bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reduction Methods for FE Analysis in Nonlinear Structural Dynamics
Authors: Spiess Holger , Wriggers Peter 
Published: December 2005

AbstractThe computation of the nonlinear motion of large structures with implicit time integration schemes is costly. In each time step a large system of linear equations needs to be solved several times. In finite element models often a fine discretization is necessary to represent the geometry and to yield accurate results for the stress field. But from experience it is known that only a small number of degrees of freedom is sufficient to account for the dominant parts of a dynamic motion. Similar to modal decomposition, methods were developed to reduce the number of degrees of freedoms in nonlinear problems. Even though it is not possible to decompose the motion into decoupled modes, a reduction of the number of degrees of freedom yields less computational effort in many cases. The choice of appropriate basis vectors is important. Often used are load‐dependent ‘Ritz’ vectors, which should be updated during the computation to yield sufficient accuracy. Dominant modes, computed by a proper orthogonal decomposition of a previous calculation can be used for repeated analyses of the same system with different loads. Significant time savings can be achieved with reduction methods. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On nonsmooth bifurcations in a simple friction oscillator
Authors: Teufel Andreas , Steindl Alois , Troger Hans 
Published: December 2005

AbstractWe consider a simple friction oscillator with one degree of freedom using a non‐smooth, three‐parameter fricion model accounting for both, a decreasing and increasing dynamic friction force depending on the relative velocity. An analysis of global non‐smooth bifurcations is performed numerically and parameter domains are computed for the existence of stick‐slip oscillations. Special emphasis is placed upon the occurrence of stick‐slip oscillations with negative relative velocity. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control of Electrodynamic Tether Vibrations in Space
Authors: Viennet Emmanuel , Steindl Alois , Troger Hans 
Published: December 2005

AbstractFirst, we simulate the behaviour of a satellite tethered with a continuous electrodynamic cable moving on a circular orbit. Second we extinguish for a simple discrete model small angle librations by controlling the current in the tether. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Note on a Longitudinal and Torsional Type of Ultrasonic Motor with two Stators
Authors: Yi Youping , Gausmann Rainer , Seemann Wolfgang , Zhong Jue 
Published: December 2005

AbstractThis paper deals with an ultrasonic motor, which consist of one rotor and two stators. The main parts of each stator are one longitudinal and one torsional piezoceramic actuator, which are used to generate the desired elliptical orbit on the stator surface. For the purpose of a high efficiency, the longitudinal and the torsional resonant frequency should ideally coincide with the operational frequency. To match the resonant frequencies, two adjustable rings are added to the stators. The influence of the mass and the position of the rings on the first longitudinal and the first torsional eigenfrequency and their mode shapes is investigated. The experimental results fit very well with the theoretical predictions and show that the adjusting rings can be used to match the eigenfrequencies of the two mode shapes. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Dynamics of Belt Drives
Authors: Zwiers U. , Braun M. 
Published: December 2005

AbstractIn modelling the dynamics of belt drives, one has to distinguish between taut and slack belts. While the former can be described by a linear model, the latter is inherently nonlinear and needs a more sophisticated analysis. The paper at hand presents an analytical approach to modelling slack belts in plane motion. To simplify the setting, the pulleys are assumed to have equal radii, such that only one quarter of the total system needs to be considered. The extension to a more general geometry is straightforward. The belt is assumed to have non‐zero bending stiffness. The slackness of the belt should be high enough to allow .exural vibrations even if the belt is inextensible. The static and the stationary solutions are formulated analytically in terms of elliptic functions. As a preliminary study, the special case of a travelling string is considered yielding a .rst insight into the complexity of belt dynamics. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Value‐Restricted Functions for Robust and Simultaneous Stability
Authors: Batra Prashant 
Published: December 2005

AbstractDifferent problems, like robust stability of interval plants, stability dependent of delay, and simultaneous stabilizability of three systems are treated via a single method. The value set properties for certain derived functions allow usage of computational analytic inequalities. This approach leads to necessary conditions for the parameters of the stability problems. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Feedforward Control Strategies for Hot Rolling in a Reversing Plate Mill
Authors: Kiefer Thomas , Heeg Roland , Kugi Andreas 
Published: December 2005

AbstractThis contribution is devoted to a new feedforward control concept for the thickness control in a hot rolling mill. The core of this concept is an accurate forward slip model for the calculation of the entry thickness profile. This forward slip is derived by means of the fundamental equations of hydrodynamics for a viscoplastic material in the roll gap. The proposed control strategy advantageously uses the additional information of the rolled plate in form of this entry thickness profile. Simulated and measured data demonstrate the feasibility of the forward slip model and the control concept. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental study of digital force control
Authors: Kisfalusi Krisztián , Stréli Tamás , Stépán Gábor 
Published: December 2005

