bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effiziente Simulation von Mehrkörpersystemen mit Kontaktbedingungen ‐ O(n) Verfahren
Authors: Gattringer Hubert , Höbarth Wolfgang , Bremer Hartmut 
Published: December 2006

AbstractAufgrund der immer größer werden Komplexität von dynamischen Systemen in Forschung und Industrie ist man an einer effizienten Simulation interessiert. Bei der dynamischen Modellierung von baumstrukturierten Mehrkörpersystemen entstehen hochgradig nichtlineare Bewegungsgleichungen. Dabei wird von einer Beschreibung in Minimalform ausgegangen. Der Rechenaufwand zur Invertierung der Massenmatrix ist enorm. Er steigt mit kubischer Ordnung (O(n)3) der Freiheitsgrade. Bei einer Modellierung des Mehrkörpersystems über die Projektionsgleichung in Subsystemdarstellung kann ein O(n) Verfahren hergeleitet werden. Werden einzelne Baugruppen (Subsysteme) zusammengefasst, lässt sich das Problem geeignet strukturieren, und über die den Subsystemen zugeordneten beschreibenden Geschwindigkeiten erhält man gut interpretierbare Zwischenergebnisse. Als Subsysteme können nicht nur starre Einheiten (z.B. Motor Getriebe Einheit), sondern auch hybride Systeme (z.B. Motor mit elastischem Balken) zum Einsatz kommen. Anstatt wie bei herkömmlichen Verfahren die Gesamtmassenmatrix invertieren zu müssen, kommt der O(n) Algorithmus mit einer Matrixinvertierung vom Relativfreiheitsgrad pro Subsystem aus. Bei einer Motor Getriebe Einheit ist das eine quadratische Matrix (Motor ‐ und Armwinkel), bei hybriden Systemen kommen als Relativfreiheitsgrade noch die Ritz Koeffizienten dazu. Werden bei dem Mehrkörpersystem zusätzliche Kontakte aktiv, so kann das mithilfe einer Kontaktkraft (Lagrangescher Parameter) ins Modell aufgenommen werden. Auch für diesen Fall kann ein effizienter Algorithmus angegeben werden, der ohne eine Invertierung der Massenmatrix auskommt. Beim Übergang zum Kontaktfall tritt unweigerlich ein Stoß auf. Dieser wird ebenfalls im Sinne des O(n) Verfahrens behandelt. Als Anwendungsbeispiel wird auf eine zweibeinige Laufmaschine eingegangen. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of the discrete null space method to domain decompositionand large deformation contact problems
Authors: Hesch Christian , Betsch P. 
Published: December 2006

AbstractWe aim at the development of energy consistent ‘mechanical’ integrators for the differential‐algebraic equations (DAEs) associated with the contact problems under consideration. First steps towards the energy consistent time integration of frictionless dynamic contact problems can be found in the works by Laursen & Chawla [4], Armero & Petöcz [1] and Laursen & Love [5]. Energy consistent mechanical integrators have been recently developed for DAE‐formulations of constrained mechanical systems (e.g. Gonzalez [3]). These works are based on the direct discretization of the underlying DAEs leading to a saddle point system to be solved in each iteration of the iterative solution procedure. Due to the presence of Lagrange multipliers this approach leads to a large number of unknowns and potential conditioning problems. To remedy these drawbacks the discrete null space method (Betsch [2]) has been recently developed. We apply the discrete null space method to both domain decomposition in the framework of nonlinear elastodynamics and large deformation contact problems. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Methodenvergleich bei der Modellierung eines Mini Segway
Authors: Höbarth Wolfgang , Gattringer Hubert , Bremer Hartmut 
Published: December 2006

