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  • 11
    Electronic Resource
    Electronic Resource
    Dynamics of spatial structure-varying rigid multibody systems (1999)
    Springer
    Archive of applied mechanics 69 (1999), S. 265-285 
    Details
    ISSN: 1432-0681
    Keywords: Key words Multibody system ; contact ; unilateral constraint ; Coulomb friction ; stick-slip ; variational inequality.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary Couplings in machines and mechanisms exhibiting backlash and friction phenomena can be modeled as multibody systems with unilateral constraints and Coulomb friction. The structure of the differential-algebraic equations describing the system depends on the state of the constraints. The contact forces occurring at active constraints are taken into account in the equations of motion as Lagrange multipliers. Additionally, the kinematic conditions of all active constraints are formulated on the acceleration level. Contact and friction laws are sufficient conditions for state transitions of active constraints, and are represented by nonsmooth characteristics. Several formulations, like the linear complementarity problem, and two different nonlinear systems of equations are presented together with their solution method. The theory is applied to a mechanical system containing three-dimensional and coupled unilateral constraints with friction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004190050219
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  • 12
    Electronic Resource
    Electronic Resource
    Mechanische Systeme mit unstetigen übergängen (1984)
    Springer
    Archive of applied mechanics 54 (1984), S. 232-240 
    Details
    ISSN: 1432-0681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Summary Impulsive motion of dynamical systems may be caused by external impulsive forces or by impulsive constraints. The second case will be investigated more thoroughly with reference to some practical problems, where impulsive contraints may lead to a reduction of the number of degress of freedom thus modifying the structure of the system considered. An example of a non-linear oscillator illustrates the theory.
    Notes: übersicht Sto\vorgänge in dynamischen Systemen können durch äu\ere Einwirkung oder durch sto\artig auftretende Zwangsbedingungen zustande kommen. Insbesondere der zweite Fall wird im folgenden betrachtet, wobei für technisch wichtige Probleme das Verschwinden von Freiheitsgraden und damit eine änderung der Systemstruktur von Interesse ist. Das Beispiel eines nichtlinearen Schwingers verdeutlicht die Theorie.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00555662
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  • 13
    Electronic Resource
    Electronic Resource
    Static analysis of a two-member linkage interacting with a given surface (1999)
    Springer
    Archive of applied mechanics 69 (1999), S. 429-442 
    Details
    ISSN: 1432-0681
    Keywords: Key words statics ; two-member linkage ; Coulomb friction ; robotics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary The static interaction of a two-member linkage with a given surface is investigated. Dry friction acts at the point of contact of the linkage with the surface. The linkage has two drives generating torques at its joints. The optimal distribution of the joint torques is determined to maximize the friction force at the point of contact. The dependence of this maximal force on the lengths of the links and on the linkage configuration is investigated. The results obtained can be applied to the analysis and optimization of various robotic systems, in particular, manipulators interacting with rough surfaces and walking machines, especially tube-crawling robots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004190050232
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  • 14
    Electronic Resource
    Electronic Resource
    Über Rasselschwingungen in Kfz-Schaltgetrieben (1986)
    Springer
    Archive of applied mechanics 56 (1986), S. 25-37 
    Details
    ISSN: 1432-0681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Summary In gearboxes of motor vehicles all components not being shifted to transmit torque may be excited to perform clattering vibrations. This type of oscillations can be resolved in a more or less stochastic sequence of impacts taking place at the edges of the gear or bearing tolerances. The energy for this impulsive process comes from motor-engine vibrations in connection with a nonlinear behaviour of the clutch. Based on an impulsive theory for multibody systems a method is presented to analyse these clattering vibrations. For optimizing the essential parameters of the system, i.e. excitation form, tolerances, damping, friction, a simulation program is developed. Clattering noise is assumed to be proportional to the energy losses due to impacts at the edges of the plays. Results compare well with practical experiences.
    Notes: Übersicht In Schaltgetrieben für Kraftfahrzeuge führen in allen Gängen diejenigen Schalträder und im Leerlauf oder im direkten Gang auch die Vorgelegewelle innerhalb ihrer Spiele Rasselschwingungen aus, die an der Momentenübertragung nicht beteiligt sind und damit wegen fehlender Verspannung klappern können. Als Erregung für diese durch Stöße verursachten Rasselschwingungen wirkt im wesentlichen die Drehungleichförmigkeit des Antriebsritzels und damit letztlich die zeitliche Schwankung des Motormoments in Verbindung mit der nichtlinearen Kupplungskennlinie. In der vorliegenden Arbeit wird, ausgehend von einer Theorie mechanischer Systeme mit unstetigen Übergängen, ein Verfahren zur praxisnahen Berechnung dieser Rasselschwingungen vorgestellt. In einem Simulationsprogramm lassen Variationen der wesentlichen Parameter, wie etwa der Erregercharakteristik, der Zahn- und Lagerspiele, der Zahn- und Lagerdämpfung sowie der Schleppmomente, Rückschlüsse auf optimale Parameterkombinationen zu. Die leicht zu ermittelnden Energieverluste bei Stößen liefern einen groben Anhaltspunkt für die Rasselgeräusche. Das gewählte Modell entspricht den beobachteten physikalischen Phänomenen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00533571
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  • 15
    Electronic Resource
    Electronic Resource
    Kurt Magnus 80th anniversary (1992)
    Springer
    Archive of applied mechanics 62 (1992), S. 361-362 
    Details
    ISSN: 1432-0681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00804596
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  • 16
    Electronic Resource
    Electronic Resource
    The principle of virtual work in mechanical and electromechanical systems (1995)
    Springer
    Archive of applied mechanics 65 (1995), S. 390-400 
    Details
    ISSN: 1432-0681
