bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aspects of computational homogenisation of microheterogeneous materials including decohesion at finite strains
Authors: Loehnert Stefan , Wriggers Peter 
Published: December 2005

AbstractDuring the last years, the development and application of new composite materials gained more and more importance. For engineering applications it is necessary to get effective material properties of such materials. In this contribution we present some aspects of computational homogenisation procedures of microheterogeneous materials which can show decohesion in a cohesive zone around the particles. Due to the decohesion we get finite deformations and .nite strains within the RVE. The geometrical and material nonlinearities cause the main dif.culties. The homogenization procedure leads to an effective stress strain curve for the RVE, and for the nonlinear elastic case one can also obtain effective material parameters. It is necessary to do statistical tests in order to get a representative result. Here we set a special focus on the adaptive numerical model, the statistical testing procedure and the different boundary conditions (pure tractions and pure displacements) applied on the RVE. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phenomenological and Numerical Simulation of Shape Memory Alloys at Finite Strains
Authors: Luig Patrick , Müller Christoph , Oberste‐Brandenburg Claus , Bruhns Otto 
Published: December 2005

AbstractA phenomenological material law for pseudo elastic NiTi shape memory alloys (SMA) is presented. The model was derived from a thermodynamical framework and is well‐suited to describe the thermomechanical coupled behaviour of the material. The material law, which was originally derived for small deformations, was extended to finite deformations using the Eulerian frame, in particular Hencky's logarithmic strain and the logarithmic rate.A first emphasis is on the physical interpretation of the material parameters and their identification. A second focus lies in the presentation of a structural example for the implementation of the material law into a commercial Finite Element code. Additionally a comparison of the numerical and experimental data of the presented example is performed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Procedure for the implicit post buckling analysis with finite elements by stabilising the global stiffness matrix
Authors: Mueller Michael 
Published: December 2005

AbstractA simple procedure for the post buckling analysis is shown. In comparison to the arc length method no additional variable is required. The algorithm finds the solution for a prescribed time step. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On Biological Activities in Organic Materials
Authors: Ricken Tim 
Published: December 2005

AbstractIn this contribution a triphasic model (solid, interstitial water containing nutrients) is proposed for the phenomenological description of transversely isotropic saturated tissues including the phenomena of growth. This is done within the framework of a macro‐mechanical description based on the Theory of Porous Media (TPM). Thereby, the constitutive equation of growth is determined by the state of stress and the local content of nutrients which are responsible for the mass exchange. The transversely isotropic behavior of the solid influences both the stress response and the internal fluid flow, which is considered using an invariant formulation of the Helmholtz free energy, transversely isotropic stress response and transversely isotropic permeability functions. After presenting the developed framework of the calculation method some representative numerical examples are examined. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Poroelastodynamic Boundary Element Method in Time Domain: Numerical Aspects
Authors: Schanz Martin , Kielhorn Lars 
Published: December 2005

AbstractBased on Biot's theory the governing equations for a poroelastic continuum are given as a coupled set of partial differential equations (PDEs) for the unknowns solid displacements and pore pressure. Using the Convolution Quadrature Method (CQM) proposed by Lubich a boundary time stepping procedure is established based only on the fundamental solutions in Laplace domain.To improve the numerical behavior of the CQM‐based Boundary Element Method (BEM) dimensionless variables are introduced and different choices studied. This will be performed as a numerical study at the example of a poroelastic column.Summarizing the results, the normalization to time and spatial variable as well as on Young's modulus yields the best numerical behavior. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On an implicit particle method for simulation of forming processes
Authors: Schilling O. , Reese S. 
Published: December 2005

AbstractTask is the simulation of forming processes using particle methods. We implemented some mesh‐free methods (the element free Galerkin method [1] and others) and the finite element method in one programme system which permits a direct comparison. For the mesh‐free methods a moving least squares approximation is applied. The shape functions are not zero or one at the nodes, thus essential boundary conditions cannot be imposed directly [2]. We use a penalty method to enforce essential boundary conditions and contact conditions. The contact algorithm (normal contact of nodes to C1‐continuous surfaces) is checked by means of the element free Galerkin method and the FEM on the basis of numerical examples which deal with forming processes. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Primal and Dual Penalty Methods for Contact Problems with Geometrical Non‐linearities
Authors: Vondrák Vít , Dostál Zdeněk , Dobiáš Jiří , Pták Svatopluk 
Published: December 2005

