Performance Of Vibration Absorber Research Articles

Low-frequency vibration absorption of magnetic quasi-zero-stiffness structures with lever mechanism

Dynamic vibration absorbers (DVAs) are widely employed in diverse engineering systems for their capacity to mitigate structural vibrations. However, traditional absorbers exhibit sensitivity to natural frequencies and present challenges in tuning within the low-frequency range. This study introduces a lever mechanism to enhance the low-frequency vibration absorption performance of magnetic quasi-zero-stiffness structures, resulting in a lever-type DVA (L-DVA). We elucidate the design philosophy behind the proposed L-DVA. An analytical model is derived based on the Lagrange equation and the frequency-response relationship is determined using the harmonic balance method. We conduct numerical and experimental analyses to assess the impact of the lever ratio, mass ratio, frequency ratio, nonlinear stiffness coefficient ratio, and damping ratio on vibration absorption performance. Furthermore, we fabricate a prototype of the L-DVA with an adjustable magnetic quasi-zero-stiffness structure, and the experimental results align with simulation outcomes. The result shows that this study is the ease of customization in the vibration absorption capabilities of magnetic quasi-zero-stiffness structures, achieved by adjusting the lever ratio. An increase in the lever ratio and tip mass effectively shifts the anti-resonant peak to a lower frequency. The decrease in the frequency ratio leads to a reduction in the anti-resonant frequency. This study validates the efficacy and feasibility of utilizing the L-DVA for low-frequency vibration absorption.

Comparative Performance Analysis of Inverse Phase Active Vibration Cancellation Using Macro Fiber Composite (MFC) and Vibration Absorption of Silicone Gel for Vibration Reduction.

This study focuses on addressing the issue of unwanted vibrations commonly encountered in various fields by designing an Active Vibration Cancellation (AVC) structure using a flexible piezoelectric composite material macro fiber composite (MFC). A comparative performance analysis was conducted between the AVC and a traditional passive gel that continuously absorbs vibrations. The results showed that AVC was more effective in mitigating vibrations, making it a promising solution for vibration control. The results of this study from extensive vibration-sensing experiments and comparisons revealed that AVC effectively cancels the vibrations and vibration absorption performance of the passive gel. These findings underline the potential of AVC as an efficient method for eliminating and managing undesired vibrations in practical applications. Specifically, AVC demonstrated a high vibration cancellation ratio of approximately 0.96 at frequencies above 10 Hz. In contrast, passive gel exhibited a relatively consistent vibration absorption ratio, approximately 0.70 to 0.75 at all tested frequencies. These quantitative findings emphasize the superior performance of AVC in reducing vibrations to levels below a certain threshold, demonstrating its efficacy for vibration control in real-world scenarios.

Integrated a nonlinear energy sink and a piezoelectric energy harvester using simply-supported bi-stable piezoelectric composite laminate

A nonlinear device is presented for simultaneous vibration absorption and energy harvesting. This device is composed of a nonlinear energy sink and a piezoelectric energy harvester (NES-EH), and its core component is the simply-supported bi-stable piezoelectric composite laminate (BPCL). Its outstanding advantages are light weight, simple and reliable structure. The theoretical model is developed to model a harmonically excited linear oscillator coupled with NES-EH. The Runge–Kutta method and the harmonic balance method (HBM) are used to solve the theoretical model numerically and analytically. The vibration suppression efficiency is utilized to quantify the vibration absorption performance, while the energy harvesting performance is assessed by bandwidth for energy harvesting and maximum voltage within the bandwidth. The effects of the excitation amplitude, the concentrated mass of NES-EH, the length and width of BPCL, and the load resistance are considered on the performances of NES-EH. The vibration absorption and energy harvesting performances of NES-EH can be improved by adjusting these parameters. In addition, the proposed NES-EH can achieve the goal of higher power density and normalized power density under low-amplitude excitation and simultaneously have a good vibration absorption effect. Finally, approximate analytical solutions are obtained by using HBM to exhibit various bifurcations and singularities.

