bluuebunny/crossref_metadata_2025_split huggingface dataset:
A finite element framework for continnua with boundary potentials
Authors: Javili Ali , Steinmann Paul 
Published: March 2010

AbstractThis contribution deals with the implications of the anisotropic boundary potential energies on deformational mechanics in the framework of the two‐dimensional finite element method at finite strains. In the first part of this work ([6])) only the isotropic boundary potentials were considered, however, in this contribution we allow for the anisotropic contributions from the boundary energies, too. The boundary effects sometimes play a dominant role in the material behavior, e.g. surface tension in fluids. The boundary potentials, in general, are allowed to depend not only on the boundary deformation gradient but also on the spatial curve‐tangent, as well. For the finite element implementation, a suitable curvilinear coordinate system attached to the boundary is defined and corresponding derivations are carried out. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Failure Analysis on Shell‐like Composite Laminates Using the Puck Criteria
Authors: Lauterbach Stefan , Balzani Claudio , Wagner Werner 
Published: March 2010

AbstractDue to their high specific strength and stiffness, carbon fibre‐reinforced polymers (CFRP) are widely used in several fields of engineering, e.g. aerospace engineering. A new design scheme aims for the exploitation of material reserves. Since design is always linked to expensive experimental investigations, reliable simulation procedures are required to lower the related costs. In terms of detecting ply failure several criteria have been proposed. In this work those of Hashin [1] and Puck [2] are applied to several numerical models and compared to experimental results [3]. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An asymmetric Least‐Squares Mixed Finite Element for Elasto‐Plasticity at Small Strains
Authors: Schwarz Alexander , Schröder Jörg 
Published: March 2010

AbstractWe present a mixed finite element based on a modified least‐squares formulation for rate‐independent elasto‐plasticity. Due to kink‐like points in the least‐squares functional, the first variation is not always continuous and a standard Newton method could fail in order to minimize the least‐squares functional. In order to keep the availability of the Newton method, we introduce a modified least‐squares approach, which guarantees the continuity of the resulting weak form. Finally, a numerical example is presented to show the applicability and performance. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Elastic‐plastic stress analysis of cracked structures using the boundary element method
Authors: Weber Wilhelm , Steinmann Paul , Kuhn Guenther 
Published: March 2010

AbstractThe application of the boundary element method (BEM) for the 3D‐stress analysis of cracked structures considering elastic‐plastic material behavior is presented. For separating the coincident crack surfaces the DUAL‐BEM is utilized. The relevant boundary integral equations (BIE) – the strongly singular displacement BIE and the hypersingular traction BIE – are evaluated in the framework of a collocation procedure. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental study on the behaviour of steel columns under seismic‐induced axial impact load
Authors: Migda W. , Jankowski R. 
Published: March 2010

AbstractIt has been observed during major earthquakes that the so called soft‐storey failure of an upper floor of a structure results in large impact load acting on structural members of the lower storeys. It may further lead to progressive collapse of the whole structure substantially intensifying human and material losses. Therefore, the aim of this paper is to investigate experimentally the behaviour of columns under bending (observed during an earthquake) that are additionally subjected to an axial plastic impact load. Steel columns with high slenderness ratio were considered in the study. In the experiment, impact load was created by a weight that was dropped onto the top of the column and stayed on it. The weight with the shape of a ball was made of clay so as to simulate more plastic impact. The results of the experiment show that the value of the permanent horizontal deformation of the column observed after impact depends much on the initial relative displacement between the base and the top of the column. As the initial displacement increases the values of the permanent deformation increases significantly indicating the significant reduction in the critical buckling force. The results obtained in the study can be utilized at the design stage of the structures in order to enhance their seismic resistance. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the heat transfer in a two‐phase hollow cylinder with piecewise continuous boundary conditions
Authors: Ostrowski Piotr 
Published: March 2010

AbstractThis consideration concern heat transfer in two‐component composite with a deterministic microstructure, which is Δ‐periodic along the angular axis and has slowly varying effective properties in the radial direction (Fig.1). Therefore, we deal here with a special case of functionally graded materials, FGM, c.f. Suresh, Mortensen (1998). The main aim of this consideration is to capture effect of the discontinuous boundary conditions on the thermal field. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reduction of Periodic Torsional Vibration using Centrifugal Pendulum Vibration Absorbers
Authors: Pfabe Mathias , Woernle Christoph 
Published: March 2010

