we extend recent advances in phase‐field‐type fracture based on operator split techniques, suggested in Miehe et al. [1], to the modeling of crack propagation in geometrically large deforming solids e.g. rubber‐like materials. An extremely robust algorithmic treatment based on an operator split scheme is introduced consisting of three steps. Updating i) a local history‐field containing the maximum reference energy, ii) the fracture phase field, and iii) the displacement field. We demonstrate the performance of proposed phase field formulation for largely deforming solids by means of a representative numerical example. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Analysis of Soils using an Abaqus‐PANDAS Interface
Authors: Schenke Maik , Ehlers Wolfgang 
Published: December 2011

AbstractThe foundation of buildings proceed from a detailed analysis of the interaction between the building and its environment in order to reduce the costs and ensure safety of the construction. A detailed and reliable analysis of the building‐foundation interaction requires suitable material definitions, an accurate description of the underground, and a model describing the geometry. Following this, a fluid‐saturated soil model, based on the the Theory of Porous Media, will be implemented into the finite‐element research‐code PANDAS, which will be connected to commercial FE package Abaqus. In this regard, one combines the powerful graphical user interface (GUI) for pre‐ and post‐processing and the algorithms of Abaqus with the convenient scripting environment for material definitions of PANDAS. Moreover, the linkage allows for a straight‐forward transfer of PANDAS material models into a well‐known and widely used commercial FE package. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermodynamics in material space‐time
Authors: Schnepp Johannes 
Published: December 2011

AbstractThe concept of material forces is well established in the continuum theory of defects. These forces are quantities in a three‐dimensional material manifold. The manifold can be augmented to a four‐dimensional material space‐time by a time‐like coordinate.The inelastic phenomena caused by moving defects are highly dissipative. So a thermodynamic theory in material space‐time seems to be indispensable. Some first steps towards such a theory are developed here. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Three‐dimensional Continuum Theory of Dislocation Plasticity ‐ Modelling and Application to a Composite
Authors: Schulz Katrin , Sandfeld Stefan , Gumbsch Peter 
Published: December 2011

AbstractThe increasing demand for materials with well defined microstructure, which is accompanied by the advancing miniaturization of devices calls for physically motivated, dislocation‐based continuum theories of plasticity. Only recently rigorous techniques have been developed for performing meaningful averages over systems of moving, curved dislocations, yielding evolution equations for a higher order dislocation density tensor. Our continuum dislocation theory allows for generalizing the planar system towards a three‐dimensional system, where dislocations may have arbitrary orientation and curvature. With the inclusion of curvature, the theory naturally takes into account a deformation‐induced increase in the overall dislocation density without having to invoke ad‐hoc assumptions about dislocation sources. A numerical implementation and some benchmark tests of this continuum theory for dislocation dynamics has already been discussed in the literature. In this paper, we apply this continuum theory to composite materials, where we analyze a plastically deforming matrix with an elastic inclusion. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlocal damage‐viscoplastic model for high temperature creep of single crystal superalloys
Authors: Trinh Bach Tuyet , Hackl Klaus 
Published: December 2011

AbstractA new nonlocal damage‐viscoplastic model for high temperature creep of single crystal superalloys is developed. It is based on the variational formulation consisting of free energy, plastic and damage dissipation potentials. Evolution equations for plastic strain and damage variables are derived from the minimum principle for dissipation potentials [1]. The model is capable of describing different stages of creep in a unified way. The evolution of dislocation densities of gamma and gamma prime phases in superalloys incorporates plastic deformation. It results in the time‐dependence of the creep rate in primary and secondary creep. Tertiary creep is taken into account by introducing local and nonlocal damage variables. Herein the nonlocal one is considered as numerical treatment to remove mesh‐dependence. Numerical results and comparisons with experimental data of the single crystal superalloy LEK94 are shown. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Geometrically Exact Incremental Variational Formulation for Phase Field Models in Micromagnetics
Authors: Ethiraj Gautam , Miehe Christian 
Published: December 2011

AbstractMagnetic materials have been finding increasingly wide areas of application. We focus here on the continuum modeling of such materials and present an incremental variational principle for a dissipative micro‐magneto‐elastic model. It describes the quasi‐static evolution of both magnetically as well as mechanically driven magnetic domains, which also incorporates the surrounding free space. Furthermore, the algorithmic preservation of the geometrical nature of the variables is an important challenge from the numerical perspective and to this end we present a novel FE discretization whereby the geometric property of the magnetization director is pointwise exactly preserved by nonlinear rotational updates at the nodes. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)