Type Of Dynamic Vibration Absorber Research Articles

Reed Design Method of Reed-DVA

Based on a new type of dynamic vibration absorber, this paper studies the change rules of stiffness and stress along with five parameters of its reed: thickness, cantilever width, outer ring width, outer ring fillet radius, and inner ring fillet radius, aiming at providing guidance for designers of reed-DVA.

Parametric excitation suppression in a floating cylinder via dynamic vibration absorbers: a comparative analysis

Parametric excitation in the pitch/roll degrees of freedom (DoFs) can induce dynamic instability in floating cylinder-type structures such as spar buoys, floating offshore wind or wave energy converters. At certain frequency and amplitude ranges of the input waves, parametric coupling between the heave and pitch/roll DoFs results in undesirable large amplitude rotational motion. One possible remedy to mitigate the existence of parametric resonance is the use of dynamic vibration absorbers. Two prominent types of dynamic vibration absorbers are tuned mass dampers (TMDs) and nonlinear energy sinks (NESs), which have contrasting properties with regard to their amplitude and frequency dependencies when absorbing kinetic energy from oscillating bodies. This paper investigates the suppression of parametric resonance in floating bodies utilizing dynamic vibration absorbers, comparing the performance of TMDs against NESs for a test case considering a floating vertical cylinder. In addition to the type of dynamic vibration absorber utilized, the paper also examines the DoF which it acts on, comparing the benefits between attaching the vibration absorber to the primary (heave) DoF or the secondary (pitch) DoF. The results show that the TMD outperforms the NES and that it is more effective to attach the vibration absorber to the heave DoF when eliminating parametric resonance in the pitch DoF.

Filter-based inerter location dependence analysis approach of Tuned mass damper inerter (TMDI) and optimal design

Tuned Mass Damper Inerter (TMDI) is a novel type of dynamic vibration absorber for achieving lightweight design while maintaining excellent control performance. Compared to traditional Tuned Mass Damper (TMD), the complex dependence characteristics of inerter bring difficulties to evaluate the control performance and design the inerter. In order to address this problem, this paper investigates the vibration control of TMDI subjected to wind and seismic loads. The closed-form solutions of the control performance of TMDI are obtained via a filter approach. By using the filter approach, the computation cost is largely reduced in calculating structural responses and control performance. Subsequently, the empirical formulas for determining optimal design parameters (frequency ratio νopt and damping ratio ζdopt) based on mass ratio μ, inertance ratio β and inerter location parameter φ is proposed. By comparing the optimal control performance of TMDI with TMD, the inerter dependence analysis is conducted to investigate the enhancement effect. An index β·(1–φ)2/μ is proposed as a criterion, where β·(1–φ)2/μ ≥ 1 indicates that the control performance of TMDI is enhanced by inerter. In addition, TMDI results in similar performance to TMD with an equivalent mass ratio μe = μ + β·(1–φ)2. Based on the investigation of an actual high-rise chimney, the proposed formulations and criterion are validated. The wind- and seismic-induced responses are reduced up to 60% and 55% respectively. The proposed method provides guidance for determining the optimal parameters of TMDIs.

Parametric Study of Dynamic Vibration Absorber with Negative Stiffness Applied to Floating Slab Track

In terms of the traditional dynamic vibration absorber (DVA), the vibration damping effect improves with the mass ratio of DVA increasing, and the vibration level of target system is effectively controlled in the case that the mass ratio of DVA is large. This characteristic restricts the application of DVA to the track because of the limited available space. This study proposes one type of DVA with negative stiffness (NSDVA) applied to floating slab track to reduce the track vibration under the condition of small mass ratio and presents a design methodology of NSDVA attached on flexible system. Firstly, the mechanical model of floating slab with NSDVA is simplified to a two-degree-of-freedom system, and theoretical expressions of NSDVA’s optimal parameters, i.e., ratio of frequency, damping and stiffness are deduced according to the fixed-point expansion theory and stability condition. Secondly, with the combination of the multi-modal control theory and the finite element method, optimal parameters of NSDVA applied to a multi-degree of freedom (MDOF) system are calculated. 3-D finite element model of floating slab-NSDVA is built in ABAQUS software, and the modal analysis of floating slab is conducted to determine the target modal and equivalent mass. Compared with the traditional Voigt type DVA, the NSDVA adopted in this paper is proved to be more effective to reduce the both floating slab and rail vibration level. The design methodology of NSDVA attached to a MDOF system presented in this paper is feasible.

