Vibration Reduction Performance Research Articles

Dynamical analysis of a stay cable with a nonlinear energy sink and time-delayed feedback control

Stay cables exist commonly in engineering and can exhibit sustainable and large vibrations under external excitations. The unexpected oscillations always lead to the fatigue and damage of structures, resulting in the economical loss. This paper studies the vibration control of a stay cable system with a nonlinear vibration absorber and time delay control. The governing equations of motion of the stay cable system under harmonic excitations are given. The stability and different bifurcations of the trivial equilibrium point of the system are analyzed. The bifurcation diagrams with respect to the control parameters are illustrated. The frequency responses of the forced system are obtained by using the harmonic balance method. Numerical simulations are performed to validate the obtained results and various dynamical phenomena are shown, such as the multi-period oscillations, quasi-periodic responses and chaotic motions. The effects of the time-delayed feedback control on the nonlinear dynamics and vibration reduction of the system are extracted. It is shown that the proper values of the time delay and feedback gain can improve the vibration reduction performance of the system, such as the suppression of the resonance peaks and elimination of the complex responses.

Bidirectional Multi-Spectral Vibration Control: Insights from Automotive Engine Mounting Systems in Two-Dimensional Structures with a Damaged Vertical Active Element

Active mounting systems have become more prevalent in recent years to effectively mitigate structure-induced vibration across the automobile chassis. This trend is particularly evident in engine mounts. Considerable research has been dedicated to this approach owing to its potential to enhance the quietness and travel comfort of automobiles. However, prior research has concentrated on a limited spectrum of specific vibrations and noise control or has been restricted to vertical vibration control. This article describes the modeling, analysis, and control of a source structure employing a multidirectional active mounting system designed to closely simulate the position and direction of an actual automobile engine mount. A piezoelectric stack actuator is connected in series to an elastic (rubber) mount to form an active mount. The calculation of the secondary force required for each active mount is achieved through the application of harmonic excitation forces. The control signal can also reduce vibrations caused by destructive interference with the input signal. Furthermore, horizontal oscillations can be mitigated by manipulating the parameters via dynamic interconnections of the source structure. We specifically examined the level of vibration reduction performance in the absence of a vertical active element operation and determined whether the control is feasible. Simulation outcomes demonstrate that this active mount, which operates in both the vertical and horizontal directions, effectively mitigates excitation vibrations. Furthermore, a simulation was conducted to mitigate the vibrations caused by complex signals (AM and FM signals) and noise. This was achieved by monitoring the system response using an adaptive filter NLMS algorithm. Adaptive filter simulations demonstrate that the control efficacy degrades in response to complex signals and noise, although the overall relaxation trend remains unchanged.

Dynamic Analysis and Optimization on Passive/Active Vibration Reduction of a Beam Structure with Distributed Smart Foams

A smart foam is a vibration absorption structure integrated with piezoelectric material and shows promise for a highly efficient structural vibration reduction both passively and actively. The arrangement of the smart foams on the primary structure is a key issue in practical engineering. In this work, the vibration reduction performances of distributed smart foams attached to a simply supported beam are investigated, and the distribution scheme is optimized. The dynamic equations of the vibration system are established for passive and active vibration reduction, respectively. The frequency responses are analyzed based on a Newmark-[Formula: see text] method, and the accuracy is verified by a finite element analysis. An optimization method based on the genetic algorithm is proposed for the smart foams’ quantity and locations. The study reveals that, with the same total attached mass (1% of the beam mass), a limited distribution of smart foams achieves a larger vibration reduction ratio than a single smart foam or uniformly distributed smart foams. For the passive reduction mode, the optimal scheme is to arrange four smart foams at the middle of the beam, and a reduction ratio of 38% is achieved. It is related to both the first-order modal shape of the beam and the mass distribution of smart foams. For the active reduction mode, the optimal scheme is to arrange two smart foams separately, and 98% of the vibration is reduced. The optimal location is no longer at the middle of the beam, because the active moment of the piezoelectric beam makes the main contribution, rather than the passive vibration absorption. This research provides an optimization method and instructions for both passive and active vibration reductions of smart foams.

Resonant pillar-type acoustic black hole for ultralow frequency vibration reduction

Abstract This paper proposes a resonant type acoustic black hole (ABH). The ABH is achieved with gradient refractive index varies from the center of the lens to its outer surface. The performance of wave focusing and vibration reduction via the ABH is explored theoretically and numerically. Results show that the designed ABH can achieve wave focusing inside the lens and provide good vibration reduction at low frequency.

