bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extension of DFM and MORPH in representative directions to viscous effects via Prony series approach
Authors: Kröger Nils Hendrik , Raghunath Rathan , Juhre Daniel 
Published: October 2016

AbstractIn this paper we present an extension of the material models DFM and MORPH formulated in representative directions via an approach for viscohyperelasticity based on a Prony series resp. integral approach. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental Validation of RVE Based Failure Simulations of Macro‐Porous Materials
Authors: Krummrich Phil Daro , Schneider Patrick , Hochrainer Thomas 
Published: October 2016

AbstractConnections between inhomogeneities and the failure behavior of brittle material may be investigated by finite element simulations of representative volume elements. Representative volume elements are typically subjected to periodic boundary conditions. Moreover, representative volume elements are often chosen as planar, i. e., two dimensional in order to reach reasonable statistics with regard to random distributions of inhomogeneities. The significance of such strongly simplified simulations needs to be validated, especially if the matrix failure is potentially dominated by defects, as is the case, e. g., in macro‐porous ceramics. We propose a quasi‐periodic concept to design specimens with cylindrical pores, which reproduce the stress state in a two dimensional representative volume element. This is achieved by a partial periodic replication of the region of interest. We suggest that material models used in simulations can be assessed by comparison between simulated and experimentally observed failure. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A finite element analysis of effects of ultrasonic welding parameters on the temperature distribution in wire bonding
Authors: Mostafavi Shimaalsadat , Markert Bernd 
Published: October 2016

AbstractWire bonding is an essential process in the automotive industry. Multi‐strand flexible aluminium cables are used for connection of different electronic components and electrical centres in cars. As an alternative for crimping technology in wire bonding, ultrasonic welding (USW) is applied, which is a rapid manufacturing process used to create solid joints between mating materials at low energy consumption compared to the known welding processes, such as oxy‐fuel welding and arc welding. An ultrasonic welding machine consists of different parts, such as pneumatic cylinder, piezoelectric converter, booster, welding sonotrode and anvil. Despite of the simplicity of the USW process, choosing the right machine and process parameters, like pressure of the pneumatic cylinder, welding time as well as vibration amplitude of the piezo‐converter, is a tricky and complicated task for obtaining an adequate bond. Experimental investigations done in this area are extremely time‐consuming and require a lot of effort. Therefore, some new approaches must be developed to understand the process in more detail. The present study focuses on the influence of the ultrasonic welding parameters, such as sonotrode pressure and vibration amplitude, on the temperature distribution at interfaces of two mating pieces in wire bonding [1,2]. Investigations are done by means of FEM simulations as well as by experiments. The results are then extended to thermo‐mechanical analysis of multi‐strand models. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Extending a finite strain hyperelastic micro‐sphere framework towards phase transformations
Authors: Ostwald Richard , Bartel Thorsten , Menzel Andreas 
Published: October 2016

AbstractA finite strain micro‐sphere framework for hyperelastic solids elaborated by Carol et al. is extended towards the modelling of phase transformations in order to simulate polycrystalline solids under large deformations such as, e.g., shape memory alloys and shape memory polymers. The implemented phase transformation mechanism is based on statistical physics and is not restricted in terms of the number of solid material phases that can be considered, though we restrict the provided examples to two phases for the sake of conceptual clarity. The specifically chosen non‐quadratic format of the Helmholtz free energy functions considered on the micro‐plane level includes Bain‐type transformation strains for each of the phases considered. Following the Voigt assumption on the micro‐scale, identical total micro‐stretches act in each of the material phases, where a multiplicative decomposition into elastic and transformation‐related contributions is applied. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A multiscale view on shape effects in the computational characterization of magnetorheological elastomers
Authors: Rambausek Matthias , Keip Marc‐André , Miehe Christian 
Published: October 2016

AbstractThis contribution highlights the influence of the shape of specimens of magnetorheological composites on their response under homogeneous magnetic fields. The analysis is performed in terms of two‐scale computational characterization using a finite strain homogenization framework. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Large strain constitutive modelling of cellulose aerogels
Authors: Rege Ameya , Itskov Mikhail 
Published: October 2016

AbstractIn this contribution, we propose a non‐linear constitutive model for cellulose aerogels subject to compression. The model is based on the cellular microstructure of aerogels formed of square shaped unit cells of varying pore sizes with an isotropic spatial distribution. Under uniaxial compression, these cells tend to bend non‐linearly until pore collapse. This cell bending is described by the extended version of the Euler‐Bernoulli beam theory for large deflections. The macroscopic free energy of the whole network is obtained by integration of the microscopic energies of cells over all spatial directions. Cellulose aerogels with different cellulose content are simulated using the proposed model. The model predictions show good agreement with experimental data. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of short fiber reinforced polymers
Authors: Röhrig Céline , Diebels Stefan 
Published: October 2016