Application of Electromagnetic Shunt Damper to Subharmonic Resonance of Superconducting Magnetic Levitation System

This study investigates the effectiveness of the electromagnetic shunt damper for reducing the amplitude of nonlinear resonance of a superconducting magnetic levitation system by numerical calculation. An electromagnetic shunt damper, a type of dynamic vibration absorber, can suppress mechanical vibration of the main system by converting a part of its vibration energy into electric energy of a subsystem consisting of an electric circuit. Since the electromagnetic force caused by superconductors has nonlinearity, complicated nonlinear resonance can occur in the superconducting magnetic levitation system in addition to its main resonance. This study especially focuses on 1/2-order subharmonic resonance, which can generate a larger vibration component at half the excitation frequency. Numerical calculations were carried out to examine how two types of electromagnetic shunt dampers consisting of LCR series and parallel circuits can effectively suppress this nonlinear resonance. As a result, it was confirmed that the parallel type electromagnetic shunt damper is more effective in reducing the amplitude of the subharmonic resonance than the series type, even under the condition of a larger excitation amplitude.

Optimization and analysis of a grounded type dynamic vibration absorber with lever component.

Dynamic vibration absorber (DVA) with large auxiliary mass has better control performance, but it is also more bulky. Therefore, the mass ratio (the ratio of auxiliary mass of DVA to mass of controlled object) is usually limited to make the DVA easy to install and suitable for engineering practice. In this paper a grounded type DVA with lever component is proposed, which aims to increase the effective mass and reduce unnecessary mass to improve control performance of the DVA. Firstly, the motion differential equations of the DVA are established and solved. Secondly, the optimum parameters are obtained based on H∞ and H2 optimization criterion. Then, the performances of the grounded type DVA equipped with and without the lever are investigated. Finally, the control performance of the DVA is compared with other three typical DVAs under H∞ and H2 criterion. In this type DVA there are no global optimum parameters, and larger frequency ratio will get better control performance. If the amplification ratio (the ratio of lever power arm to lever resistance arm) is greater than 1, the introduced lever will contribute to control performance of the DVA. Its control performance is better than those of other three typical DVAs. The use of the lever can increase the effective mass of the DVA, thereby improving the control performance of the DVA. The DVA can achieve good performance at small mass ratio by adjusting amplification ratio, which may provide theoretical basis for the design of new kinds of DVAs.

Online detection and control of car body low-frequency swaying in railway vehicles

Low-frequency swaying is an abnormal vibration of railway vehicles. It is manifested by a low-frequency and high-amplitude swaying of the car body, which continues for a period of time, posing a significant threat to the passengers’ ride comfort and even the vehicle operation safety. However, the complexity of swaying makes the alleviation of this hazard by the conventional suspension parameters and available wheel-rail profile optimisation schemes quite problematic. This study analyses the specifics of vibration signal detection and active low-frequency vibration absorption, based on which a comprehensive set of implementable and universal process approaches to detect and control the low-frequency swaying is proposed. First, the intrinsic parameters of various stages of the swaying signal were obtained via the wavelet packet transform. Based on this, two online detection methods based on a single intrinsic parameter and a combination of intrinsic parameters were proposed. Subsequently, an active low-frequency inerter-spring-damper (ISD) type dynamic vibration absorber (DVA) control strategy was adopted to suppress low-frequency swaying. Finally, full-vehicle models with passive suspension and active low-frequency ISD-DVA were established to investigate the effect of online detection and control of low-frequency swaying. The results obtained proved that the proposed method could promptly detect and accurately identify different swaying stages of the railway vehicle, and the active ISD-DVA is instrumental in the low-frequency swaying elimination and overall improvement of the vibration performance of railway vehicle systems.

Optimal design for high-performance passive dynamic vibration absorbers under random vibration