Design and vibration characteristics of sandwich constrained damping gasket for diaphragm air pump

There are certain problems of vibration reduction and isolation relevant to the working stability of diaphragm air pumps. To make the diaphragm air pump meet the use requirements, a sandwich-constrained damping gasket is designed and prepared in this paper. The research focuses on examining the impact of varying damping layer thickness on the efficacy of damping gaskets in reducing and isolating vibrations. Meanwhile, with the increase of the damping layer thickness, the total vibration severity of the diaphragm air pump body continues to increase, indicating a weakened performance of vibration reduction, while the vibration isolation performance is gradually improved.

Distributed active vibration control for helicopter based on diffusion collaboration

The active vibration control technology has been successfully applied to several helicopter types. However, with the increasing of control scale, traditional centralized control algorithms are experiencing significant increase of computational complexity and physical implementation challenging. To address this issue, a diffusion collaboration-based distributed Filtered-x Least Mean Square algorithm applied to active vibration control is proposed, drawing inspiration from the concept of data fusion in wireless sensor network. This algorithm distributes the computation load to each node, and constructs the active vibration control network topology of large-scale system by discarding the weak coupling secondary paths between nodes, achieving distributed active vibration control. In order to thoroughly validate the effectiveness and superiority of this algorithm, a helicopter fuselage model is designed as the research object. Firstly, the excellent vibration reduction performance of the proposed algorithm is confirmed through simulations. Subsequently, specialized node control units are developed, which utilize STM32 microcontroller as the processing unit. Further, a distributed control system is constructed based on multi-processor collaboration. Building on this foundation, a large-scale active vibration control experimental platform is established. Based on the platform, experiments are carried out, involving the 4-input 4-output system and the 8-input 8-output system. The experimental results demonstrate that under steady-state harmonic excitation, the proposed algorithm not only ensures control effectiveness but also reduces computational complexity by 50%, exhibiting faster convergence speed compared with traditional centralized algorithms. Under time-varying external excitation, the proposed algorithm demonstrates rapid tracking of vibration changes, with vibration amplitudes at all controlled points declining by over 94%, proving the strong robustness and adaptive capability of the algorithm.

Multi-Objective Collaborative Optimization of Stiffness and Damping Performance of Acoustic Black Hole Plate

This paper uses embedded Acoustic Black Hole (ABH) on the wallboard for structure lightening and improving the performance in broadband vibration reduction. The distribution and size of multiple ABHs affect the generalized static stiffness (GSS) and the upper limit of the structure's maximum kinetic energy (ULMKE) in practical applications, which express the ability to resist static load and vibration reduction performance, respectively. In this research, the structure's GSS and ULMKE are considered optimization objectives due to the trade-off between them. The method based on the Pareto optimal solution is adopted to optimize the layout and the radii of the ABHs. The Non-dominated Sorting Genetic Algorithm (NSGA-II) is used as the multi-objective optimization algorithm. Two 2D-ABHs embedded in a plate are optimized as numerical examples. The optimization generated several groups of Pareto optimal solutions, providing more feasible solutions for different applications faster. The verification further proved the necessity and the effectiveness of multi-objective optimization.

Machine Learning-Driven Design Optimization of Buckling-Induced Quasi-Zero Stiffness Metastructures for Low-Frequency Vibration Isolation.

Metastructures, artificial arrangements of micro/macrostructures, possess unique properties and are of significant interest in aerospace, stealth technology, and various other applications. Recent studies have focused on quasi-zero stiffness metastructures, providing an outstanding vibration isolation capability. However, existing methods are constrained to low preloads and lack the consideration of structural analysis, despite their intended use in practical structures. This study introduces metastructures with quasi-zero stiffness characteristics under high preloads by inducing local buckling. An optimization framework combining deep reinforcement learning and finite-element analysis is employed to derive an optimal model that considers both structural safety and quasi-zero stiffness characteristics. To validate the optimization results, quasi-zero stiffness metastructures are fabricated via 3D printing, and compression and vibration experiments are conducted. The fabricated metastructures exhibit quasi-zero stiffness characteristics under a high target preload along with outstanding vibration reduction performance, even in the low-frequency range.

