Passive Vibration Control Research Articles

Internal resonance analysis of bio-inspired X-shaped structure with nonlinear vibration absorber

In this paper, a vibration isolation system based on bio-inspired structure with a nonlinear absorber is proposed. The nonlinear vibration properties and complex dynamical characteristics are explored elaborately in the presence of internal resonance. Lagrange’s principle is employed to derive the governing equations, which can describe the coupled nonlinear vibration system. The method of multiple scales is utilized to obtain the steady-state responses of the coupled system. It is found that the frequency-amplitude relationships reveal the typical nonlinear phenomena including jumping and multi-value. The influences of parameters on the dynamical characteristics are discussed in detail. Numerical integrations are directly implemented on the vibration equations to verify the aforementioned analytical results. And furthermore, bifurcations and chaotic motions are detected in the bifurcation diagrams via the Poincare section techniques. The proposed system and the corresponding researches would be of significance for the design and practical applications of the passive vibration control.

Control of pendulum oscillations by Tuned Liquid Dampers

This paper is concerned with passive vibration control of pendulum-type structures. Specifically, low-frequency vibrations are addressed, such as those occurring in ropeway passenger cabin oscillations. Since low frequency vibration control devices are advantageously realized by liquid absorbers, a Tuned Liquid Damper is considered here. Equations of motions for a planar mechanical model of a mathematical pendulum are derived for the two-degree-of-freedom system composed of the pendulum and the fundamental sloshing mode of the liquid. The derived mathematical models are validated by experimental investigations. To mitigate wave breaking phenomena in the sloshing liquid, a so-called floating roof proposed in literature is implemented in the experimental models. It is shown that passive control by means of the Tuned Liquid Damper is as efficient as a Tuned Mass Damper with the same mass, provided that the nonlinear damping behavior of the liquid is properly taken into account in the design of the sloshing damper.

A Passive Vibration Control Method of Modular Space Structures Based on Band Gap Optimization

Modular space structure has become a research hotspot in the aerospace field. In the microgravity and weak damping space environment, modular space structures may continuously vibrate due to the transient excitation caused by satellite attitude adjustment or space debris impact, which will make the structure unstable. Therefore, a passive vibration control method based on band gap design is proposed for the modular space structures. Firstly, a modular spectral element model based on the super element is established, and the modular spectral element model is expanded into modular space structures. Then, band gap characteristics of the modular space structure are analyzed and optimized to improve the wave isolation ability. The numerical simulation shows that the elastic wave in the band gap can be effectively isolated and the band gap is significantly improved by optimizing structural parameters.

Vibration Control of Functionally Graded Panels using Parallel Resonators

Functionally graded materials (FGM) are often an integral part these days in many engineering applications, such as, nuclear structural components, spacecraft and marine structures, thermal barrier coatings used for military applications, etc. These structures are also susceptible to dynamic loads varying from harmonic to impulse type of loadings which are in the form of rotating engines, sudden blasts and others. These loadings often pose serious threats to the structural systems by inflicting fatigue damages or by driving the system in tune with its resonating frequency that eventually lead to the complete collapse of the structure. Therefore, a vibration control strategy needs to be devised to protect these structures from unwanted vibrations due to the external loading. A passive vibration control strategy is proposed in the present research work to control the vibration response of a flat panel made of functionally graded material. At first, the FG plate is numerically modelled using the finite element (FE) method to calculate its response due to a point harmonic force. Ceramic (Alumina) is used for the top part of the FG plate while the bottom is made of metal (Aluminium) and the material property is smoothly varied from ceramic to metal using the power law distribution. Then, several resonators consisting of spring-mass system and parallel to each other are attached to both sides of the panel to isolate the response in the resonating frequency ranges. The FE model for the FG plate with resonator is developed and the controlled vibration response is obtained. The controlled response indicates that the resonators are efficient to produce band-gaps in the resonating frequency regime compared to the bare FG plate.

