Passive Dynamic Vibration Absorber Research Articles

H∞ Control-Based Optimization Design for Active and Passive Dynamic Vibration Absorber

H∞ Control-Based Optimization Design for Active and Passive Dynamic Vibration Absorber

A novel nonlinear variable damping device and its application for the systems with uncertain parameters

This paper deals with the performance of a novel nonlinear viscous dashpot with variable damping. The new proposed dashpot can be utilized in devices for instance dynamic vibration absorbers (DVAs). When the vibration absorber is tuned to the bridge's fundamental frequency, it represents a robust effect in controlling the vibrations of the bridge; however, a DVA is very sensitive to frequency detuning. The proposed nonlinear dashpot can be applied in a passive vibration absorber and upgrades it to a nonlinear variable damping one. Since the parameter of such DVA can be adjusted, it is the so-called nonlinear adjustable DVA. The mentioned dashpot, provides a quadratic nonlinearity for the damping element. The proposed dashpot in this study possesses a simple mechanism, which can handle large range of flow rates of fluid, smoothly without turbulence, in the oil channel. To investigate the effectiveness of an adjustable vibration absorber, a semi-active DVA with variable damping, and stiffness elements is applied on a footbridge; where, the footbridge is experienced variations of the fundamental frequency over time, and is subjected to a walking pedestrian. For the case study in the present study, a vibration reduction of 31% in comparison with the attached traditional passive DVA with constant parameters was achieved. The results show that, by using the proposed nonlinear dashpot, presented in this study, into an attached DVA, the footbridge will experience about 10% more deflection reduction concerning a classical linear DVA.

Optimal analysis on low frequency line spectrum sound control of power equipment using dynamic vibration absorber

As generated by alternating current with the frequency of 50 Hz, the noise characteristics of power equipment reveal to be low frequency and line spectrum. The paper proposed a method to reduce the noise of the power equipment by installing dynamic vibration absorber (DVA) on the surface of it. The coupling between the attached DVA and the equipment may lead to undesirable frequency shift of the DVA itself, which will diminish the noise suppression effect of the whole system. The traditional passive DVA design method does not consider the effect of dynamic coupling. To solve this problem, global demodulation algorithm is applied to analyze the optimal parameters of DVA, which is integrated in the model of power equipment, to get the lowest single frequency radiated sound power level (SPL) of the equipment. The finite element model is established to verify the noise reduction optimal effect. The results show that the noise reduction effect of the optimized system is significantly improved compared with that using the classical parameter setting. The research can provide references for noise reduction optimization of power equipment in the future.

Design and Implementation of Passive Dynamic Vibration Absorber for Vibration control of rotating mass unbalanced Air Blower

Frequently it is found in the industry that unbalances of the rotating components generate vibration due to centrifugal force. Here an attempt has been made to reduce vibrations caused by unbalance in the impeller of the Air Blower. The Dynamic Vibration Absorber (DVA) device is designed in such a way that optimal tuning damping factor and mass ratio were found as same as that obtained by using higher order of perturbation method. The designed DVA brings Vrms values within the limit set by ISO 10816-3 for Unlimited Long-Term Operation Allowable. More than 50% appreciable vibration reduction was measured in radial horizontal and vertical direction both at the motor drive and non-drive end.

Enhanced motion control performance of the tuned mass damper inerter through primary structure shaping

The tuned mass-damper-inerter (TMDI) is a linear passive dynamic vibration absorber widely considered in the literature to mitigate the motion of dynamically excited primary structures. Previous studies focused on optimal TMDI tuning approaches and connectivity arrangements to improve motion control efficiency for some given primary structure. This paper investigates the influence of the elastic and mass properties of the primary structure to the TMDI motion control performance. This is pursued through an innovative parametric study involving a wide range of tapered beam-like cantilevered primary structures with different continuously varying flexural rigidity and mass distributions equipped with TMDIs optimally tuned for resonant harmonic and for white noise excitations. Optimal TMDI tuning and performance assessment are expedited through a novel simplified two-degree-of-freedom dynamic model which accounts for the properties of the primary structure. It is found that reduced free-end displacement and TMDI stroke are achieved for primary structures in which the ratio of flexural rigidity over mass decreases faster with height resulting in vibration modal shapes with higher convexity. The latter is quantified though the average modal curvature shown to be well-correlated with TMDI motion control improvement. It is concluded that judicial shaping of the primary structure extends the applicability of the TMDI to structures where connecting the inerter away from the free-end is practically challenging while contains the magnitude of the inerter and damping forces exerted to the primary structure. Therefore, this study paves the way towards combining optimal TMDI tuning with primary structure design for improved performance to dynamic loads.

