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Showing papers on "Dynamic Vibration Absorber published in 1999"


Book
11 Feb 1999
TL;DR: In this paper, the authors describe the response of structures to non-Harmonic motions and non-harmonic forces, and the control of Vibration by localized additions and added damping.
Abstract: The Response of Structures to Harmonic Forces. Receptance and Dynamic Stiffness. The Response of Structures to Prescribed Harmonic Motions. The Response of Structures to Non-Harmonic Excitation. Factors Controlling Beam and Plate Vibration. The Control of Vibration by Structural Design. The Control of Vibration by Localized Additions. The Control of Vibration by Added Damping. The Control of Vibration by Resilient Isolation. The Control of Vibration by Combined Methods. Index.

377 citations


Journal ArticleDOI
TL;DR: The control performance of three types of mass dampers on suppressing excessive building vibration is studied and compared in this article, where the building is modeled as a single-degree-of-freedom system.

160 citations


Journal ArticleDOI
TL;DR: In this article, a variable stiffness vibration absorber is used for controlling a principal mode and the stiffness is controlled by the microcomputer under the auto-tuning algorithm for creating an anti-resonance state.

97 citations


Journal ArticleDOI
TL;DR: In this paper, the use of multiple Delayed Resonators (DRs) in suppressing tonal vibrations of multi-degree-of-freedom mechanical structures is discussed, and a strategy called stability charts is used not only to resolve the stability but also to find out the tuning speed of the absorption.

76 citations


Journal ArticleDOI
TL;DR: In this article, the authors considered a plant model possessing curvature and inertia nonlinearities and introduced a second-order absorber that is coupled with the plant through user-defined cubic nonlinearity.
Abstract: We study the dynamics of a nonlinear active vibration absorber. We consider a plant model possessing curvature and inertia nonlinearities and introduce a second-order absorber that is coupled with the plant through user-defined cubic nonlinearities. When the plant is excited at primary resonance and the absorber frequency is approximately equal to the plant natural frequency, we show the existence of a saturation phenomenon. As the forcing amplitude is increased beyond a certain threshold, the response amplitude of the directly excited mode (plant) remains constant, while the response amplitude of the indirectly excited mode (absorber) increases. We obtain an approximate solution to the governing equations using the method of multiple scales and show that the system possesses two possible saturation values. Using numerical techniques, we perform stability analyses and demonstrate that the system exhibits complicated dynamics, such as Hopf bifurcations, intermittency, and chaotic responses.

74 citations


Journal ArticleDOI
TL;DR: In this article, the response of a linear SDOF system subjected to harmonic excitation to which a Tuned Vibration Absorber with linear stiffness and dry friction damping is attached is considered.
Abstract: The response of a linear SDOF system subjected to harmonic excitation to which a Tuned Vibration Absorber with linear stiffness and dry friction damping is attached is considered. Based on an intuitive examination of the physical behaviour of the system, closed-form expressions for TMD optimum parameters and for the steady-state amplitudes of vibration are presented. Two examples allow the comparison between the predicted behaviour and that found by numerically integrating the equations of motion.

62 citations


Journal ArticleDOI
TL;DR: In this article, the performance of non-linear shock isolators with Coulomb damper, three-element isolator, four-stage isolator and two-stage isolateator were compared.

62 citations


Patent
01 Dec 1999
TL;DR: In this paper, the pendulum rod and pendulum damper are used in a wind power station to control the stiffness of the rotor blades and the damper load in the machine house.
Abstract: The damper (40) and pendulum rod (3) pivot form a closed unit made up of one or more elastomer modules, possibly supplemented by additional mechanical or hydraulic dampers. The modules have distance disks to control their stiffness and are spread round the rod pivot point. The rod (3) itself should be flexible and possibly made up of elastomer components, using several rods and their pivots if so desired. The wind powerstation comprizes tower and machinery house (39) equipped with the rotor blades (35) and the damper load (1) should be arranged above the rod pivot, notably in the machine house (39).

