bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical and experimental investigations of dynamic contact phenomena in jointed structures
Authors: Süß Dominik , Geisler Johannes , Willner Kai 
Published: November 2010

AbstractStructural dynamic properties like stiffness and damping are strongly influenced by contact phenomena in jointed structures. Therefore numerical and experimental investigations are presented, in order to understand and predict the behaviour of such mechanical devices. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the effect of different parameterizations of the flow rule on the efficiency of variational constitutive updates
Authors: Bleier Nikolaus , Bruhns Otto T. , Mosler Jörn 
Published: November 2010

AbstractThe numerical efficiency of so‐called variational constitutive updates for finite strain plasticity theory is analyzed. These updates compute the unknowns such as the plastic strains by minimizing an appropriate functional. Within the present paper, different parameterizations of the flow rule are utilized within the variational constitutive update scheme. It is shown that comparing to the return‐mapping algorithm, the variational updates require significantly less iteration steps and thus, is numerically highly efficient. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mechanic‐Stochastic Model for the Simulation of Polycrystals
Authors: Montalvo‐Urquizo Jonathan , Bobrov Pavel , Schmidt Alfred , Wosnoik Werner 
Published: November 2010

AbstractA mechanic‐stochastic model for the mechanics of polycrystal material based on the single crystal orientations is presented. With this method, the distributions of strain and stress tensor components can be obtained in practice. Specific examples of computed distributions are shown, together with the distributions of the FEM‐calculated mechanical responses of a polycrystal. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Estimate of the Thermoelastic Properties of Pyrolytic Carbon based on an Image Segmentation Technique
Authors: Böhlke T. , Lin S. , Piat R. , Heizmann M. , Tsukrov I. 
Published: November 2010

AbstractThe submicrostructure of Pyrolytic Carbon (PyC) can be described as an aggregate of approximately coherent domains with different orientations. The domains themselves exhibit a hexagonal material symmetry. In order to apply statistical homogenization schemes [1] which predict the thermomechanical properties in terms of the microstructural characteristics, a quantitative description of PyC microstructures based on experimental data is a precondition. In the study, a new efficient image segmentation technique is applied which extracts from micrographs the one‐ and two‐point correlation functions of domain orientation which are necessary for computing bounds of the thermo‐elastic properties of PyC. The segmentation technique, which segments the micrograph into regions with approximately coherent orientations, uses the distribution of Local Binary Patterns (LBPs) [4] for determining the similarity of adjacent image regions. This region‐based algorithm yields a first coarse image segmentation. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
3D finite element analysis of biofilm growth considering nutrient diffusion
Authors: Bolea Albero Antonio , Bertsch Christine , Böl Markus 
Published: November 2010

AbstractThere exist a lot of models that are able to describe the behavior of biofilm systems. They can be classified into (1) analytical models, (2) pseudo‐analytical models, and (3) numerical models. Based on the numerous advantages of numerical models in this work a 3D mechanical biofilm model is discussed and implemented into a finite element program in order to simulate growth effects coupled with the nutrient diffusion through the biofilm. Based on three‐dimensional biofilm structures, numerical examples are presented in order to show the ability of the new modeling approach. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiscale modeling of multiphase "in situ" composite
Authors: Bontcheva Nikolina , Parashkevova Ludmila 
Published: November 2010

AbstractThe elastic‐plastic behaviour of rapidly solidified Al based (FeSi)‐enriched alloys containing intermetallic compounds is considered. A new multilevel mechanical model for the “in situ” composite is proposed considering the aluminium matrix as a micropolar elastic plastic Cosserat material and the hardening phases as pure elastic ones. A two steps homogenization procedure is applied to obtain the overall properties of the multiphase “in situ“ composite, taking into account the existence of different sizes of intermetallic inclusions. A variational approach is applied to evaluate the equivalent stress on macro level at the transition from micro to macro scale. The model is developed using information provided by microstructural investigations and EDX analysis. The multistage bulk material manufacturing process from rapid solidified powders or ribbons is simulated using the Finite Element Method. The model is implemented as user subroutines into the FE code MARC. Numerical simulations are provided, corresponding to different values of metal forming parameters. The influence of the different inclusions sizes on the hardening behavior is discussed. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermoviscoelasticity of fibre reinforced rubbery polymers
Authors: Dal Hüsnü , Kaliske Michael , Hickmann Rico , Cherif Chokri , Jurk Rene , Heinrich Gert 
Published: November 2010