Parameter Analysis of Vibration Damping and Energy Harvesting Performance of Bionic Suspension

The traditional damping structure usually transfers the vibration energy into heat, dissipated and without harvesting. But for harsh environments, such as military activities and lunar probe patrols, the vibration energy can be extracted, and realize the purpose of self-power condition monitoring. In this paper, a bionic suspension with energy-harvesting property is proposed based on bionic configurations. The bionic suspension adopts a symmetrical three-link arrangement to simulate the arrangement of bones, and a horizontal spring to simulate muscles. The micro-generator embedded in the knee joint provides the main damping force for the overall structure and also plays a role in harvesting energy. The dynamic equation and virtual prototype model are established, and the effects of parameter changes on the performance of vibration reduction and energy harvesting are analyzed, and the relationship between the two is revealed. The results show that the parameters to achieve their respective optimal performance are not consistent in the trend, though it is difficult to obtain the best performance of both, it can be designed according to the specific functions to be satisfied. This structure can be utilized as a general model for vibration reduction and energy harvesting scenarios, providing new ideas for self-powered sensing and condition monitoring configurations.

Analysis of vibration and noise reduction performance of 3D flower-shaped resonance structure with low-frequency bandgap

In this paper, two single-phase acoustic metamaterials that can produce localized resonance effects are proposed. Dispersion curves and vibrational modes of each structure are plotted using finite element software, and the bandgap properties and bandgap opening mechanism of these structures are explored by comparing the energy band structures and vibrational forms. Then the topological optimization of the flower-shaped structure was performed to obtain two new structures with bandgaps having lower onset frequencies. Finally, the accuracy of the frequency range corresponding to the bandgap is verified by transmission curves and stress cloud diagrams, and the vibration attenuation ability of several structures is analyzed. The results show that each new structure has excellent bandgap properties and vibration attenuation performance due to the local resonance effect, and the topology optimization method of adding spheres to the circular plate has a very good improvement of bandgap properties at low frequencies. This paper provides a means for structure optimization of single-phase material phononic crystals, a method for analyzing the vibration and noise reduction properties of the structures, and several three-dimensional phononic crystals with potential for practical applications.

Preparation and properties of silica fume@polyure-thane urea cement composites

In this study, a new material was synthesized by compounding silica fume and polyurethane urea, which is used to evaculate the vibration reduction performance of concrete. The mechanical and damping properties of silica fume@ polyurethane urea (SF@PUU) reinforced cement paste were investigated. Also, FT-IR, XRD, TG analysis, and SEM are included. The results indicated that SF@PUU leads to the production of high damping ratio cement pastes. The damping capacities of SF@PUU cement composites, where the damping mechanism included internal, external, and multiphase friction within the cement matrix. Additionally, SF@PUU created a constrained-layer damping structure in cement paste to improve the damping properties. The review confirmed that SF@PUU subjected to proper treatments can be as the replacement to cement in concrete or as a damping filler. However, more investigation is required into the dimensional stability and durability of SF@PUU-based concrete.

Dynamics and vibration reduction performance of asymmetric tristable nonlinear energy sink

With its complex nonlinear dynamic behavior, the tristable system has shown excellent performance in areas such as energy harvesting and vibration suppression, and has attracted a lot of attention. In this paper, an asymmetric tristable design is proposed to improve the vibration suppression efficiency of nonlinear energy sinks (NESs) for the first time. The proposed asymmetric tristable NES (ATNES) is composed of a pair of oblique springs and a vertical spring. Then, the three stable states, symmetric and asymmetric, can be achieved by the adjustment of the distance and stiffness asymmetry of the oblique springs. The governing equations of a linear oscillator (LO) coupled with the ATNES are derived. The approximate analytical solution to the coupled system is obtained by the harmonic balance method (HBM) and verified numerically. The vibration suppression efficiency of three types of ATNES is compared. The results show that the asymmetric design can improve the efficiency of vibration reduction through comparing the chaotic motion of the NES oscillator between asymmetric steady states. In addition, compared with the symmetrical tristable NES (TNES), the ATNES can effectively control smaller structural vibrations. In other words, the ATNES can effectively solve the threshold problem of TNES failure to weak excitation. Therefore, this paper reveals the vibration reduction mechanism of the ATNES, and provides a pathway to expand the effective excitation amplitude range of the NES.