A new vibration isolator integrating tunable stiffness-damping and active driving properties based on radial-chains magnetorheological elastomer

In this study, a new vibration isolator integrating tunable stiffness-damping and active driving properties based on Magnetorheological Elastomer (MRE) embedding radial iron chains is proposed. Displacement/base excitations and periodic fluctuation current tests have been utilized to illustrate the fundamental dynamic properties and function of the proposed MRE vibration isolator. The force–displacement/velocity characteristics under different amplitudes/frequencies/currents input show the significant tunable range of the stiffness and damping and hysteresis loop area under the displacement excitation test, which is also described by the established Hyperbolic hysteresis model. Under the base excitation test with the sweep sinusoidal acceleration signals, it has been shown that the transmission properties can be adjusted by the applied current, and has a significant dependency on the amplitude of the acceleration excitation due to the Payne effect. Finally, it has been illustrated that the MRE component can drive a mass of 78 times self-weight in a 10 Hz excitation frequency under the periodic fluctuation current input. Therefore, the adjustable stiffness-damping and active driving force properties of the MRE material itself make the proposed MRE vibration isolator show great application potential in the passive, semi-active and active vibration control area with the fail-safe property.

Biomechanical Upper Limb Model for Postural Tremor Absorber Design

The current work promotes the use of non-invasive devices for reducing involuntary tremor of human upper limb. It concentrates on building up an upper limb model used to reflect the measured tremor signal and is suitable for the design of a passive vibration controller. A dynamic model of the upper limb is excited by the measured electromyography signal scaled to reach the wrist joint angular displacement measured by an inertial measurement unit for a patient with postural tremor. A passive tuned-mass-damper (TMD) placed on the hand is designed as a stainless-steel beam with a length of 91 mm and a cross-sectional diameter of 0.79 mm, holding a mass of 14.13 g. The damping ratio and mass position of the TMD are optimized numerically. The fundamental frequency of the TMD is derived and validated experimentally through measurements for different mass positions, with a relative error of 0.65%. The modal damping ratio of the beam is identified experimentally as 0.14% and increases to 0.26–0.46% after adding the mass at different positions. The optimized three TMDs reduce 97.4% of the critical amplitude of the power spectral density at the wrist joint.

Hierarchical model predictive vibration control for high‐rise structures using semi‐active tuned liquid column damper

Vibration control for high-rise structures has become more important as buildings become more lightweight. Tuned liquid column dampers are an established approach for this problem, as they do not consume high amounts of energy while achieving high damping forces. The natural frequency of tuned liquid column dampers (TLCDs) can be changed semi-actively by modifying their column geometry. As shown by previous studies, this approach increases the control performance of the damper and allows a larger application field. However, this modification simultaneously provokes strong nonlinearities, which need to be addressed for controller design. In this contribution a model-based controller for such TLCDs is proposed, which explicitly accounts for the nonlinear dynamics of the coupled system consisting of a multi-storey structure with a semi-active TLCD. To account for various system dynamics of the structure, a hierarchical nonlinear model predictive controller (NMPC) in combination with a multi-start strategy is formulated. In addition, an extrapolation algorithm is developed to determine an approximation of the future trajectory of the structure's induced excitation load. The excitation trajectory is then incorporated in the NMPC framework. For validation, a frequency response analysis and a case study are conducted on a 20-storey benchmark structure, which is equipped with a semi-active TLCD. The study is carried out in simulation, and the results are compared with passive vibration control. With the proposed hierarchical control, a significant improvement is shown in the reduction of structural vibrations over the relevant spectrum of excitation frequencies up to a mean of 50%.

An experimental study of tuned liquid column damper controlled multi-degree of freedom structure subject to harmonic and seismic excitations.

