Parameters Of Dynamic Vibration Absorber Research Articles

Spectro-geometry dynamic analysis of FG-GPLRC cylindrical shell with periodically embedded dynamic vibration absorbers

This study presents a theoretical model of the functionally graded graphene platelet-reinforced composite (FG-GPLRC) cylindrical shell with periodically embedded dynamic vibration absorbers (DVAs) under different boundary constraints. The material parameters of the FG-GPLRC were first determined using the Halpin-Tsai micromechanical method and the general law of mixing. The energy expression for the system is developed based on the first-order shear deformation theory (FSDT). A simplified model of the DVA is carried out, which consists of a mass block, a linear damper and a linear spring after simplification. Displacement field vectors of the cylindrical shell are established based on the spectro-geometric method (SGM). The Rayleigh-Ritz method was used to determine the vibration response of the coupled model. The validity of the proposed method is confirmed through comparing with results from existing literature and finite element method (FEM) calculations. The effect of boundary conditions, FG-GPLRC material properties, geometrical parameters of cylindrical shells, distribution parameters of DVAs, and damping coefficient on the steady-state vibration of the coupled model is investigated on this basis.

Performance Analysis of a Vibration Absorber with the Inerter Element and Amplifying Mechanism

Based on the good performance of the new control elements, we introduce the viscoelastic model, the amplification mechanism and the inerter element into the dynamic vibration absorber (DVA). Then, we take it as the research object to obtain the DVA parameters when the system achieves the optimal vibration reduction effect based on the fixed-point theory. Finally, it is eventually demonstrated that the DVA discussed in this paper possesses significant benefits in mitigating vibrations, which provides theoretical basis and data support for the parameters design of DVAs in engineering application.

H∞ Optimization of Three-Element-Type Dynamic Vibration Absorber with Inerter and Negative Stiffness Based on the Particle Swarm Algorithm.

Dynamic vibration absorbers (DVAs) are extensively used in the prevention of building and bridge vibrations, as well as in vehicle suspension and other fields, due to their excellent damping performance. The reliable optimization of DVA parameters is key to improve their performance. In this paper, an H∞ optimization problem of a novel three-element-type DVA model including an inerter device and a grounded negative stiffness spring is studied by combining a traditional theory and an intelligent algorithm. Firstly, to ensure the system's stability, the specific analytical expressions of the optimal tuning frequency ratio, stiffness ratio, and approximate damping ratio with regard to the mass ratio and inerter-mass ratio are determined through fixed-point theory, which provides an iterative range for algorithm optimization. Secondly, the particle swarm optimization (PSO) algorithm is used to further optimize the four parameters of DVA simultaneously. The effects of the traditional fixed-point theory and the intelligent PSO algorithm are comprehensively compared and analyzed. The results verify that the effect of the coupling of the traditional theory and the intelligent algorithm is better than that of fixed-point theory alone and can make the two resonance peaks on the amplitude-frequency response curves almost equal, which is difficult to achieve using fixed-point theory alone. Finally, we compare the proposed model with other DVA models under harmonic and random excitation. By comparing the amplitude-frequency curves, stroke lengths, mean square responses, time history diagrams, variances and decrease ratios, it is clear that the established DVA has a good vibration absorption effect. The research results provide theoretical and algorithm support for designing more effective DVA models of the same type in engineering applications.

Optimal Design and Sensitivity Analysis of the Dynamic Vibration Absorber With Amplifying Mechanism

Abstract This work optimizes a dynamic vibration absorber (DVA) model equipped with an additional amplifying mechanism using the H∞ optimization criterion, which aims to minimize the maximum frequency response amplitude of the primary structure. This optimization problem is widely investigated using the fixed-point method, which, however, works only when the primary structure is undamped and gives approximate solutions at best. Instead, we seek the exact solutions, and a resultant-based optimization scheme is accordingly proposed, which allows handling purely univariate polynomial equations in the solving procedure to guarantee the convergence and global optimum conditions. Consequently, exactly numerical and closed-form optimal DVA parameters are obtained when the primary structure is damped and undamped, respectively. Furthermore, we are also interested in the effect of the amplifying mechanism on vibration suppression, showing that it functions as a convenient equivalent mass ratio regulator to benefit the DVA performance. Finally, the presented sensitivity analysis reveals the effect of the small variations of the DVA stiffness and damping on the vibration suppression performance and the role of the amplifying mechanism in balancing such two components’ uncertainties. This work generalizes the existing exact H∞ optimization methods and provides a guideline for the enhanced DVA design using the amplifying mechanism.