A novel high-performance passive non-traditional inerter-based dynamic vibration absorber

This paper presents the performance evaluation for a novel high-performance nontraditional inerter-based dynamic vibration absorber called NIDVA-C4. For the easy physical parameter tuning for the proposed device, the Extended Fixed-Points Technique (EFPT) is applied, and then short closed-form solutions are provided for the undamped systems. Subsequently, performance evaluation is carried out by computing two performance measures, which are the H∞ and H2 performance indices. For both H∞ and H2 criteria, constrained and unconstrained multivariable non-linear optimization problems are formulated, which are solved through the formulation of sets of high-order nonlinear equations. For H∞ optimization, the nondimensional FRF function of NIDVA-C4 is minimized at resonant frequencies considering the harmonic force excitation case. For H2 optimization, two random vibration excitation cases are considered which are the following; random force and ground motion excitation cases. For both random vibration excitation cases, the variances of the squared modulus of the frequency response function are computed for undamped primary structure. Considering the mass ratio range from 1% to 10%, from H∞ performance evaluation, the numerical results revealed that the proposed device yields improvements of 2–15% and 23–33% when compared to the inerter-based dynamic vibration absorber (IDVA-C6) or rotational inertial double tuned mass dampers and classic DVA, respectively. On the other hand, for the random force excitation case, improvements of 1–16% and 14–27% can be obtained. Furthermore, for the random acceleration excitation case, the NIDVA-C4 provides dynamic performances of 2–6% and 15–20% compared with the IDVA-C6 and classic dynamic vibration absorber (DVA), respectively. Finally, to appreciate the vibration attenuation in the time domain, numerical simulations were carried out considering the randomly excited mechanical 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.

Analysis and Optimization of the Novel Inerter-Based Dynamic Vibration Absorbers

Passive dynamic vibration absorber (DVA) is widely used in structural vibration reduction, and the higher efficient DVA is always required for some special situations. This paper aims to propose the novel inerter-based dynamic vibration absorbers (IDVAs) to enhance the performance of the passive DVA. First, several novel IDVAs are presented by matching the inerter with DVA in different places. Then, the closed-form optimal parameters of six kinds of IDVAs are obtained based on the classical fixed-point theory. The obtained parameters demonstrates that all the inerters connected between the primary system and absorber system do not provide improvement for the performance of DVAs, while all the inerters connected to the earth can improve the performance of DVAs. Moreover, the comparisons among the IDVAs show that the inerter connected to the earth in the grounded DVA (IR2 in this paper) performs the best performance in vibration absorption. More than 30 % improvement can be obtained from IR2 as compared with other IDVAs. Finally, the further comparison among the IDVAs under white noise excitation also shows that IR2 is superior to other IDVAs. The results may provide theoretical basis for design of the optimal IDVA in engineering practice.

Optimal tuned mass-damper-inerter (TMDI) design for seismically excited MDOF structures with model uncertainties based on reliability criteria

The tuned mass-damper-inerter (TMDI) is a recently proposed linear passive dynamic vibration absorber for the seismic protection of buildings. It couples the classical tuned mass damper (TMD) with an inerter, a two-terminal device resisting the relative acceleration of its terminals, in judicial topologies, achieving mass-amplification and higher-modes-damping effects compared to the TMD. This paper considers an optimum TMDI design framework accommodating the above effects while accounting for parametric uncertainty to the host structure properties, modeled as a linear multi degree of freedom system, and to the seismic excitation, modeled as stationary colored noise. The inerter device constant, acting as a TMD mass amplifier, is treated as a design variable, whereas performance variables sensitive to high-frequency structural response dynamics are used to account for the TMDI influence to the higher structural modes. Reliability criteria are adopted for quantifying the structural performance, expressed through the probability of occurrence of different failure modes related to the trespassing of acceptable thresholds for the adopted performance variables: floor accelerations, interstory drifts, and attached mass displacement. The design objective function is taken as a linear combination of these probabilities following current performance-based seismic design trends. Analytical and simulation-based tools are adopted for the efficient estimation of the underlying stochastic integral defining the structural performance under uncertainty. A 10-story building under stationary Kanai-Tajimi stochastic excitation is considered to illustrate the design framework for various TMDI topologies and attached mass values. It is shown that the TMDI achieves enhanced structural performance and robustness to building and excitation uncertainties compared to same mass/weight TMDs.

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.

