bluuebunny/crossref_metadata_2025_split huggingface dataset:
Implementation of a dissipation based path‐following method and its application to the simulation of nonlocal quasi‐brittle damage
Authors: Prüger Stefan , Balzani Daniel 
Published: March 2018

AbstractThe implementation of a path‐following method for the simulation of quasi‐brittle failure is discussed, which employs a constraint function based on the overall dissipation increment associated with the softening material. Spurious mesh‐dependency is avoided by a nonlocal integral formulation of the isotropic damage model. The performance of the method is illustrated for a one‐dimensional bar problem in which snap‐back behavior is observed immediately after damage initiation. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micromechanical Damage Modeling of Long Fiber Reinforced Composites With the Parametric Method of Cells
Authors: Schmerbauch Mario , Erler Felix , Matzenmiller Anton , Levi‐Sasson Aviad , Haj‐Ali Rami , Aboudi Jacob 
Published: March 2018

AbstractMicromechanical damage modeling is presented with the parametric high‐fidelity generalized method of cells for a long fiber reinforced composite. Two models for a planar single fiber repeating unit cell, including damage, are proposed. The first one, implemented with the spatial continuum damage mechanics, is based on the idea that volumetric defects occur in the material phases. The other one, modeled with the interface damage mechanics, is founded on the view that cracks as surface‐like de‐ fects cause the stress degradation. The potential and ability of both approaches to predict damage in first‐order homogenization is shown by comparing the simulation results with each other as well as with test data under uniaxial and biaxial stress loading. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A continuum model for intralaminar damage progression and delamination in layered composites
Authors: Höwer Daniel , Stier Bertram , Bednarcyk Brett A. , Fish Jacob , Reese Stefanie , Simon Jaan‐Willem 
Published: March 2018

AbstractThe accurate prediction of progressive damage is one of the key challenges in the design of layerd composites. To this end, a continuum damage model has been proposed recently, which can account for both inter‐ and intralaminar damage. This is accomplished by a modification of the damage interaction parameters. The procedure is applied to the example of a [0/90/0] carbon fiber reinforced cross‐ply. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of crack growth under mixed‐mode loading in 1D piezoelectric quasicrystals
Authors: Wang Zhibin , Ricoeur Andreas 
Published: March 2018

AbstractLacking translational symmetry in particular directions, quasicrystals (QC) are a new class of materials besides crystals and amorphous solids, where 1D means the atomic arrangement is quasiperiodic in one direction. Since the very first discovery in 1982, QCs have been implemented in many fields due to their peculiar properties. This work adopts the generalized linear elastic framework of fracture theory in quasicrystals and develops numerical tools to compute fracture quantities and crack growth paths. Under the intrinsic mixed‐mode loading, crack growth in several specimens is simulated and the influences of the phonon‐phason coupling effect as well as the electric field are investigated. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermally loaded elastic‐plastic shrink fit with FGM‐hub
Authors: Apatay Tunç , Arslan Eray , Mack Werner 
Published: March 2018

AbstractSubject of the investigation is an elastic‐plastic shrink fit with solid inclusion and functionally graded hub in a state of generalized plane strain. It is shown that by appropriate grading a substantial weight reduction while maintaining a satisfactory performance at elevated temperature during operation can be achieved. In particular, numerical results are given for a steel/aluminum FGM‐hub. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Advanced Rebar Formulation within a Thermo‐Mechanically Coupled Tire Simulation
Authors: Berger Thomas , Kaliske Michael 
Published: March 2018

