Vibration Control Effect Research Articles

ОБЗОР СОВРЕМЕННЫХ ДЕМПФИРУЮЩИХ СПЛАВОВ В КОНТЕКСТЕ ПЕРСПЕКТИВ АГРОПРОМЫШЛЕННОГО ПРИМЕНЕНИЯ

The article provides an information and analytical review of progressive scientific and technical solutions in the field of industrial use of modern damping alloys from the point of view of increasing the effectiveness of vibration control and industrial noise in the operation of machinery and equipment of the agro-industrial complex. In accordance with the generalized classification system for high-damping alloys, a comprehensive characteristic of alloys with an improved ability to dissipate (absorb) the energy of vibrations that occur in dynamically loaded parts (nodes) of agricultural machinery is presented. The main groups of damping alloys for effective vibration protection of elements of agroengineering systems have been identified by systematizing scientific and practical information about the key features of the most common alloys in science and industry with increased damping (dissipative) properties. It has been established that such iron-carbon alloys as alloyed steels and gray cast irons are among the most promising vibration- and noise-absorbing metal materials for the manufacture of agrotechnical facilities operating in the mode of cyclic and shock effects. The indicated iron-carbon alloys have demonstrated an increased ability to dissipate the energy of sound vibrations over a wide temperature range with an acceptable set of physico-mechanical, technological and operational parameters. It was found out that the mass use of non-ferrous metal alloys in the agro-industrial complex as vibration- and noise-absorbing metal materials is hindered by their high cost, as well as a rather limited combination of physico-mechanical (functional) properties, especially in the range of elevated temperatures. For this reason, it is recommended to pay attention to the study, development and modernization of special multicomponent damping coatings that can be applied to the main material of agrotechnical facilities using various technologies.

Seismic response prediction of a damped structure based on data-driven machine learning methods

Damping technology has been widely used because of its good vibration control effect. However, due to the strong nonlinearity of the added dampers, accurately predicting the seismic response of damped structures remains a challenge. This study investigates the application of interpretable machine learning (ML)-based and deep learning-based approaches to the prediction of the maximum inter-storey displacement of a damped structure. A comprehensive database consisting of 13,855 structural responses to ground motions was collected. Seven traditional interpretable ML algorithms including random forest and extreme gradient boosting (XGBoost), a convolutional neural network based on large receptive field, and seismic wave transformer (SWT) model based on a transformer network were developed. The predictions show that the error of the SWT based on unsupervised feature extraction is reduced by 50.90% compared with that of the optimal XGBoost in ensemble learning. Although the SWT has the highest global accuracy, XGBoost is found to have a smaller error when the structure is in a linear state with peak ground acceleration as partition index, so an aggregation model (AM)-based structural response prediction method was also proposed. The accuracy of the AM improved by 27.95% compared with that of the SWT. In contrast with other ML models, the proposed AM is more advantageous in terms of computational efficiency and accuracy.

Experimental Study and Seismic Design of Swing Story-Lateral Force Resisting Structural System

A seismic vibration control system, consisting of a swing story substructure, a lateral force resisting substructure and connecting dampers, is recently proposed. The analytical model and optimization method based on the stability maximization and H2 criteria have been established. In this paper, excellent vibration control effects of the proposed system are verified through the small-scale shaking table tests on a two-story model. Experimental results demonstrate the accuracy of the analytical model and the validity of the vibration control strategy. Through numerical analyses of benchmark structures, the input energy of the optimally designed system is remarkably mitigated, and favorable vibration control effects for reducing both inter-story drifts and absolute floor accelerations under earthquake ground motions are verified by comparing with conventional moment-resisting frame structures. In addition, significant control effects can be achieved when the optimal stiffness is greater than the critical buckling stiffness. A seismic design flow chart of the intensity-reduced design method is proposed based on the numerical analyses and the Chinese Seismic Design Code of Buildings. The results indicate that the seismic intensity-reduced design for the proposed system is feasible.