AbstractThis contribution presents a possibility how to characterize composite materials with respect to experimental testing. Furthermore a modeling approach is presented based on the experimental results.Composite materials, like short fiber reinforced polymers, are of great interest because of their good properties for industrial applications. In this work a polybutylene terephthalate (PBT) reinforced by short glass fibers (GF) is characterized. An overview of the properties of the investigated material which are obtained from results of cyclic uniaxial tensile tests under monotonous and cyclic loading at a constant strain rate is given. The short fiber reinforced PBT shows elasto‐plastic material behavior and damage. The complete strain information in all directions is obtained by an optical area analysis over the whole surface using a digital image correlation (DIC) software. The optical sytem uses four cameras to realize a 360°‐3D‐measurement by a two‐sided stereography [2]. Based on the results of the experimental investigations with uniaxial tensile tests, a one‐dimensional macroscopic model to describe the material behavior is introduced and the results of the simulation are provided. The modeling description takes into consideration the observed behavior like elasto‐plasticity and damage. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Variational Treatment and Stability Analysis of Coupled Electro‐Mechanics
Authors: Vallicotti Daniel , Teichtmeister Stephan , Keip Marc‐André , Miehe Christian 
Published: October 2016

AbstractDielectric materials such as electro‐active polymers (EAPs) belong to the class of functional materials which are used in advanced industrial environments as sensors or actuators and in other innovative fields of research. Driven by Coulomb‐type electrostatic forces EAPs are theoretically able to withstand deformations of several hundred percents. However, large actuation fields and different types of instabilities prohibit the ascend of these materials. One distinguishes between global structural instabilities such as buckling and wrinkling of EAP devices, and local material instabilities such as limit‐ and bifurcation‐points in the constitutive response. We outline variational‐based stability criteria in finite electro‐elastostatics and design algorithms for accompanying stability checks in typical finite element computations. These accompanying stability checks are embedded into a computational homogenization framework to predict the macroscopic overall response and onset of local material instability of particle filled composite materials. Application and validation of the suggested method is demonstrated by a representative model problem. © 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microplane modeling of cyclic behavior of concrete: a gradient plasticity‐damage formulation
Authors: Zreid Imadeddin , Kaliske Michael 
Published: October 2016

AbstractA microplane model is developed to simulate the behavior of concrete under cyclic loading conditions. Pure damage mechanics or pure plasticity models yield satisfactory results for concrete under monotonic loading but cannot capture correctly the unloading and reloading response. Therefore, coupling damage and plasticity is necessary for accurate constitutive modeling of concrete. The microplane model offers a straightforward approach to simulate induced anisotropy by formulating the material laws on many randomly oriented planes. Distinguishing between compression and tension response using the proper plastic yield function and damage laws is considered. Furthermore, gradient enhancement is employed to handle the pathological mesh sensitivity related to strain softening. The new formulation is implemented within a 3D finite element code and a numerical example is simulated and compared to experiments in order to evaluate the capabilities of the model. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A multiscale approach to thermoplastic deformation
Authors: Čanađija Marko , Munjas Neven , Brnić Josip 
Published: October 2016

AbstractThe paper applies a multiscale formulation to thermoplasticity problems. The plasticity model is based on the variationally consistent formulation at the micro level. It is suitable for problems involving large strains. The temperature field is calculated at the macro level and is assumed to be homogeneous at the micro level. The proposed formulation is implemented in the Abaqus software by means of user subroutines. User subroutines are introduced both at the macro and at the micro level. The consistent tangent operator is calculated by the numerical differentiation procedure. Implementation details are briefly addressed. Finally, the methodology is verified on a representative example and relevant results are presented and discussed. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impact of heterogeneously distributed solid particles in the transition zone between porous and free flow domain
Authors: Falkner Nadine , Steeb Holger 
Published: October 2016

AbstractWe present a direct numerical simulation approach for the simulation of shallow water flow using the particle based meshfree Smoothed Particle Hydrodynamics (SPH) method. Simulations of single phase flow are done to characterize the occurring flow parameters on both macro‐scale and pore‐scale. More precisely, we examine initiation of motion and sediment transport as appearing at the interface between a free flow and porous flow domain under parallel flow conditions. Therefore we evaluate three theoretical models presenting analytical solutions for this coupled problem. Moreover, we discuss the influence of heterogeneities at the interface on forces on single grains by implementing and testing various microstructures into our numerical model. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Model reduction for multi‐component porous‐media models of biological materials using POD‐DEIM
Authors: Fink Davina , Ehlers Wolfgang 
Published: October 2016