AbstractFibre or textile reinforcement is commonly used in order to enhance the directional mechanical and thermal properties of rubbery polymers. For the quantitative analysis and design of fibre reinforced elastomeric materials, precise description of the composite behaviour plays a crucial role. To this end, a coupled thermomechanical formulation at finite strains is presented. The anisotropic thermal and mechanical properties are homogenized analytically throughout the constitutive description. For the description of the directional mechanical properties, logarithmic strain measures at fibre orientation direction are introduced in order to describe the fibre behaviour. The viscosity plays a crucial role in the heating of rubber components under cyclic loading. Contribution of thermodynamically consistent heat sources to the thermal problem are also considered. The coupled finite element implementation based on the isothermal split algorithm is demonstrated by a benchmark numerical example. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the thermo‐mechanically coupled simulation of poly‐crystalline Shape Memory Alloys
Authors: Junker Philipp , Hackl Klaus 
Published: November 2010

AbstractWe present a thermo‐mechanically coupled model for poly‐crystalline shape memory alloys which accounts both for the localized phase transformations and the resulting heat production. The model is based on the physical principles of energy conservation and entropy maximization. Choosing an appropriate ansatz for the entropy production the evolution equation for the phases can be derived as well the heat conduction equation. The results show good agreement to experimental findings. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiscale Modelling of the Effective Viscoplastic Material Behaviour of Textile‐Reinforced Polymers Using XFEM
Authors: Kästner Markus , Obst Martin , Brummund Jörg , Ulbricht Volker 
Published: November 2010

AbstractIn this contribution a modelling approach using numerical homogenisation techniques is applied to predict the effective nonlinear material behaviour of composites from simulations of a representative volume element (RVE). Numerical models of the heterogeneous material structure in the RVE are generated using the eXtended Finite Element Method (XFEM) which allows for a regular mesh. Suitable constitutive relations account for the material behaviour of the constituents. The influence of the nonlinear matrix material behaviour on the composite is studied in a physically nonlinear FE simulation of the local material behaviour in the RVE ­ effective stress‐strain curves are computed and compared to experimental observations. The approach is currently augmented by a damage model for the fibre bundle. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A micromechanically motivated model for ferroelectrics combined with polygonal finite elements
Authors: Kaliappan Jayabal , Menzel Andreas , Arunachalakasi Arockiarajan , M Srinivasan Sivakumar 
Published: November 2010

AbstractPiezoelectric materials are one of the most prominent smart materials due to their strong electromechanical coupling behaviour. Ferroelectric ceramics behave like piezoelectric materials under low electrical and mechanical loads, but exhibit pronounced nonlinear response at higher loads due to microscopic domain switching. Modern smart devices consist of complex geometries that may force the ferroelectrics employed within them to experience higher fields than they were originally designed for, so that the material responds within its nonlinear region. Hence, models predicting the nonlinear effects of ferroelectrics under complex loading cases are important from the design point of view. Within standard finite element models dealing with electromechanical problems, each grain may be subdiscretized by several finite elements. This problem can be approximated or rather overcome by a polygonal finite element method, where each grain is modelled by solely one single finite element. In this contribution, a micromechanically motivated switching model for ferroelectric ceramics, as based on volume fraction concepts, is combined with polygonal finite element approach. Related representative numerical examples allow to further study and understand the nonlinear response of this material under complex loading cases. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Formation of persistent slip band‐structures during cyclic loading in finite‐strain crystal plasticity
Authors: Kochmann Dennis M. , Hackl Klaus 
Published: November 2010

