bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Rayleigh quotient iteration for quadratic eigenvalue problems
Authors: Miller Urs , Gaul Lothar 
Published: December 2011

AbstractFor the direct solution of quadratic eigenvalue problems of the form (λ2M + P + Q)x = 0, a generalization of the Rayleigh quotient iteration is presented. Numerical simulations show good convergence for problems where the eigenvalues have nonzero imaginary part. The method is used to calculate eigenvalue paths of parameter dependent problems in structural dynamics. Bifurcations with double eigenvalues, which can occur in the path, are passed by using a perturbation of the velocity dependent matrix P. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear dynamic effects in automotive clutches
Authors: Tikhomolov Arsenty , Fidlin Alexander 
Published: December 2011

AbstractDynamic effects appearing in the dry friction clutches are very complex. The reason for this is the usual design of the clutches including complex two dimensional friction, unilateral contacts and nonlinear springs. The final quality of the clutch system for a customer depends among other criteria on the awareness of dynamic effects, which can affect functioning and comfort negatively.One of the usual nonlinear dynamic effects in the friction clutch is presented in this work. That is the problem of dynamic disengagement which can cause significant safety problems. First of all the global nonlinear dynamic behavior is considered roughly by means of an analytical approach. Secondly a MBS‐model, which includes not only the nominal design of the clutch system but also dispersion of several parameters, is used in order to identify the influence of the asymmetry on the dynamic behavior. Analytical and numerical results are compared with measurements. Finally a possible solution of the considered problem is presented. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A finite element model for biofilm volume growth
Authors: Bolea Albero Antonio , Böl Markus 
Published: December 2011

AbstractIn this work, we present a continuum‐based approach for biofilm volume growth. The deformation gradient will be multiplicatively decomposed into two parts: a growth part due to bacteria formation and an elastic part due to the interaction with the environment. In order to define the growth behaviour of biofilms, we use the Monod approach that depends non‐linearly on the substrate concentration. The substrate concentration in the biofilm is computed by means of a diffusion process, which includes substrate consumption, together with the mechanical behaviour as part of a coupled problem. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A finite element formulation of a viscoelastic model for dielectric elastomers
Authors: Bueschel Alexander , Klinkel Sven , Wagner Werner 
Published: December 2011

AbstractSmart materials by definition, are solids, fluids or gases which react independently on changing external conditions and modify one or more properties without external stimuli. Sensu lato an external energy can produce the reaction, such as stress, temperature, moisture, pH, magnetic or electric fields. The distinguishing characteristic for electroactive polymers (EAP) is, that they react with a deformation by the application of an electrical field. This contribution presents a nonlinear electro‐viscoelastic model for dielectric elastomers and its finite element implementation. This type of smart materials belong to the group of EAP's and consists out of soft elastomer between compliant and conducting electrodes. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Constitutive modelling of adhesively bonded joints
Authors: Burbulla F. , Matzenmiller A. 
Published: December 2011

AbstractThe non‐associated I1‐J2‐plasticity model accounts sufficiently well for the different mechanical behaviour of crashoptimized high‐strength adhesives under combined shear and tensile loading. This model is extended to material softening due to damage, rate‐dependency and a constitutive description for the mechanical behaviour of adhesively bonded joints under compression. The material parameters are identified by means of the FE‐analysis for the experimental setup of a sample of bluntly glued double tubes. A comparison of the simulated results with the experimental data proves the validity of the model. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Deep Drawing of Carbon Fibre Prepregs
Authors: Hankeln Frederik , Mahnken Rolf 
Published: December 2011

AbstractThe simulation of prepregs must regard highly anisotropic, viscoelastic and thermal‐chemical properties. To this end a constitutive model is split into an anisotropic elastic part, which represents the fibre fraction and an isotropic, viscoelastic part, representing the matrix. The second part also contains curing, causing a dependency on time and temperature. During real deep‐drawing processes large deformations up to 50 % occur, which is considered in a formulation at large strains. This model contains an anisotropic elastic part based on a Neo‐Hooke law enhanced by an anisotropic part. A viscoelastic part is added using Hencky‐strains and the work‐conjugate Hill‐stress to transfer a model for small strains into large strains. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Extension of the Arruda‐Boyce model to the modelling of the curing process of polymers
Authors: Hossain Mokarram , Steinmann Paul 
Published: December 2011

AbstractA phenomenologically motivated finite strain general framework to simulate the curing of polymer have been developed and discussed in our recently published papers [2,4]. The Arruda‐Boyce model is a classical hyperelastic model for polymeric materials. This contribution presents an extension of the Arruda‐Boyce model towards modelling the curing process of polymers following our previous framework. In this paper, we will show how to model the elastic behaviour and shrinkage effects of the polymer curing process in the isothermal case using the Arruda‐Boyce model. Several numerical examples have been demonstrated to verify our newly proposed modified approach in case of curing process. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A homogenization method for heterogeneous materials using a multi‐scale technique
Authors: Müller Wolfgang H. , Brandmair Andreas 
Published: December 2011