AbstractBei einem Mini Segway handelt es sich um ein einachsiges Fahrzeug mit instabilem Aufbau. Bei der Modellierung von Fahrzeugen ohne Quergleiten der Rädermüssen nichtholonome Bindungen eingeführt werden. Es gibt verschiedeneMöglichkeiten, diese Bindungen zu berücksichtigen. Anhand eines Segway Modells werden unterschiedliche Vorgehensweisen zur Modellbildung aufgezeigt. Als analytische Methode wird Lagrange II verwendet. Hier muss die Bindung auf Geschwindigkeitsebene vorerst offen gelassen werden. Sie kann aber nachträglich mittels Kontaktkraft (Lagrangescher Parameter) oder mittels Nachprojektion in die freien Geschwindigkeitsrichtungen (Maggi Gleichung) eingebracht werden. Als synthetische Methode zum Aufstellen der Bewegungsgleichung wird die Projektionsgleichung verwendet. Bei dieser Methode können direkt die nichtholonomen Minimalgeschwindigkeiten verwendet werden. Zusätzlich wird versucht, die Bewegungsgleichung mit Hilfe von reduzierten Koordinaten zu ermitteln. Hierbei treten bei der Verwendung von analytischen Methoden große Probleme auf, da die verwendeten, reduzierten Koordinaten die Geschwindigkeitsbindung bereits implizit erfüllen, was andererseits die Projektionsgleichung zu einem universell einsetzbaren Werkzeug macht. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An Experimental and Numerical Study of Deformable Bodies Contact
Authors: Jiang Yu , Eberhard Peter 
Published: December 2006

AbstractThis study deals with the impact of a rotating disc elastically striking a strip. We establish an experimental setup including a disc with a throwing machine controlled by a dSPACE‐Autobox to generate the translational and rotational motions of the disc, a properly fixed strip and a high‐speed digital camera system with an image processing package to capture kinematical data of the disc. The effects of strip flexibility and disc initial normal velocity before impact are investigated in detail. For interpreting the experimental results a hybrid impact model is developed which can provide not only generally good predictions compared with measurements but also some insight into the influences of strip flexibility and disc initial motions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient integration of flexible multibody dynamics
Authors: Leyendecker S. , Betsch P. , Steinmann P. 
Published: December 2006

AbstractThe modelling of flexible multibody dynamics as finite dimensional Hamiltonian system subject to holonomic constraints constitutes a general framework for a unified treatment of rigid and elastic components. Internal constraints, which are associated with the kinematic assumptions of the underlying continuous theory, as well as external constraints, representing the interconnection of different bodies by joints, can be accounted for in a likewise systematic way. The discrete null space method developed in [0] provides an energy‐momentum conserving integration scheme for the DAEs of motion of constrained mechanical systems. It relies on the elimination of the constraint forces from the discrete system along with a reparametrisation of the nodal unknowns. The resulting reduced scheme performs advantageously concerning different aspects: the constraints are fulfilled exactly, the condition number of the iteration matrix is independent of the time step and the dimension of the system is reduced to the minimal possible number saving computational costs. A six‐body‐linkage possessing a single degree of freedom is analysed as an example of a closed loop structure. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Three‐dimensional modelling of discrete particles by superellipsoids
Authors: Lillie Claudia , Wriggers Peter 
Published: December 2006

AbstractDiscrete Elements are used for the simulation of granular materials (sand, ballast) as well as for molecular assemblies. Circles (2D) and spheres (3D) are often used in literature on the Discrete Element Method (DEM) however they represent a strong idealisation of the real geometry. Superellipsoids provide the opportunity to generate a wide variety of three‐dimensional geometrical shapes (e.g. sphere, cube, cylinder).The motion of each particle is described by means of rigid body dynamics. Suitable numerical integration methods are necessary which are able to conserve the essential physical quantities like momentum energy etc.. Possible choices are e.g. the explicit Verlet‐Leapfrog method for the translation and the explicit fourth order Runge‐Kutta method for the rotation. The implemented contact formulation takes damping as well as friction into account. Efficient implementation of the contact search is the main aim of this part of the work. It is subdivided into the neighbourhood search and the local search. A bisection algorithm is used to calculate the gap between two superellipsoids within the search. For the neighbourhood search two binning algorithms were implemented and compared for several packages of particles. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Kompensation der Lagefehler der Inertialsensoren in einer IMU
Authors: Meinicke Alexander , Woernle Christoph , Wagner Jörg 
Published: December 2006

AbstractDie Sensoren in Inertial Measurement Units (IMU) weisen Lagefehler auf. Werden diese Lagefehler nicht identifiziert und rechnerisch kompensiert, können erhebliche systematische Messfehler entstehen. Im vorliegenden Beitrag werden die Kompensationsgleichung sowie die erforderliche Genauigkeit bei der Identifikation der Lagefehler hergeleitet. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Problem of unilateral constraints in the dynamics of the floor loaded with a machine
Authors: Mironowicz Władysław , Sęk Marcin 
Published: December 2006