Low-frequency broadband vibration reduction based on a square spiral beam local resonance phononic crystal

Low-frequency vibration poses a great danger to both industrial production and human health. Therefore, the development of efficient low-frequency vibration reduction structures remains a focus of academic and engineering research. In this paper, a novel low-frequency vibration reduction local resonance phononic crystal (LRPnC) plate with a square spiral beam LRPnC design is proposed. Through finite element simulation, the band structure and vibration characteristics of the LRPnC are first analyzed. On this basis, a gradient LRPnC plate with rainbow trapping effect is constructed by gradient arranging unit cells with different structural parameters to achieve broadband vibration reduction. Finally, the vibration reduction performance of the designed structure is experimentally verified. The finite element analysis results show that the designed gradient LRPnC plate can provide more than 20 dB of transmission attenuation over the full frequency range of 20–200 Hz. And the experimental results are consistent with the simulation results.

Analysis of vibration reduction performance of vibration isolation system based on particle damping

Taking ship vibration isolation systems as the research subject, the particle damper was applied to ship vibration isolation systems to study its vibration reduction performance. The energy dissipation mechanism of particle dampers is analyzed, and an energy dissipation calculation model is derived. The combined method of simulation and experimentation is employed to study the influence of parameters such as particle material, filling rate, particle diameter, and collision coefficient of restitution on the vibration reduction performance of particle dampers. The impact laws of these parameters are summarized, demonstrating that particle dampers can produce excellent vibration reduction performance when applied in ship vibration isolation systems, and reasonable parameter recommendations are provided. Response surface method (RSM) is used to fit an accurate energy dissipation prediction model and calculate the optimal performance parameters. This paper serves as a valuable reference for the parameter design, optimization, and practical engineering applications of particle dampers.

Low frequency bandgap characteristics of a 3D chiral acoustic metamaterial structure

It has been proved that bandgaps in acoustic metamaterials can block elastic waves in certain frequencies, which offer an unprecedented solution to the low-frequency vibration control. However, there are still challenges of low bandgap frequencies and wide bandwidth. Meanwhile, chirality breaks the symmetry of the structures, which could also contribute to the formation of bandgaps in acoustic metamaterials. Based on research background mentioned above, this work proposes a type of novel 3D chiral acoustic metamaterial structures. The dispersion relations are investigated by using the Bloch's theorem. Then, the specimens are fabricated by 3D printing combined with glue processing. A series of tests is carried out to study their vibration characteristics. It is shown that the simulated results of the structures are in good agreement with experimental results, which verified the validity of the numerical models. The dispersion relations and corresponding frequency-response curves are plotted. After embedding fillers, the bandgaps of structures decrease about 62.4 % and total bandwidth decrease about 46.5 %. In addition, the regularity of bandgaps in structures with different parameters are analyzed and the structure optimized accordingly shows good vibration reduction performance in low-frequencies. This work can provide a new possibility for engineering application in the field of vibration and noise control.

Structural design and multi-objective optimization of a novel asymmetric magnetorheological damper

The MRD with continuously adjustable damping, small compression, and large extension for asymmetric output may improve all-terrain vehicle impact resistance and vibration reduction performance in a variety of conditions. A novel conical flow channel asymmetric MRD (CFC-MRD) is proposed to solve the structure complexity stroke sacrifice, and lack of failure protection concerns in currently studied asymmetric MRD structures. In the design, the non-parallel plate magnetic circuit characteristics of CFC-MRD are investigated, including theoretical analysis and finite element modeling, and the correctness of the model is proved by testing. Considerations in multi-objective optimization include special performance imposing extra restrictions, and making the work more complicated and prone to local optima. To address this, the Nelder–Mead approach is utilized, which decreases the complexity of the optimization model while simultaneously managing performance conflicts. And a collaborative optimization strategy employing Comsol and Matlab tools is applied to improve optimization efficiency. The greatest difference between theoretical optimized values and real values is less than 6.77% in the experiments, showing the efficiency of the CFC-MRD structure design and optimization process.

Low-frequency bandgap characteristics and vibration attenuation performance of metamaterial-tailored concrete-filled steel tube columns