AbstractAs shown in various experiments, coupling between the thermal and the mechanical field of a rolling tire in contact with a rigid surface can be observed. An increase of its temperature over time when rolling with a constant velocity can be seen. This phenomenon is caused by the viscoelastic material properties, where the dissipated energy will lead to a heating of the rubber. Also the constitutive behaviour will change, when the temperature increases. A nonlinear viscoelastic material model is chosen to model an amplitude dependency of the time dependent behaviour of the rubber, proposed by Bergström and Boyce [1].Another important part of a tire are the reinforcements, which are embedded inside the rubber. These consist mostly of steel or polyester. These materials are not known for a dissipative behaviour and will not contribute to the heating of the tire. However, they also change their properties with increasing temperature and have a significant influence on the overall tire properties. Even without a contribution to the heating, the reinforcements will change its conductivity and have to be taken into account.For an accurate and efficient way to model the thermo‐mechanical coupling, an in‐house framework [2] will be presented, by use of the Arbitrary Langrangian Eulerian formulation and a commercial code. It is assumed, that the temperature in circumferential direction will stay constant and instant coupling effects are negligibly small. Therefore, the problem is split into a thermal and a mechanical part, and the coupling quantities (dissipated energy and temperature) are updated in a sequential manner.A common practise to model the reinforcements in tires is to use smeared layers, which leads to some difficulties. First of all, the modelling is only valid for a really small spacing between the bars. Another problem is, that the smeared layers have to fit with the nodes of the rubber matrix. Because of that, the mesh has to be refined, which leads to an increasing computation time and can cause numerical difficulties, due to too small elements.In this contribution, a different way of modelling the rebars within a thermo‐mechanical coupled algorithm is presented without the assumption of a smeared layer and treat them as single rebars. In numerical examples, the advantages of the proposed method are presented and the difference to the classical approach is shown. Also, the influence of the reinforcements on the stiffness, heat generation and rolling resistance of the tire, will be discussed. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A machine‐learning approach to load‐monitoring based on guided waves
Authors: Hesser Daniel F. , Markert Bernd 
Published: March 2018

AbstractThe research field of structural health monitoring (SHM) describes the way to assess the structural integrity. The research objectives are broadly diversified, which are all addressing the improvement of SHM technologies. It is important to optimise the capability of sensor networks by applying intelligent signal processing models. These intelligent systems predict the health state based on acquired data in a real‐time environment. Piezoelectric sensor networks and guided‐wave based analyses are combined with machine learning to create an efficient load‐monitoring routine. This load‐monitoring approach is chosen to track any changes in the environmental conditions, which causes most of the problems in reference signal based damage detection. Therefore, the proposed load‐monitoring method can be used to compensate the influence of external changes on the acquired signals and improve the performance and robustness of future SHM systems. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the electromechanical coupling in rotordynamics of electrical machines
Authors: Boy Felix , Hetzler Hartmut 
Published: March 2018

AbstractIn this contribution the modelling of electromechanical interactions in electrical machines is revised and analysed. Based on Lagrange's equations of the second kind, approaches from literature are classified concerning the coupling between mechanical motion and electrical system behaviour. It is shown, that the modelling has a significant influence on the assessment of oscillations. This circumstance is shown investigating self‐excited oscillations in a 2‐pole asynchronous machine. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A note on a double‐serial switch‐spring‐parallel semi‐active connection element
Authors: Dahlmann Martin , Min Chaoqing , Sattel Thomas 
Published: March 2018

AbstractSubject is a semi‐active connection element consisting of two identical subsystems in series. Each subsystem is composed of one spring and one switch in parallel. The switch can prevent spring movement when closed. Thus, the potential energy in the spring is stored. The use of two subsystems in series allows to direct power from extension and compression into different springs, yielding two spring forces with different directions. Due to the mass inertia, fast switching between the two spring forces controls the position of a connected mass. Thus, the semi‐active connection element behaves similar to an actuator with the limitation that the average work vanishes. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase Field Modeling of Ductile Fracture in Soil Mechanics
Authors: Aldakheel Fadi , Kienle Daniel , Keip Marc‐André , Miehe Christian 
Published: March 2018