    Keywords: virtual work ; electromechanical systems ; unifying modelling ; constraints ; mechatronics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary The principle of virtual work is applied to electromechanical systems as the foundation of a unifying concept for modelling mechatronical systems. After the presentation of an important result in the field of mechanics, the expansion of the principle on electrical networks and electromechanical systems is shown. The use of the principle of virtual work in the domain of electromechanics yields an analogous form to the central equation of mechanics which is valid for holonomic and nonholonomic systems. The electrotechnical part of the system is confined to networks. The derivation of the mathematical model is demonstrated on the example of a simple electromechanical oscillation circuit. In addition, the physical systems are separately treated, taking into account the explicit constraints on the basis of the Lagrangian multiplier method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00787532
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  • 17
    Electronic Resource
    Electronic Resource
    Unilateral problems of dynamics (1999)
    Springer
    Archive of applied mechanics 69 (1999), S. 503-527 
    Details
    ISSN: 1432-0681
    Keywords: Key words Unilateral contact ; multibody dynamics ; complementarity ; friction ; impact
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary Contact processes may be described by local discretizations, by rigid representation or by mixed methods incorporating both ideas. A rigid body approach is proposed for the dynamics of mechanical systems, achieving good results also for multiple-contact problems. Contacts in multibody systems are mainly considered, with the corresponding contact constraints varying with time, thus generating structure-variant systems. The equations of motion for dynamical systems with such unilateral behavior are discussed, solution methods and applications are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004190050240
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  • 18
    Electronic Resource
    Electronic Resource
    Fast evaluation of friction forces in traction-drive contacts including thermal effects (2000)
    Springer
    Archive of applied mechanics 70 (2000), S. 479-488 
    Details
    ISSN: 1432-0681
    Keywords: Key words Traction drive ; friction ; contact ; rheology ; thermal effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary  In automotive traction drives, power is transmitted by friction forces. The friction forces result from the shear stresses developed in lubricated and highly loaded contacts between rolling bodies. Due to the kinematics of a traction drive, shear velocities occur in both the rolling direction and perpendicular to it. Due to these shear velocities and by normal pressure, the lubricant is forced to build up shear stresses. The increase of the shear stresses may be modelled by a nonlinear viscous element. The describing differential equations are coupled by the equivalent shear stress, which defines the nonlinear behaviour of the element. A fast method is described to evaluate the coupled differential equations. By using a known analytical approximation for the equivalent shear stress, the differential equations are decoupled and can be solved analytically. In an iterative procedure the equivalent shear stress is updated, and the complete solution is found. The iterative method is extended to account for thermal effects in the contact.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004190000083
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  • 19
    Electronic Resource
    Electronic Resource
    Ein Näherungsverfahren für flüssigkeitsgefüllte Kreisel (1974)
    Springer
    Archive of applied mechanics 43 (1974), S. 306-316 
    Details
    ISSN: 1432-0681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Summary We consider gyros containing liquid in several completely filled tanks. Averaging the Helmholtz vorticity equations over the liquid volume yields a set of ordinary differential equations with constant coefficients, which describe the problem approximately. The coefficients depend only on a simple boundary value problem. The usefulness of the method is tested by general and numerical comparisons.
    Notes: Übersicht Es werden Kreisel mit vollständig gefüllten Flüssigkeitsbehältern betrachtet. Durch integrale Mittelung der Helmholtzschen Wirbelgleichungen über das Flüssigkeitsvolumen erhält man für das Problem einen Satz gewöhnlicher Differentialgleichungen mit konstanten Koeffizienten, die nur noch von einem einfachen Randwertproblem abhängen. Allgemeine und numerische Vergleiche bestätigen die Brauchbarkeit dieses Näherungsverfahrens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00537219
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  • 20
    Electronic Resource
    Electronic Resource
    Seltsame Attraktoren in Zahnradgetrieben (1988)
    Springer
    Archive of applied mechanics 58 (1988), S. 113-125 
    Details
    ISSN: 1432-0681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Summary Clattering vibrations in gear-boxes may be described as a sequence of impulsive processes [3, 5]. The motion between two impacts during teeth-meshing can be represented analytically. This leads to discrete and invertible mappings for the motion in phase-space. As a result one gets strange attractors or periodical behaviour according to the set of parameters under consideration. Transitions from periodic to chaotic states (and vice versa) are indicated by Ljapunov's exponents. Some parameter influences become visible by applying estimates of the phasespace boundaries. The examples of a one-stage and a two-stage gearing show advantages of the method as compared to usual numerical simulations.
    Notes: Übersicht Rassel- und Klapperschwingungen in Zahnradgetrieben lassen sich als Folgen von Stoßprozessen beschreiben [3, 5]. Dabei kann man die Bewegung von einem Stoß zum nächsten im allgemeinen analytisch darstellen. Dies ermöglicht die Herleitung diskreter und invertierbarer Abbildungsfunktionen und damit eine Darstellung der Bewegung im Phasenraum als eine Art Poincaré-Abbildung. Als Ergebnis erhält man je nach Parametersituation seltsame Attraktoren oder Fixpunkte, die sich verzweigen. Die Übergänge von periodischen zu chaotischen Zuständen und umgekehrt werden vom Verlauf der Ljapunov-Exponenten angezeigt, strukturelle Aussagen werden mit Hilfe von Abschätzungen der Phasenraumgrenzen möglich. Die Anwendungsbeispiele des einstufigen und zweistufigen Stirnradgetriebes zeigen die Vorteile des Verfahrens, insbesondere gegenüber gewöhnlichen numerischen Simulationen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00536231
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