AbstractFor modern microelectronics solders lifetime and stability predictions are important. To perform such an analysis material properties are required. As electronic devices and the corresponding amount of matter used become smaller, the influence of a changing microstructure on mechanical properties must be considered. First some analytical methods were conducted for upper and lower bounds ignoring the exact geometric distribution of the solder phases. Second, analytical equations derived for geometries such as laminate structures were applied to examine the influence of the geometry on homogenized properties. Third, a multi‐scale approach for periodic media was presented allowing for a more general analysis of structures. We assume that the solder material is composed of periodic cells, which represent the properties of the whole structure. Composite materials with periodic structures can be investigated by using at least two scales. A global scale is related to the whole piece of material whereas a local scale is related to the periodic cell only. The constitutive equations are stated and a homogenization technique for the elastic properties of arbitrary structures is derived. The resulting equations are solved numerically and results are presented. Again, for layered materials closed‐form formulas are derived and compared to the numerical results. The method is also used to obtain effective mechanical properties for materials with linear hardening. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dislocation Transport in Single Crystals and Dislocation‐based Micromechanical Hardening
Authors: Wulfinghoff Stephan , Glavas Vedran , Böhlke Thomas 
Published: December 2011

AbstractThe higher‐dimensional kinematical dislocation continuum theory of Hochrainer (2006) and a homogenized version thereof by Hochrainer, Zaiser and Gumbsch (2010) are reviewed. A three‐dimensional Finite Element solution of the homogenized theory is presented, interpreted physically and compared to the results of the Geometrically Necessary Dislocations theory. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiphase Field Modeling Chemical Vapor Infiltration of SiC/SiC Composite
Authors: Zhu Yaochan , Schnack Eckart , Li Aijun 
Published: December 2011

AbstractA novel multiphase field model is formulated to describe the complex microstructure evolution during Chemical Vapor Infiltration(CVI), which is one of the important method to produce the SiC matrix composites reinforced by SiC fibers in ceramic engineer. The model is composed of a set of nonlinear partial differential equations by coupling Ginzburg‐Landau type phase field equations with mass balance equation. Mathematically, the codeposition of SiC, Si and C during CVI process is a typical free boundary problem. When this problem is handled by multiphase field method, it's greatly facilitated because of the implicitly boundary‐tracking technique by phase field order parameters. This typical multiphysic field problem is solved by finite element software COMSOL. The numerical results show good agreement with experimental research. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Capillary Effects and Phase Transition under Freezing and Thawing Load in Liquid and Gas Saturated Porous Media
Authors: Bluhm Joachim , Bloßfeld Wolfgang Moritz , Ricken Tim 
Published: December 2011

AbstractIn this article, a quadruple macroscopic model for the simulation of freeze‐thaw cycles in liquid‐ and gas filled porous media is presented. Attention is paid to the description of capillary effects and phase transition. In effect, this model describes the following aspects: expansion of ice during freezing, liquid and gas pressure on the surrounding surfaces, capillary effects, temperature distribution, and the influence of filter velocities. The illustrated results of the numerical example show that the simplified model is capable of predicting physical and experimental observations. Besides the influence of heat of fusion, especially, capillary suction as well as frost suction in liquid‐ and gas filled porous media under cycling thermal loading will be presented. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A FEM‐BEM approach for Fluid‐Structure Interaction
Authors: Brändli Silvan , Abdel‐Maksoud Moustafa , Düster Alexander 
Published: December 2011

AbstractIn an earlier attempt to solve problems of Fluid‐Structure Interaction (FSI), a high‐order finite element code, which can be applied to solve problems of Computational Structural Dynamics (CSD) has been coupled to a Lattice Boltzmann (LB) fluid solver. In order to extend this approach to maritime applications and to increase the computational efficiency, the CSD solver is coupled to a fluid solver based on the Boundary Element Method (BEM). In this way, the computational effort for the discretisation of the fluid is significantly reduced. In this paper the proposed coupling scheme is discussed and compared to a FSI scheme where the BEM is replaced by a method based on the Reynolds‐averaged Navier‐Stokes equations (RANSE). Special emphasis is placed on the question of how to exchange the data between the different discretisation schemes and the development of a stable and efficient coupling scheme for FSI simulations. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A cellular automaton model for boundary friction of PEEK and PEEK6
Authors: Bubser Florian , Ostermeyer G.‐P. 
Published: December 2011