AbstractThe engineering practice indicates that in industrial ferro ‐ concrete constructions there are various irregularities and damages which may hare significant influence on it's stiffness and consequently on it's vibration. In the paper one of fore ‐ mentioned issues i.e. weakening or loss of connection between selected parts of the structure is considered. More precisely it is the problem of unilateral constraints in elastic constraints between the ferro ‐ concrete slab floor and the machine placed on it. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ein innovatives Sensorkonzept zur “Schmerzdetektierung”
Authors: Ostermeyer G. P. , Schiefer F. 
Published: December 2006

AbstractEin Zusammenhang von Schmerz und technischen Systemen ist bislang nahezu unerforscht. Dabei lässt sich eine bestimmte, physiologisch beschriebene Schmerzart durchaus auf technische Anwendungen beispielsweise in der Robotik oder Prothetik abbilden. Der nozizeptive Schmerz dient Lebewesen im Allgemeinen als Warnsystem und wird auch als sinnvoller Schmerz bezeichnet. Das Ziel ist es, auf technischem Wege diese Schmerzart detektieren zu können und damit weitere Kriterien zur Beurteilung der Funktion von Systemen zu finden. Das Sensorkonzept beruht auf der Idee, dass zwischen den Eigenschaften von Schmerz und Wärme Analogien existieren [3]. Die Erhöhung bestimmter Eigenschaften äußerer Einwirkungen führt zu einer Vergrößerung sowohl des Schmerzes als auch der Wärme. Das Ausbleiben der Einwirkungen führt zum Nachlassen des Schmerzes bzw. zum Abklingen der Wärme. Die Sensoridee führt zur Anwendung der Mesoskopischen Vielteilchentheorie [1, 2], mit der u. a. die Energieumwandlung in Wärmeenergie bei Stoß‐ und Reibvorgängen in den Grenzschichten der Kontaktkörper thermodynamisch korrekt beschrieben werden kann. Mit Hilfe des entwickelten Sensorkonzeptes wird ein Energieeintrag gemessen, der implizit frequenzselektive Informationen über die Ruckbeanspruchung enthält. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Autonomer Mobiler Roboter mit Scara‐Armeinheit
Authors: Stadlbauer Klaus , Bremer Hartmut 
Published: December 2006

AbstractAutonome Mobile Roboter sind heutzutage schon vielfältig im Einsatz. Ob zum Reinigen von Flughäfen, zum Transport von Gütern oder zum Erkunden fremder Planeten, sie alle haben gemein, dass sie autonom agieren und reagieren müssen. Die Modellierung dieses nichtholonomen Roboters welcher von der Kon.guration einem konventionellen Automobil entspricht erfolgt mit Hilfe der Projektionsgleichung in Subsystemdarstellung. Der große Vorteil der Projektionsgleichung liegt darin, dass die nichtholonomen Bindungen implizit in diesem System enthalten sind. Weiters ist das Verfahren sehr.exibel bei der Wahl der Referenzkoordinatensysteme. Die SCARA‐Armeinheit (SCARA = Selective Compliance Assembly Robot Arm) wird in vertikaler Lage als Manipulator angebracht. Hier sieht man den Vorteil der Projektionsgleichung in Subsystemdarstellung, da ohne großen Rechenaufwand beliebig viele weitere Arme hinzugefügt werden können. Die Bewegungsgleichung wird in den Zustandsraum transformiert und mittels einer nichtlinearen Zustandsrückführung eingangs‐/ausgangslinearisiert. Mit Hilfe eines diesem linearisierten System überlagerten linearen Reglers kann das Gesamtsystem geregelt werden. In diesem System übernimmt die Steurung bzw. Regelung eine Embedded‐ Computer Plattform, die über das Echtzeitsystem RT‐Linux angesteuert werden soll. Natürlich muss hierbei gewährleistet werden, dass die Rechenzeit der Plattform den Anforderungen der Sensoren, der Pfadplanung und der Regelung gerecht wird. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Regularization of 2D frictional contacts for rigid body dynamics
Authors: Stamm W. , Fidlin A. 
Published: December 2006