AbstractThis work outlines a rigorous framework for the ductile failure of frictional materials in elastic‐plastic soil mechanics undergoing large strains. Describing soil crack formation can be achieved in a convenient way by recently developed continuum phase field approaches to fracture, which are based on the regularization of sharp crack discontinuities [1]. This avoids the use of complex discretization methods for crack discontinuities, and can account for complex crack patterns. For frictional materials, a non–associative Drucker–Prager‐type elastic‐plastic constitutive model suitable for a wide range of applications in soil mechanics is developed. It is linked to a failure criterion in terms of the elastic‐plastic work density that drives the fracture phase field. We demonstrate the modeling capabilities and algorithmic performance of the proposed formulation by a representative numerical example that describes soil crack formation using elastic‐plastic fracture mechanics. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phenomenological modelling of curing phenomena in a PU based adhesive
Authors: Landgraf Ralf , Ihlemann Jörn 
Published: March 2018

AbstractIn this contribution, the phenomenological material modelling of a polyurethane based adhesive including the curing process is considered. First, the underlying chemical process is regarded. To this end, differential scanning calorimetry experiments were carried out, models for the reaction heat and a so called degree of cure were formulated, and the corresponding model parameters were identified. Moreover, uniaxial tension tests with cyclic loading scenarios on the fully cured material were conducted and revealed typical behaviour of elastomers, like hysteresis, Mullins effect and permanent set. Based on the experimental results, a constitutive model has been formulated to capture the mechanical behaviour of the material in the fully cured state. Finally, an approach to capture changes of the mechanical behaviour during the curing process has been realized. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Automated modeling of nickel‐based superalloys
Authors: Munk Lukas , Beese Steffen , Reschka Silvia , Wriggers Peter 
Published: March 2018

AbstractThroughout the last 60 years, nickel (Ni) based superalloys have been the standard high‐temperature material used in mobile and stationary gas turbines. The ever increasing temperatures necessitate further improvements of those alloys, foremost, enhancing their creep‐resistance. Creep denotes a macroscopic, permanent change of shape which, amongst other effects, stems from thermally and mechanically induced dislocation movement. The key microstructural feature of most modern alloys is a uniform distribution of particles of the L12‐ordered γ′ phase which are embedded into the nickel‐based matrix. Most importantly, these particles are impenetrable to matrix‐dislocations. This leads to numerous dislocation effects encountered in such microstructured alloys. A wealth of different material modeling‐approaches exists in the literature which try to capture creep behavior. Due to the multiscaled nature of the physical problem, most crystal plasticity approaches are phenomenological and, thus, rely on many parameters. Finding suitable constitutive equations that capture experimental results becomes a challenge. A large deformation crystal plasticity framework has been set up which allows for an efficient comparison of different material formulations. This has been achieved by the use of AceGEN. The analytically generated tangent‐subroutine is linked into a FEAP polycrystal plasticity model and thus, global quadratic convergence is reached. In future work, a variety of flow rules, dislocation density based (cross‐) hardening formulae and parameters can be studied in a unified way [6]. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical modeling of dynamic recrystallization in polycrystals
Authors: Nguyen Hai Van , Ebrahimzade Vahid , Hackl Klaus , Renner Jörg , Trinh Bach Tuyet 
Published: March 2018

AbstractThis paper is devoted to developing a mathematical model of dynamic recrystallization phenomena based on the earlier work of K. Hackl and J. Renner [1] for polycrystalline materials. In this model a variational approach employing a distribution function for dynamic recrystallization processes of polycrystalline materials is presented. It is based on a marching algorithm at the microscale as well as a homogenization procedure to arrive at the macroscale. The newly proposed theory is now used to improve the variational approach. Then this theory is applied within the homogenization procedure. A comparison of the present model with existing phenomenological ones is given. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Modeling of Memristive Material Behavior in the Context of the Finite Element Method
Authors: Obst Jonathan , Franze Andreas , Balzani Daniel 
Published: March 2018

