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Item type:Publication, Access status: without files , Twin Rotor Damper for Human-Induced Vibrations of FootbridgesFootbridges often have a lightweight and slender design. As a result, they tend to be susceptible to human-induced vibrations. In this paper, the application of the twin rotor damper (TRD), an active mass damper consisting of two eccentrically rotating masses, for the control of human-induced footbridge vibrations is presented. A proof-of-concept prototype is developed for a real-world slender steel footbridge that is sensitive to human-induced vibrations. First, a numerical study is performed to design a TRD to mitigate human-induced vibrations. Based on these results, a TRD prototype was designed and built. Second, the performance of the TRD is evaluated on-site. The response of the footbridge to human-induced loading is measured under both uncontrolled and controlled conditions and compared to corresponding numerical simulations. The measurements confirm the results of the numerical simulations. They show that the TRD prototype is able to effectively damp human-induced vibrations of a real-world footbridge and validate the TRD design.Publicationtype: Journal Article93 - Some of the metrics are blocked by yourconsent settings
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); 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 Article166 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Twin rotor damper for the damping of stochastically forced vibrations using a power-efficient control algorithm(2018-01-20); ; ; ; The twin rotor damper (TRD), an active mass damper, uses the centrifugal forces of two eccentrically rotating control masses. In the continuous rotation mode, the preferred mode of operation, the two eccentric control masses rotate with a constant angular velocity about two parallel axes, creating, under further operational constraints, a harmonic control force in a single direction. In previous theoretical work, it was shown that this mode of operation is effective for the damping of large, harmonic vibrations of a single degree of freedom (SDOF) oscillator. In this paper, the SDOF oscillator is assumed to be affected by a stochastic excitation force and consequently responds with several frequencies. Therefore, the TRD must deviate from the continuous rotation mode to ensure the anti-phasing between the harmonic control force of the TRD and the velocity of the SDOF oscillator. It is found that the required deviation from the continuous rotation mode increases with lower vibration amplitude. Therefore, an operation of the TRD in the continuous rotation mode is no longer efficient below a specific vibration-amplitude threshold. To additionally dampen vibrations below this threshold, the TRD can switch to another, more energy-consuming mode of operation, the swinging mode in which both control masses oscillate about certain angular positions. A power-efficient control algorithm is presented which uses the continuous rotation mode for large vibrations and the swinging mode for small vibrations. To validate the control algorithm, numerical and experimental investigations are performed for a single degree of freedom oscillator under stochastic excitation. Using both modes of operation, it is shown that the control algorithm is effective for the cases of free and stochastically forced vibrations of arbitrary amplitude.Publicationtype: Journal Article144 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Active vibration control of a three degree of freedom oscillator using two eccentrically rotating massesAn active mass damper utilizing rotating masses to damp the vibrations of an oscillator with two translational degrees of freedom in a horizontal plane and one rotational degree of freedom about a vertical axis is presented along with a corresponding closed-loop control algorithm. The damper consists of two masses rotating about a single vertical axis, powered by two actuators. In a preferred mode of operation, these masses rotate with a nearly constant and equal angular velocity in opposite directions, thus producing a harmonic control force in a single horizontal direction. By varying the relative angular position of the rotating masses, this control force can be directed in an arbitrary direction and used to damp the translational motion. In previous research, a control algorithm was derived for this purpose. The rotational degree of freedom can additionally be controlled by producing a moment by imposing angular accelerations on the rotating masses. In this paper, the previous control algorithm is augmented such that the rotational degree of freedom is additionally controlled. The augmented control algorithm is verified with help of numerical simulations.Publicationtype: Conference Paper164 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , An analytic comparison regarding steady-state damping performance between the twin rotor damper and a dynamic vibration absorberA novel active mass damper, the twin rotor damper (TRD), was presented in previous research, including control algorithms for monofrequent vibrations. In this paper, the steady-state damping performance is evaluated by applying a harmonic excitation force to a single degree of freedom (SDOF) oscillator with and without the action of the damping device. Using the velocity of the SDOF oscillator as feedback, adequate steady-state damping performance can be achieved with the TRD by setting the control force of the TRD in antiphase to the velocity of the SDOF oscillator. An analytic solution describing the steady-state damping performance is derived. The analytic solution allows for the comparison with a dynamic vibration absorber (DVA) of comparable size (stroke) and control mass. The analytic comparison shows that the TRD achieves greatly better damping performance than the DVA.Publicationtype: Conference Paper156 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Closed-Form Steady-State Response Solution of the Twin Rotor Damper and Experimental ValidationIn previous research, the twin rotor damper (TRD), an active mass damper, was presented including control algorithms for monofrequent