A novel lever-type inerter-based vibration absorber

A novel Lever-type Inerter-based Vibration Absorber (LIVA) is proposed. The proposed LIVA is based on a lever supported on a flexible auxiliary structure, connecting between the primary structure and a paralleled inerter-dashpot system. Based on analytical H∞ and H2 optimization, the formulas of the optimal parameters for the LIVA are derived. The parametric influences on optimal parameters and control performance of the LIVA are systematically investigated. Consequently, the control performance of the LIVA can be enhanced by increasing the auxiliary mass, lever ratio, or the frequency of the auxiliary structure. Considering practical aspect, the influences of damping ratios are discussed to compensate the assumptions adopted in analytical optimization. Thus, a design criterion is proposed to ensure the effectiveness of the LIVA. Finally, the vibration absorption performance of the LIVA is illustrated and compared through time domain analysis subjected to a recent earthquake event. The results have shown that the proposed LIVA exhibits a superior control performance than traditional TMD and another lever-type vibration absorber reported in a literature due to the leverage and inertance effects. Moreover, compared to the existed lever-type vibration absorbers with a fixed fulcrum, the proposed LIVA supported by a flexible auxiliary structure appears more feasible in practice.

Design of Axially Symmetric Fluid–Spring Vibration Absorber with Five DOFs Based on Orthogonal Experiment

The strong and complex vibration from a manipulator for anchor drilling will damage the key components of the manipulator and produce noise at the same time. According to its vibration characteristics, a fluid–spring vibration absorption approach with five degrees of freedom (DOFs) is proposed, which has perfect symmetry, and a vibration absorber was designed with a symmetrical structure. Employing the generalization formula of the Bernoulli equation and dynamic equation, a fluid–spring coupling damping coefficient equation was constructed. Vibration transmissibility was used as the evaluation index of vibration absorption performance. The elastic coefficients of the tension spring and torsion spring, the area ratio of circular through-holes to the vibration-absorbing plate, and the radius of circular through-holes were the main independent factors influencing the damping coefficients. An orthogonal experiment with four factors and four levels was designed. Using FLUENT and SIMULATION to implement joint simulations, the distribution law of the flow fields and the damping coefficients of each approach were obtained, and then the best combination of factors was selected. Taking a manipulator used for anchor drilling in Huainan of China as a case study, using the designed fluid–spring vibration absorber, the vibration displacements in the five DOFs were reduced by 68.32%, 49.82%, 52.17%, 49.01%, and 57.09% respectively, indicating a good vibration absorption performance with symmetry about the z→-axis.

Vibration energy accumulation and absorption characteristics of pseudo acoustic black hole wedge

The Acoustic Black Hole (ABH) is an effective structure for harvesting and dissipating energy from flexural waves. It works by reducing the thickness of the ABH wedge in a power law relationship with m ≥ 2, which rapidly decreases the local phase velocity of flexural waves and leads to an energy convergence effect. However, the vibration performance may differ if the tapered wedge does not meet the requirements of a typical ABH. This article introduces and discusses two types of “pseudo-ABH” wedges: linear-degenerate ABH and step-degenerate ABH. These wedges do not follow the power-law and continuity conditions of typical ABH, respectively. To establish the dynamic models of pseudo-ABH wedges, the lumped-mass transfer matrix method (LTMM) and traveling wave analysis are introduced and validated using analytic solutions of the non-uniform one-dimensional Euler-Bernoulli beam and finite element method. Meanwhile, a good match between the results of the Timoshenko and Euler-Bernoulli beam theory also indicates the correctness of our model. The energy ratio and reflection coefficient are defined to characterize the energy accumulation effect and vibration absorption performance of the pseudo-ABH wedges. The vibration performance of the linear-degenerate ABH is closer to the typical ABH than the step-degenerate ABH. The step-degenerate ABH has more effective energy accumulation and reduction performance for individual frequencies. However, as the number of segments in the step-degenerate ABH increases, its dynamic performance becomes closer to that of the typical ABH. The novelty of this article is to study vibration energy accumulation and absorption characteristics of pseudo acoustic black hole wedges using LTMM model, disclose the differences of linear and step degenerate ABH for their performance, and recommend the step degenerate ABH in place of the typical ABH of a power law thickness relationship.