AbstractIn the context of clinical treatment, reliable models of biological materials can provide further information of the occurring processes. For this purpose, the prediction of various simulation scenarios or real‐time simulations is desirable. A broad variety of biological materials, such as intervertebral discs or skeletal muscles, exhibit a porous microstructure and are conveniently simulated using a macroscopic continuum‐mechanical modelling approach. Therefore, the complex inner structure is regarded in a multi‐phasic manner using the Theory of Porous Media (TPM). The solution of the descriptive set of coupled partial differential equations (PDE) is approximated with the finite‐element (FE) method.In the context of FE simulations, computing time and numerical effort is an important issue because the number of degrees of freedom (DOF) of such coupled problems can become very large. To reduce the numerical effort, the method of proper orthogonal decomposition (POD) is applied in combination with the discrete‐empirical interpolation method (DEIM). Using the POD method, representative state variables (so‐called snapshots) are stored in pre‐computations using the initial full system and are approximated with a low‐dimensional subspace. Additionally, snapshots of the nonlinear terms of the differential equation are stored to approximate the nonlinearities using the DEIM. Dealing with porous‐media problems in biomechanical applications, the primary variables (such as the solid displacement or the pore pressure) exhibit a different temporal behaviour. In order to take this into account, the snapshots are divided in separated parts for each primary variable. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
3D Fluid‐Structure Interaction Experiment and Benchmark Results
Authors: Hessenthaler Andreas , Friedhoff Stephanie , Röhrle Oliver , Nordsletten David A. 
Published: October 2016

AbstractTesting and comparison of well‐known and recently developed numerical methods and algorithms are the key for their thorough assessment and continued improvement. We will present a short overview of a new 3D FSI experiment that proposes steady and dynamic test cases (referred to as Phase I and Phase II), complementing well‐known standard benchmark problems. In this context, we discuss a mathematical FSI model, that has previously proofed capable of good predictions, and demonstrate that the periodic steady‐state solution for Phase II is insensitive to the initial deformation of the solid. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computational characterization of ferroelectric solids with a 3D Preisach model based on an orientation distribution function
Authors: Labusch Matthias , Schröder Jörg 
Published: October 2016

AbstractFerroelectric or ferromagnetic materials show an interaction between mechanical deformations and polarization or magnetization. A few multiferroic materials possess both ferroic properties and exhibit a magneto‐electric (ME) coupling. These ME properties can be achieved in two‐phase composites, which combine ferroelectric and ferromagnetic characteristics. To predict a realistic material behavior and a more precise ME coefficient, the application of suitable material models which describe the nonlinear hysteretic behavior is of particular importance. In the present contribution we focus on the characterization of a nonlinear ferroelectric material behavior, in terms of a 3D Preisach model based on an orientation distribution function. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling the constitutive behavior of ferroelectric, ferromagnetic and multiferroic materials by using the condensed method (CM)
Authors: Lange Stephan , Ricoeur Andreas 
Published: October 2016

AbstractDue to the multifunctional applicability, smart materials are of particular interest in the field of material modeling. Most of the developed models, describing the nonlinear behavior, are implemented within the framework of the Finite Element Method (FEM). However, most investigations are restricted to simple boundary value problems (BVP) under uniaxial loading and their goal is the calculation of hysteresis loops. Regarding this circumstance, the so‐called condensed method (CM) is introduced to investigate the macroscopic polycrystalline ferroelectric material behavior at a global material point without any kind of discretization scheme. In the presented paper, the CM is extended towards ferromagnetic and multiferroic material behavior. Moreover, numerical results for a pure ferromagnetic behavior and a comparison between the magnetoelectric coupling coefficient calculated by the FEM and the CM are presented. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A phase field model for martensitic transformations with a temperature‐dependent separation potential
Authors: Schmidt Simon , Plate Carolin , Müller Regina , Müller Ralf , Meiser Jerome , Urbassek Herbert M 
Published: October 2016

AbstractMetallic materials often exhibit a complex microstructure with varying material properties in the different phases. Of major importance in mechanical engineering is the evolution of the austenitic and martensitic phases in steel. The martensitic transformation can be induced by heat treatment or by plastic surface deformation at low temperatures. A two dimensional elastic phase field model for martensitic transformations considering several martensitic orientation variants to simulate the phase change at the surface is introduced in [1]. However here, only one martensitic orientation variant is considered for the sake of simplicity. The separation potential is temperature dependent. Therefore, the coefficients of the Landau polynomial are identified by results of molecular dynamics (MD) simulations for pure iron [1]. The resulting separation potential is applied to analyse the mean interface velocity with respect to temperature and load. The interface velocity is computed by use of the dissipative part to the configurational forces balance as suggested in [3]. The model is implemented in the finite element code FEAP using standard 4‐node elements with bi‐linear shape functions. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of contaminant migration in groundwater: A continuum mechanical approach using in the theory of porous media
Authors: Seyedpour S.Morteza , Ricken Tim 
Published: October 2016