59 citations


Journal ArticleDOI
TL;DR: In this article, a high performance vibration absorber requires a high loss factor behavior over a wide temperature and frequency range, and an investigation was carried out to prepare such materials based on poly(vinyl chloride), chlorinated polyethylene, and epoxidized natural rubber ternary blends.
Abstract: A high performance vibration absorber requires a high loss factor behavior over a wide temperature and frequency range. An investigation was carried out to prepare such materials based on poly(vinyl chloride), chlorinated polyethylene, and epoxidized natural rubber ternary blends. The loss factor and damping behavior of several compositions were measured using a viscoelastic spectrometer and a polymer-laminated steel cantilever-beam damping device. Suitable compositions were found to give good mechanical properties and high loss factor over a wide temperature and frequency range. It was also observed that flake-type fillers improve the damping behavior. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 855–863, 1999

47 citations


Journal ArticleDOI
TL;DR: In this paper, the authors proposed a dynamic vibration absorber (DVA) with an air damper consisting of a piston and a cylinder, which can be represented by the Maxwell model where a spring element and a dashpot are connected in series.
Abstract: In this paper, we propose a dynamic vibration absorber (DVA) with an air damper consisting of a piston and a cylinder. First, it will be shown that the air damper can conveniently be represented by the Maxwell model where a spring element and a dashpot are connected in series. The air damper has no ability to return the piston to its original position. For this reason, it is necessary for the piston to be supported by a spring which is placed in parallel with the damper. The air damped DVA can then be modeled by the three-element model. Many studies have been done on the Voigt type of DVA, and the accurate expressions of optimum tuning and damping parameters have already been derived by Hahnkamm and Brock et al. However, only a few papers have been published on the three-element type of DVA, and reliable expressions for it have not been derived until now. Therefore, we began our work by trying to derive expressions for optimum parameters of the three-element type of DVA. It was clear that the optimized three-element type of DVA is superior to the conventional Voigt type of DVA. The optimum parameters which we obtained from our expressions were tested on a vibratory model. The experiments showed that the our expression is very useful for designing the air damped DVA.

47 citations


Journal ArticleDOI
TL;DR: In this article, a variable-damping dynamic absorber was constructed and its performance was verified with a three-story structural model, and an adaptive neural network control system composed of a forward model network for system identification and a controller network was introduced to control the variable damping element of the dynamic absorbers.
Abstract: This paper describes a variable-damping dynamic absorber applying Electrorheological (ER) fluid to the damping element of a conventional-type dynamic absorber. A prototype of variable-damping dynamic absorber was constructed and its performance was verified with a three-story structural model. The special ability of the present dynamic absorber is to reduce the vibration amplitude at several frequencies by a single dynamic absorber. ER fluid is functional fluid whose yield shear stress can be changed by the applied electric field strength. Because of its peculiar property, ER fluid has been applied to various mechanical components such as shock absorbers and engine mounts for vehicles, clutches, valves, etc. One of the practical ways in applying ER fluid to mechanical components may be to expand the performance of conventional mechanical components by combining ER fluid effectively with them. In this sense, this paper shows a successful application of ER fluid to a conventional-type dynamic absorber. An adaptive neural network control system composed of a forward model network for system identification and a controller network was introduced to control the variable-damping element of the dynamic absorber. The numerical simulations show good agreements with the experimental results.

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a roof isolation system based on the concept of a damped vibration absorber and made the roof, rubber bearings, and viscous dampers respectively constitute the mass, spring, and dashpot of such an absorber.
Abstract: Presented are the features of a roof isolation system that is proposed as a device to reduce the seismic response of buildings. Presented also are the details of and results from analytical and experimental studies conducted with a small-scale laboratory model to assess the feasibility and effectiveness of such a device. The roof isolation system entails the insertion of flexible laminated rubber bearings between a building's roof and the columns that support this roof, and the installation of viscous dampers that are connected to the roof and a structural element below the roof. It is based on the concept of a damped vibration absorber and on the idea of making the roof, rubber bearings, and viscous dampers respectively constitute the mass, spring, and dashpot of such an absorber. The model considered in the analytical and experimental studies is a 2.44-m high, five-storey, moment-resisting steel frame, with a fundamental natural frequency of 2.0 Hz. In the experimental study the frame is tested with and without the proposed roof isolation system on a pair of shaking tables under a truncated version of one of the accelerograms from the 1985 Mexico City earthquake. In the analytical study, the frame is also analysed with and without such a system and under the same ground motion except that the ground motion accelerations are properly magnified to study the effectiveness of the roof isolation system when the frame is stressed beyond its linear range of behavior. It is found that the suggested device effectively reduces the seismic response of the frame, although the extent of this reduction depends on how large its non-linear deformations are. Based on these findings, it is concluded that the proposed roof isolation system has the potential to become a practical and effective way to reduce earthquake damage in low- and medium-rise buildings.