This work is motivated to determinate the optimal design for various types of Dynamic Vibration Absorbers (DVAs) under the effect of random loads. These devices are the following: DVAs connected in parallel or series; two degree-of-freedom traditional dynamic vibration absorber (2dof-TVA) with translational and rotational motion; and inerter-based DVAs (IDVA-C6, C4, and C3). These types of DVAs were selected by their high effectiveness for suppressing vibration however a comparative study on their dynamic performance has not yet been performed. Two different excitation sources of random loads are studied in this paper which are random ground motion and force excitation. An optimum design for majority of these devices has not yet been computed when subjected to random ground motion excitation, and therefore in this paper are computed. For random force excitation, some numerical solutions for the optimal design of these devices have not yet reported which in this paper are computed in order to compare the dynamic performance for each device with respect to that of the classic DVA. For both random excitation cases, the H2 optimization criteria is used to analytically compute the variance of squared modulus of frequency response of the undamped primary structure, and then nonlinear unconstrained optimization problems are formulated in order to obtain the optimal design. Numerical solutions revealed that the IDVA-C6, C3, and DVAs connected in series presents more than 13% and 10% improvement with respect to the classic DVA for random ground motion and force excitation cases, respectively. These devices can widen the suppression band (SB) from 30% to 40% for mass ratios values from 1% to 10%. It means that devices are more effective and robust for mitigating vibration than the classic DVA. In addition, the rotational inertial double tuned mass damper (IDVA-C6) has the same relative dynamic performance (RDP) and suppression band index (SB) than the double-mass dynamic vibration absorber arranged in series. For practical application where the mounting space of the DVA is extremely reduced, the DVAs connected in series could be more convenient to use than IDVA-C6. The concept of equivalent mass ratio is introduced in order to explain the superiority of these devices with respect to the classic DVA. Finally, in H∞ optimization criteria, the IDVA-C6 presents the same vibration amplitudes at all excitation frequency range and suppression band than DVAs connected in series.

Vibration Response Suppression of Space Structure using Two U-Shaped Water Container

Nowadays, a passive vibration control technique using dynamic vibration absorbers (DVA) has drawn many researchers’ attention in the structural dynamic field. The reason is that this technique is simple and it can work effectively in reducing the vibration response when its parameters are optimally designed. The DVA fundamental concept is the addition of a new vibration system to the primary system. This new system addition causes reduction of the vibration response of the primary system during excited by a dynamic load. One simple technique to realize the DVA for structural application is by using water vibration. This research is aimed to develop one type of dynamic vibration absorber using the water vibration system in a U-shaped container for a two-story building structure model. Besides being used as the dynamic absorber, this U-shaped container is also functioned as the water storage tank in the building. Regarding reduce the first bending mode response of the structure in x-z and y-z plane, two U-shaped water storage tanks are placed on the upper floor of the building. The dimensions of the water storage tanks are designed so that the natural frequency of moving water in the tank is the same as the natural frequency of the first bending mode of the structure in x-z and y-z plane. The performance of dynamic absorber is evaluated by applying the impulsive and seismic loads on the building. The simulation results show that the U-shaped water storage tank placed on the upper floor of the building can reduce the response amplitude of the structure under impulsive loads. Meanwhile, for the seismic load case, the performance of dynamic absorber is clearly seen when the excitation frequency is close to the natural frequency of the building structure.

Nonlinear Series-Type Tuned Mass Damper-Tuned Sloshing Damper for Improved Structural Control

A novel type of dynamic vibration absorber (DVA) is proposed, which consists of a tuned mass damper (TMD) and tuned sloshing damper (TSD) connected in series to the structure. The system enables the expensive viscous damping devices (VDDs) associated with traditional TMDs to be omitted from the design. A linearized equivalent mechanical model and a nonlinear multimodal model are developed to investigate the proposed system. A TMD–TSD is nonlinear due to the quadratic damping associated with liquid drag, which ensures the system performance is amplitude-dependent. Simple expressions for the optimal TSD–TMD mass ratio, tuning, and damping ratios are employed to design a TMD–TSD coupled to a single degree-of-freedom (SDOF) structure. Frequency response curves for the structure, TMD, and TSD degrees-of-freedom are created for several excitation amplitudes, and the nonlinear behavior of the system response is evident. The performance of the TMD–TSD is evaluated against traditional TMD and TSD systems—with the same total mass—by computing the effective damping produced by each system. The proposed system is found to provide a superior acceleration reduction performance and superior robustness against changes to the frequency of the primary structure. The proposed system is, therefore, an effective and affordable means to reduce the resonant response of tall buildings.

Exact Optimization of a Three-Element Dynamic Vibration Absorber: Minimization of the Maximum Amplitude Magnification Factor

In this study, the maximum amplitude magnification factor for a linear system equipped with a three-element dynamic vibration absorber (DVA) is exactly minimized for a given mass ratio using a numerical approach. The frequency response curve is assumed to have two resonance peaks, and the parameters for the two springs and one viscous damper in the DVA are optimized by minimizing the resonance amplitudes. The three-element model is known to represent the dynamic characteristics of air-damped DVAs. A generalized optimality criteria approach is developed and adopted for the derivation of the simultaneous equations for this design problem. The solution of the simultaneous equations precisely equalizes the heights of the two peaks in the resonance curve and achieves a minimum amplitude magnification factor. The simultaneous equations are solvable using the standard built-in functions of numerical computing software. The performance improvement of the three-element DVA compared to the standard Voigt type is evaluated based on the equivalent mass ratios. This performance evaluation is highly accurate and reliable because of the precise formulation of the optimization problem. Thus, the advantages of the three-element type DVA have been made clearer.