Method for Controlling Full-Frequency Band Environment Vibration by Coordinating Metro Vibration Sources and Propagation Paths

Floating slab tracks (FSTs) are used to reduce the impact of vibration on precision instruments and historical relics along metro lines; however, ground vibration is universally amplified at the natural frequency of the tracks. In this study, a full-frequency control method that considers frequency matching for environmental vibrations, in combination with metro vibration sources and propagation paths, was developed based on the bandgap theory of the periodic structure. The effectiveness of this method was analysed by establishing a three-dimensional metro train–FST coupled model and a finite element analysis model of track bed–tunnel–soil–row piles. The results show that ground vibration can be reduced by approximately 3–5 dB at the natural frequency of the FST by adjusting the bandgap range of the periodic piles to 7–9 Hz, eliminating the adverse effect of vibration amplification at the natural frequency of the FSTs. The proposed control method shows good vibration control effects and can effectively minimise ground vibration in the full-frequency range.

Preparation of microscale multi-layered viscoelastic polymers and analysis of their noise control effects on composite structures

Multi-layered design is an effective method to improve the damping performance of structures. The existing research focuses more on the multi-layered design of the structure from the macro-perspective, but lacks attention to the material itself from the micro-perspective. Thus, whether microscale multi-layered (MML) viscoelastic polymers have advantages in damping performance is not clear. Moreover, damping materials preparation and structural noise control is an interdisciplinary study. The noise and vibration control effect of MML viscoelastic polymers in actual composite structures needs to be further investigated. This paper conducts such a study on these issues. First, two different types of MML viscoelastic polymers, i.e., free damping (FD) and micro-constrained damping (MCD) composites, were prepared, and their material properties were characterized. Second, the frequency-dependent damping loss factors and elastic modulus of the different damping composites were identified. The influences of damping composite types and MML designs on material damping loss factor and elastic modulus were compared. Third, a prediction model of vibroacoustic behaviours of the honeycomb sandwich structure was established and validated to investigate the noise and vibration control effects of the MML damping composites on composite structures. The influences of the types, numbers of layers and application positions of the MML damping composites on the honeycomb sandwich structure were studied. The results indicated that MML design is helpful to improve the damping performance of viscoelastic polymers, but its influence on different damping composites is quite different. For noise control, MML-FD is more suitable for controlling airborne sound propagation, while MML-MCD is more suitable for controlling structural sound propagation.

Experimental study of structural vibration control of 10-MW jacket offshore wind turbines using tuned mass damper under wind and wave loads

As slender structures, offshore wind turbines (OWTs) are prone to vibration and deformation under wind and waves. Tuned mass dampers (TMDs) have become among the most promising vibration-mitigation methods owing to their simplicity and practicability. To study the vibration control effect of a TMD on a jacket OWT under wind and wave conditions, we conducted a fully coupled dynamic model test of a 1/75 scale jacket OWT with and without a TMD. The physical model of the jacket OWT included scaled rotor-nacelle assembly (RNA) and support structure models. For the scaled RNA model, a redesigned blade model was used to ensure similarity of the aerodynamic thrust loads without modifying the scaled test winds. Drivetrain and pitch-control system models were designed to simulate the operating state of an actual OWT. The support structure model was established based on the hydro-structural elastic similarity. Furthermore, a TMD model was designed and manufactured based on the first mode of the scaled OWT. A fully coupled dynamic model test of a 10 MW jacket OWT with a TMD under wind and wave conditions was performed, and the vibration-mitigation performance of the designed TMD model on the structural responses of the scaled OWT model was evaluated.