AbstractThe nonlinearity caused by two or more bodies in contact is often source of computational difficulties. Probably the most popular solution method is based on direct iterations with the non‐penetration conditions imposed by the penalty method [1]. The method enables treatment of other non‐linearities such as in the case of large displacements.In this paper we are concerned with application of a variant of the FETI domain decomposition method that enforces feasibility of Lagrange multipliers by the penalty [5]. The dual penalty method, which has been shown to be optimal for small displacements, is used in inner loop of the algorithm that treats large displacements. We give results of numerical experiments that demonstrate high efficiency of the FETI method with the dual penalty. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determining Material Parameter of Solder Alloys by Nanoindentation
Authors: Weinberg K. , Sterthaus J. , Müller W. H. 
Published: December 2005

AbstractEnvironmental awareness motivates the replacement of traditional plumbiferous solder joints in microelectronic devices by new material alloys. In our group mechanical properties of some lead‐free alloys are determined by nanoindentation experiments. We use a Microsystems‐Nanoindenter Machine with Berkovich tip and apply standard techniques to extract the material properties from the measured load‐displacement curves. To assess the quality of our experimental results we model and analyze the setup by finite element computations. By comparing the real (input) material data with the results determined from the load‐displacement curves we analyze the obtained data in dependence of strength and stiffness of the materials under consideration. For low‐strength material we point out deviations. By inverse analysis we adapt numerically elastic modulus and yield stress to experimentally measured load‐displacement curves. To obtain information on the material's work hardening we suggest the use of a blunt indenter tip, e.g., a spherical indenter. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Nonlinear Galerkin Scheme Involving Vectorial and Tensorial Spherical Wavelets for Solving the Incompressible Navier‐Stokes Equation on the Sphere
Authors: Fengler Martin J. 
Published: December 2005

AbstractThe spherical Navier‐Stokes equation plays a fundamental role in meteorology by modelling meso‐scale (stratified) atmospherical flows. This article introduces a wavelet based nonlinear Galerkin method applied to the Navier‐Stokes equation on the rotating sphere. In detail, this scheme is implemented by using divergence free vectorial spherical wavelets, and its convergence is proven. To improve numerical efficiency an extension of the spherical panel clustering algorithm to vectorial and tensorial kernels is constructed. This method enables the rapid computation of the wavelet coefficients of the nonlinear advection term. Thereby, we also indicate error estimates. Finally, extensive numerical simulations for the nonlinear interaction of three vortices are presented. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Solution of Transonic Flow in SE1050 Cascade
Authors: Foř J. , Fürst Jiří , Dobeš Jiří , Halama Jan , Kozel Karel 
Published: December 2005

AbstractThe SE1050 cascade is an open test case (QNET network) of plane turbine cascade measured at the IT ASCR wind tunnel. The two regimes with subsonic and supersonic outletMach number were selected for numerical simulation. Several numerical methods have been developed and also several turbulence models have been implemented. Comparison of computed results and experimental data gives us opportunity to discuss main features of transonic flow field in well designed turbine cascade, possibilities of its numerical capturing (grid quality, numerical viscosity, turbulence model, boundary layer transition) and its influence on prediction of energy losses. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Large Eddy Simulation of turbulent confined coaxial swirling jets
Authors: García‐Villalba Manuel , Fröhlich Jochen , Rodi Wolfgang 
Published: December 2005

AbstractLarge eddy simulations of swirling flow in a coaxial‐jet combustor are reported. Two experimental test cases have been chosen from the literature. In both cases the configuration consists of two coaxial jets which enter into an expansion duct with the annular jet being swirled, the inner jet unswirled. The main features of the flow are well predicted in the simulations. The mean velocities and the turbulent fluctuations are compared with the experimental data and show good agreement. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical solution of 2D and 3D backward facing step flows
Authors: Kozel Karel , Louda Petr , Příhoda Jaromír 
Published: December 2005

AbstractThe work deals with numerical modelling of flow through 2‐dimensional (2D) and 3‐dimensional (3D) backward facing step. In laminar case, we apply several higher order upwind and central discretizations and compare numerical results with measurements. The turbulent regime is considered in 2D as well as in 3D and influence of secondary flow is observed. Different modifications of low‐Re two equation turbulence models and an explicit algebraic Reynolds stress model (EARSM) are considered. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison of analytical and numerical solution for optimal vortex diffuser design
Authors: Mehrle Andreas H. , Gittler Philipp 
Published: December 2005

AbstractThe contribution deals with optimization of wing tip devices, so called vortex diffusers. A comparison is given between an analytical approach for obtaining the optimal circulation loading and the results of a numerical investigation using a lifting line method. The purpose of most wing tip devices is to reduce the induced drag of the main wing by converting vortex energy into thrust. In order to achieve an optimal design, a variational formulation originally proposed by Betz and Prandtl for air screws is applied to the circulation distribution of the diffuser blades. In extension to the inviscid formulation, a viscous correction is applied in order to account for frictional forces. In an effort to validate the analytical results, a comparison is given with numerical solutions from a lifting line method. The loading of the diffuser blades is parametrized and optimized with respect to resulting thrust by use of a quasi‐Newton gradient method. Comparison shows that, knowing the velocity distribution in the near wake of the wing, considerable decrease of induced drag may be achieved making use of vortex diffusers. Although actual circulation loading may differ between the analytical and numerical estimation, resulting thrust agrees within a few percent. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Multigrid Algorithm for Hybrid Joint PDF Simulations in Complex Geometries
Authors: Rembold Benjamin , Jenny Patrick 
Published: December 2005