Broadband vibration control of a structure by using a magnetorheological elastomer-based tuned dynamic absorber

A passive dynamic vibration absorber (DVA) is a mass-spring system that suppresses the vibration of a structure at a particular frequency. The DVA is especially effective when its excitation frequency is close to its tuned frequency. Fixing the physical properties of the DVA limits the application to a narrowband, harmonically excited vibration problem. A frequency-tunable DVA that can modulate its stiffness provides adaptability to the vibration control device against non-stationary disturbances. In this paper, we suggest a broadband frequency-tunable DVA whose natural frequency can be extended to more than 300% of the base value by using magnetorheological elastomers. We first conducted a magnetic field analysis by using a finite element method, through which the formation of a strong magnetic field within the core was observed. By taking full advantage of the frequency adjustability of the proposed DVA, we evaluated the real-time vibration control performance for an acoustically excited plate having multiple resonant peaks. The results show that the vibration of the structure can be effectively reduced with an improved performance by using a DVA instead of a passive absorber.

Hybrid vibration absorber with detached design for global vibration control

A new hybrid vibration absorber, with detached passive and active parts, is designed, analyzed and tested. This is an alternative approach in case the traditional bundled hybrid vibration absorber with collocated active and passive control elements cannot be applied. In fixed-free structures like buildings and towers, a passive dynamic vibration absorber is very popular for vibration control at or near the free ends. Active control may be introduced to improve performance, but space or weight may be limited in some applications. It may not be practical to attach an actuator near the passive part. The new approach provides more flexibility to retrofit a passive dynamic vibration absorber into a high performance hybrid vibration absorber by installing the actuator at a more suitable location than collocated with the passive part. The proposed hybrid vibration absorber is based on the pole-placement control strategy. Its controller is able to deal with a possible nonminimum-phase secondary path caused by noncollocated actuator sensors. This feature does not exist in a bundled hybrid vibration absorber with collocated actuator sensors. The performance of the new hybrid vibration absorber is analyzed in this study. Experimental and simulation results are used to verify the theoretical results and demonstrate the excellent performance of the new hybrid vibration absorber for vibration control at multiple points. A bundled hybrid vibration absorber with collocated passive and active elements is compared with the proposed hybrid vibration absorber with detached control elements, using experimental and simulation results. It was found that the vibration attenuation performance of the proposed hybrid vibration absorber can be better than the traditional bundled hybrid vibration absorber. The optimal actuator location, which is not necessarily the coupling point of the passive resonator, can be selected numerically by a proposed procedure. One could miss a better solution for vibration control if he/she only uses the bundled hybrid vibration absorber without considering the detached hybrid vibration absorber as a possible alternative.

Active vibration control in Duffing mechanical systems using dynamic vibration absorbers

Abstract This paper deals with the multi-frequency harmonic vibration suppression problem in forced Duffing mechanical systems using passive and active linear mass–spring–damper dynamic vibration absorbers. An active vibration absorption scheme is proposed to extend the vibrating energy dissipation capability of a passive dynamic vibration absorber for multiple excitation frequencies and, simultaneously, to perform reference position trajectory tracking tasks planned for the nonlinear primary system. A differential flatness-based disturbance estimation scheme is also described to estimate the unknown multiple time-varying frequency disturbance signal affecting the differentially flat nonlinear vibrating mechanical system dynamics. Some numerical simulation results are provided to show the efficient performance of the proposed active vibration absorption scheme and the fast estimation of the vibration disturbance signal.

Design and analyses of axial semi-active dynamic vibration absorbers based on magnetorheological elastomers

Magnetorheological elastomers are a new kind of magnetorheological materials mainly composed of polymer rubber and micro-sized magnetizable iron particles. Dynamic vibration absorbers based on magnetorheological elastomers are widely used in vibration systems with small amplitude since they have the advantages of no sealing equipments, good stability, and rapid response. In this article, a shear-mode semi-active dynamic vibration absorber based on magnetorheological elastomers is proposed, and the dynamic design principle of an axial semi-active dynamic vibration absorber attached to ship shafting is studied. The material preparation of magnetorheological elastomers and their properties under different magnetic fields are discussed. The structure of a single semi-active dynamic vibration absorber is designed, and theoretical analysis of shift-frequency property of a single semi-active dynamic vibration absorber is also investigated. The magnetic flux density of magnetorheological elastomers in the semi-active dynamic vibration absorber is analyzed using ANSYS software. A compact and efficient semi-active dynamic vibration absorber for shafting axial vibration control is proposed. Furthermore, a linear relationship is found between the excitation current and the natural frequency of a single semi-active dynamic vibration absorber. The results show that the designed axial semi-active dynamic vibration absorbers have better performance than classic passive dynamic vibration absorbers in terms of frequency-shift property and vibration absorption capacity.