Low-frequency vibrations, such as earthquakes and wind loads, may negatively affect the proper operation of buildings and bridges and even lead to structural failure. Even though, in the past two decades, metamaterial-based structures have been utilized in structure vibration suppression, they are mainly used in the mitigation of high-frequency vibrations, and it has been an open challenge to suppress low-frequency vibrations below 100Hz and ensure adequate bearing capacity in engineering structures. In this work, we present metamaterial composite column structures with built-in local resonators to achieve the low-frequency vibration mitigation effect. Compared to ordinary concrete-filled steel tube (CFST) columns, the metamaterial columns (meta-columns) can utilize the rubber shear modulus to create a low-frequency flexural bandgap in 30–50 Hz. Dynamic stiffness is introduced in the Timoshenko beam and Bloch's theorem, the metamaterial analytical model is established, and the bandgap generation mechanism and vibration reduction effect are analyzed in conjunction with numerical simulations. Then, the bandgap effect and vibration attenuation law of the meta-columns are investigated by shaker tests at different acceleration amplitudes. Guided by theory and simulations, we have successfully fabricated several meta-composite columns with low-frequency bandgaps, which attenuate up to half of the vibrational energy near the bandgap center. The bandgap ranges derived from the theoretical and numerical models show a high degree of consistency with the experimental results, with deviations generally within 10 %, all indicating that a bandgap exists near the resonator self-oscillation frequency. Additionally, the bandgap is significantly affected by the number of unit cells and resonators, especially the meta-column with fewer resonators fails to form a bandgap where the top response is smaller than the bottom response. As the number of resonators and metamaterial units increases, the meta-columns exhibit wider bandgap and stronger vibration reduction performance.

Dynamic analysis and experimental investigation of particle damping for the vibration reduction and isolation of floating raft using the two-phase flow theory of gas-particle

ABSTRACT To ensure an effective and smooth operation of shipborne equipment and show ships’ vitality, the floating raft is universally used to reduce mechanical vibration and underwater-radiated noise. However, the vibration amplification phenomenon still occurs in low-frequency excitation of shipborne equipment. Accordingly, a new idea for enhancing vibration reduction and isolation performance of floating rafts for shipborne equipment based on particle damping is proposed. Considering particle-particle frictions and collisions inside the damper, a mathematical model of particle damping using the two-phase flow theory of gas-particle is derived for the dynamic analysis combined with the finite element method. The damping effect for vibration reduction is obtained by dynamic analysis with different dampers-installation schemes in raft structures. An experimental platform for the floating raft with particle dampers is built. Comparing its dynamic analysis with experimental investigation results, the rationality and feasibility of the mathematical model of particle damping are demonstrated. In addition, this research further indicates that particle damping enhances the vibration isolation performance of floating rafts in low-frequency excitation for shipborne equipment, which is of great practical significance to improve the combat effectiveness of ships.

Medium-high frequency vibration control of an industrial pipeline using squeeze-mode magnetorheological dampers

Due to fluid excitation and the vibration of connected equipment, industrial pipelines are prone to long-term medium-high frequency and small amplitude vibration. Magnetorheological (MR) dampers with a multi-stage squeeze plate structure were proposed to solve the problem of medium-high frequency vibration in the industrial pipeline. The dynamic characteristics of the industrial pipeline were analyzed to determine the installation position of the MR dampers. The mechanical properties of the proposed squeeze-mode MR dampers were tested, and the hyperbolic tangent mechanical model of the MR damper was established. The vibration control model of the industrial pipeline was built for simulation analysis. In addition, the Acceleration-Driven-Damper (ADD) control and the Proportional-Integral-Derivative (PID) control were used for simulation to predict the vibration reduction effect. Constant current experiments and control algorithm experiments were carried out on the vibration control platform of the industrial pipeline. The experimental results show that the maximum vibration attenuation rate of the MR dampers with constant current reaches 61.95%, while those with ADD control and PID control are 65.43% and 67.46%, respectively. Therefore, the squeeze-mode MR dampers can effectively reduce the medium-high frequency vibration of the industrial pipeline, and the control algorithms can further improve the vibration reduction performance.

Suppressing friction-induced stick-slip vibration through a linear PZT-based absorber and energy harvester

AbstractIn this paper, a PZT (lead zirconate titanate)-based absorber and energy harvester (PAEH) is used for passive control of friction-induced stick-slip vibration in a friction system. Its stability condition coupled with PAEH is analytically derived, whose efficiency is then demonstrated by numerical simulation. The results show that the structural parameters of the PAEH can significantly affect the system stability, which increases with the mass ratio between the PAEH and the primary system, but first increases and then decreases with the natural frequency ratio between the PAEH and the primary system. The impacts of the electric parameters of the PAEH on the system stability are found to be insignificant. In addition, the PAEH can effectively suppress the stick-slip limit cycle magnitude in a wide working parameter range; however, it does not function well for friction systems in all the working conditions. The stick-slip vibration amplitude can be increased in the case of a large loading (normal) force. Finally, an experiment on a tribo-dynamometer validates the findings of the theoretical study, in which the vibration reduction and energy harvesting performance of the PAEH is fully demonstrated.