AbstractSince HP‐Labs developed the first memristor as a technical device in 2008 (cf. [1]), electrical engineers are aware of its potential of revolutionizing electronics (cf. [2]). As analogies have a long tradition in various fields of science it is quite obvious to transfer the idea of the memristor in electric circuit theory to mechanics by electro‐mechanical analogies. This transfer already led to a generalized classification of devices for dynamical systems [3]. In particular, a mechanical memristor for a system with one single degree of freedom is a displacement‐dependent dashpot.To investigate the behavior of continuous solids which show memristive properties, the development of suitable three‐dimensional material models is desired. Thus, this paper investigates the implementation of a memristive material model in the context of the Finite Element Method. Therefore, one‐dimensional memristive material models are analyzed and a continuum‐mechanical, memristive material model is developed based on an adaption of the KELVIN‐VOIGT‐Model. Example problems are simulated to verify the characteristics of this material class. In particular, the slipknot‐shaped hysteresis of the stress‐strainrate‐curve and the memory effect can be shown. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An explanation of damage and failure in cellulose aerogels: modeling approach
Authors: Rege Ameya , Itskov Mikhail 
Published: March 2018

AbstractCellulose aerogels can be considered as foam‐like materials and have recently been modeled using micro‐mechanical approaches. The proposed microcell based models describe the constitutive response of these aerogels based primarily on the bending of the cell wall fibrils, and show good agreement with experimental data. Under compression, the cell walls are considered to undergo nonlinear bending. On the other hand, under tension the deformation in the cell walls is attributed to both, bending and stretching. Accordingly, the total aerogel network energy is divided into a bending one and a tension one. The cell walls undergoing such combined loading fail after reaching a critical normal stress value, and are then considered to no longer contribute to the total network energy. Material constants in these models are obtained from experimental observations, like for example, the pore‐size data analysis, thus resulting into physically motivated models. Finally, the models are also shown to be effective in predicting the constitutive response of other polysaccharidic aerogels. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of large strain creep with static and dynamic recovery under cyclic loading conditions
Authors: Shutov Alexey , Larichkin Alexey , Shutov Valeriy 
Published: March 2018

AbstractA new material model of finite strain metal creep is proposed. Transient effects occurring shortly after abrupt changes of the applied stress are captured by the model using the concept of nonlinear kinematic hardening. The evolution of the backstress tensor is affected by the static and dynamic recovery. In order to broaden the applicability range, the model includes the classical Kachanov‐Rabotnov damage evolution. Large strain kinematics is described using the assumption of a nested multiplicative split. The model is thermodynamically consistent, objective, and w‐invariant. The model is validated in MSC.MARC, basing on experimental data for the D16T aluminium alloy. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Grain boundary kinetics in polycrystalline material using orientation dependent interface energy
Authors: Khan Asim Ullah , Hackl Klaus , Baitsch Mattias 
Published: March 2018

AbstractThe Polycrystalline materials grain boundary structure, crystalline texture and grain surface morphology, each plays an important role in interface transport. Among the different surface evolution phenomenas, the objective of the current work is to study the kinetics of grooving by surface diffusion only. Most of the existing theoretical and computational models use two dimensional grooving with one dimensional surface evolution. Hackl, et al. [2] have presented a novel variational model of surface motion using a thermodynamic extremum principle for grooving and wetting under diffusion. This model is further extended to a three dimensional grain structure using two dimensional surface evolution [1].In this paper, the kinetics of grooving for a periodic polycrystalline aggregate is studied. An ansatz function for grain boundary energy is defined as a functional of grain orientation and boundary inclination. For such orientation dependent grain boundary energy, Herring's relation must be satisfied locally at each triple point of intersecting boundaries thus we have four equations at each node in a representative volume element(RVE). Such an overdetermined system is solved using a non‐linear optimization method with weak constraints for the grain boundary energies. The evolution of surface grooves is studied with isotropic surface energy and mobility. The effect of line mobility on surface evolution is also studied for the chosen RVE. A comparison is made between orientation dependent grain boundary energies and isotropic grain boundary energies. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of cyclic deformation behaviour of railway disc brakes under thermomechanical loading
Authors: Zhang Le , Ma Songyun , Markert Bernd 
Published: March 2018