Journal ArticleDOI
TL;DR: In this paper, an active nonlinear vibration absorber is proposed to suppress the vibrations of flexible steel beams when subjected to single and simultaneous two-mode excitations, where the feedback and control signals are quadratic.
Abstract: We present an account of an implementation of an active nonlinear vibration absorber that we have developed. The control technique exploits the saturation phenomenon that is known to occur in quadratically-coupled multi-degree-of-freedom systems subjected to primary excitation and possessing a two-to-one internal resonance. The technique is based on introducing an absorber and coupling it with the structure through a sensor and an actuator, where the feedback and control signals are quadratic. First, we consider the case of controlling the vibrations of a single-degree-of-freedom system. We develop the equations governing the response of the closed-loop system and use the method of multiple scales to obtain an approximate solution. We investigate the performance of the control strategy by studying its steady-state and transient characteristics. Additionally, we compare the performance of the quadratic absorber with that of a linear absorber. Then, we present theoretical and experimental results that demonstrate the versatility of the technique. We design an electronic circuit to emulate the absorber and use a variety of sensors and actuators to implement the active control strategy. First, we use a motor and a potentiometer to control the vibration of a rigid beam. We develop a plant model that includes Coulomb friction and demonstrate that the closed-loop system exhibits the saturation phenomenon. Second, we extend the strategy to multi-degree-of-freedom systems. We use PZT ceramics and strain gages to suppress vibrations of flexible steel beams when subjected to single- and simultaneous two-mode excitations. Third, we employ Terfenol-D, a nonlinear actuator, and accelerometers to control the vibrations of flexible beams. In all instances, the technique is successful in reducing the response amplitude of the structures.

Journal ArticleDOI
TL;DR: A frequency domain technique to achieve automatic tuning of the absorber despite parametric uncertainties in the absorbers model is presented, based on gradient analysis of a frequency transfer function.
Abstract: A recent active vibration absorption scheme, the delayed resonator (DR), is considered. This method uses a very simple delayed partial state feedback control law. This simple but unconventional control invites some challenging practical problems, among which is the highlight of this paper: automatic tuning of the absorber despite parametric uncertainties in the absorber model. A frequency domain technique to achieve this objective is presented. It is based on gradient analysis of a frequency transfer function. It is shown that the routine can be implemented in real-time due to its simplicity and recurrent nature. The theoretical findings are also experimentally verified on an oscillating beam. Excellent vibration suppression is obtained not only under excitations with fixed frequency but also for those of sweep frequency type.

Journal ArticleDOI
TL;DR: In this paper, a stabilization method for 1/3-order subharmonic resonance with an autoparametric vibration absorber was proposed, where a damped pendulum system was attached to the main system as an absorber, in order to induce 1:2 internal resonance.
Abstract: The paper proposes a stabilization method for 1/3-order subharmonic resonance with an autoparametric vibration absorber. A main system with nonlinear spring stiffness and harmonic excitation, i.e., subjected to a sinusoidally changed magnetic force, is introduced as a model which produces 1/3-order subharmonic resonance. A damped pendulum system, whose natural frequency is in the neighborhood of one-half of the main system, is attached to the main system as an absorber, in order to induce 1:2 internal resonance. The 1/3-order subharmonic resonance which occurs in the case of locked pendulum is avoided due to energy transfer between the main system and the absorber, and due to energy dissipation by the absorber. It is also theoretically shown that a stable nontrivial steady state with respect to the 1/3-order subharmonic frequency component is changed into an unstable one due to the absorber. Experimental results show the validity of the autoparametric vibration absorber for the 1/3-order subharmonic resonance.

Journal ArticleDOI
TL;DR: In this paper, the free and forced vibrations of a double-membrane system of two rectangular membranes attached together by a Winkler elastic layer are studied analytically, and the solutions of the free vibrations are obtained by the Bernoulli-Fourier method.

22 Jul 1999
TL;DR: In this article, a surface-micromachined two-degree-of-freedom system that was driven by parallel-plate actuation at antiresonance was demonstrated, which consisted of an absorbing mass connected by folded springs to a drive mass.
Abstract: A surface-micromachined two-degree-of-freedom system that was driven by parallel-plate actuation at antiresonance was demonstrated. The system consisted of an absorbing mass connected by folded springs to a drive mass. The system demonstrated substantial motion amplification at antiresonance. The absorber mass amplitudes were 0.8-0.85 pm at atmospheric pressure while the drive mass amplitudes were below 0.1 pm. Larger absorber mass amplitudes were not possible because of spring softening in the drive mass springs. Simple theory of the dual-mass oscillator has indicated that the absorber mass may be insensitive to limited variations in strain and damping. This needs experimental verification. Resonant and antiresonant frequencies were measured and compared to the designed values. Resonant frequency measurements were difficult to compare to the design calculations because of time-varying spring softening terms that were caused by the drive configuration. Antiresonant frequency measurements were close to the design value of 5.1 kHz. The antiresonant frequency was not dependent on spring softening. The measured absorber mass displacement at antiresonance was compared to computer simulated results. The measured value was significantly greater, possibly due to neglecting fringe fields in the force expression used in the simulation.