Drill-string stability and stress localization: Influence of complex delay effects and dry friction

With the aim of enhancing the understanding of the complex dynamics of deep drilling, an integrated model with complex time delays and Stribeck friction is presented for studies on the axial-torsional dynamics of a drill string. Various aspects of the drill string are considered, including spatial distribution, structural and external damping, dry friction-induced damping, boundary conditions, and complex bit-rock interactions. The drill-string structure is spatially discretized by using the finite element method. With the resulting discretized complex delay system, stability analysis is conducted following the semi-discretization procedure. Through parametric studies, the effects of drilling parameters, dry friction, boundary conditions, and rock-strength properties on the drilling stability are obtained. Subsequently, an optimally tuned boundary condition with compliance is deployed at the top drive to expand the stable region and mitigate self-excited vibrations in the operational parameter space of drilling. To find the distribution of stress along the drill string, numerical simulations are conducted. The dynamical stress caused by self-excited vibrations is illustrated in the spatial–temporal plane. Strain and stress analysis reveal wave propagation along the drill string, including traveling and standing waves. The dynamic effective stress along the drill string is studied, and the von Mises effective stress is determined by combining the axial stress and torsional stress. On the basis of this information, the locations of the vulnerable points along the drill string are found in terms of structural strength. Finally, the tuned boundary condition at the top is deployed in the numerical simulations to show vibration control effectiveness. The results point to two possible vibration-cancellation approaches that can benefit from a tuned top boundary. The findings of this work can serve as a basis for identifying the locations of vulnerable points and alleviating the levels of axial-torsional vibrations in drilling applications.

Dynamic analysis of damping structures considering support stiffness

An analysis method for the random seismic response of viscoelastic damper structures with support is proposed. This method considers the influence of support stiffness and analyzes the dynamic characteristics associated with support stiffness. It also combines the advantages of the complex modal method (CMM) and the pseudo-excitation method (PEM), improving the complex integration operation in calculating the spectral moments and variances of random seismic responses. The support and the viscoelastic damper constitute the equivalent damper. The damper's constitutive relationship and structural dynamic equations are decoupled to calculate conveniently the frequency domain solution of the responses. Second, the quadratic decomposition of the power spectral density function (QD-PSDF) is applied to simplify the power spectrum and obtain the closed-form solution of spectral moments and variances. Finally, the structural dynamic characteristics and the influence of support stiffness on the vibration control effect of the equivalent damper are investigated based on the closed-form solution. The structural dynamic reliability is also discussed according to the first excursion failure criterion. The results demonstrate that the damper's control effect and structural reactions are reduced, while the dynamic reliability is also enhanced when increasing support stiffness. The performance of the structure and damper tends to stabilize when the support coefficient reaches a specific level.

Mechanical Characteristics and Vibration Control of Railway Signal Relay

Introduction: In order to solve the problems of time-consuming and poor effects of traditional mechanical vibration control methods for the relay, the mechanical characteristics and vibration control of railway signal relays are studied in this paper. Based on the analysis of the mechanical characteristics of railway signal relays, the mechanical characteristic parameters of the relay, such as contact force, initial pressure, contact clearance, and overtravel are explored. On this basis, mechanical vibration control is completed based on particle swarm optimization. Methods: First, sensors are used to collect the data on the railway signal relay, and the mechanical vibration control model of the railway signal relay is built. Then, the structure of the PID vibration controller and LQR vibration controller in the model is analyzed. Finally, the controller parameters are adjusted through particle swarm optimization to improve the mechanical vibration control effect of the relay. Results: The simulation results show that the average signal-to-noise ratio of the method is 67dB, the collected data has low noise, and the control time is short, which is 1.4 s. Conclusion: The displacement of the railway signal relay controlled by the method is always less than 0.15 mm, and the control effect is good, which can be widely used in practice.

Vibration control of adjacent buildings based on tuned viscous mass damper

In this paper, two adjacent buildings of unequal height are established using finite-element software, and damping devices are connected between the two buildings. The results of three models were obtained through non-linear analysis. These include the adjacent building model (CAIM-T) based on the tuned viscous mass damper, the adjacent building model (CAIM-V) with the viscous damper connection (CAIM-V) and adjacent building structure no additional damping model (CAIM). The results show that through reasonable parameter design and adjustment, compared with the CAIM system, the CAIM-T system and the CAIM-V system can weaken the interlayer drift and floor acceleration of the building structure, and the CAIM-T system has better vibration control effect than the CAIM-V system.