AbstractA one degree of freedom experimental rig was designed and manufactured to test the stability properties of digital force control and to compare the theoretical and measured stability charts. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Model Reduction for a Class of PDAE Systems
Authors: Reis Timo 
Published: December 2005

AbstractWe investigate a class of input‐output sytems which consist of partial differential equations whose boundary values fulfill some differential algebraic conditions. Abstractly, these systems can be written down as descriptor systems with an infinite dimensional state space. The aim is to find finite dimensional approximations of these systems and to give error estimates. This means, we approximate a system governed by partial differential algebraic equations (PDAE) by a differential algebraic one. As error measure, we take the ℋ∞‐norm. Applications are e.g. given by the model reduction of time delay systems. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computation of Lie Derivatives of Tensor Fields Required for Nonlinear Controller and Observer Design Employing Automatic Differentiation
Authors: Röbenack Klaus 
Published: December 2005

AbstractDifferential‐geometric concepts are widely used in nonlinear controller and observer design. The design algorithms often require certain types of Lie derivatives. In the past, these derivatives have been computed symbolically. The author suggests an alternative approach based on automatic differentiation. The computation of Lie derivatives of different tensor fields is discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computer Algebra Tests on Identifiability of Nonlinear Implicit Dynamical Systems
Authors: Zehetleitner Kurt , Schlacher Kurt 
Published: December 2005

AbstractIn this contribution criteria on identifiability of system parameters of nonlinear implicit dynamical systems, also denoted differential algebraic equation systems (DAEs), are presented. Two interesting questions can be posed in this context: We ask for identifiability along a given trajectory and the existence of a trajectory through a given point in the state space such that the parameters are identifiable along it. A computer algebra algorithm to test these properties is provided. As a special case systems in explicit form are considered and a mechanical example is shown as application. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Contact of Planar Flexible Multibody Systems Using a Linear Complementarity Formulation
Authors: Ebrahimi Saeed , Eberhard Peter 
Published: December 2005

AbstractDescriptions leading to Linear Complementarity Problems (LCPs) are well established in the contact modeling of rigid multibody systems and have a very strong mathematical basis. These approaches yield exact solutions for contact problems consisting of contact (force/acceleration level) and impact (impulse/velocity level). By utilizing these methods, also frictional contact can be handled appropriately, see [1] and [2].In this paper a formulation for extending these methods for consideration of planar deformable bodies is given. In the case of deformable bodies, a finite wave propagation speed is inherent and, thus, impact computations on impulse/velocity level which lead to jumps in velocity are no longer required. In this paper only the case of continual contact is taken into account. For this purpose, the complementarity relations are reformulated in such a way that contact modeling of constrained and non‐constrained planar deformable bodies is possible, too. In this formulation, deformable bodies are modeled based on the moving frame of reference approach with modal coordinates which is frequently used for the simulation of deformable multibody systems [3]. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ein Reduktionsalgorithmus für die Bewegungsgleichungen von Mehrkörpersystemen
Authors: Keppler Rainer , Barthels Pierre , Seemann Wolfgang 
Published: December 2005

AbstractAuf der Basis des Roberson‐Wittenburg'schen Mehrkörperformalismus wurde ein Programm entwickelt, daß die Bewegungsgleichungen baumstrukturierter Mehrkörpersysteme in analytischer Form generiert. Es wird ein Algorithmus vorgestellt, der den Auswerteaufwand der Bewegungsgleichungen verringert. Grundidee ist dabei, Terme geringen Einflusses zu eliminieren. Die Effizienz des Algorithmus wird anhand räumlichern‐fach Pendel demonstriert. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modellierung einer adaptronischen Kompensationseinheit für Werkzeugmaschinen mit Parallelkinematiken
Authors: Rudolf Christian , Wauer Jörg 
Published: December 2005

AbstractBei Werkzeugmaschinen mit Parallelkinematiken mit zwei bzw. drei translatorischen Freiheitsgraden sind die rotatorischen Freiheitsgrade kinematisch gesperrt. Aufgrund von Fertigungs‐ und Montageungenauigkeiten kommt es zu Verspannungen in der Kinematikstruktur. Daraus resultieren Verlagerungen des Werkzeug‐ bzw. des Werkst ückhalters und die Fertigungsgenauigkeit der Maschine und damit die Werkstückqualität werden reduziert. Der translatorische Anteil dieser Maschinenfehler kann durch die genannte Kinematikklasse korrigiert werden, der rotatorische Anteil nur sehr begrenzt.Durch den Einsatz kraftgeregelter Piezoaktoren in den Streben sollen die rotatorischen Maschinenfehler im laufenden Betrieb korrigiert werden. Ein erster Schritt hierzu ist die Modellbildung einer beliebigen Strebe, in die ein Modell eines Piezoaktors integriert ist. Die Strebe wird am Kopfende geführt und soll am Fußende eine Kraft erfahren. Durch Analyse und Simulation können die Einflüsse verschiedener Maschinen‐ und Prozessparameter untersucht werden. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A time‐stepping method for non‐smooth mechanical systems
Authors: Studer Christian , Glocker Christoph 
Published: December 2005