A tuned liquid column damper (TLCD) is a passive vibration control device that not only mitigates unwanted structural vibrations but also acts as a water storage facility in a building. These aspects of TLCD make its application specifically suited for building structures. Previously, many experimental works on TLCDs have been conducted considering a single degree of freedom (SDOF) structure. However, the performance of TLCDs to control the response of multi-degree of freedom (MDOF) structure has rarely been studied experimentally. Therefore, this study has investigated the performance of a tuned liquid column damper (TLCD) on a multi-degree of freedom (MDOF) structure using shake table testing. A four-storey steel frame structure equipped with TLCD at the top of the fourth storey has been studied. Experimental normalized frequency response curves for MDOF structure equipped with TLCD have been determined. For this purpose, a series of harmonic loadings including frequencies 0.65 Hz, 1.17 Hz, 1.30 Hz, 1.43 Hz and 1.95 Hz have been applied in addition to historic earthquake loading. Peak and root-mean-square (RMS) accelerations have been discussed in detail for all the applied loadings at each storey level of the structure. For comparison purposes, the percentage reductions in peak and RMS accelerations have been calculated and compared. Also, RMS displacements and inter-storey drifts have been presented for resonant and seismic excitations. Both in time and frequency domains, responses of controlled MDOF structure have been analyzed and compared with uncontrolled structure. Results confirmed that TLCD has improved the MDOF structure responses at harmonic loadings frequencies near resonance and historic earthquake excitations. Furthermore, the improvement in the responses of MDOF structure with TLCD is more prominent at harmonic loadings compared to historic earthquake loading.

Development of new passive vibration control system in coupled structures with block and tackle

An innovative passive vibration control system employed pulley tackle mechanism (Movable Pulley Damper System: MPDS) in coupled structures is proposed in this paper. A cable can be continuously stretched several times to connect the two buildings through the pulley blocks to amplify the relative displacement and provide the high energy absorption efficiency to the damper linked at the middle of the wire. The principle and the theoretical formulation of the system are initially discussed. Also, the effectiveness of the MPDS is examined through the shaking table tests using a scaled-down building model. The experiments demonstrate the ability of the MPDS to mitigate the building response during earthquake excitations as well as the successful amplification of the damping effect. The validity of the mathematical formulation and the equivalent modeling of the MPDS using the truss elements are confirmed by comparing the analytical and the experimental results.

Enhanced vibration absorption of plates with circular metasurface composed of lossy acoustic black hole subunits

Metasurfaces and acoustic black holes (ABHs), as two kinds of emerging structures exhibiting extraordinary performances in steering and trapping waves, respectively, both have attracted extensive attention of researchers due to their potential applications in vibration control. However, studies combining the merits of them are rarely reported. In this paper, we propose a lossy circular ABH metasurface (LCAM) composed of gradient ABH subunits pasted with damping layers to realize the enhanced omnidirectional vibration absorption of plates in broadband, which is attributed to the introduced multiple reflection effect in the lossy ABH subunits. The phase shifts of the lossy ABH subunits are derived by using the transfer matrix method and integral method, and the effective loss factors are obtained through the effective medium theory. Based on the theoretical analyses, the LCAM is designed, and the results of simulations and experiments show that the designed LCAM realizes enhanced omnidirectional vibration absorption of the plate. The LCAM is applied to plates with different dimensions and boundary conditions to show its strong adaptability. Our design improves the ABH effect by taking advantages of the multiple reflection effect in metasurfaces, which provides an effective method for passive structural vibration control.

Exploiting internal resonances in nonlinear structures with cyclic symmetry as a mean of passive vibration control

The purpose of this paper is to study how internal resonances can be used to mitigate the vibration of cyclically symmetric systems exhibiting geometrical nonlinear effects. The method of multiple scales is employed to derive specific conditions that allow such energy transfers. This novelty is confirmed through numerical investigations, and an application to decrease the vibration of the system is proposed. A simplified yet realistic blade model with geometrical nonlinearities is considered. It includes pre-twist, pre-bending and warping, and is duplicated to create a full bladed rotor with cyclically symmetric properties. As the model of the whole structure may become enlarged, it is further reduced via the normal form approach. The harmonic balance method is then employed to obtain periodic solutions, localize bifurcation points and then follow bifurcated branches. These numerical solutions are used in complement with the aforementioned theoretical conditions to investigate the energy transfer properties of the mechanical system. Through these simulations, an effective range of amplitude excitation is defined to obtain internal resonances leading to an overall vibration mitigation of the system.