AbstractNew developments of more environmentally friendly combustion engines cause high fluctuating torques acting on the crankshaft, drive train and auxiliary units. Those result in noise and vibration that are unintentional, especially in automotive engineering. Dual flywheels to damp the vibration are reaching their limits and alternatives have to be found. Centrifugal pendulum vibration absorbers (CPVA) are a long known, energy saving tool to compensate non‐uniform torques. Their main advantage is that they are tuned to a specific order instead of one fixed frequency and therefore they are rotational speed adaptive. This paper presents the fundamentals of CPVA, as well as the equation of motion (EOM), and it shows an analysis for all relevant design parameters. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of a pyroshock test device
Authors: Lacher Alexander , Juengel Nikolas , von Wagner Utz 
Published: March 2010

AbstractPyroshocks are transient motions of structural elements due to explosive loading induced by the detonation of ordnance devices incorporated into or attached to the structure. In space programs the simulation of pyroshocks is a fixed part of the test requirement for instruments and equipments of space vehicles. Therefore, by the use of various test devices such as hammer pendulums the excitation of a pyroshock has to be reproduced which, so far, has led to rather empirical knowledge. In the current work a better predictability of pyroshocks is focussed in order to reduce the duration of test periods. As an approach numerical and analytical calculations are used for the simulation of in‐plane wave propagation in rods and rectangular disks due to mechanical impacts. Furthermore, the results obtained from different mathematical and mechanical theories are compared with data received from conducted experiments. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A surveillance of structural oscillations of industrial robots using optimal control at energy performance index
Authors: Kaliński Krzysztof J. , Jasiński Krzysztof 
Published: March 2010

AbstractHere is considered vibration of non‐stationary carrying system of the IRb‐6 robot. For a use of vibration surveillance an algorithm of modal control at energy performance index in the frequency domain has been applied. Purpose of the algorithm proposed is to minimise vibration amplitude of manipulating ends, and thus – to increase capacity of modern robot lines as well as, improve accuracy and repeatability of robot positioning. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the bending and tension of thermoelastic shells undergoing phase transitions
Authors: Eremeyev Victor A. , Pietraszkiewicz Wojciech 
Published: March 2010

AbstractApplying the general non‐linear theory of shells undergoing phase transitions, we derive the balance equations along the singular surface curve modelling the phase interface in the shell. From the integral forms of balance laws of linear momentum, angular momentum, and energy as well as the entropy inequality we obtain the local static balance equations along the curvilinear phase interface. We also derive the thermodynamic condition allowing one to determine the interface position on the deformed shell midsurface. The theoretical model is illustrated by the example of thin circular cylindrical shell made of two‐phase material subjected to tensile forces and bending couples at the shell boundary. The elastic solution reveals the existence of the hysteresis loop whose size depends upon values of several loading parameters. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Formulation of Additive Finite Anisotropic Thermo‐Plasticity in Logarithmic Lagrangean Strain‐Entropy Space
Authors: Ulz Manfred H. 
Published: March 2010

AbstractA phenomenological model of rate‐independent thermo‐plasticity at finite strains is discussed. The formulation is based on an additive decomposition of the strain measure into an elastic and plastic part as proposed by Green and Naghdi. A constitutive model in the logarithmic Lagrangean strain‐entropy space is developed capable of modelling isotropic elastic and anisotropic plastic material behaviour. The staggered solution scheme for coupled thermo‐mechanical problems employs an isentropic phase for the deformation and an iso‐geometrical phase for the thermal field. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effective Flow Potentials for Anisotropic Polycrystals
Authors: Tsotsova Rumena , Böhlke Thomas 
Published: March 2010

AbstractIn this paper a micromechanically based flow potential for anisotropic fcc polycrystals is derived that takes into account the crystallite orientation distribution function (codf) in terms of tensorial texture coefficients. The effective flow potential is based on a representation theorem for anisotropic scalar functions depending on a 2nd‐order tensor. A priori unknown functions in the representation are determined by defining and solving explicitly a minimization problem over SO(3). Important analytical properties of the coefficient matrix of the minimization problem are discussed. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Material behaviour of filler‐reinforced rubber materials under cyclic loading processes, experiments and FEM‐simulations based on finite viscoelasticity.
Authors: Rendek Martin , Lion Alexander 
Published: March 2010

AbstractA threedimensional constitutive model of finite viscoelasticity will be presented. It considers the amplitude dependence and is based on a Maxwell chain with intrinsic time scales. This type of viscoelasticity is thermodynamically consistent and provides a basis for modelling other effects (e.g. temperature dependence). The parameter identification for this model is possible in both the frequency and the time domain. Some finite element implementation and simulation results in the time domain are presented. The numerical simulation of multifrequent and other more complicated loading processes is possible only in the time domain. A very interesting loading process is a cyclic deformation with changing amplitudes in order to simulate the transient dynamic behavior of the Payne‐effect. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Analysis of Strains and Stresses in Stretched Specimens at Microstructure Level
Authors: Malag Leszek , Kukielka Leon 
Published: March 2010