Patent
12 Jul 1999
TL;DR: In this paper, a speed-adaptive dynamic-vibration absorber for a shaft rotatable about an axis, including a hub part on which at least one inertial mass is provided, is presented.
Abstract: A speed-adaptive dynamic-vibration absorber for a shaft rotatable about an axis, including a hub part on which at least one inertial mass is provided. The at least one inertial mass, starting from a middle position in which its center of gravity is the greatest distance from the axis, is moveable back and forth relative to the hub part along a path of motion in deflection positions in which the distance of the center of gravity of the at least one inertial mass changes with respect to the middle position, the path of motion having a radius of curvature which changes at least section-by-section with increasing deflection of the inertial mass out of the middle position.

Journal ArticleDOI
TL;DR: In this article, an active nonlinear vibration absorber scheme for flexible structures is demonstrated. The absorber exploits the nonlinear transduction of nonbiased Terfenol-D actuators.
Abstract: An active nonlinear vibration absorber scheme for flexible structures is demonstrated. The absorber exploits the nonlinear transduction of nonbiased Terfenol-D actuators. It uses a quadratic feedba...

Proceedings ArticleDOI
17 Oct 1999
TL;DR: A simple acceleration feedback algorithm was used which approximates a two degree of freedom dynamic vibration absorber where the damping coefficient can be adjusted by the acceleration feedback gain and the resulting damping ratio was increased.
Abstract: A multi degree of freedom manipulator can be commanded to generate base forces by utilization of the dynamic equations relating joint torques or joint accelerations to base forces. This can be extended to a full order case with three base moments and three base forces. In the experiments described two forces were sufficient to damp the fundamental modes. With a force command capability a variety of damping algorithms can be used to determine the desired force. A simple acceleration feedback algorithm was used which approximates a two degree of freedom dynamic vibration absorber where the damping coefficient can be adjusted by the acceleration feedback gain. The resulting damping ratio of the fundamental mode was increased by factors of between 18 and 191.

Journal ArticleDOI
TL;DR: In this paper, the results of a full-scale installation of a passive vibration absorber, called a Liquid Column Vibration Absorber (LCVA), on a 67m high steel frame communications tower were investigated.

Proceedings ArticleDOI
02 Jun 1999
TL;DR: In this article, a piezoelectric shunt with a resistor and an inductor circuit for passive damping has been studied to augment weakly damped lag mode stability of a hingeless helicopter rotor blade in hover.
Abstract: To augment weakly damped lag mode stability of a hingeless helicopter rotor blade in hover, piezoelectric shunt with a resistor and an inductor circuits for passive damping has been studied. A shunted piezoceramics bonded to a flexure of rotor blade converts mechanical strain energy to electrical charge energy which is dissipated through the resistor in the R-L series shunt circuit. Because the fundamental lag mode frequency of a soft-in-plane hingeless helicopter rotor blade is generally about 0.7/rev, the design frequency of the blade system with flexure sets to be so. Experimentally, the measured lag mode frequency is 0.7227/rev under the short circuit condition. Therefore the suppression mode of this passive damping vibration absorber is adjusted to 0.7227/rev. As a result of damping enhancement using passive control, the passive damper which consists of a piezoelectric material and shunt circuits has a stabilizing effect on inherently weakly damped lag mode of the rotor blades, at the optimum tuning and resistor condition.

Journal ArticleDOI
TL;DR: In this article, the authors proposed a novel active vibration absorption technique for eliminating undesired torsional oscillations in rotating mechanical structures, called the centrifugal delayed resonator (CDR).
Abstract: The centrifugal delayed resonator (CDR) is a novel active vibration absorption technique for elim inating undesired torsional oscillations in rotating mechanical structures. The key idea is to reco...

Journal ArticleDOI
TL;DR: In this article, an experimental comparison of the dynamic performance of an Electrorheological and a Magnetorheological fluid when subjected to impulsively applied loads is presented. Butler et al. measured the transient characteristics of the two fluids under various mechanical force levels and under DC excitation of the fluid in conjunction with a digital controller to provide a constant applied electrical field.
Abstract: This paper is concerned with an experimental comparison of the dynamic performance of an Electrorheological and a Magnetorheological fluid when subjected to impulsively applied loads. The ER device was built as a squeeze cell incorporating an ER fluid sandwiched between two electrodes which, during impact, move towards each other, whilst the MR device was a commercially available vibration absorber. Each device was mounted in an experimental rig which was capable of determining the instantaneous responses of the fluids. The transient characteristics of the devices were assessed for various mechanical force levels and, for the ER device, under DC excitation of the fluid in conjunction with a digital controller to provide a constant applied electrical field.