A position optimization strategy of the dynamic vibration absorber for the noise control of the power equipment

Power equipment shows obvious low frequency line spectrum noise characteristics due to the power frequency. The effective noise control of the power equipment can be achieved by installing dynamic vibration absorbers (DVAs) on the structure surface of electrical equipment. However, if DVAs are not installed properly, considering the cases that they are installed at the vibration mode node position, the low radiation vibration mode and the redistribution of the integrate vibration power, the vibration and noise absorbing performances of DVAs may degrade. In order to achieve efficient vibration absorption and noise reduction on the power equipment, this paper proposes a low-frequency noise reduction technology for power equipment based on DVAs. The position optimization of the DAVs using in the power equipment is studied for the first time. Aimed at the single frequency radiated sound power of equipment, the integrate radiated sound power of the equipment is minimized through adjusting the position parameters of DVAs. A numerical case is studied to verify the effectiveness of the proposed DVAs position optimization. The results show that the noise control effect of the power equipment with the optimized DVAs is significantly improved. The method proposed in this paper solves the noise problem of the power equipment, which provides reference for power noise control.

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.

Vibration Characteristics and Reduction Analysis of Lifting Pipe under Ocean Current

Effects of vibration absorbers on the lifting pipe in deep-sea mining have been attracting more and more attention in the recent three decades; however, there are very few reports about the influence of ocean current on the pipe vibration in the literature. Considering the geometrical features of the prototype, this paper establishes the physical model, mathematical model, and simulation model of the lifting subsystem. A comprehensive finite element model for the deep-sea mining system by the OrcaFlex is developed to explore the influences of buffer mass and sailing velocity on the deflection angle and the axial load and stress of the lifting pipe. Analytical and numerical simulations have been formulated to illustrate variation rule of longitudinal vibration and axial stress at the position of pump and buffer for the lifting subsystem to determine the dynamic vibration absorber parameters. In this paper, MATLAB and Orcaflex software are used to verify the mathematical model. The simulation results show that the attaching DVAs can effectively reduce the axial stress, and longitudinal displacement at certain positions of the lifting pipe.

Dynamics analysis of a novel in-wheel powertrain system combined with dynamic vibration absorber

Poor ride comfort is one of the drawbacks of in-wheel-drive electric vehicles (IWD-EVs). Structural schemes of the in-wheel powertrain system combining dynamic vibration absorber (IWP-DVA) can be applied to improve the ride comfort performance of the IWD-EVs without excessive useless weight. In this scheme, the in-wheel-drive motor is suspended as a mass block, thereby a dynamic vibration absorber (DVA) is mounted on the unsprung mass to absorb the vibration. This study developed a novel IWP-DVA involving a pair of symmetrical external-geared-slider-rocker (EGSR) mechanisms and a differential gear mechanism. In this paper, the novel IWP-DVA’s effectiveness in preventing the driving torque and the mass block’s travel from interacting was verified based on the static analysis of the single-EGSR mechanism, where the negative phenomena of stroke depletion due to the driving torque exists. For investigating the ride comfort responses and tuning the spring/damper parameters, a dynamics model of a quarter vehicle system equipped with the novel IWP-DVA was constructed by using screw theory and Lagrange method. After the selection of the DVA parameters, an analysis of the results of ride comfort tests showed that the novel IWP-DVA could improve the ride comfort with a sufficient stroke.