AbstractCyclic loading of single‐ and polycrystals gives rise to complex structures and patterns on the material's microscale, which highly affect the macroscopic stress‐strain response. The formation of microstructures in finite‐strain crystal plasticity has been reasoned to stem from the non‐quasiconvexity of the underlying energetic potentials. As a consequence of such a lack of convexity, the material reduces its energy by breaking up into fine‐scale fluctuations of minimizing sequences, which correspond to the experimentally observed microstructures. Based on an incremental setting and relaxed potentials, we describe the formation and the time‐continuous evolution of laminate structures during cyclic loading. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vergleich zweier Ansätze zur Beschreibung nichtlinearer Viskoelastizität auf Basis des Maxwell‐Elements
Authors: Landgraf Ralf , Ihlemann Jörn 
Published: November 2010

AbstractViele Werkstoffe, wie Kunststoffe oder Elastomere, zeigen viskoelastisches Materialverhalten. Der Ansatz zur Modellierung dieses Materialverhaltens kann mit Hilfe sogenannter rheologischer Ersatzmodelle veranschaulicht werden, wobei ein wichtiger Bestandteil das Maxwell‐Element ist. Da die genannten Werkstoffe zum Teil großen Deformationen unterzogen werden, ist eine Modellierung des gesamten Materialverhaltens und somit auch des Verhaltens eines einzelnen Maxwell‐Elementes im Rahmen der nichtlinearen Kontinuumsmechanik durchzuführen. Es werden nunmehr zwei aus der Literatur bekannte Formulierungsvarianten für die kontinuumsmechanische Beschreibung des Materialverhaltens entsprechend eines Maxwell‐Elementes verglichen. Zunächst werden beide Modelle in einer ideal inkompressiblen Formulierung derart hergeleitet, dass sich bei einem Grenzübergang zur linearen Theorie identische Beziehungen ergeben. Weiterhin erfolgt eine Darstellung der numerischen Umsetzung sowie der Ergebnisse aus numerischen Untersuchungen unter homogenen Belastungen. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Boundary value problems of the theory of viscoelasticity for Kelvin‐Voight materials
Authors: Svanadze Maia M. 
Published: November 2010

AbstractIn this paper, the classical Kelvin‐Voight model of the linear theory of viscoelasticity is considered and the following results are obtained: the fundamental solution of the equation of steady vibrations is constructed, the basic properties of plane waves and elastopotentials are established, the uniqueness theorem of the internal and external boundary value problems (BVPs) are proved, the existence theorems for classical solutions of the BVPs by means of the potential method and the theory of two‐dimensional singular integral equations are proved. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the plane non‐stationary heat transfer in two‐phase hollow cylinder with radially graded material properties
Authors: Ostrowski Piotr 
Published: November 2010

AbstractThis consideration concerns heat transfer in two‐component composite with a deterministic microstructure, which is ‐periodic along the angular axis and has slowly varying effective properties in the radial direction (Fig.1). Therefore, we deal here with a special case of functionally graded materials, FGM, c.f. Suresh, Mortensen (1998). The main aim of this consideration is to capture effect of the discontinuous boundary conditions on the thermal field. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A micro‐sphere approach applied to the modelling of phase‐transformations
Authors: Ostwald Richard , Bartel Thorsten , Menzel Andreas 
Published: November 2010

AbstractWe present an efficient model for the simulation of phase‐transformations in polycrystalline materials. As a basis, we use a thermodynamically consistent, one‐dimensional phase‐transformation model, which is embedded into a micro‐sphere formulation in order to be able to simulate three‐dimensional boundary value problems. The underlying evolution equations are solved efficiently using a newly developed explicit integration scheme that has been proved to be unconditionally A‐stable. A numerical example by means of a deformation in simple shear is additionally provided in this contribution. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermoviscoplasticity of Glassy Polymers in the Logarithmic Strain Space Based on the Free Volume Theory
Authors: Schänzel Lisa‐Marie , Miehe Christian 
Published: November 2010