Unified description of passive vibration control for buildings based on pole allocation applied to three‐degree‐of‐freedom model

Unified description of passive vibration control for buildings based on pole allocation applied to three‐degree‐of‐freedom model

Passive flow control of vortex-induced vibrations of a low mass ratio circular cylinder oscillating in two degrees-of-freedom

Offshore wind turbine towers are often placed vertically before installation at ports. At certain wind speeds, these towers are subject to vortex-induced vibrations and can lose up to a third of their fatigue live within a few days. So far, helical strakes have primarily been used in the upper part of the towers. These have so far proven to be not effective enough to suppress vortex-induced vibrations. The aim of this study was to develop a passive flow control method for offshore wind turbine towers and to experimentally investigate its efficiency.Experiments were performed in a circulating water tank to investigate using fin plates to suppress vortex-induced vibration of fully submerged flexible cylinders in flows at Reynolds numbers, referred to the cylinder diameter, between 1.4 × 104 and 8.0 × 104. The corresponding non-dimensional reduced velocities (normalized via the free stream velocity, the excitation frequency, and the diameter of the cylinder) were between 1.1 and 6.1. The cylinders’ of aspect ratio 18.8 had a mass ratio of 0.535. This mass ratio, referred to the mass of an oscillating cylinder normalized by the mass of displaced fluid, was below the critical mass ratio of 0.545. Each cylinder consisted of a polyvinyl chloride pipe mounted as a cantilever beam on a six degrees-of-freedom piezoelectric transducer. The top end of the cylinders was free to oscillate in the streamwise and lateral directions. An accelerometer was placed near their tops to measure accelerations and, via twofold integration, to retrieve top-end cylinder motions. A Laser Doppler Velocimetry system was employed to measure free stream velocities at the inlet of the water channel and wake velocities behind the cylinder. The wake velocities were used to calculate shedding vortex frequencies. Dynamic forces and displacements were also measured. Results demonstrated that fin plates attached to the cylinders mitigated their vibrations considerably. Optimized fin plate arrangements reduced amplitudes of streamwise and lateral vibration by 81 and 75%, respectively, and amplitudes of lateral forces acting on the cylinders by between 40 and 75%. Low uncertainty estimates of measured values substantiated the reliability of the results.

Enhancing the seismic performance of building structures equipped with composite braces in mega bracing configuration

SummaryIn this research, a new passive vibration control system for building structures is presented. The proposed system improves the seismic performance of non‐moment steel structures using the ultra‐high‐performance concrete‐filled steel tube (UHPCFT) braces. In this system, pre‐tensioned tendons are considered to equalize the tensile and compressive capacity of the brace members which are installed as large scale concentrically braced frames (CBFs) (i.e., mega bracing frames [MBFs]) in order to minimize the induced forces in the other structural elements (i.e., beams, columns and slabs). To investigate the feasibility of the proposed system, three 8‐, 12‐, and 15‐story structures are considered. Also, buckling restrained braced frames (BRBFs) and normal concrete filled steel tube (NCFT) braces are considered for the comparison purposes. Furthermore, the effectiveness of the proposed technique is evaluated considering the performance point values and fragility assessment results calculated using a near‐field pulse‐like earthquake record set. Comparison of the simulation results demonstrates that, for all the considered earthquake records, the proposed system remarkably attenuates the structural demand value and collapse probability for all the considered structures. Also, it has demonstrated that type of the nonlinear analysis affects the damage mode.