Enhancement of a dynamic vibration absorber by means of an electromagnetic shunt

In this study, we address the reduction of structural vibrations by means of an electromagnetic shunt damper (EMSD) combined with a mechanical dynamic vibration absorber (DVA). Two architectures, that differs in the placement of the EMSD with respect to the DVA, are tested, showing that one of them enhances the vibration control. In parallel, three shunt architecture are tested: a resistive shunt, a resonant conservative shunt and a resonant dissipative shunt. Optimal values of the EMSD and DVA parameters are obtained; then, the performances of all architecture, according to relevant criteria, are estimated and compared to a single DVA or a single EMSD. The case of a conservative DVA, that creates an anti-resonance, is particularly targeted. It is shown that the performances rely on two free parameters only: the mass ratio for the DVA and the electromagnetic coupling factor for the EMSD, thus giving generic abacuses that can be applied to any practical cases. Finally, experiments are proposed and a good agreement with the theoretical results is obtained, thus validating them.

Optimal parameters of dynamic vibration absorber for linear damped rotary systems subjected to harmonic excitation

Dynamic vibration absorber (DVA) is a simple and effective device for vibration absorption used in many practical applications. Determination of suitable parameters for DVA is of significant importance to achieve high vibration reduction effectiveness. This paper presents a method to find the optimal parameters of a DVA attached to a linear damped rotary system excited by harmonic torque. To this end, a closed-form formula for the optimum tuning parameter is derived using the fixed-point theory based on an assumption that the damped rotary systems are lightly or moderately damped. The optimal damping ratio of DVA is found by solving a set of non-linear equations established by the Chebyshev's min-max criterion. The performance of the proposed optimal DVA is compared with that obtained by existing optimal solution in literature. It is shown that the proposed optimal parameters are possible to obtain superior vibration suppression compared to existing optimal formula. Extended simulations are carried out to examine the performance of the optimally designed DVA and the sensitivity of the optimum parameters. The simulation results show that the improvement of the vibration performance on damped rotary system can be as much as 90% by using DVA.

Optimization control for dynamic vibration absorbers and active suspensions of in-wheel-motor-driven electric vehicles

This study addresses the challenges of ride comfort improvement and in-wheel-motor vibration suppression in in-wheel-motor-driven electric vehicles. First, a mathematical model of a quarter vehicle equipped with a dynamic vibration absorber and an active suspension is developed. Then, a two-stage optimization control method is proposed to improve the coupled dynamic vibration absorber–suspension performance. In the first stage, a linear quadratic regulator controller based on particle swarm optimization is designed for the dynamic vibration absorber to suppress the in-wheel-motor vibration, in which the dynamic vibration absorber parameters and linear quadratic regulator controller weighting factors are optimally matched by using the particle swarm optimization algorithm. In the second stage, a finite-frequency H∞ controller is designed in the framework of linear matrix inequality optimization for the active suspension to improve vehicle ride comfort. Suspension performance factors, including suspension working space and road-holding ability, are taken as constraints in both stages. The proposed method simultaneously improves vehicle ride comfort and suppresses in-wheel-motor vibration. Finally, the effectiveness and superiority of the proposed method are illustrated through comparison simulations.

Closed-form solutions to optimal parameters of dynamic vibration absorbers with negative stiffness under harmonic and transient excitation

In this present paper, two configurations of dynamic vibration absorber in conjunction with negative stiffness (NSDVA) are investigated and their parameter optimization is conducted according to two tuning methodologies: the fixed points theory and the stability maximization criterion. Closed-form solutions to the optimal parameters of NSDVAs are analytically derived and are expressed in terms of ratio between the negative stiffness and mechanical stiffness of primary system. Allowable bounds on negative stiffness are specified with the consideration of stability requirement, based on which the ultimate control performance of NSDVAs could be imagined. Furthermore, an optimal negative stiffness ratio is defined within the stable region when the NSDVAs are tuned by the fixed points theory. Finally, numerical simulations are carried out in both harmonic and free vibration scenarios. Simulation results suggest that the inclusion of negative stiffness in the coupled system can significantly improve the vibration control performance in terms of broadening the frequency bandwidth of vibration suppression, decreasing the peak vibration amplitude of primary system and confining the stroke length of NSDVAs. Meanwhile, the negative stiffness can enhance the damping capability of coupled system, engendering an accelerated convergence of transient disturbances.