AbstractIn this contribution a new constitutive model of finite thermo‐visco‐plastic behavior of amorphous glassy polymers and details of its numerical implementation are outlined. In contrast to existing kinematical approaches to finite plasticity of glassy polymers, the formulation applies a plastic metric theory based on an additive split of Lagrangian Hencky‐type strains into elastic and plastic parts [1, 3]. The characteristic strain hardening of the model is derived from a polymer network model, the thermo‐visco‐plastic flow rule in the logarithmic strain space uses structures of the free volume flow theory [4]. The integration of this micromechanically motivated approach in a three‐dimensional computational model is the key novel aspect of this work. An important aspect of this work is the model validation based on experimental findings, whereas the excellent performance of the proposed formulation is demonstrated by means of numerical examples. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of thermo‐mechanical loading processes on amorphous thermoplastic polymers
Authors: Müller Susanne , Hempel Philipp , Seelig Thomas 
Published: November 2010

AbstractA constitutive model for the thermo‐mechanical behavior of amorphous thermoplastic polymers is presented that accounts for the dependence of the macromolecular network and entropic hardening on large temperature changes. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Are plastic yielding and work hardening sensitive to the boundary conditions?
Authors: Le Khanh Chau , Sembiring Pramio 
Published: November 2010

AbstractThe plane strain shear of a single crystal strip with one active slip system placed in a mixed device with one clamped and one free boundary is considered. Since dislocations pile up against only the clamped boundary, the plastic yielding and work hardening differ essentially from those of a hard device, showing clearly their sensitivity to the boundary conditions. An analytical solution to this problem within continuum dislocation theory is found explicitly which exhibits the energetic and dissipative thresholds for dislocation nucleation, the Bauschinger translational work hardening, and the size effects. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Explicit solution of the boundary value problems of the theory of elasticity for solids with double porosity
Authors: Tsagareli Ivane , Svanadze Maia M. 
Published: November 2010

AbstractIn this paper the Aifantis' theory of elasticity for solids with double porosity is considered and the 2D boundary value problem (BVP) of static is investigated. The uniqueness theorem of the internal BVP is proved. The explicit solution the BVP is constructed in the form of absolutely and uniform convergent series for a circle. The numerical solution of the BVP for a circle is obtained. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anisotropic multiplicative elastoplasticity for the prediction of earings in sheet forming
Authors: Vladimirov Ivaylo N. , Schwarze Marco , Reese Stefanie 
Published: November 2010

AbstractIn this work, the simulation of earings in cup drawing by means of a recently developed anisotropic combined hardening material model is discussed. The model represents a multiplicative formulation of anisotropic elastoplasticity in the finite strain regime with nonlinear kinematic and isotropic hardening. Plastic anisotropy is described by the use of second‐order structure tensors as additional arguments in the representation of the yield function and the plastic flow rule. The evolution equations are integrated by a form of the exponential map that preserves the plastic volume and the symmetry of the internal variables. Finite element simulations of cylindrical cup drawing processes are performed by means of ABAQUS/Standard where the discussed material model has been implemented into a user‐defined reduced integration solid‐shell element. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micro‐Mechanical Modelling of Anisotropic Time‐Dependent Healing Effects in Rubber‐like Materials
Authors: Weinhold Georg W. , Itskov Mikhail 
Published: November 2010