AbstractIn the paper an incremental methodology was proposed for the determination of the states of stresses and strains in specimens while taking into account the strain history and the strain rate history during a tension stress, and a new methodology to determine mechanical characteristics of metal materials. An equation of motion and deformation of the specimen was introduced while using a variational formulation and the finite element method. The results of numerical simulations which illustrate the methods proposed, were presented. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Non‐linear elastic behavior of filler aggregates
Authors: Dargazany Roozbeh , Itskov Mikhail 
Published: March 2010

AbstractA filled rubber network consists of polymer chains which are suspended between filler aggregates. In this contribution, the nonlinear elastic behavior of the aggregated filler particles inside the rubber matrix is investigated. Previously, by using scaling theory, the influence of initial length and fractal dimension of aggregates on the elastic response of aggregated structures was studied. Here we additionally take into account a deformation induced evolution of the aggregate structure. To this end, the directional topology of the aggregate structure is represented by its backbone chain. Thus, the analytical approach proposed describes not only the geometrically but also the physically non‐linear behavior of aggregates. Our solution can further be generalized for colloidal structures as for example granular materials or suspended solid structures. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microstructural changes and material parameter development
Authors: Müller W. H. , Brandmair A. , Sheshenin S.V. , Savenkova M. 
Published: March 2010

AbstractAt previous GAMM‐meetings the first two authors reported on the spinodal decomposition and coarsening in lead‐containing as well as lead‐free solders. They derived an extended diffusion equation for the corresponding computer modelling on the basis of a multi‐component theory of mixtures. Consequently, they performed numerical studies that are capable of predicting quantitatively the development of SnPb and AgCu microstructures. Knowing this development is quite important from a technological point‐of‐view in order to quantify the current joining capability of the solder material (“Resteigenschaften”). On the basis of these results this paper now attempts to predict the corresponding change of the materials properties, in particular of the elastic constants. This is done by means of a homogenization technique developed by the last two authors. In this paper we will briefly summarize the results related to the extended diffusion equation, present numerical simulations of the coarsening process, outline the theory underlying the homogenization and, finally, show how the material properties behave over time. Wherever possible, alternative analytical solutions for the homogenized constants are also presented (e.g., by laminate theory). (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
2D modelling of thin skeletonal elastic shallow shells
Authors: Michalak B. , Woźniak Cz. 
Published: March 2010

AbstractThe subject of this contribution is a certain thin skeletonal elastic shallow shell. The aim of analysis is to derive and apply a 2D‐macroscopic model for shallow shells with the non‐uniformly oscillating microstructure. The main feature of the proposed mathematical model is that the microstructure length parameter λ is similar compared to thickness δ of the shell (λ ≃ δ). The formulation of approximate mathematical model of these shells is based on a tolerance averaging approximation [5]. The general results of the contribution will be illustrated by the analysis of a specific problem. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of Active Noise and Vibration Control with Finite Elements and Boundary Elements
Authors: Ringwelski Stefan , Gabbert Ulrich 
Published: March 2010

AbstractA recently developed coupled finite element‐boundary element modeling scheme for the design of active noise and vibration control of multi‐coupled structural‐acoustic systems is presented. The approach allows the computation of structural vibrations and resulting sound fields. By means of an example, the paper describes the theoretical background of the coupled approach. In order to show the performance of the developed approach, test simulations are carried out in the frequency domain. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison of passive and active elements of reduction of vibrations
Authors: Białas K. 
Published: March 2010

AbstractThe main aim of this work is the introduction of analysis and synthesis of mechanical systems including passive and active elements reducing vibrations. In results of synthesis were received structures and parameters of a discrete model meeting the defined requirements concerning the dynamic features of the system, in particular, the frequency spectrum. In this work is also comparison of these two kind of elements, passive and active, of reduction of vibrations. The approach adopted makes it possible to undertake actions aiming at the elimination of phenomena resulting in the unwanted operation of machinery or generation of hazardous situations in the machinery environment. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The numerical simulation of a typical fluid‐structure interaction problem
Authors: Stoia‐Djeska Marius , Frunzulică Florin 
Published: March 2010