AbstractIn hybrid joint probability density function (joint PDF) algorithms for turbulent reactive flows the equations for the mean flow discretized with a classical grid based method (e.g. finite volume methods (FVM)) are solved together with a Monte Carlo (particle) method for the joint velocity composition PDF. When applied for complex geometries, the solution strategy for such methods which aims at obtaining a converged solution of the coupled problem on a sufficiently fine grid becomes very important. This paper describes one important aspect of this solution strategy, i.e. multigrid computing, which is well known to be very efficient for computing numerical solutions on fine grids. Two sets of grid based variables are involved: cell‐centered variables from the FVM and node‐centered variables, which denote the moments of the PDF extracted from the particle fields. Starting from a given multiblock grid environment first a new (refined or coarsened) grid is defined retaining the grid quality. The projection and prolongation operators are defined for the two sets of variables. In this new grid environment the particles are redistributed. The effectiveness of the multigrid algorithm is demonstrated. Compared to solely solving on the finest grid, convergence can be reached about one order of magnitude faster when using the multigrid algorithm in three stages. Computation time used for projection or prolongation is negligible. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On effectiveness of parallelization of upwind difference LU‐scheme fornumerical modelling of spatial flows in airbag combustion chamber
Authors: Rychkov Alexander , Shokina Nina 
Published: December 2005

AbstractThe technology of parallelization of the upwind LU difference scheme is presented for numerical modelling of three‐dimensional non‐stationary flow in the airbag combustion chamber. The parallel computations are done in the High Performance Computing Center Stuttgart (Germany). (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Large Scale Oscillations in the Continuous Casting Process
Authors: Schwarze Rüdiger , Rückert Antje , Leonhardt Ronny , Obermeier Frank 
Published: December 2005

AbstractLong‐term oscillations of the flow in a continuous casting tundish are investigated numerically and experimentally. The numerical model is based on the Reynolds averaged Navier‐Stokes equations (URANS). A comparison between numerical results and experimental data from a water model is presented. Frequencies due to long‐term oscillations are resolved in the simulation. These frequencies are in satisfactory agreement with the experimental results of LDA measurements. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical modelling of interaction process of low‐temperature plasma
Authors: Shokin Yu. I. , Rychkov A. D. 
Published: December 2005

AbstractThe problem of the interaction of high‐temperature reactive gas mixture with semi‐infinite solid propellant plate is investigated. The ignition conditions of the plate are determined in the framework of the well known model of burning powder with constant surface temperature when the heat flux into plate is limited by some critical value. The gas medium is generated due to the fluid (water or methane) evaporation under the action of the impulse electric high‐powered discharge in the semi‐closed volume. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Forms of Unsteady Flow in a 2‐D Channel
Authors: Sobieski W. , Badur J. 
Published: December 2005

AbstractThe paper describes results of a numerical simulations of air flow in a turned off, 2D channel with the plain nozzle. Simulations are based on an earlier experiment, carried out by Dyban, Mazur and Epik (1971). In the featured channel it has been observed several bifurcation forms, depending on the flow velocity and geometry relations. Basing on the numerical simulations results, the integral characteristics of the flow areas has also been presented. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Premixed Turbulent Combustion Modelling Using Level Set Approach
Authors: Vítek Oldřich , Polášek Miloš , Kozel Karel , Macek Jan 
Published: December 2005

AbstractThe paper deals with a level set approach application to SI engine combustion modelling, which is based on solving an additional transport equation to determine the flame front propagation. The presented work is an extension of the paper [6]. The influence of engine speed, air excess, swirl number, engine load as well as application of different turbulence model, in.uence of mesh coarseness and model fine‐tuning constants are investigated and the results are presented. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification of Finite‐Motion Parameters of Serial Chains via Measurement of 6 × 6 Stiffness Matrices
Authors: Abel Annette , Colonna Frank , Kecskeméthy Andrés 
Published: December 2005