Parametric study of pendulum type dynamic vibration absorber for controlling vibration of a two DOF structure

Passive dynamic vibration absorbers (DVAs) are often used to suppress the excessive vibration of a large structure due to their simple construction and low maintenance cost compared to other vibration control techniques. A new type of passive DVA consists of two pendulums connected with spring and dashpot element is investigated. This research evaluated the performance of the DVA in reducing the vibration response of a two degree of freedom shear structure. A model for the two DOF vibration system with the absorber is developed. The nominal absorber parameters are calculated using a Genetic Algorithm(GA) procedure. A parametric study is performed to evaluate the effect of each absorber parameter on performance. The simulation results show that the optimum condition for the absorber frequencies and damping ratios is mainly affected by pendulum length, mass, and the damping coefficient of the pendulum´s hinge joint. An experimental model validates the theoretical results. The simulation and experimental results show that the proposed technique is able be used as an effective alternative solution for reducing the vibration response of a multi degree of freedom vibration system.

Analytically optimal parameters of fractional-order dynamic vibration absorber

In this paper the optimal parameters of the fractional-order Voigt type dynamic vibration absorber (DVA) are analytically studied for two cases, named as H∞ and H2 optimization criteria. At first the approximately analytical solution is obtained by the averaging method when the primary system is subjected to harmonic excitation. Then the optimal fractional coefficient and order are obtained based on H∞ optimization criterion, which is designed to minimize the maximum amplitude magnification factor of the primary system. Based on H2 optimization criterion, the optimal fractional parameters are obtained to reduce the total vibration energy of the primary system over the whole-frequency range. The comparisons of the approximate solutions with the numerical ones in the two cases are fulfilled, and the results verify that the approximately analytical solutions are correct and satisfactorily precise. At last the control performance of the fractional-order Voigt type DVA is compared with the classical integer-order counterpart, and it could be concluded that the fractional-order DVA has superiority in vibration engineering, and fractional-order element could replace the traditional damper and spring simultaneously in some cases.

Modeling and analysis of a structure semi-active tuned liquid damper system

A tuned liquid damper (TLD), which is similar to a tuned mass damper (TMD), is a type of dynamic vibration absorber (DVA) that can be employed to reduce wind induced resonant vibrations of a structure. Improved TLD performance could be realized by equipping TLDs with variable energy dissipating capabilities such as damping screens, which can be adjusted through a certain mechanism, permitting optimal control performance to be maintained over a wide range of loading conditions in a semi-active mode of control. In this paper, a control strategy based on a gain scheduling scheme is utilized by controlling the inclination angle of the damping screen(s) and consequently the screen loss coefficient value(s). The gain scheduling control strategy is employed on a simple single-story structure equipped with a semi-active TLD (SA-TLD) in order to maintain the optimal damping value (ζTLD − opt) based on averaged or instantaneous structural response tracking and a prescribed look-up table. Results are assessed using experimental values from tests conducted on conventional passive TLDs. A performance comparison between a semi-active TLD control system and a conventional passive TLD control system is carried out. The fluid response amplitude for a SA-TLD is also investigated and compared to that of a passive TLD. Copyright © 2016 John Wiley & Sons, Ltd.

Research on the design of non-traditional dynamic vibration absorber for damped structures under ground motion

An analytical approach is presented to investigate the optimal problem of non-traditional type of Dynamic vibration absorber (DVA) for damped primary structures subjected to ground motion. Different from the standard configuration, the non-traditional DVA contains a linear viscous damper connecting the absorber mass directly to the ground instead of the main mass. There have been many studies on the design of the non-traditional DVA for undamped primary structures. Those studies have shown that the non-traditional DVA produces better performance than the standard DVA does. When damping is present at the primary system, there are very few works on the non-traditional dynamic vibration absorber. To the best of our knowledge, there is no study on the design of non-traditional DVA for damped structures under ground motion. We propose a simple method to determine the approximate analytical solutions of the nontraditional DVA when the damped primary structure is subjected to ground motion. The main idea of the study is based on the criterion of the equivalent linearization method to replace approximately the original damped structure by an equivalent undamped one. Then the approximate analytical solution of the DVA’s parameters is given by using known results for the undamped structure obtained. Comparisons have been done to validate the effectiveness of the obtained results.