A pendulum-based absorber-harvester with an embedded hybrid vibro-impact electromagnetic-dielectric generator

In this paper, a novel hybrid vibro-impact electromagnetic-dielectric generator (VI EDG) is proposed, which is further embedded into a pendulum structure to form a pendulum-based absorber-harvester (PAH) system. The PAH system can convert the vibration energy into electrical one with the help of the VI EDG, and has the potential to reduce the swing amplitude of the pendulum. The physical model of the PAH system is first introduced, and its governing equations involving the dynamical and electrical parts are derived based on the Euler-Lagrange’s equation of a non-conservative system. Next, the governing equations of the PAH system are validated experimentally by measuring the swing motion of the pendulum under a given harmonic excitation. On this basis, the system energy harvesting performance under different excitation parameters (amplitude and frequency) and dimensional parameters (the rod’s length and the distance between two dielectric elastomer membranes) is fully investigated and explained through numerical simulations. Finally, the vibration absorption performance of the VI EDG is discussed by comparing the peak-to-peak values of the swing motions between the proposed PAH system and the conventional pendulum without embedded VI EDG. Research results show that the proposed VI EDG can not only effectively harvest ambient vibration energy from the pendulum system, but also has the potential to absorb the vibration of the system.

A Small-Amplitude Control Method of the Nonlinear Energy Sink Vibration Absorption System

The nonlinear energy sink (NES) is an effective method to weaken or eliminate the line spectra feature of ship machinery equipment. However, due to the strong nonlinearity of the NES, there are multistable attractors in the NES vibration absorption system. Moreover, when the excitation characteristics or working conditions of the mechanical equipment change, the NES may migrate from the small-amplitude motion state to the large-amplitude motion state, resulting in a high-amplitude solitary branch response and thereby lowering its vibration absorption efficiency. In this study, the small-amplitude control of the NES nonlinear vibration absorption system has been studied by using the open-loop-plus-nonlinear-closed-loop (OLPNCL) method. First, the dynamic equation of the NES nonlinear vibration-absorbing system was formulated, and its global behavior was analyzed. The regulations of global features and coexisting attractors were found out. Second, the migration between different attractors was carried out under the OLPNCL control, which can ensure that the system always works at the lowest line spectrum intensity and the best overall vibration absorption performance. Finally, the simulation results verify the feasibility and effectiveness of the OLPNCL method and achieve effective vibration absorption in the low-frequency range and line spectrum control under variable operating conditions.

Friction properties of the single-crystal Si in collision sliding contacts under different lubrication conditions

With the development of nanotechnology, micro-nano electromechanical systems are widely used in various high-precision instruments, e.g., micro-nano satellites, pico-satellites, in which single-crystal Si is always employed. In outer space, there will be random collisions in space mechanisms caused by unexpected and irregular small disturbances especially under the microgravity environment. In this paper, a molecular dynamics model is used to simulate the motion of the mechanism based on the motion characteristics of random collisions happened within space mechanisms, and irregular collisions are represented by sinusoidal vibrations of the indenter in Y and Z directions. The friction properties of the collision sliding contacts under the lubrication of gold films with different layers are investigated. The results show that a nine-layer gold film presents good vibration absorption and lubrication performance. Then, rectangular textures are designed and made on the gold film. The textured surface can significantly reduce the friction forces at high vibration frequencies. In addition, the friction properties of a molybdenum disulfide (MoS2) film and the combined lubrication behaviors of molybdenum disulfide films and gold films are studied. The molybdenum disulfide film shows excellent friction properties at different vibration frequencies, and the combination of molybdenum disulfide and gold films can significantly reduce the average friction force within a specific vibration frequency range.