AbstractTo determine the dynamic response of a structure under the influence of the fluid flow one must solve a coupled computational fluid dynamics (CFD) and computational structural dynamics (CSD) mathematical problem. This paper presents the comparison of two methods for the calculation of the fluid‐structure interaction. The first one is of explicit‐implicit type and uses a staggered time advancement of the fluid and structure problems. The second uses a fully implicit discretization in the physical time of the fluid‐structure equations and an explicit advancement in the dual‐time. The physical fluid‐structure problem is accompanied by the equations of the mesh motion, which are written as for a pseudo‐structural system with its own dynamics. Representative numerical results are presented for the two degrees of freedom tipical section in unsteady transonic flow. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Notes on the Computation of Effective Electro‐Mechanical Moduli
Authors: Keip Marc‐André , Schröder Jörg 
Published: March 2010

AbstractThe present work deals with the computational determination of effective material properties of electro‐mechanically coupled materials. In this context, a two‐scale homogenization ansatz for piezoelectric ceramics based on an FE2‐approach is utilized. In this way we are able to compute the overall macroscopic material moduli for microheterogeneous structures. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of diffusional processes from the microscopic and macroscopic point of view
Authors: Ilic Sandra , Hackl Klaus 
Published: March 2010

AbstractWithin this contribution, the modeling of diffusional processes will be elucidated by the example of solution‐precipitation creep. This deformation process occurs in polycrystalline and granular materials exposed to high temperatures and moderate stresses. The presence of water facilitating the material transport in the intercrystalline space especially intensifies the process. The continuum‐micromechanical model presented here considers the velocities of the material transport and the grain‐boundary motion caused in this way to be the main contributions to the dissipation term characteristic for this process. Simulating the real macrostructures in addition requires coupling with homogenization techniques. To this end, our particular choice pertains to the multiscale FE method with the advantages that it is adapted to the case of finite deformations and that it is applicable in the limit case when the ratio of the characteristic lengths of the micro‐ and macroscale tends to zero. As a final result, application of the mentioned method gives information on the time dependency of macroscopic deformations. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic Stall Measurements
Authors: Schneemann Jörge , Wolken‐Möhlmann Gerrit , Peinke Joachim 
Published: March 2010

AbstractForces acting statically on an airfoil in laminar flow are well known. Under turbulent conditions dynamic effects (like dynamic stall) take place. There are different theoretical models to describe dynamic stall, but very little experimental data. We present dynamic stall measurements using an FX 79‐W‐151A airfoil in a closed test section of a wind tunnel with laminar inflow. Dynamic stall was induced by pitching the foil sinusoidally. Lift forces were measured using the pressure distribution on the wind tunnel walls. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Proposal for an Invariant Nonlinear Eddy Viscosity Model based on a Consistent 4D Turbulence Modelling Approach
Authors: Frewer Michael 
Published: March 2010

AbstractThe aim of this new approach is to demonstrate that modelling on a 3D spatial manifold is not equivalent to modelling on a true 4D space‐time manifold within Newtonian physics. In the framework of turbulence modelling it will be shown that by geometrically reformulating the averaged Navier‐Stokes equations on a 4D non‐Riemannian manifold without changing the physical content of the theory, additional modelling restrictions will naturally emerge which are absent in the usual Euclidean (3 + 1)D formulation. By proposing a non‐linear eddy viscosity model within the k − ϵ family for high turbulent Reynolds numbers the new invariant modelling approach will demonstrate its clear superiority over current (3 + 1)D modelling techniques. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Measurements with a 2D Laser‐Cantilever‐Anemometer compared to an x‐wire probe
Authors: Puczylowski Jaroslaw , Hölling Michael , Peinke Joachim 
Published: March 2010

AbstractThe 2D Laser‐Cantilever‐Anemometer (2D‐LCA) was developed to measure flow velocities in two dimensions. A sensitive meausuring principle adopted from atomic force microscopes allows a spatial and temporal resolution comparable to modern x‐wire anemometry. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling electrospinning of nanofibres
Authors: Kowalewski Tomasz A. , Barral Serge 
Published: March 2010

AbstractElectrospinning is based on so‐called bending instability which results in an erratic spiralling motion of the liquid jet as it proceeds towards a collecting electrode, where it is eventually deposited as a mat of micro/nanosized fibres. Most electrospinning models formulated within the slender approximation rely, however, on an inconsistent description of electrostatic interactions which renders them grossly inappropriate whenever the discretization is either too coarse or too fine. The present work aims at proposing a discrete slender model which is numerically consistent (allowing use of arbitrary fine meshes) and remains accurate even for coarse meshes. At the same time, efficient numerical techniques based on hierarchical charge clustering are introduced that drastically decrease computational times. Finally, a versatile boundary value method is implemented to enforce fixed‐potential boundary conditions, allowing realistic electrode configurations to be investigated. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)