Seismic response analysis of submerged floating tunnel considering non-uniform excitation and flexible-support boundary effect

In order to ensure the safety of submerged floating tunnel(SFT) during operation, it is necessary to carry out SFT response analysis under environmental loads. Given that SFTs are often constructed in valley areas situated in seismic zones, the aseismic performance of SFT needs to be investigated. However, there are important factors of non-uniform excitation and flexible-support boundary which have not been explored thoroughly. Non-uniform excitation affects the load input characteristics while flexible-support boundary affects the dynamic characteristics of structure itself. In this paper, we built a multi-point seismic wave synthesis model which fits well with the target power spectrum and a numerical response analysis model which reflects the dynamic characteristics of SFT structure well. The results based on the proposed model show that vertical non-uniform excitation can significantly increase the peak value of SFT tether tension and tube displacement with flexible-support boundary under whether artificial or natural seismic wave series input. While flexible-support boundary can availably produce vibration control effect on peak value of tether tension and tube response of whether displacement or stress indices under non-uniform wave series input. This work can provide reference for dynamic safety assessment and vibration control design of SFT to improve the development of ocean space.

Train-Induced Vibration Prediction and Control of a Metro Depot and Over-Track Buildings

To predict and control the train-induced vibration in depot buildings, a case study of the depot of Tianjin Metro, Line 5, was conducted. The platform of the depot has been constructed and is in use, and the construction of over-track buildings has not been completed. Firstly, an in situ measurement was performed to obtain the train loads and validate the numerical model. Secondly, a finite element model of the track–soil–depot structure was established. The train was simplified as a series of two spring-mass models and the train load was simulated using the measured rail acceleration. The calculated results were validated by the measurement data. To predict the vibration responses of the over-track building to be built, a sub-system of the over-track building was added to the numerical model. Finally, the vibration control effect of vibration isolation bearings was discussed. The results indicate that vibrations exceeded guideline limits without mitigation measures in some rooms of the over-track building. The dominant frequency of the building floors is 31.5 Hz. Vibration isolation bearings effectively mitigated the vibrations, and the IL reached approximately 7–15 dB at about 31.5 Hz.

Effect of negative stiffness nonlinearity on the vibration control effectiveness of tuned negative stiffness inerter damper

Recently, tuned negative stiffness inerter damper (TNSID) integrating the advantages of both negative stiffness and inerter elements has been proposed and verified to be effective for structural vibration control. In previous studies, the stiffness of the negative stiffness element was normally regarded as a constant for simplicity. However, it is well-known that negative stiffness is generally accompanied by nonlinearity, which may lead to undesirable nonlinear vibrations and unstable responses. Therefore, in this paper, the influence of the nonlinearity of negative stiffness, including weakening and strengthening nonlinear negative stiffness, on the performances of two representative TNSIDs with different configurations is investigated. The working mechanisms and optimal parameters of the TNSIDs with simplified linear negative stiffness are introduced firstly. Following that, based on the harmonic balance method, the dynamic responses of the two TNSIDs with different nonlinear negative stiffness are attained. The unstable problems and performance degradation caused by the nonlinearity of negative stiffness are analysed. Parametric studies are further carried out to evaluate the effects of the nonlinear coefficient, excitation amplitude, internal frequency ratio, and damping ratio on the performances of the two nonlinear TNSIDs. Moreover, to eliminate the impact of the negative stiffness nonlinearity, a new structural parameter optimization is conducted by minimizing the maximum displacement amplitude-frequency response of the TNSIDs. The results indicate that the nonlinearity of negative stiffness could lead to the bend and jump of the displacement amplitude-frequency response curves of TNSIDs, as well as superharmonic resonances, especially when the performance of TNSIDs is sensitive to the variation of negative stiffness. Besides, the unstable areas and the maximum displacement amplitude-frequency responses of TNSIDs are dependent on the excitation amplitude and nonlinear coefficient. To avoid the unstable vibration phenomenon and maintain effective vibration control performance, TNSID-P2 is recommended to be equipped with a weakening negative stiffness under both moderate and strong excitations, while TNSID-P1 should be designed with a weakening negative stiffness and work under a moderate excitation due to its performance being highly sensitive to the variation of negative stiffness.