Optimal mass ratio of vibratory flap for vibration control of clamped rectangular plate

Abstract Dynamic vibration absorbers generally have been used to suppress harmonic excitation of plate like structures at a point of attachment and at a given frequency. The vibratory flap is a plate type dynamic vibration absorber and has been developed to suppress plate vibrations over entire plate in more than one frequency. This paper presents an experimental study of transverse vibration of harmonically excited, clamped rectangular plate with vibratory flap. The investigation aims to discover the effect of the mass ratio of the flap on dynamic response of the plate. Consequently, the mass ratio has been optimized to get best attenuation in the first and second target frequencies. The study reveals that, the attenuation in vibration of the plate has increased to a large extent due to the use of optimized vibratory flap. Finally, the experimental results of the plate with optimized flap have been compared with finite element analysis results.

Parameters Optimization for a Kind of Dynamic Vibration Absorber with Negative Stiffness

A new type of dynamic vibration absorber (DVA) with negative stiffness is studied in detail. At first, the analytical solution of the system is obtained based on the established differential motion equation. Three fixed points are found in the amplitude-frequency curves of the primary system. The design formulae for the optimum tuning ratio and optimum stiffness ratio of DVA are obtained by adjusting the three fixed points to the same height according to the fixed-point theory. Then, the optimum damping ratio is formulated by minimizing the maximum value of the amplitude-frequency curves according toH∞optimization principle. According to the characteristics of negative stiffness element, the optimum negative stiffness ratio is also established and it could still keep the system stable. In the end, the comparison between the analytical and the numerical solutions verifies the correctness of the analytical solution. The comparisons with three other traditional DVAs under the harmonic and random excitations show that the presented DVA performs better in vibration absorption. This result could provide theoretical basis for optimum parameters design of similar DVAs.

Approximated analytical frequency response of a pendulum structure attached with two orthogonal dynamic vibration absorbers

Vibration of a pendulum can be reduced by single dynamic vibration absorbers (DVAs) moving in tangential or in normal direction of pendulum's orbit. The first DVA works in the linear zone while the second one works in the nonlinear zone. This paper uses the equivalent linearization technique to obtain an analytical form of the frequency response of a nonlinear pendulum structure, which is attached with both types of DVA. The numerical calculations are carried out to verify the analytical results. Some useful conclusions on the optimal parameters of the DVA can be found from the analytical solution.

Study on the performance of magnetorheological elastomers and engineering application

Filling an elastomeric material with magnetisable particles makes it possible for mechanical properties such as elastic modulus to be reversibly and rapidly controlled by an applied magnetic field. In this study, we designed some magnetorheological elastomer samples working in compressive mode and measured their properties under various magnetic fields. The purpose of this research is to demonstrate the use of magnetorheological elastomers as field-dependent springs in dynamic vibration absorbers. This paper describes two types of dynamic vibration absorbers: a traditional dynamic vibration absorber and a self-adaptive dynamic vibration absorber based on magnetorheological elastomers. We introduced these two types of dynamic vibration absorber to a mass-varying structure subject to earthquake activity. The results show that the MRE vibration absorber performed much better than the traditional dynamic vibration absorber.

Different pendulum type dynamic vibration absorber aplication

The paper considers the methods of calculation and optimization of different pendulum type dynamic vibration absorbers for the vibration reduction of elongated elements. Discrete-continuous models of the dynamics of oversize elongated elements based on the Timoshenko beam theory with attached discrete elements are presented. Algorithms for the vibration reduction of elongated machine elements are obtained. Noise and vibration are associated with many mechanical systems including industrial, household appliances, transportation machinery and buildings. Many of these structures are made up of beam type elements. Once the system parameters are defined, beam system vibration can be reduced using passive damping. The dynamic vibration absorber is effective, reliable and inexpensive device to reduce vibration, caused by harmonic or narrow-frequency disturbance. In the classical theory of dynamic vibration absorber, the primary structure is modeled by a mass-spring system, though other models also find interesting theoretical and engineering applications. In particular, pendulum type systems with a solid body at a fixed rotation point play an important role as a model in many branches of mechanical engineering, transport and construction. The application effect of the pendulum type dynamic vibration absorber with shock masses may significantly differ from using the mass-on-a spring system. Research and optimization of different type dynamic vibration absorbers are performed. Timoshenko beam with different clamping conditions and different type dynamic vibration absorbers are used as a model for many real systems, described in the literature. Methods of decomposition and numerical synthesis are considered based on the adaptive schemes. Structures of elongated elements of machines and buildings with regard to their interaction with the system of dynamic vibration absorbers are examined. The optimization method of dynamic vibration absorbers to reduce excessive vibration of the Timoshenko beam system under harmonic and shock perturbations is developed.