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    Item type:Publication, Access status: without files ,
    Active vibration control of an oscillator with two translational degrees of freedom using centrifugal forces created by two eccentrically rotating masses
    (2018-03-01)
    Bäumer, Richard
    ;
    Starossek, Uwe
    An active mass damper for vibration control of an oscillator with two translational degrees of freedom is presented along with the corresponding closed-loop control algorithm. The damper consists of two eccentrically rotating masses. In a preferred mode of operation, the masses rotate in opposite directions with a mostly constant angular velocity about a single axis. The resulting force is a harmonic control force. Its direction is determined by the relative angular position of the masses. In previous research, a similar control algorithm for vibration control of a single degree of freedom oscillator has been proven to be effective. In this paper, the control algorithm is augmented such that it can be applied to an oscillator with two translational degrees of freedom. Various state variables are introduced and a feedback control algorithm is developed. The presented algorithm ensures that the rotational motion of the masses is smooth and that the control force has the required orientation. The algorithm is verified experimentally with a test setup for the damping of free vibrations and numerically for stochastically forced vibrations. Finally, the device is compared with a conventional active mass damper. It is shown that the power demand and the energy consumption of the presented device are smaller than those of the conventional active mass damper.
    Publicationtype: Journal Article
      166
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    Probability distribution and moments of the first-excursion time for dynamic systems under non-Poisson impulse processes: Markov approach based on integro-differential Chapman-Kolmogorov equations
    (2016-06-01)
    Iwankiewicz, Radoslaw Marek
    The present paper deals with the problem of the first-excursion time for the response of dynamic systems to non-Poisson (renewal) impulse process excitations. As the state vector of the dynamic system is a non-Markov process, no method is directly available for the derivation of the equations for the cumulative distribution function or moments of the first-excursion time. The original non-Markov problem is converted into a Markov one by recasting the excitation process with the aid of an auxiliary, pure-jump stochastic process characterized by a Markov chain, leading to the augmentation of the state space of the dynamic system by auxiliary Markov states. The conditional probability density—discrete probability distribution function characterizing jointly the augmented state vector, as well as the cumulative distribution function of the first-excursion time (defined as a mixed-type, joint cumulative distribution-discrete probability function), satisfy the set of backward integro-differential Chapman-Kolmogorov equations. The recursive integro-differential equations for statistical moments of the first-excursion time are also obtained. For four example non-Poisson impulse processes the explicit equations are obtained.
    Publicationtype: Journal Article
      70