Dynamic characteristics and active vibration control effect for shape memory polymer composites

Shape memory polymer composites (SMPCs) are widely used as a new type of composite material in space expansion structures, which are prone to vibration and resonance in a space environment. A new type of macro fiber composite (MFC) can be used to control the vibration of the structure. Based on Kirchhoff plate theory, the differential equations of motion for composite laminates are derived. Theoretical analysis of SMPC cantilever plates with varying carbon fiber content is carried out. In addition, the effects of local temperature changes on the dynamic characteristics of SMPC with different fiber content are studied. The vibration differential equations of the SMPC cantilever plate were obtained by using the separation variable method and the modal vibration superposition principle. The state-space equations of the system were established based on the transfer function, and the frequency response was determined by sine sweep excitation of the SMPC specimen. The open-loop and closed-loop vibration active control of SMPC specimens was investigated using the classical proportional integral derivative (PID) procedure. Finally, the effect of carbon fiber content on the vibration active control characteristics of SMPC structures was analysed.

Seismic Performance Analysis of the Two-Dimensional Isolation Device for Double-Layer Grid Structure

The isolation technologies are adopted to protect the long-span space structures from serious damage under the action of earthquakes. When the isolation system is applied to the space structures, both horizontal and vertical vibration control effects on the structures should be concerned. In this paper, a two-dimensional earthquake isolation and mitigation device (TEIMD) composed of a high-damping viscoelastic (VE) core pad and VE dampers is proposed. Based on the dynamic shear experiment results of the VE damper, the energy dissipation capability of VE material is preferable. Then, the nonlinear equivalent stiffness and equivalent damping ratio of the TEIMD in horizontal and vertical directions are evaluated by using the numerical simulation method. The TEIMDs are arranged on the column top of a double-layer grid structure to assess the isolation effectiveness of the novel device. The dynamic analysis results of the double-layer grid structure with and without TEIMD reveal that this novel device can significantly reduce the acceleration response of the upper grid by relying on the strong energy dissipation performances in the horizontal and vertical directions. This research also verifies the feasibility of applying the TEIMD to the double-layer grid structure, which can effectively dissipate the vertical vibration energy of the structure.

The vibration mitigation of jacket offshore platform based on inerter nonlinear energy sink

The application of the traditional passive vibration control system is limited by the demand for large mass. To ameliorate this situation, the inerter nonlinear energy sink (NES) is introduced and applied, as the substitute for the traditional passive vibration control system, to vibration mitigation of jacket offshore platform under random wave loading, since it has the clear advantage of obtaining apparent vibration control effect through low amounts of added mass. For one thing, the equation of jacket offshore platform including inerter NES is developed considering wave loads. For another, the optimal parameters of inerter NES are obtained through Particle Swarm Optimization (PSO) using numerical simulations. Both analytical and numerical results strongly support that the inerter NES contributes greatly to vibration suppression, compared with traditionally tuned mass dampers (TMD). To explore more practical benefits, further comparison between the vibration mitigation of inerter NES and the optimal TMD system, considering different masses and stiffness, is made right after, which verifies the effectiveness and robustness of inerter NES. Based on the above study and results, it proves valid to conclude that the inerter NES system allows practical application of vibration mitigation for marine structures.