AbstractNowadays a common material for journal bearings is PEEK (Polyetheretherketon) which is increasingly used under boundary friction. A Cellular Automaton model is developed to describe the boundary layer dynamics of PEEK and its composite PEEK6 sliding against a steel surface. Whereas PEEK is a homogeneous synthetic material, PEEK6 contains also carbon fibres for stability and fillers working as solid lubricants. The automaton shows a representative area of the real surface. The processes in the interface are described by a set of rules based on physical assumptions and measurements. Based on these rules the simulations show the dependency of friction and wear on the load spectrum. The discrete simulation allows to observe the topographic development of the PEEK and PEEK6 surface as well as the build‐up of a transfer film on the steel surface. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Simulation of Free Surface‐Structure‐Interaction with Multi‐Regional Mesh Deformation
Authors: Fuchs Vilmar , Wünsch Olaf 
Published: December 2011

AbstractThe Fluid‐Structure‐Interactions (FSI) for technological constructions on sea are becoming nowadays very important in view of growing consumption of renewable energy sources. Exceptionally the offshore wind farms are exposed to extreme weather conditions due to breaking and non‐breaking wave loads. This work presents numerical Finite‐Volume‐Method (FVM) analysis of fluid and structure interactions with water waves impact on elastic solid structures. We develop a Free Surface‐Structure‐Interaction (FSSI) solver in OpenFAOM [1] with multi‐regional mesh deformation. A two dimensional numerical water impact model on a damping element prototype of an offshore wind turbin tower is investigated. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Two‐dimensional analysis of a crack in quasicrystal materials
Authors: Gao Yang , Ricoeur Andreas , Zhang Liangliang 
Published: December 2011

AbstractThe two‐dimensional problem of a crack in three‐dimensional quasicrystals subject to far field loadings is studied. The analysis is based on the generalized Lekhnitskii's formalism. The analytical expressions for both the entire fields and the asymptotic fields near the crack tip are determined. The fracture quantities of quasicrystals, i.e., field intensity factors, energy release rates and so on, is a prerequisite. Numerical results for a Griffith crack under phason loading Mode I and II conditions are poltted. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micro‐Electro‐Elastic Modeling of Electric Field‐ and Stress‐Driven Domain Wall Motion
Authors: Zäh Dominic , Rosato Daniele , Miehe Christian 
Published: December 2011

AbstractRecently, increasing interest in functional materials such as piezoceramics has been shown. Such materials are characterized by properties, which can be significantly changed by external stimuli, such as stress, electric or magnetic fields. We outline a micro‐electro‐elastic model for the evolution of electrically and mechanically poled domains incorporating the surrounding free space. To this end, recently developed incremental variational principles (Miehe & Rosato [1]) for local dissipative response need to be extended to gradient‐type phase‐field models, including an embedding into the free space. The variational setting serves as a natural starting point for a compact and symmetric finite element implementation, considering the mechanical displacement, the electric polarization treated as an order parameter, and the electric potential induced by the polarization as the primary variables. The latter is defined on both the solid domain as well as the surrounding free space. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical modelling of coupling mechanisms during freezing in porous materials
Authors: Zhou Mengmeng , Meschke Günther 
Published: December 2011

AbstractFreezing of porous materials is of interest for a wide range of engineering disciplines such as civil‐, geotechnical and environmental engineering as well as food industry. The freezing process is characterized by various couplings between the phase transition and the liquid transport within the pore space, accompanied by considerable deformations. This paper presents a macroscopic three‐phase finite element model of liquid‐infiltrated porous media subjected to freezing. For the description of the associated coupled thermo‐hydro‐mechanical behavior, the governing balance equations of the problem are formulated based upon the constitutive relations derived within the framework of thermo‐poro‐elasticity. The applicability of the model is shown by a simulation example of artificial ground freezing with coupled thermal‐hydro‐mechanical processes. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Asymptotics for a thin elastic fiber in contact with a rigid foundation
Authors: Bare Zoufine , Orlik Julia 
Published: December 2011

AbstractIn this work a 3‐D contact elasticity problem for a thin fiber and a rigid foundation is studied. We describe the contact condition by a linear Robin‐boundary‐condition (by meaning of the penalized and linearized non‐penetration and friction conditions). The Robin parameters are scaled differently in the longitudinal and cross‐sectional directions. The dimension of the problem is reduced by a standard ([3], [4]) asymptotic approach with an additional expansion suggested to fulfil the contact conditions. The 3‐D contact conditions result into 1‐D Robin‐boundary‐conditions for corresponding ODEs. The Robin‐coefficients of the 1‐D problem depend on the ones from the 3‐D statement and on the cross‐section of the fiber. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microscale modelling and homogenization of fiber structured materials
Authors: Fillep Sebastian , Steinmann Paul 
Published: December 2011