AbstractThis paper describes a procedure for identifying geometric and stiffness parameters of a mechanical serial chain of know structure by measuring spatial 6×6 stiffness matrices at different positions. The method uses standard optimization routines to determine model parameters such that the model stiffness matrix features in the Frobenius norm the closest distance possible to the measured matrix. From this local identification, a rough model of parameters of finite‐motion is created, from which new measuring positions are guessed. By applying this step repeatedly, a model for finite‐displacement parameters can be obtained by a sequence of small force‐displacement tests. The method is tested with a dummy device consisting of a revolute joint connecting two rigid links dressed with soft material to mimic for example muscle masses of a surrogate mechanism for the elbow joint of a human arm. Two robots grasping the upper and lower arm generate the motion while the force measurement is carried out by a six‐axis force sensor. This makes the method potentially suitable for detecting anatomical parameters by in‐vivo measurements. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental and Numerical Investigations for Cyclic Thermal Shocks
Authors: Gockel Franz‐Barthold , Mahnken Rolf 
Published: December 2005

AbstractThermal shock is an extreme form of thermo‐mechanical loading. Detailed investigations of thermal shock and live time analysis close to reality are necessary in industrial engineering in order to get a good prediction of life expectancy of high quality and safety relevant machine components. The first part of this paper concentrates on experimental investigations of macroscopic quantities like temperature, deformation, damage and crack propagation. Additionally first results on parameter studies for finite element thermal shock simulations on the thermal‐mechanical problem are summarized. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Alternative high resolution sensor to hot‐wire and hot‐film anemometer
Authors: Hölling Michael , Barth Stephan , Peinke Joachim 
Published: December 2005

AbstractWe present a new type of high resolution sensor for turbulent flow measurements based on the optical detection of a deflected cantilever. The Laser‐Cantilever‐Anemometer (LCA) can be used in air as well as in water without any changes in setup. Experiments for testing the functionality of this sensor in turbulent air flows show that the measured data with the LCA match the data obtained with a hot‐wire anemometer up to several kHz. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Finite element model updating for damage detection
Authors: Kompalka A. S. , Reese S. 
Published: December 2005

AbstractIn this contribution we derive the iterative finite element model updating algorithm. The ability of the method to detect the damage is verified by means of a simulation with a reference finite element model. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transfer Function and the State Space Model Identification of a Funnel Shaped Piezoelectric Structure for the Controller Design Purposes
Authors: Nestorović‐Trajkov Tamara , NachKöppename Heinz , Gabbert Ulrich 
Published: December 2005

AbstractFor the controller design purposes in order to suppress vibration magnitudes of a funnel shaped piezoelectric shell structure the mathematical model of the structure was identified in the form of the transfer function and the state space representation. The excitation of the structure with different signal types as well as the measurement of the responses were achieved using the piezoelectric actuator and sensor patches attached to the funnel. From the frequency responses obtained as a ratio of the Fast Fourier Transforms between the appropriate sensor and the actuator signals, discrete‐time transfer functions were determined by best curve fitting of the model‐based frequency response. For the state space model identification the subspace based identification approach was used. Obtained models were used for the optimal LQ controller design. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification of the Running‐State of Railway Wheelsets
Authors: Reicke L. , Popp K. 
Published: December 2005

AbstractHigh‐speed trains require a reliable monitoring of the current running‐state to detect exceptional running‐conditions which can occur due to track irregularities, wear in the wheel‐rail contact or chassis damages. A sophisticated monitoring not only classifies the running‐state in terms of safe operation but also derives the causes to enable condition‐based maintenance.The running‐state can be characterized by the dynamic interaction in the contact patch inducing forces and torques and leading to forced and self‐excited structural vibrations of the wheelset. It is very difficult to measure structural vibrations directly and therefore it is convenient to observe them by accelerations in longitudinal, transversal and vertical direction at the left and right axle‐boxes of each wheelset. The transient behavior of structural vibrations can be well analyzed by timefrequency transforms. A decomposition into the principal eigenmodes is achieved by model‐based preprocessing. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimentelle Untersuchung zum anisotropen Verhalten eines Polypropylen‐Schaums
Authors: Schmitt Joachim , Diebels Stefan 
Published: December 2005

AbstractAn Beispiel eines Polypropylenschaums wird ein anisotropes elastisch‐viskoplastisches Stoffmodell vorgestellt. Über einachsige Druckversuche werden die nötigen Parameter ermittelt und die Besonderheiten des anisotropen Modells anhand von Fließ.ächenschnitten verdeutlicht. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Buckling and damage of dynamically loaded plates in shock tubes
Authors: Stoffel Marcus , Schmidt Rüdiger , Weichert Dieter 
Published: December 2005

AbstractIn this study circular metal plates are subjected alternately to impulsive loadings in shock tubes. The aim is to develop an experimental method to measure the buckling shapes of shock wave‐loaded plates during the impulse duration. Furthermore, the measurements are used to validate failure modes predicted in finite element simulations. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)