Patent
21 Apr 1999
TL;DR: In this article, a shape memory alloy (SMA) was used to adaptively tune the frequency of a vibration absorber to the primary mass in a simple and straightforward manner.
Abstract: The present invention relates to a vibration absorber in which an absorber end mass is coupled to a primary mass by means of a cantilevered beam, wherein at least a portion of the beam comprises a shape memory alloy (SMA). Preferably, the end mass is coupled to the primary mass with several discrete SMA wires which may be individually heated. When each of the SMA wires is heated above a predetermined temperature, the SMA material undergoes a phase change which results in a change in the stiffness of the SMA wire. Heating of the various wires in various combinations allows the operational frequency of the absorber to be actively tuned. The frequency of the absorber may therefore be tuned to closely match the current vibrational frequency of the primary mass, thereby allowing the absorber to be adaptively tuned to the frequency of the primary mass in a simple and straightforward manner.

Patent
29 Dec 1999
TL;DR: In this article, a selectively tuned vibration absorber comprising a stack of viscoelastic polymer damping plates, secured together with spacers at both ends and having metal tuning weights attached onto the topmost plate in the stack is presented.
Abstract: A selectively tuned vibration absorber comprising a stack of viscoelastic polymer damping plates, secured together with spacers at both ends and having metal tuning weights attached onto the topmost plate in the stack. The apparatus is secured to the low frequency drive unit of an in-wall loudspeaker with a metal mounting plate between the vibration absorber and the low frequency drive unit. Both ends of the vibration absorber are cantilevered over a tuning mounting plate centered between the ends of the unit, the degree of cantilever and the mass in the metal weights added to the topmost damping plate being variable such that the vibration absorber may be tuned to resonate at the fundamental resonance frequency of the low frequency drive unit.

Dissertation
01 Jan 1999
TL;DR: In this paper, the authors present a statement of originality and acknowledgment of the authorship of their work. But they do not discuss the authors' research process and their methodology.
Abstract: viii Statement of Originality ix Acknowledgements x CHAPTER

Patent
09 Jul 1999
TL;DR: In this paper, a rotating speed adaptive vibration absorber is proposed to provide a long life and sure operability guarantee, where the inertia mass member from a rotary shaft is changed along an operating track curved to be partitioned by the curved track and the pin.
Abstract: PROBLEM TO BE SOLVED: To provide a revolving speed adaptive vibration absorber obtaining particularly a long life and sure operability SOLUTION: In this revolving speed adaptive vibration absorber, a plurality of inertia mass members 2 adjacent in a peripheral direction are supported respectively by two hold parts 3 adjacent in a peripheral direction in a hub part, a pin 5 is included in these hold parts, and this pin can be rolled on the inertia mass member curved mutually in a reverse direction and curved tracks 4, 4' in the hub part 1, in this way, when a rotational vibration overlapped in a rotary motion is generated, a space of the inertia mass member from a rotary shaft 6 is changed along an operating track curved to be partitioned by the curved track and the pin, the inertia mass member is contained in at least one annular chamber 11 of the hub part, and a lubricant can be received in this chamber Further, at least one through part 7 is provided in at least one of the inertia mass members and/or the hub part, so as to supply the lubricant to the curved track by the through part

Patent
10 Feb 1999
TL;DR: A wheel seat for a roller skate includes a shoe, a wheel seat, multiple vibration absorbers, multiple bolts and rollers and having vibration absorbing absorbers on its wheel seat as discussed by the authors.
Abstract: A wheel seat for a roller skate includes a shoe, a wheel seat, multiple vibration absorbers, multiple bolts and rollers and having vibration absorbers on its wheel seat. The wheel seat connecting to the bottom of the shoe is provided on both sides of and beneath it with multiple positioning grooves for mounting the vibration absorbers which each comprises an external housing and an inner slide.

Patent
10 May 1999
TL;DR: The revolution vibration absorber, mainly used for the crankshaft of a vehicle, consists of several weights, radial arranged around the hub and joined to the hub with bolts, moving in curved slots as mentioned in this paper.
Abstract: The revolution vibration absorber, mainly used for the crankshaft of a vehicle, consists of several weights (2), radial arranged around the hub (1) and joined to the hub with bolts (5), moving in curved slots (4,9,12). Vibrations caused by the rotating crankshaft are absorbed by an oscillating and longitudinal rocking motion of the weights. At least one of the slots (9,12) is joined to a lubrication system (7,17) in order to reduce premature wear and tear of the parts.