AbstractVarious phenomena occurring on the macrosscale result from physical and mechanical behaviour on the microscale [1]. For the mechanical modeling and simulation of the heterogeneous composition of fiber structured material, in addition to the material properties the contact between the fibers has to be taken into account. The material behaviour is strongly influenced by the material properties of the fiber, but also by the geometrical structure. Periodically arranged fibers like woven, knitted or plaited fabrics and randomly oriented ones like fleece can be distinguished in their arrangement. In consideration of different lengthscales the problem involves, it is necessary to introduce a multiscale approach based on the concept of a representative volume element (RVE). The macro‐micro scale transition requires a method to impose the deformation gradient on the RVE by suited boundary conditions. The reversing scale transition, based on the HILL‐MANDEL condition, requires the equality of the macroscopic average of the variation of work on the RVE and the local variation of the work on the macroscale [2]. For the micro‐macro transition the averaged stresses have to be extracted by a homogenization scheme. From these results an effective material law can be derived. Beside the theoretical aspects, we present the stress‐strain relation for RVE‐models and different boundary conditions. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear homogenization using the nonuniform transformation field analysis
Authors: Fritzen Felix , Böhlke Thomas 
Published: December 2011

AbstractThe homogenization of physically nonlinear composite materials with anisotropic morphology is investigated using the nonuniform transformation field analysis (NTFA) first introduced by [1, 2]. In this contribution a three‐dimensional finite element implementation (see [3]) of the NTFA is used for the homogenization of composite with morphological anisotropy (see also [4]). The main focus is on the application to structural problems with spatially varying orientation of near‐spherical and needle‐shaped particle reinforcements. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Adaptive Multi‐scale Modeling Error Estimation for Composites
Authors: Hajibeik Nasim , Temizer İlker , Löhnert Stefan , Wriggers Peter 
Published: December 2011

AbstractAbstract Analysing composite materials through efficient higher‐order homogenization techniques requires accurate simulations of highly heterogeneous domains. However the validity of the homogenization response in regions with highly localized variations is still questionable. A scale adaptation strategy is developed for a more accurate analysis of generally inelastic macrostructures, where a transition from a homogenized description to an explicit micro‐structural resolution is pursued. The designated zones of interest are indicated through two different methods of error estimation. First for mesh refinement approaches, the discretization error is estimated using an indicator developed by Zienkiewicz‐Zhu and studying L2 norm. Furthermore a second adaptation zone is identified based on a post‐processing step on the homogenized solution and corresponds to regions with high strain‐gradients, the gradient of the deformation gradient. In the designated sub‐domains a micro‐structure representation will replace the homogenized area. The introduced scale‐adaptivity method returns an inexpensive and more accurate analysis of composite materials. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Configurational forces in a multiscale approach to piezoelectric materials
Authors: Khalaquzzaman Md. , Müller Ralf , Ricker Sarah , Xu Baixiang 
Published: December 2011

AbstractDue to the growing interest in determining the macroscopic material response of inhomogeneous materials, computational methods are becoming increasingly concerned with the application of homogenization techniques. In this work, a two‐scale classical homogenization of an electro‐mechanically coupled material using a FE2‐approach is discussed. We explicitly formulated the homogenized coefficients of the elastic, piezoelectric and dielectric tensors for small strain as well as the homogenized remanent strain and remanent polarization. In the homogenization different representative volume elements (RVEs), which capture the micro‐structure of the inhomogeneous material, are used to represent the macroscopic material response. Two different schemes are considered. In the first case, domain wall movement is not allowed, but in the second case the movement of the domain walls is taken into account using thermodynamic considerations. Later this technique is used to determine the macroscopic and microscopic configurational forces on defects [2]. These defect situations include the driving force on a crack tip. The effect of the applied electric field on configurational forces at the crack tip is investigated. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling and numerical simulation of multiscale behavior in polycrystals via extended crystal plasticity
Authors: Klusemann Benjamin , Bargmann Swantje , Svendsen Bob 
Published: December 2011

AbstractThe purpose of this work is to exploit the algorithmic formulation of models for multiscale inelastic materials whose behavior is influenced by the evolution of inelastic microstructure and the corresponding material or internal lengthscales. The models for extended crystal plasticity are based on the formulation of rate potentials whose form is determined by (i) energetic processes via the free energy, (ii) kinetic processes via the dissipation potential, and (iii) the form of the evolution relations for the internal‐variable‐like quantities upon which the free energy and dissipation potential depend. Examples for these latter quantities are the inelastic local deformation or dislocation densities as GNDs. Different algorithmic implementations are discussed, namely the algorithmic variational approach and the dual mixed approach. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)