Design and experiment of an adaptive dynamic vibration absorber with smart leaf springs

An adaptive dynamic vibration absorber (ADVA) is designed for low-frequency vibration suppression. The leaf springs are applied as the tuning stiffness elements. The principle of variable stiffness is analyzed to obtain the effective range of the first natural frequency variation. A classic simply supported manipulator is selected as the controlled system. The coupled dynamic model of the manipulator-ADVA system is built to obtain the maximum damping efficiency and the vibration absorption capacity of the designed ADVA. An experimental platform is set up to verify the theoretical results. It is revealed that the ADVA can adjust the first natural frequency on a large scale by changing the curvature of the leaf springs. The amplitude of the manipulator is reduced obviously with the installation of the designed ADVA. Finally, based on the short-time Fourier transformation (STFT), a stepwise optimization algorithm is proposed to achieve a quick tuning of the natural frequency of the ADVA so that it can always coincide with the frequency of the prime structure. Through the above steps, the intelligent frequency tuning of the ADVA is realized with high vibration absorption performance in a wide frequency range.

Vibration reduction of footbridges subjected to walking, running, and jumping pedestrian

In this paper, the performance of vibration absorbers in reducing the vertical deflections of the footbridges subjected to human activities is studied. The vertical component of the pedestrian force during walking, running, and jumping is simulated as a moving time-dependent force model. The optimal parameters for the attached vibration absorbers are defined to minimize the deflection of the footbridge. The effectiveness of each vibration absorber is reviewed for different types of excitations. Results show reductions of 91%, 95%, and 96% in terms of the amplitude of vibration for the footbridge with the optimized tuned mass damper subjected to walking, running, and jumping, respectively, in comparison with a bare footbridge. The performance of the tuned mass dampers optimized numerically in the present study is compared with the tuned mass dampers possessing parameters achieved analytically. The damped footbridge with the numerically optimized tuned mass damper under walking, running, and jumping pedestrian experienced a deflection reduction of 9%, 34%, and 37%, respectively, concerning the tuned mass damperwith analytical parameters.

Vibration absorption performance of resilient wheel in metro train running on long-span cable-stayed bridge

ABSTRACT To control the vibration of long-span cable-stayed bridge (LSCSB) caused by running train on metro line, vibration suppression effect of resilient wheel on the metro train–LSCSB coupled system is deeply investigated. Firstly, metro train–LSCSB system coupled dynamic model considering resilient wheels is formed. Then, the effects of resilient wheels on the dynamic characteristics of metro train–LSCSB system are investigated. Finally, the optimal stiffness ratiois determined, and the stiffness and damping of the resilient wheel are also optimized. Results show that: The resilient wheel reduces lateral vibration of LSCSB at 2–20 Hz. For the adopted metro train–LSCSB system, satisfactory vibration absorption effect can be obtained when stiffness ratio of the resilient wheel is 0.67–1. The optimal stiffness and damping of resilient wheel are recommended to be 30 MN/m and 300 kN·s/m.

An electromagnetic torsion active vibration absorber based on the FxLMS algorithm

Dynamics vibration absorbers are an effective solution to the problem of vibration. However, there are relatively few applications in low-frequency torsional vibration control. Therefore, for low-frequency torsional vibration, this paper proposes an electromagnetic torsional active vibration absorber, and establishes an active control system based on the filter-x least mean square (FxLMS) algorithm. First of all, the electromagnetic torsion actuator structure is designed with an electromagnetic-permanent magnetic hybrid structure, and the theoretical model of electromagnetic torque is established. Moreover, the influence of structural parameters on the linear stable interval of electromagnetic torque is analyzed, and the effective stroke range of electromagnetic torsion actuator is determined. Then, based on the FxLMS algorithm, the control system of the electromagnetic torsion active vibration absorber is established, and the theoretical model of the secondary channel transfer function is obtained. Furthermore, it is verified by simulation analysis, the results show that the electromagnetic torsional active vibration absorber can achieve good low-frequency torsional vibration absorption performance and is significantly better than without control under the excitation of harmonic torque and white noise torque. Finally, an experimental investigation is carried out on the electromagnetic torsion active vibration absorber based on the FxLMS algorithm to verify the feasibility and effectiveness of the electromagnetic torsion active vibration absorber.