OPTIMIZATION OF DYNAMIC VIBRATION ABSORBERS BASED ON EQUAL-PEAK THEORY

Abstract The present paper proposes a new procedure to determine the optimal parameters of a dynamic vibration absorber (DVA), considering both damped and undamped primary system. The DVA design is formulated as an optimization problem in which the objective function is constructed based on Den Hartog's equal-peak method. The DVA parameters are selected to minimize the response of the primary system when it is subjected to harmonic force or base motion. Firstly, we propose a numerical strategy based on Frequency Response Curve (FRC) in which the parameters of the absorber are updated by minimizing the objective function. The results are presented for a set of reference parameters, which demonstrate the feasibility of the proposed method for determining the optimal parameters of the absorber for both excitations. Taking into account the system response with respect to reference parameters, the bilinear interpolation technique was employed in order to obtain explicit formulas of the damping and frequency ratios of the DVA.

A novel design of the dynamic vibration absorbers for damped main systems under torsional excitation using least squares estimation of the equivalent linearization method

Torsional vibration usually occurs in the working process of machines and equipment such as in transmission drive and working shaft of machine tool. To reduce this vibration, the dynamic balancing method and dual mass flywheel systems are applied. There are fewer researches that used the dynamic vibration absorber for reducing the torsional vibration. However, an analytical solution for designing the optimal parameters of dynamic vibration absorbers attached to the damped main system is found to be difficult and complicated. This paper proposes a novel idea to approximately replace an original damped main system by an equivalent undamped system using the least squares estimation of equivalent linearization method. An explicit closed-form expression of the optimal damping ratio and tuning parameters of dynamic vibration absorber are determined for the undamped main system under torsional excitation. The expressions are quite simple and have effective practical applications. Numerical results for time and frequency responses of the system are presented to reveal stronger effect and accuracy of the proposed solution on the damped main system. It is observed that the torsional vibration of the damped main system has been reduced significantly also in the resonant region. The proposed expressions of the optimal parameters are powerful tools for design dynamic vibration absorber to reduce the torsional vibration of rotary system such as the transmission and working shafts, etc.

Suppressing Wind-Induced Oscillations of Prismatic Structures by Dynamic Vibration Absorbers

The suppression of oscillations of an elastically mounted prism under galloping by a dynamic vibration absorber (DVA) with linear damping and stiffness is investigated. A model considering the dynamic coupling of the prism and the DVA is constructed, with the aerodynamic loads acting on the system represented by a quasi-steady approximation. Based on the coupled nonlinear governing equations of motion, a linear analysis is first conducted to explore the coupled frequency and damping, and the onset speed of galloping in the presence of the DVA. Subsequently, the normal form of the Hopf bifurcation for the coupled system near the onset of galloping is derived to characterize the type of instability (supercritical or subcritical), while evaluating the effects of the DVA parameters. The results show that with appropriate parametric values, the DVA has great impact on the onset speed of galloping and can significantly alleviate the oscillation amplitude of the prism.

A global-local approach to the design of dynamic vibration absorber for damped inverted pendulum structures

In practice, an inverted pendulum can be used to model many real structures as the arms of robots, soil structures, or fluid structures. However, the study on the design of dynamic vibration absorber for inverted pendulum structures is very limited in the literature. To the best knowledge of the authors, however, there has been no study on the dynamic vibration absorber when the primary inverted pendulum structure is damped. This paper deals with the optimization problem of dynamic vibration absorber for inverted pendulum structures. Two novel findings of the present study are summarized as follows. First, the optimal parameters of dynamic vibration absorber for undamped inverted pendulum structures are given by using \(H_{\infty }\) optimization. Second, the authors suggest a so-called global-local approach to determine approximate expressions for optimal parameters of a pendulum type absorber attached to a damped inverted pendulum structure. Finally, a numerical simulation is done for an example of the articulated tower in the ocean to validate the effectiveness of the results obtained in this work.