AbstractTime‐stepping algorithms allow a robust simulation of dynamical problems with many unilateral constraints and friction. It's idea is to calculate velocity updates instead of accelerations. As a consequence, contact behaviour and impact can be treated by the same equations. The unilateral constraints are modelled by set‐valued force laws. The resulting inequalities can be solved by writing inclusions as non‐linear equations. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Modelling of Prestressed Medium Thickness Uniperiodic Plates
Authors: Baron Eugeniusz 
Published: December 2005

AbstractThe aim of this contribution is to propose and apply a new averaged 2D ‐model for the analysis of vibration and stability problems of prestressed uniperiodic, elastic, medium thickness plates. Contrary to the known homogenized model [3], the proposed model describes the effect of the period length on the overall plate behaviour. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On a von Kármán System for Anisotropic Viscoelastic Plates
Authors: Bock Igor 
Published: December 2005

AbstractWe deal with a nonlinear system of equations describing the in‐plane displacements and the deflection of the anisotropic viscoelastic plate made of a long memory material acting under the perpendicular load. We derive the full von Kármán system for the in‐plane displacements and the deflection of the middle surface of the plate. The system contains the nonlinear integropartial differential operators applied to the in‐plain strain tensor and to the tensor product of the displacement gradients. If the right‐hand side of the system fulfils some estimate then the existence of a weak solution can be derived using the Rothe's method. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Flexural Properties of Fiber‐Reinforced Composites
Authors: Haasemann Georg , Ulbricht Volker 
Published: December 2005

AbstractTo describe the macroscopic mechanical behavior of composite materials with biaxial weft‐knitted fabric reinforcement, a difference between the flexural and tensile stiffness must be taken into account. Due to the periodic structure of the composite, the material behavior can be investigated on a unit cell. A homogenization technique based on the Hill‐Mandel energy balance is used to replace a heterogenous Boltzmann medium by a homogenous COSSERAT continuum. To simulate the material behavior, this homogenization method is applied to the Binary Model. Tensile, shear and bending tests were performed to verify the simulation results. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transient dynamic response of sandwich shells with transversely compressible core
Authors: Hohe Jörg , Librescu Liviu 
Published: December 2005

AbstractThe present study provides an investigation of the effect of the transverse core compressibility on the dynamic buckling response of sandwich structures. The study utilizes a previous v. Kármán type higher‐order model for shallow sandwich shells. An analytical solution is obtained by means of an extended Galerkin procedure in conjunction with an explicit fourth order Runge‐Kutta algorithm to solve the transient problem. In an example analysis, it is observed that the transverse core compressibility can have strong effects even on the global response of sandwich structures. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
FE Treatment of InhomogeneitiesWithin the Intervertebral Disc
Authors: Karajan N. , Ehlers W. , Markert B. , Acartürk A. , Wieners C. 
Published: December 2005

AbstractOne natural category of porous materials is represented by the intervertebral disc (IVD) as a charged, hydrated, biological soft tissue. The challenge of describing the IVD lies in its complex microstructure consisting of mostly ionized water and collagen fibers embedded in an extracellular meshwork of charged protein compounds. As a naturally grown material, its inner structure and thus, the associated physical properties are inhomogeneously distributed over the 3‐d domain of the IVD.The substantial increase of people suffering from low back pain also causes a higher research interest regarding numerical simulation techniques, aiding the design of new implants. The Finite Element Method (FEM) in combination with an elaborated model has the potential to be the best choice.In order to ef.ciently simulate the physiological behaviour of the IVD on the macroscale, the electro‐chemomechanical couplings between the constituents as well as the viscoelastic and anisotropic properties of the extracellular matrix must be considered. Moreover, the fiber vectors, which represent the aligned collagen in a continuum mechanical sense, as well as the location dependent material parameters must be inhomogeneously distributed over the discretized IVD. These requirements are implemented in the framework of the Theory of Porous Media (TPM), which consistently allows for the description of multiphasic continua with internal interactions. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Direct central impact of different elastic bodies of rotation
Authors: Marchenko Tetiana 
Published: December 2005

AbstractA direct central collision of two bodies of revolution is studied. A nonstationary mixed boundary‐value problem with an unknown moving boundary is formulated. Its solution is represented by a series in term of Bessel functions. An infinite system of Volterra equations of the second kind for the unknown expansion coefficients is derived by satisfying the boundary conditions. The basic characteristics of the collision process are determined depending on the physic‐mechanical properties of the bodies. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Objective stress rates in repeated elastic deformation cycles
Authors: Meyers Albert , Bruhns Otto , Xiao Heng 
Published: December 2005