AbstractClassic rigid body mechanics does not provide frictional forces acting in a 2D contact interface between two bodies during sticking. This is due to the statical undeterminacy related with this problem. Many technical systems, e.g. disk clutches, have such surface‐to‐surface contacts and it is sometimes desirable to treat them as rigid body systems despite the 2D contact. Alternatively it is possible to model the systems using elastic instead of rigid bodies, but this might lead to certain drawbacks. Here a new regularization model of such 2D contacts between rigid bodies is proposed. It is derived from a material model for elasto‐plasticity in continuum mechanics. Only dry friction is taken into account. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimization of spatial tracks using a morphing approach
Authors: Tändl Martin , Kecskeméthy Andrés 
Published: December 2006

AbstractThis paper describes an approach for optimizing multibody systems involving spatial tracks, addressing the problem of finding an optimal set of design parameters when no good initial guess is available. In this setting, it is common that, due to nonlinearities of the objective function and singularities in the kinematic model, the optimization fails to converge or to find feasible points at all. The present paper presents a three‐stage procedure for sequentially guiding a standard optimization routine from an arbitrary initial guess to the optimal configuration. The approach has been tested when optimizing real roller coaster tracks with respect to passenger acceleration and compared with a genetic algorithm implementation, showing that objective function morphing renders faster for the regarded type of systems. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rotational motion of a discretized buckled beam
Authors: Troger H. , Pissarev A. , Steindl A. 
Published: December 2006

AbstractWe study a simple discretized model of a vertical cylindrical beam with circular cross‐section which is clamped at its lower end and free at its upper end. If the beam is longer than a critical length the initially straight configuration will loose its stability and the beam will buckle due to its own weight. Now the base of the buckled beam is rotated about its vertical axis. Several different families of steady state motions are detected for the undamped system. Their stability is investigated. Moreover it is shown that there is a big difference in the behavior of the discretized model of the beam whether internal damping is included in the model or not. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Energy consistent time integration of planar multibody systems
Authors: Uhlar Stefan , Betsch Peter 
Published: December 2006

AbstractThe planar motion of rigid bodies and multibody systems can be easily described by coordinates belonging to a linear vector space. This is due to the fact that in the planar case finite rotations commute. Accordingly, using this type of generalized coordinates can be considered as canonical description of planar multibody systems. However, the extension to the three‐dimensional case is not straightforward. In contrast to that, employing the elements of the direction cosine matrix as redundant coordinates makes possible a straightforward treatment of both planar and three‐dimensional multibody systems. This alternative approach leads in general to differential‐algebraic equations (DAEs) governing the dynamics of rigid body systems. The main purpose of the present paper is to present a comparison of the two alternative descriptions. In both cases energy‐consistent time integration schemes are applied. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Finite Swelling with Weakly Fulfilled Boundary Conditions
Authors: Acartürk A. , Ehlers W. , Markert B. 
Published: December 2006

AbstractBiological soft tissues exhibit a swelling behaviour and consist of multiple phases, a solid phase composed of collgagen fibers and charged PGA chains and a fluid phase composed of the liquid solvent and the ions of dissolved salt.In this contribution, the Theory of Porous Media (TPM) model consists of four constituents, a charged solid and an aqueous solution composed of water and the ions of dissolved salt. The solid is modelled by a finite elasticity law accounting for the multiphasic micro structure, whereas the fluid is considered as a viscous Newtonian fluid. One finally ends up with the volume balance of the fluid, the concentration balance of the cations, the momentum balance of the overall mixture. The resulting set of partial differential equations is solved within the framework of the FEM. Therefore, the weak forms are derived and the resulting set of equations for the primary variables pore pressure p, cation concentration c and solid displacement uS , is implemented into the FE tool PANDAS. Finally, a three dimensional example of a swelling hydrogel disc is shown. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of the Human Body Vibrations for the Seated Vehicle Driver
Authors: Arghir Mariana , Rodean Simona 
Published: December 2006

AbstractThe paper presents some aspects about the dynamic response of the human body subjected to the vertical vibration in the travel inside the auto vehicle. There is a model presented in the specialized literature. This is transformed for the given study because was necessary to realize the vertical vibration along the human body. There are two different studies: using a linear lumped parameter systems seat ‐ human body model; using a nonlinear lumped parameter systems seat‐human body model. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of Eigenstresses and Damage in Arterial Walls
Authors: Balzani Daniel , Schröder Jörg , Gross Dietmar 
Published: December 2006