vibrations. In a preferred mode of operation, the continuous rotation mode, two eccentric masses rotate in opposite directions about two parallel axes with a mostly constant angular velocity. The resulting control force is harmonic. Within this paper, the steady-state response of a single-degree-of-freedom (SDOF) oscillator subjected to a harmonic excitation force with and without the TRD is studied. A closed-form solution is presented and validated experimentally. It is shown that the TRD provides damping to the SDOF oscillator until a certain frequency ratio is reached. The provided damping is not only dependent on the design parameters of the TRD but also depends on the steady-state vibration amplitude. The solution serves as a powerful design tool for dimensioning the TRD. The analytical closed-form solution is applicable for other active mass dampers.Publicationtype: Journal Article79 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Alternating the twin rotor damper between two modes of operation to eliminate small vibrationsIn previous research, the twin rotor damper (TRD), an active mass damper, was presented. In a preferred, energy-efficient mode of operation, the continuous rotation mode, two eccentric control masses rotate with constant angular velocities about two parallel axes in opposite directions. The resulting centrifugal forces combine into a directed harmonic control force that can be used for the control of structural vibrations. In another, more power-demanding mode of operation, the swinging mode, both control masses oscillate about certain angular positions. For both modes of operation, corresponding control algorithms have been developed. Furthermore, it has been found that the continuous rotation mode is not efficient for the damping of small vibrations, whereas the swinging mode can bring small vibrations to rest. In this paper, a control algorithm is presented, which uses the continuous rotation mode for large vibrations and the swinging mode for small vibrations. To validate the control algorithm, the TRD is numerically and experimentally applied on a single degree of freedom oscillator. The efficiency of the algorithm is studied for free vibrations.Publicationtype: Journal ArticleScopus© Citations 1 271 325 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Active vibration control using centrifugal forces created by eccentrically rotating massesThe twin rotor damper (TRD) is a newly developed active mass damper. It is presented here along with respective closed-loop control algorithms. The greatest advantage of the device is its low power demand when operated in a preferred mode of operation, the continuous rotation mode. In this mode, two eccentric masses rotate in opposite directions about two parallel axes with a mostly constant angular velocity. The resultant force is harmonic and can be used for the control of structural vibrations. To study the effect of the TRD on a single degree-of-freedom (SDOF) oscillator, various state variables are introduced and a feedback control algorithm is developed for the continuous rotation mode of operation. For reaching and leaving the continuous rotation mode, ramp-up and ramp-down trajectories are developed. These trajectories are designed such that the power and energy demand as well as the mechanical wear on the device are minimized. The feedback control algorithm is validated on a test setup. The damping effectiveness and the low power and energy demands encourage further investigation of the device under stochastic loading and comparisons with other active mass dampers.Publicationtype: Journal Article71 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , An energy approach for the active vibration control of an oscillator with two translational degrees of freedom using two auxiliary rotating massesAn active mass damper implementing two auxiliary masses rotating about a single axis is presented. This device is used for the vibration control of an oscillator performing translational motion in a plane (two translational degrees of freedom). In a preferred mode of operation, both auxiliary masses rotate with the same constant angular velocity in opposite directions. The resultant of the produced harmonic centrifugal forces is used for the vibration control. The direction of this control force can be altered by slightly varying the angular velocity of the auxiliary masses. Using an energy approach, a control algorithm was derived. The control algorithm ensures that the control force effectively damps the oscillator when it is displaced in a single, arbitrary direction. Numerical simulations were performed, showing that the presented device with the corresponding control algorithm effectively damps the vibrations on the oscillator.Publicationtype: Journal ArticleScopus© Citations 1 247 356 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Control strategies for active vibration control via twin rotor damper(International Association for Bridge and Structural Engineering, 2015); The twin rotor damper (TRD) is an active mass damper. It comprises a pair of eccentric masses that rotate about parallel axes. In a preferred mode of operation, the continuous rotation mode, the two masses rotate with constant angular velocity in opposite directions. The resultant of the induced centrifugal forces is a directed harmonic force that can be used for damping. In previous theoretical work, a control algorithm for the continuous rotation mode was developed. However, when the vibration amplitudes become small, this control algorithm does not lead to the desired constant motion of the rotors. The TRD can even re-excite the motion of the system instead of damping it. Various approaches can be used for preventing these undesired effects. For instance, a second identical TRD unit can be added. When the vibration amplitudes are large, both units work in unison and damp the motion. When the vibration amplitudes become small, a phasing is introduced between the two units so that the control forces of both units more and more neutralize each other. Control strategies implementing this and an alternative approach have been developed and proven experimentally.Publicationtype: Conference Paper32