Experimental and Numerical Study of Energy Dissipation Components of a New Metallic Damper Device

PurposeThe novel metallic damper device for passive vibration control of structures, which is designed primarily for seismic protection of buildings, is described in this paper. It consists of the base plate, fixed into foundation, with two concentric cycles of vertical components and a middle steel activating plate anchored to the isolated structure. During an earthquake, the middle steel activating plate moves together with main structure causing bending of vertical components. Seismic energy is absorbed due to plastic deformation of the vertical components of the damper. The performance of various vertical components, the key elements of the novel damper is studied in this paper. The advantages of this type of damper reflect in its ability to adapt its own features depending on the intensity of the earthquake and that it has equivalent characteristics in every horizontal direction due to rotational symmetry.MethodsSixteen experimental tests of the vertical components of the damper, were conducted to obtain their hysteretic behaviour. Numerical models using the finite element method and the Abaqus/Standard software were developed, validated and verified with experimentally obtained results.ResultsThe experimental results show significant energy absorption of the vertical components of the novel damper. Numerical models can be used in further research instead of expensive experimental tests.ConclusionsThe vertical components of the novel damper possess extraordinary hysteretic performance. If the components of the energy dissipation device are properly designed for maximum displacements, the device is not expected to suffer heavy damage or total failure during earthquakes.

Active Vibration Control Technology in China

In the field of engineering, vibration usually leads to structural wear, fatigue, loosening and fracture, which has always been a head-scratching problem to engineers. Researchers introduced a series of solutions to attenuate vibration, such as a physical isolator, damper, or absorber, which later has been named passive vibration control (PVC) technology. The basic idea of PVC is to transfer the vibration energy of the main structure to local/additional structures and finally convert it to heat dissipation. Actually, PVC technology has been widely applied in all fields of engineering. However, with the development of industrialization, the disadvantages of PVC, like poor flexibility, large mass and volume, and limited vibration reduction effect, restrict its application in extreme environments. Under such circumstances, an alternative technology called active vibration control (AVC) has gradually attracted extensive attention. AVC introduces the sensors, actuators and control theory into the vibration control system and reduces or eliminates the unwelcome vibration by adjusting the inherent parameters such as stiffness or damping of the structures dynamically, or directly adding secondary vibration sources to suppress the vibration by superposition principle. Compared with PVC, AVC has the advantages of high flexibility, strong environmental adaptability and good low-frequency control capacity. The prototype of AVC can be traced back to the patent for active noise elimination proposed by German physicist Lueg in the 1930s. In the 1950s, Chinese scientist Hsue-shen Tsien published Engineering Cybernetics [1], a monograph that extended the automatic control theory into practical engineering, which laid the theoretical foundation for AVC. Subsequently, various AVC technologies, e.g., active vibration isolation, active vibration damping, and active vibration absorption, have been widely investigated. Nowadays, AVC has been developed into a multi-disciplinary technology including dynamics, cybernetics, system theory, information theory, and other disciplines.

Vibration suppression using tuneable flexures acting as vibration absorbers

Vibration suppression is an area of engineering that is vital for the development of manufacturing of low stiffness structures. A diversity of passive, active and semi-active vibration control techniques exist in the literature, many of them focused on the tool or the workpiece, while little attention has been paid into the dissipation capabilities of the fixtures. In this paper, the vibration attenuation capabilities of tuneable flexures are presented, proving the ability of beam-shaped supports to mitigate the vibration induced by the manufacturing process (e.g. machining loads) to the workpiece. The proposed modelling approach puts a solid theoretical basis on how to construct flexures tuned in such a way to allow their natural frequency to match the frequency of excitation, thus absorbing the energy from the workpiece and keeping it at low vibration levels. By means of a multiple-degree-of-freedom (MDOF) model and considering the system as three different bodies with springs and dampers, the dynamic behaviour of the system is examined theoretically starting from the geometry and material of the flexures on which the fixturing system is based. This is further validated with finite element analysis (FEA) as well as experimental results showing a low discrepancy between the models on the prediction of the resonant frequencies of up to a 0.6%. The importance of understanding the critical clamping load for the locking of the contact surfaces is also presented, as it is indispensable for the proper functioning of the flexures-based fixturing system. Finally, the vibration suppression capability of the flexures at the targeted frequency is experimentally validated and proved to substantially reduce (ca. 90%) the vibration response of the workpiece when compared with the non-suppressed frequencies. The proposed model represents an avenue to address the inverse problem for the design of a fixture with vibration absorption capabilities, depending on the manufacturing process parameters, the workpiece and the chatter that needs to be suppressed.