AbstractOver the past few decades, soil and subsequently groundwater contamination have raised growing concern as factors threatening the life of humans and other organisms as well as agricultural production sustainability. This study focuses on continuum mechanical multi‐phase, multi‐component formulation within the theory of porous media (TPM) to simulate the convective as well as diffusive driven contaminant tranport in groundwater including conversion processes. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Magneto‐Mechanically Coupled Phase‐Field Model at Large Deformation
Authors: Sridhar Ashish , Keip Marc‐André , Miehe Christian 
Published: October 2016

AbstractThe aggregate magneto‐mechanical behavior of magneto‐rheological elastomers (MREs) stems from the magnetic properties of the ferromagnetic inclusion and the mechanical properties of the matrix material. We propose a large deformation micro‐magnetic theory, to predict the behavior and interaction of ferromagnetic particles inside an elastomeric matrix. A rate‐type variational principle, with the magnetization as the order parameter is proposed. A large deformation Landau‐Lifshitz‐Gilbert equation for the time evolution of the magnetization, is obtained directly from the proposed variational principle. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
External boundary value problems in the quasi static theory of elasticity for triple porosity materials
Authors: Svanadze Merab 
Published: October 2016

AbstractIn this paper the quasi static linear theory of elasticity for materials with triple porosity is considered. Basic external boundary value problems (BVPs) of steady vibrations are formulated. The uniqueness and existence theorems for regular (classical) solutions of these BVPs are established. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
External boundary value problems in the quasi static theory of viscoelasticity for Kelvin‐Voigt materials with double porosity
Authors: Svanadze Maia M. 
Published: October 2016

AbstractIn the present paper the linear quasi static theory of viscoelasticity for Kelvin‐Voigt materials with double porosity is considered. The basic external boundary value problems (BVPs) of steady vibrations in this theory are formulated. The uniqueness and existence theorems for regular (classical) solutions of the BVPs are proved by using of the potential method (boundary integral equations method) and the theory of singular integral equations. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A stereographic projection based phase field model for ferromagnetics
Authors: Zhou Ziqi , Yi Min , Xu Bai‐Xiang 
Published: October 2016

AbstractBy using the stereographic projection to satisfy the constant magnetization magnitude, a constraint‐free phase field model is developed for ferromagnetic materials. Implemented by finite element method, the model is shown to be capable of simulating magnetic domain, vortex, and hysteresis curves. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Aspects of computational homogenization in magneto‐mechanics
Authors: Zabihyan Reza , Mergheim Julia , Javili Ali , Steinmann Paul 
Published: October 2016

AbstractIn the present work, the behavior of heterogeneous magnetorheological elastomers undergoing large deformations under the action of magnetic fields is studied. First‐order computational homogenization is used to derive the homogenized stresses and magnetic inductions of the macro‐structure from the response of the underlying micro‐structure. Different types of boundary conditions are applied to solve the micro problem where the constitutive law is assumed to be known. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Partitioned treatment of surface‐coupled problems with application to the fluid‐porous‐media interaction
Authors: Jamei Said , Asgharzadeh Pouyan , Ehlers Wolfgang 
Published: October 2016

AbstractEmploying a decoupled solution strategy for the numerical treatment of the set of governing equations describing a surface‐coupled phenomenon is a common practice. In this regard, many partitioned solution algorithms have been developed, which usually either belong to the family of Schur‐complement methods or to the group of staggered integration schemes. To select a decoupled solution strategy over another is, however, a case‐dependent process that should be done with special care. In particular, the performances of the algorithms from the viewpoints of stability and accuracy of the results on the one hand, and the solution speed on the other hand should be investigated.In this contribution, two strategies for a partitioned treatment of the surface‐coupled problem of fluid‐porous‐media interaction (FPMI) are considered. These are one parallel solution algorithm, which is based on the method of localised Lagrange multipliers (LLM), and one sequential solution method, which follows the block‐Gauss‐Seidel (BGS) integration strategy. In order to investigate the performances of the proposed schemes, an exemplary initial‐boundary‐value problem is considered and the numerical results obtained by employing the solution algorithms are compared. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)