AbstractThe Eulerian elastoplastic description of initially isotropic materials essentially depends on the accurate formulation of the elastic deformation. This is often represented by Truesdell's hypoelastic equation, which involves an objective stress rate. Many objective stress rates have been presented in the past. With Bernstein's integrability conditions it has been shown that only a particular rate, namely the logarithmic stress rate, makes the hypoelastic relation exactly integrable.Here, we propose a simple, one‐parameter closed deformation cycle to demonstrate the error which will considerably accumulate over several cycles, whenever a non‐appropriate stress rate is in use. For this, several objective stress rates are compared in this cycle and the residual stresses at the end of the cycles are examined. By such a simple procedure the mathematical results of non‐integrability are evidenced by example. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stability of nonlinear viscoelastic systems under stochastic excitation
Authors: Potapov Vadim 
Published: December 2005

AbstractThe dynamic behaviour of viscoelastic system with due account of finite deflections but under condition of small strains is described by the system of nonlinear integro‐differential equations. On an example of a thin plate subjected to loads, which are assumed as random wide‐band stationary noises and applied in the plate plane, the stability of nonlinear systems is considered. The stability in a case of finite deflections of the plate is considered as stability with respect to statistical moments of perturbations and almost sure stability. For the solution of the problem, a numerical method is offered, which is based on the statistical simulation of input stochastic stationary processes, which are assumed in the form of Gaussian ”colored” noises, and on the numerical solution of integro‐differential or differential equations. The conclusion about the stability of the considered system is made on the basis of Lyapunov exponents. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A finite strain viscoplasticitymodel for cold compaction processes ofmetal powders
Authors: Bier Wolfgang , Hartmann Stefan 
Published: December 2005

AbstractThe production of metal parts by powder metallurgical methods is of increasing interest due to energy and material efficiency of the processes. However, there is still a lack of reliable numerical methods and constitutive models to describe the compaction process from the loose powder to the green (un‐sintered) compact via die‐compaction or cold isostatic pressing. A new phenomenological constitutive model within the framework of viscoplasticity with internal variables is developed. A central part of the model is a unique and smooth single surface yield function. The applied evolution equations together with the assumed associated flow rule and the convexity of the yield function guarantee thermodynamic consistency of the model. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spherical indentation into a fcc single crystal – the squaring of the circle?
Authors: Eidel Bernhard , Gruttmann Friedrich 
Published: December 2005

AbstractSpherical microindentation into the (100) surface of a fcc single crystal results in a remaining indent shape which looks rather like a square than like a circle. This contribution aims to elucidate this curious phenomenon observed in a recently performed experiment within SFB 298 at TU Darmstadt. The applied methodology is threefold: (i) On the modelling side, a phenomenological orthotropic finite‐strain plasticity model is proposed and applied within finite‐element simulations. (ii) On the experimental side, the topography of the indentation crater is reconstructed by means of scanning‐electron microscopy along with image‐processing. (iii) Experimental observations are explained by plastic slip mechanisms. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling and Simulation of Polyoxymethylene
Authors: Hartmann Stefan 
Published: December 2005

AbstractThis essay is aimed at a brief representation of a constitutive model for a plastic called polyoxymethylene. This kind of plastic shows phenomena like tension‐compression asymmetry, non‐linear rate‐dependence as well as a pronounced relaxation behaviour. The tension‐compression asymmetry is modelled by the elastic part of the equilibrium stress state whereas the hysteretic part is described by an Armstrong&Frederick‐type evolution equation. A particular viscosity function is used for describing the evolution of the viscous strains occuring in the overstress part. The model is able to represent most of the aforementioned phenomena in tension, compression and torsion experiments. In the second part of the article, the implementation of the constitutive model into the .nite element program ANSYS is described followed by a test calculation treating a nut of a bolt. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An observation on the physical essence of elastoplastic deformations
Authors: Xiao Heng , Bruhns Otto , Meyers Albert 
Published: December 2005

AbstractOn account of the basic physical feature of elastoplastic deformations, namely, the occurrence of internal self‐equilibrated stress field upon removal of external loadings, a process of destressing an elastoplastic body with non‐uniform stress field would inevitably lead to loss of the line element concept in the resultant incompatible unstressed configuration. This would mean the loss of the kinematic ground or prerequisite for defining kinematic quantities in usual material continua. Then, an additional variable labelled as “elastic” or “plastic” via destressing could not be endowed with the necessary kinematic and physical content characterising a deformation quantity and, accordingly, might actually be a formal variable in mathematical sense. Thus follows an observation that the elastoplastic deformation would be an inherently inseparable physical entity. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)