AbstractFiller‐reinforced rubber‐like materials demonstrate deformation induced softening, known as the Mullins effect. This softening can be reversible in a certain range (healing).The previously introduced concept of network evolution (NE) explains the Mullins effect as the result of a filler‐polymer network rearrangement [1]. It is assumed that debonding of polymer chain segments from rigid aggregates does not effect the number of active segments. Furthermore, debonded chains are still active as a part of a longer chain.Now, considering the entropic vibration of polymer chains, entanglement of chains to the rough aggregate surfaces is assumed. This process inverse to the NE leads to a micro‐mechanical model of time‐dependent recovery of the deformation induced softening. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
FEM Simulation of a Micromechanical Model for Textured Polycrystalline Shape Memory Alloys with n‐Variants
Authors: Wilmanns Stefan , Mahnken Rolf 
Published: November 2010

AbstractThis paper is about the numerical implementation of a known, but advanced model with a projected Newton algorithm and a residual including only two vectors of unknowns. In a complex stress driven example the superelastic behavior is investigated. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Die Nanoindentation als Instrument zur Bestimmung materialspezifischer Kennwerte als Funktion der Temperatur
Authors: Müller Wolfgang H. , Worrack Holger 
Published: November 2010

AbstractNeben mechanischen Beanspruchungen sind mikroelektronische Bauteile stets einer wechselnden thermischen Belastung ausgesetzt. Für die Gewährleistung zuverlässiger Fügeverbindungen ist daher die Kenntnis der materialspezifischen Kennwerte der Fügewerkstoffe in Abhängigkeit der Temperatur zwingend erforderlich. Die Nanoindentation erlaubt es aus einem Härteversuch Härte, Elastizitätsmodul und Fließgrenze der Probenmaterialien zu ermitteln. Eine zusätzliche HOTSTAGE‐Erweiterung ermöglicht zudem Messungen zwischen Raumtemperatur und +500°C. Neben dem Kalibrierwerkstoff Fused Silica und einem Kupferwerkstoff wurden verschiedene bleifreie Lote indentiert. Während bei Quarz und Kupfer die Entlastungskurve nahezu ideal verläuft und die implementierte Auswertesoftware korrekte Werte berechnet, neigen die Lotmaterialien bei steigenden Temperaturen zum Kriechen und die automatisierte Bestimmung der Materialkonstanten gestaltet sich somit schwierig. Diesem Problem versucht man sich nun mit einem viskoelastischen Materialmodel anzunähern. Ziel ist es dabei aus dem Kriechverhalten viskoelastische Parameter zu berechnen, die dann wiederum benutzt werden sollen, um die materialspezifischen Kennwerte bestimmen zu können. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gradient Plasticity for Single Crystals
Authors: Wulfinghoff Stephan , Böhlke Thomas 
Published: November 2010

AbstractThe kinematic relationship between classical single crystal kinematics and geometrically necessary dislocations will be clarified by a demonstrative example. The starting point for the dynamics is the contribution of geometrically necessary dislocations to the free energy, which leads to a kinematic hardening law. A simple two‐dimensional shear example will be discussed. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stability of a steady flow guided by flexible walls
Authors: Bach Karolina , Hetzler Hartmut , Seemann Wolfgang 
Published: November 2010

AbstractFlexible channels conveying fluid may loose stability by divergence or flutter, thus leading to undesirable dynamic behaviour. A lot of investigations have already been done on this subject, each involving structural models expressing a specific type of stiffness. The aim of this contribution is to investigate and compare systematically the influence of various types of structural stiffness on the stability behaviour of the coupled problem. Therefore, a simple, yet general model is built. The fluid is bounded by a rigid and an elastical supported, flexible wall, which exhibits bending and extensional stiffness and considers effects of pre‐load. The influence of the various characteristics on the stability of the steady state is discussed and a perturbation approach is used to investigate the influence of small nonlinearities. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Execution of active reduction of vibrations by means of kinematic excitations
Authors: Białas Katarzyna 
Published: November 2010

AbstractThe major objective of this study is to show how to carry out the process of structural and parametrical synthesis that is understood as a method intended to seek for the structure and parameters of a discrete model of the system with active suppression of vibrations. Active components are implemented as mechanical components with kinematic excitations. The other objective is to analyze how the active subsystem interacts with the overall investigated structure. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)