Dynamic Vibration Absorber Design to Suppress Boring Chatter: Absorber Parameters Identification Based on Modal Correlation

The dynamic vibration absorber (DVA) is generally used to suppress the machining vibration in boring processes. The DVA consists of an additional massspringdamper sub-system, and needs accurately tuning of its natural frequency and damping ratio to match the main structure for vibration control. For obtaining the optimal performance of the DVA, the parameters of the DVA used in a boring bar is identified using modal correlation method, which combines the finite element analysis method with test modal method to validate the FEMs results. The analysis results show that the modal correlation method is an effective and simple method to accurately identify the dynamic parameters of DVA and guarantee the optimal design of the DVA for boring chatter control.

Design of three-element dynamic vibration absorber for damped linear structures

The standard type of dynamic vibration absorber (DVA) called the Voigt DVA is a classical model and has long been investigated. In the paper, we will consider an optimization problem of another model of DVA that is called three-element type DVA for damped primary structures. Unlike the standard absorber configuration, the three-element DVA contains two spring elements in which one is connected to a dashpot in series and the other is placed in parallel. There have been some studies on the design of the three-element DVA for undamped primary structures. Those studies have shown that the three-element DVA produces better performance than the Voigt DVA does. When damping is present at the primary system, to the best knowledge of the authors, there has been no study on the three-element dynamic vibration absorber. This work presents a simple approach to determine the approximate analytical solutions for the H∞ optimization of the three-element DVA attached to the damped primary structure. The main idea of the study is based on the criteria of the equivalent linearization method in order 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. The comparisons have been done to verify the effectiveness of the obtained results.

On the resonant vibration of a flexible railway car body and its suppression with a dynamic vibration absorber

The geometric filtering phenomenon is first analyzed with a simplified vertical vehicle model. Analytical solutions obtained with this model show that geometric filtering phenomenon consists of ‘wheelbase filtering’ and ‘bogie spacing filtering’ effects. The wheelbase filtering effect occurs when there is neither car body bounce nor pitch response at certain track wavelengths, whereas the bogie spacing filtering effect occurs when there is a null in either the car body bounce or pitch response at particular track wavelengths. Then, the correlated frequency response function for railway vehicles is defined to assess the effect of geometric filtering upon the resonant frequencies of a flexible car body. It is found that if the car body’s first bending frequency coincides with the peak values of bounce acceleration transmissibility, that is, it is near the null pitch response frequencies, resonant vibration of the flexible car body will happen. Finally, to suppress the resonant vibration of the flexible car body, it is proposed to use a dynamic vibration absorber (DVA) suspended under the car body underframe. The DVA parameters are optimized according to car body bending frequency and the null pitch frequency. The optimal DVAs show very good performance and robustness in suppression of the car body resonant vibration.

Parameter Design of Heave Compensation System of Deep-Sea Mining Based on Dynamic Vibration Absorber and its Experimental Study

To ensure the safety and the production efficiency as well as the component lifetime of deep-sea mining system, a novel heave compensation system of deep-sea mining based on dynamic vibration absorber was proposed in the light of 5000m deep sea poly-metallic mining system of China in this paper. According to the work condition of heave compensation system, the response of deep-sea mining ship under random wave of sea state 4 in China’s deep sea poly-metallic mining field are numerically simulated in time domain. The proposed heave compensation system was simplified to a two-degree-of-freedom system stimulated by the displacement motion of the deep-sea mining ship and its dynamic model was built. Taking the minimum of the displacement variance of the proposed heave compensation system as the optimal object and considering the allowed displacement of the dynamic vibration absorber itself, the computation formula of the optimum parameters of dynamic vibration absorber for heave compensation system of deep-sea mining is derived. Thus the parameter of dynamic vibration absorber was determined and its effect on the performance index of the heave compensation system was simulated and compared. The dynamic vibration absorber with optimum parameters was simulated and tested on the test bench of double-storey mass-spring vibration system in the lab. The results of the example show that the performance of vibration control of the designed dynamic vibration absorber is satisfactory and the computational formulas given in the paper are effective. The results also verified that the heave compensator based on dynamic vibration absorber with the optimal parameters can have good performance of heave compensation and it is practical to isolate the lifting pipeline and its deployment platform from the vibration of the ship motion induced by the irregular wave with simplicity and less energy consumption. This work in the paper will be of great theoretical guidance in the optimum design of the dynamic vibration absorber for heave compensation system of deep-sea mining.