Experimental Study on Vibration Absorption Performance of Floating Slabs of Vibration Isolation Pads in Metro Shield Tunnels

The monolithic track bed with isolated damping pad and floating slab is a common design of urban subways in recent years.The type of track bed, urban subway lines usually pass through densely populated areas of the city, and subway trains.In the course of driving, it is inevitable that large track vibration noise will be produced. In order to reduce the impact of track vibration noise on the daily life of surrounding residents, noise reduction measures must be considered during track design. Isolated shock absorber floating board The monolithic track bed is one of them. Compared with the steel spring floating slab monolithic track bed, it has the technical characteristics of “low engineering cost, more convenient construction, and good noise reduction effect”. In order to study its damping effect, we selected two working conditions of straight line and curve for comparison. It can be seen from the comparison results with the ordinary track bed: (1) The acceleration level of the shock-absorbing cushion tunnel wall in the straight section is greater than the ordinary track bed section within 1∼10Hz, and is close to the ordinary track bed section within 12.5∼20Hz, at 25 It is smaller than the section of ordinary track bed within ∼1000Hz. (2) The maximum Z-vibration level measured from the tunnel wall is most suitable for evaluating the seismic source intensity of the subway, and the seismic source intensity of the subway line is 65.69 dB.

Parameters optimization of dynamic vibration absorber based on grounded stiffness, inerter, and amplifying mechanism

In the field of dynamics and control, some typical vibration devices, including grounded stiffness, inerter and amplifying mechanism, have good vibration isolation and reduction effects, especially in dynamic vibration absorber (DVA). However, most of the current research studies only focus on the performance of a single device on the system, and those DVAs are gradually becoming difficult to meet the growth of performance demand for vibration control. On the basis of Voigt dynamic vibration absorber, a novel dynamic vibration absorber model based on the combined structure of grounded stiffness, inerter, and amplifying mechanism is presented, and the analytical solution of the optimal design formula is derived. First, the motion differential equation of the system is established, and the normalized amplitude amplification factor of the displacement is calculated. It is found that the system has three fixed points unrelated to the damping ratio. The optimal frequency ratio is obtained based on the fixed-point theory. In order to ensure the stability of the system, it is found that inappropriate inerter coefficient will cause the system instable when screening optimal grounded stiffness ratio. Accordingly, the best working range of inerter is determined. Finally, optimal grounded stiffness ratio and approximate optimal damping ratio are also obtained. The influence of inerter coefficient and magnification ratio on the response of the primary system is analyzed. The correctness of the derived analytical solution is verified by numerical simulation. Compared with other dynamic vibration absorbers, it is verified that presented model has superior vibration absorption performance and provides a theoretical basis for the design of a new type of dynamic vibration absorbers.

An integrated nonlinear passive vibration control system and its vibration reduction properties

A novel integrated nonlinear passive vibration control system with the function of vibration isolation and absorption is proposed by applying a bio-inspired isolator and a nonlinear energy sink (NES). The designed integrated system has excellent vibration isolation capability in the low-frequency bands and can decrease the resonance amplitude simultaneously. The nonlinear dynamic model of the integrated passive vibration control system is established. The displacement transmissibility is employed to evaluate the vibration reduction performance of the integrated system by the harmonic balance method. The coupling mechanism of vibration isolation and absorption is revealed through studying the effects of the parameters on the vibration isolation and absorption performance. It is found that due to the nonlinear weak coupling between the bio-inspired isolator and the NES, they can promote each other in the vibration isolation and absorption. Experiments are conducted to validate the advantageous vibration reduction properties of the system. And the design methodology of the integrated passive vibration control system is also elaborated for practical applications. The integrated nonlinear passive vibration control system would provide an innovative method for vibration control in various engineering practice.