A smart dynamic vibration absorber for suppressing the vibration of a string supported by flexible beams

This study aims to effectively and robustly suppress the vibration of tension-stabilized structures (TSSs) using a smart dynamic vibration absorber (DVA). In recent years, a strong need has emerged for high-precision and high-functionality space structural systems for realizing advanced space missions. TSSs have attracted attention in this regard as large yet lightweight structural systems with high storage efficiency. A fundamental issue in the application of TSSs is vibration control of strings, of which TSSs are predominantly composed. In particular, the suppression of microvibrations is difficult because the deformation is almost perpendicular to the direction of vibration. A DVA is an effective device for suppressing microvibrations. However, the damping performance is sensitive to changes in dynamic properties. Furthermore, aging degradation and temperature dependence negatively affect DVA performance. This study aimed to develop a smart, active DVA with self-sensing actuation to improve robustness. A small cantilever with a piezoelectric transducer was utilized as a smart DVA. Numerical simulations and experiments showed that a passive DVA and the smart DVA suppressed vibrations but that the smart DVA showed improved effectiveness and robustness.

J1010603 DCモータとLR回路を用いたばねとダッシュポット不要の動吸振器の研究([J101-6]制振(2))

This paper presents a passive dynamic vibration absorber using a DC motor and an LR circuit instead of a spring and a dashpot. The combination of the DC motor and LR circuit equivalently works as a mechanical spring and a dashpot. The dynamic vibration absorber using the DC motor and LR circuit enables tuning of the natural frequency and damping ratio with ease. This paper describes the derivation of the governing equations of the proposed dynamic vibration absorber, derivation of an equivalent mechanical model of the proposed method and simulations.

Optimization of passive vibration absorbers to reduce chatter in boring

This paper is focused on the optimal selection of the parameters of a passive dynamic vibration absorber (DVA) attached to a boring bar. The boring bar was modeled as an Euler–Bernoulli cantilever beam and the stability of the system was analyzed in terms of the bar and the absorber characteristics. To obtain the optimum parameters of the absorber, a classical method for unconstrained optimization problems has been used. The selection criterion consisted of the maximization of the minimum values of the stability lobe diagram. Empirically fitted expressions for the frequency and damping ratio of the DVA (which permit to obtain its stiffness and damping) are proposed. These expressions are fully applicable when the damping ratio of the boring bar is non-null as it is in practical operations. The computed results show a clear improvement in the stability performance regarding other methodologies previously used.

Design of an adaptive–passive dynamic vibration absorber composed of a string–mass system equipped with negative stiffness tension adjusting mechanism

In this study, a new adaptive–passive dynamic vibration absorber design is discussed. The proposed design is composed of a string under variable tension with a central mass attachment as an undamped dynamic vibration absorber (DVA), a negative stiffness mechanism as a string tension adjustment aid and a tuning controller to make it adaptive. The dependency of the natural frequencies of this system on the string tension is determined analytically and verified using the finite element method. It is analytically shown that with the help of a negative stiffness element, the tuning force requirement is almost zero throughout the whole operation range. A string tension adjustment algorithm is proposed, which tunes the DVA system depending on the magnitude and frequency of the most dominant component of the vibration signal. Finally, a prototype of the system is built and a series of experiments are conducted on the prototype that validate the analytical and numerical calculations.

Semi-active on–off damping control of a dynamic vibration absorber using Coriolis force

A passive dynamic vibration absorber (DVA) moving along a pendulum can cause the nonlinear Coriolis damping to reduce the pendulum swing. This paper proposes a simple semi-active on–off damping controller to improve the passive Coriolis DVA. The aim of the on–off damping control is to amplify the DVA resonance motion to increase the energy dissipated. Moreover, the paper finds the analytical solution of the harmonic vibration of semi-active controlled system. The accuracy of the analytical formulas and the superior performance of the semi-active DVA are verified by numerical simulations.

Nonlinear dynamical analysis and parameters optimization of four semi-active on-off dynamic vibration absorbers

In this paper the averaging method is used to research the approximately analytical solution of a semi-active on-off dynamic vibration absorber (DVA). At first the approximately analytical solutions for the two existing semi-active on-off DVAs, named as velocity-velocity based ground-hook control and displacement- velocity based ground-hook control, are established by the averaging method. Then two other new semi-active on-off DVAs, named as velocity-displacement based ground-hook control and displacement-displacement based ground-hook control, are presented for the first time in this paper and also researched analytically. Moreover, all the optimal parameters of the four semi-active DVAs, including the stiffness and the maximum and minimum damping ratio of the subsystem, are optimized to make the peak of the displacement transmissibility curve minimum, based on the amplitude-frequency equations from approximately analytical solutions. The comparisons of the displacement transmissibility obtained from the approximate solutions and the numerical ones are fulfilled, and the results certify that the approximate solutions have satisfactory precision. At last, the statistical results of the stochastic responses of the primary systems, including the original single degree-of-freedom system, the optimally passive DVA system, and the four semi-active on-off DVA systems, are obtained when subject to random excitation. The results show that the two new semi-active DVAs presented in this paper are almost as excellent as the existing two semi-active DVAs, and all of the four semi-active DVAs have better control performance than the optimally passive DVA.