AbstractMetallic materials of railway disc brakes exhibit viscoplastic deformation behaviour under cyclic thermomechanical loadings. In this study, a viscoplastic Chaboche model is applied to describe the inelastic deformation behaviour in the braking process incorporating the inhomogeneous variation of temperature. The rate‐dependent hardening behaviour of 28CrMoV5‐8 steel is modelled by employing combined nonlinear isotropic and kinematic hardening rules. Furthermore, a numerical integration algorithms of the constitutive model is developed by using the implicit backward Euler method. The constructed nonlinear algebraic equations are solved by coupling the improved Pegasus method [4] and Newton method. The proposed model is implemented in the finite element code ABAQUS via a user‐defined material subroutine (UMAT). Finally, finite element simulations including sliding friction and heat transfer between disc and pads are performed for the case of an emergency braking. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerische Strömungsanalyse von Kraftwerkstrennpfeilern unter Verwendung von RANS‐Turbulenzmodellen
Authors: Alfarra Anas , Seidel Christian , Ostermann Lars 
Published: March 2018

AbstractBei der Entwicklung von Wasserkraftanlagen ist die numerische Strömungsanalyse ein wichtiges Werkzeug für die Kraftwerksoptimierung. Auf Grund ihrer Effizienz und weitverbreiteten Anwendung im Wasserbau sind hierbei die numerischen Verfahren auf Basis von Flachwassergleichungen von besonderem Interesse. In [1] wurde das Potenzial solcher Verfahren bei der Optimierung der Strömung um Kraftwerkstrennpfeiler erfolgreich aufgezeigt und Optimierungskriterien herausgearbeitet sowie der Nachweis erbracht, dass die qualitative Formoptimierung mit Flachwassergleichungen möglich ist. Die Frage nach dem Turbulenzeinfluss stellt in diesem Kontext einen interessanten Aspekt dar, weshalb am Beispiel des Kraftwerktrennpfeilers dieser mittels eines RANS‐Turbulenzmodelles [2] für eine geschlossene Kanalströmung untersucht und mit den Ergebnissen in [1] und [4] verglichen wird. Die Unterschiede beider Modellansätze werden herausgearbeitet, der Einfluss der Turbulenz erklärt und die ermittelten Optimierungskriterien hinsichtlich ihrer Gültigkeit auch bei Berücksichtigung der Turbulenz überprüft sowie die durch den Turbulenzeinfluss verursachten Strömungsphänomene aufgezeigt. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Boundary element and finite element analysis for the efficient simulation of fluid‐structure interaction and its application to mold filling processes
Authors: Harmel Maximilian , Sauer Roger A. 
Published: March 2018

AbstractMetal casting and polymer molding are widely used for the economical shape processing of complex geometries. In these manufacturing processes, a liquid melt (metal, mineral or synthetic) is filled into a mold with a cavity of the desired shape. Cooling and solidification of the melt results in a product with almost the same shape as the cavity. Numerical simulations can be employed to increase the accuracy of the process. To this end, boundary element method for Stokes flow and a finite element formulation for liquid membranes are investigated in this work. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical study on the fluid‐structure interaction in a model aquatic canopy flow
Authors: Meller Richard , Tschisgale Silvio , Fröhlich Jochen 
Published: March 2018

AbstractThis work presents numerical simulations and selected results of the flow over aquatic canopies, consisting of artificial flexible rectangular blades, arranged in a well‐defined order. The results obtained with three different Reynolds and Cauchy numbers are compared with experimental data achieving good agreement. The considered range of Cauchy numbers represents three different types of canopies ranging from rigid up to highly flexible plants. The transient flow data and blade positions are statistically analyzed to gain deeper understanding of the complex physical processes for this kind of fluid structure interaction. For example, the correlation of role of large scale motion of the flexible blades in conjunction with coherent vortex structures of the flow is addressed. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)