Experimental Research on the Vibration Absorption Performance of Medium Damping Fasteners in Metro Shield Tunnel

Medium damping fasteners have the advantages of low cost, easy maintenance, and convenient in gauge adjustment, etc., which are gradually and widely used in metro construction. In order to study the performance of medium damping fasteners in a driving environment, we performed measurement on site about the vertical and lateral displacement of the rail, as well as the vertical acceleration of the rail and the tunnel wall on a straight and curved metro cross-section with medium damping fasteners. By comparing with the results of ordinary fasteners, it can be seen that: (1) The medium damping fastener has a vibration reduction effect on the vertical acceleration level of the tunnel wall in the frequency range of 6.3∼31.5Hz and 50∼80Hz; moreover, it has a vibration reduction effect on the lateral acceleration of the tunnel wall in the frequency range of 5∼31.5 Hz and 50∼80 Hz. (2) The vertical and lateral displacement of the rail and the gauge change with the medium damping fasteners are larger than those of the ordinary fasteners. (3) The maximum Z vibration level measured from the tunnel wall is most suitable for evaluating the source strength of the metro, wherein the source strength of this metro line is 88.42 dB.

Steady-state responses of mechanical system attached to non-smooth vibration absorber with piecewise damping and stiffness

The steady-state dynamic characteristics of non-smooth vibration absorbers are investigated. The complexification-averaging method is used to obtain the steady-state response equation of a harmonic excited primary system attached to the non-smooth absorbers, with the equation solved using a Matlab program based on the least square method. Research results indicate that the traditional purely nonlinear absorber loses its efficacy after the excitation amplitude reaches a certain value. The non-smooth absorber with piecewise linear damping, by contrast, can suppress vibration of the primary system within a larger range of excitation amplitude than the purely nonlinear absorber. Then, the cubic stiffness component is substituted by a piecewise stiffness component to further enhance the performance of the above non-smooth absorber and good results are obtained. The non-smooth absorber with both piecewise damping and stiffness shows the stronger vibration absorption performance. In addition, the differences of higher branches of response which induced by the three absorbers are analyzed and discussed.

Dynamic analysis of a new autoparametric pendulum absorber under the effects of magnetic forces

Autoparametric pendulum absorber is an effective device to suppress vibrations and has been used widely in many fields of engineering. However, the vibration absorption of the conventional pendulum absorber is effective only in a small bandwidth. To tackle this problem, a novel model of the autoparameteric absorber with attached magnets is proposed in this paper. Under the effects of the attractive magnetic forces produced by the magnets, the pendulum will absorb more vibration energy of the primary system. In this way, the performance of the pendulum absorber can be improved. In this research, the dynamic response of this new system is studied analytically and the vibration absorption performance is analyzed. Firstly, the magnetic forces produced by the permanent magnets are investigated analytically and the results are validated numerically. Then the response of the system is analyzed using the method of varying amplitudes and the results are validated by a numerical method. The optimal values of the parameters of the absorber are studied by using the small parameter expansion method. Finally, the optimal performance of this new absorber is analyzed, including the vibration amplitude of the hosting structure and absorption bandwidth. The results show that the vibration amplitude of the hosting structure is smaller and the absorption bandwidth is larger as compared to the conventional pendulum absorber.

Performance of non-smooth nonlinear energy sink with descending stiffness

The traditional nonlinear energy sink (NES), i.e., a smooth and cubic NES, can cause stable higher branch of response of primary systems with increasing excitation forcing. For this reason, the traditional NES is only effective in a certain excitation range. A kind of non-smooth NES with descending stiffness is proposed for expanding this effective range. The non-smooth NES has a higher cubic nonlinear stiffness in the initial range, and the stiffness is reduced as its amplitude exceeds the initial range. The governing equation of motion for a linear primary oscillator attached to the non-smooth NES is obtained in the case of harmonic excitation. The complexification-averaging method is used to obtain the steady-state equation of the system. A least square-based program with the help of a Runge–Kutta-based program is used to analyze the dynamic behaviors of the system. The results demonstrate that the non-smooth NES can eliminate the stable higher branch, therefore expanding the effective excitation range, until the excitation amplitude increases to a very high level. The influences of the piecewise boundary and the stiffness of the secondary stage of the non-smooth NES on the vibration absorption performance are investigated, and the drawbacks of this NES design are discussed. Finally, a structural design based on the theoretical results of the non-smooth NES is proposed, which is composed of permanent magnets, a smooth and discontinuous oscillator and linear springs.