Number vs size of electro-mechanical tuneable vibration absorbers for aeronautical applications: a case study

This paper presents a case study on the tuning and flexural vibration control effects generated either by many-small-scale or few-large-scale electromagnetic tuneable vibration absorbers on a model section of an aircraft fuselage structure. The absorbers are formed by a coil-magnet seismic transducer connected to a tuneable resistive-inductive shunt. The control of both tonal and broad-band disturbances is investigated with reference to the number, and thus the size, of the units. The principal aim of the paper is to address the key question on whether, for a fixed total weight of the absorbers, it would be preferable to have a small number of comparatively larger and heavier units or a greater number of comparatively smaller and lighter units. To this end, the first part of the paper presents a comprehensive scaling analysis based on fundamental principles of the physical properties and tuning laws of the electromagnetic tuneable vibration absorbers. Then, the second part of the paper presents a simulation study on the optimal-tuning and the vibration control effects of setups with 4, 8, 16, 32 electromagnetic tuneable vibration absorbers whose total weight is kept equal to 6% of the weight of a model fuselage structure. The study shows that arrangements with many small-scale units produce larger vibration control effects than setups formed by comparatively fewer, larger scale, units. However, the operation frequency range of the EM-TVAs tends to shift to higher frequencies with downsizing. Moreover, the size of the optimal shunt inductance that would guarantee the tuning of the EM-TVAs tends to grow as the unit is downscaled such that an artificially large inductor may be required.

Tuned Mass Damper Design of Substation Post Switchgear in Gale Area

Post switchgear of substation in a gale area is a typical wind-sensitive structure. In order to reduce the wind-induced response of substation post switchgear in a gale area, in this paper, according to the theoretical formula of the optimal frequency ratio and the optimal damping ratio of TMD given by Den Hartog, a tuned mass damper (TMD) is proposed to reduce the vibration of the first-order vibration mode outside the plane of the structure. The Simulink simulation model of the simplified structure with TMD is established and the fluctuating wind speed of the equipment is simulated by the Kaimal wind speed spectrum. The wind vibration control effect of TMD is checked, and the rationality of the TMD design is verified.

Self-tuning vibration control using piezoelectric patches and RL shunts set to maximise electric power absorption

This paper presents experimental results on the flexural vibration response of a thin plate structure subjected to a stochastic disturbance. The plate is equipped with five piezoelectric patches connected to shunt circuitry to reduce the resonant response of a target flexural mode. The shunts are synthesized digitally to mimic a resistor-inductor connected in parallel. Firstly, the study assesses the vibration control effects produced by the shunts, contrasting the time-averaged flexural kinetic energy of the panel and the time-averaged electric power absorbed by the shunts filtered in a narrow band centred on the resonance frequency of the target mode. This analysis shows that both cost functions results on the same optimal tuning parameters, which provides a benchmark for the vibration control. Next, it investigates the online tuning of the resistive and inductive components of the shunt by implementing an extremum seeking algorithm set to maximise the time-averaged electric power absorbed locally by the shunt filtered in a narrow band centred on the resonance frequency of a target mode. The study shows that indeed the resistive and inductive components in the shunts connected to the five patches converges to the optimal values with the application of extremum seeking algorithm and this leads to a minimisation of the spectral flexural response vibration at the resonance frequency of the target mode by 18 dB.

Model test analysis of control effect of building foundation elastic pad on subway environmental vibration

Building foundation elastic pad is one of the important measures for subway vibration control. In order to understand the subway vibration control effect of elastic pad on superstructure, two identical concrete test blocks were poured on site near a subway line. Taking the real subway vibration load as the input source strength, the vibration isolation effect of elastic pad on upper concrete mass block was compared and analyzed; At the same time, the influence of the backfill around the underground foundation of the building on the vibration isolation effect is simulated and analyzed. The backfill has a non negligible restraint effect on the building, improves the vertical natural frequency of the "building elastic pad" system, and then reduces the vibration isolation effect of the elastic pad. Therefore, it is very necessary to lay the elastic pad on the side wall around the building to reduce the lateral restraint effect of the backfill.