AbstractAn anisotropic damage model is used for the numerical simulation of an overstretched artery taking into account eigenstresses occurring in unloaded configurations of arteries. In order to guarantee the existence of minimizers we use a polyconvex energy function for the description of the hyperelastic behavior in the physiological range of deformations in arterial walls. The basic assumption underlying the applied damage model is that the damage occurs mainly in fiber direction. As a numerical example we consider the cross‐section of a diseased artery and apply a high internal pressure in order to obtain the damage distribution at the overstretched configuration. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An anisotropic viscoelastic soft tissue model at large strains
Authors: Görke Uwe‐Jens , Günther Hubert , Bucher Anke , Kreißig Reiner 
Published: December 2006

AbstractSoft biological tissues represent complex inhomogeneous, and as a rule multiphase materials subjected to large strains under in vivo mechanical conditions. Apart from a number of other structural‐related features they are characterized by a ratedependent material behavior which is attributed to fluid‐solid interactions as well as intrinsic viscoelastic properties of the solid matrix. The authors propose to model rate‐dependent phenomena of the solid phase of soft biological tissues within the context of a thermodynamically consistent phenomenological material approach resulting from an overstress concept. Due to the presence of directed fibrous constituents soft tissues should be considered as anisotropic materials. Therefore, the viscous overstress model has been completed by a transversely isotropic approach. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theory and Implementation of Time‐Dependent Fibre Reorientation in Transversely Isotropic Materials
Authors: Himpel Grieta , Menzel Andreas , Kuhl Ellen , Steinmann Paul 
Published: December 2006

AbstractTransversely isotropic materials are commonly described by one characteristic direction in the material configuration, which commonly is assumed to be constant. However, for some applications it makes sense to consider a reorientation of the characteristic direction, as for instance the orientation of biological materials adapts to the mechanical loading, see e.g. Kuhl et al. [4]. Other examples are piezoelectric materials, which reorient due to electric or mechanical loading, as described in Smith [7], and liquid crystals changing their orientation on account of electric or magnetic fields, see Ericksen [1]. Furthermore simulations with a reorientation of the characteristic direction can be used in the context of optimisation of composites. In this contribution we restrict ourselves to the modelling of hyper‐elasticity and assume a time dependent reorientation of the characteristic direction with respect to the principal strain directions, see for instance Menzel [5]. Thereby we concentrate on the numerical implementation into a finite element code. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Suitable initial conditions for multiphasic FE computations of spinal discs
Authors: Karajan N. , Ehlers W. , Markert B. 
Published: December 2006

AbstractThe intervertebral disc (IVD), as a complex representative of charged, hydrated biological soft tissues, is of great research interest regarding numerical simulation techniques. Herein, especially the Finite Element Method (FEM) plays a major role in combination with a macroscopic model based on the Theory of Porous Media (TPM). Following this, two phases are introduced: the extracellular matrix exhibiting a nonlinear viscoelastic behavior and the viscous interstitial fluid. Furthermore, the resultant solid and fluid phases are electrochemically active by carrying fixed negative charges and containing dissolved ions and cations, respectively. This characteristic causes an osmotic pressure (Donnan osmosis), which is superimposed with the hydraulic contribution to a total pore pressure.In this contribution two numerical simulations of a free swelling experiment with different initial conditions are discussed. Herein, one can proceed from an overall stress‐free reference configuration, which leads to a prestressed but undeformed solid skeleton. Secondly, a non stress‐free initial state is investigated, which will be computed to an equilibrium state between the osmotic pressure and the solid extra stress leading to a deformed and prestressed solid skeleton. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Description of Growth in Saturated Living Tissues
Authors: Ricken Tim 
Published: December 2006

AbstractA comprehensive model for biological tissues must include the anisotropic tissue structure, the interstitial liquid wich saturated the tissue and the growth mechanism of the tissue. In the present contribution this is done by use of a three phasic model with a solid, liquid and nutrient phase in the framework of the porous media theory (TPM). In order to characterize the transversal isotropic skeleton behavior, an invariant formulation of the Helmholtz free energy function and the permeability tensor is suggested. The growth mechanism is characterizes by a mass transfer between the nutrient and solid phase. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)