Development of Vibration Control Structure on Suspended Ceiling Using Pulley Mechanism

A suspended ceiling system (SCS) is one of the most fragile and non-structural elements during earthquakes. However, effective seismic protection technologies for enhancing the suspended ceiling system have not been developed other than the steel bracing system. An innovative passive vibration control system is proposed in this paper, which equipped a damper-employed pulley amplification mechanism into the indirect suspended ceiling system, named the pulley–damper ceiling system (PDCS). Theoretical formulation and the detailed information on the system were presented first. In addition, a new rotational damper composition consisting of a non-linear viscous damper was developed to follow the large wire-cable stroke. Six types of the full-scale ceiling specimens of a 15.6-square meter area with different configurations were constructed for the preliminary experiments to evaluate the seismic performance and feasibility of PDCS under simulated earthquake motions. The comparative results of the shake table test demonstrated that the application of PDCS is capable of controlling both displacement and acceleration of the ceiling panels. This study also presents the nonlinear time history analyses by modeling a wire-cable as an equivalent truss element to transmit the relative displacement of the ceiling system to the damper. The analytical model accurately simulated the dynamic behavior of PDCS.

Improvement and Field Testing of Tuned Mass Piezo-Damper with Electricity-Generating Capacity

Converting the mechanical energy of road infrastructures into electricity by the piezoelectric effect is a challenge for which numerous researchers dedicated huge efforts. Most of the studies attempted to excite the piezoelectric using the vibration of the structure itself but faced the problem caused by the difference in the natural frequencies of the piezoelectric and of the structure. Focusing on bridge structures, our research team conceived a system using the vibration of a bridge device intended to vibrate, namely the Tuned Mass Damper (TMD), rather than relying on the vibration of the whole structure. The combination of the TMD with the piezoelectric technology creates an ideal machine which, in addition to its role as passive vibration control device, can produce free and effective electrical energy. This paper presents the improvement as well as laboratory and field tests of the so-called Tuned Mass Piezo-Damper (TMPD) with the different configurations devised throughout its development. The test results show that the final configuration of the TMPD can produce meso-scale energy.

Improvement on the passive method based on dampers for the vibration control of spacecraft solar panels

In this study, a passive vibration control method termed as translational root mounting method is proposed and investigated, for suppressing the low frequency vibrations of spacecraft solar panels. The translational root mounting method employs dampers installed at the roots of solar panels to dissipate the dynamic energy. The key of translational root mounting method is that translational root mounting method modifies the fundamental mode shape of the solar panel, by releasing the translation freedoms at its root. The root of the solar panel then has translational freedom instead of rotational freedom. As a result of mode shape modification, the translational root mounting method enables the root dampers to have sufficient working stroke, however without obviously reducing the solar panel’s fundamental frequency. Finite element model of a satellite solar panel with the length of 7 [Formula: see text] is established. Applying the finite element model, the limitation of a conventional passive vibration control method based on rotational root mounting is illustrated. To verify and illustrate the principle of translational root mounting method, the free vibration of the 7 [Formula: see text]-length satellite solar panel controlled by translational root mounting method is analyzed by finite element method. Finite element analysis (FEA) results indicate that the effect of a conventional passive control method is not obvious unless dampers with quite large damping coefficients are employed. In contrast, applying dampers with much smaller damping coefficients, the effect of translational root mounting method is fantastic comparing with the conventional passive method. To optimize the translational root mounting method and theoretically compare it to the conventional passive vibration control method, the solar panel is simplified into a non-linear one-degree of freedom system, and the analytical solution of its low frequency vibration is derived. Applying the analytical solution, it is found that damping ratio of the whole solar panel system does not increase with the damper’s damping coefficient, instead there are optimum values of damping coefficient. Applying the translational root mounting method, for the discussed 7 [Formula: see text]-length satellite solar panel, the damping ratio of which can be elevated from 0.0027 to 0.326.