Vibration Suppression Capability Research Articles

Application of non-smooth NES in vibration suppression of rotor-blade systems

The non-smooth nonlinear energy sink (NSNES) is used to suppress the vibration of the rotor-blade system. Firstly, the structure and working principle of the NSNES for rotor-blade system are introduced. Then, the dynamics model of the rotor-blade-NSNES system is established by Lagrangian method. And then, numerical simulations are applied to evaluate the vibration suppression ability of the NSNES on rotor and blade. The results show that the suppression rates of NSNES on the rotor and the blade can reach 81% and 74% in steady state resonance under given parameters, respectively; and for transient vibration of blade, a 1.85 times dissipating speed is obtained in rotor-blade system with NSNES than that without NSNES. In particular, NSNES has better vibration suppression capability than linear dynamic vibration absorber (LDVA) when both have the same vibration absorption mass.

Minimum-time S-curve commands for vibration-free transportation of an overhead crane with actuator limits

S-curve commands are ubiquitous in servo drives owing to their simplicity and smoothness. Nevertheless, they need to be adapted for use in flexible systems, where the problem of residual vibration must be addressed. This paper proposes a simple motion planning method for the vibration-free transfer process of an overhead crane using S-curve commands. Based on a position baseline S-curve, which is generated from a bang-off-bang acceleration profile, two approaches are proposed to build the vibration suppression capability. One is an embedding method that injects the essential terminal conditions for vibration-free transportation into the baseline S-curve command without altering its original form. The other is a shaping method inspired from the input shaping technique. In both schemes, the baseline S-curve is parameterized to establish minimum-time optimization problems, in which maximum velocity and maximum acceleration of the actuator are explicitly taken into consideration. The minimum-time solutions are successfully obtained by solving constrained (discrete) nonlinear programs. An online trajectory generation can be realized using the proposed approach. Both simulation and experimental results are given to verify the effectiveness of the proposed method.

Design optimization of a giant magnetostrictive driving system for large stroke application considering vibration suppression in working process

Light weight and low energy consumption of giant magnetostrictive driving system (GMDS) signify two main challenges facing in aerospace engineering, which conflict with the capability of the GMDS to some extent. For aim of addressing this dilemma, meanwhile realizing a large stroke and passive vibration suppression in space environment, this article proposes a GMDS scheme consisted of giant magnetostrictive actuator and compliant amplification mechanism, and moreover introduces a new design optimization strategy. First, a novel GMDS is proposed for realizing those functions. Then, three sectors, namely the electromagnetic conversion sector, the magnetic energy transfer sector and the magneto-mechanical conversion sector, are divided according to energy flow structure theory, to accurately evaluate the energy consumption. Therefore, the key energy consumption model of each sector could be formulated clearly by the aid of equivalent circuit diagram, equivalent magnetic circuit diagram and work-energy theory. Afterward, the equivalent vibration suppression natural frequency model of the compliant amplification mechanism is formulated through pseudo-rigid-body model method (PRBM), for evaluating the vibration suppression capability. Next, the equivalent mass of the whole system could be constructed on basis of the key components parameters. Finally, the design optimization strategy is proposed and implemented to capture the global optimal solution. Additionally, the performance of the optimized GMDS is validated by finite element analysis and experimental tests.

Adaptive Sliding-Mode Control of an Offshore Container Crane With Unknown Disturbances

In this paper, an adaptive sliding-mode control (ASMC) for offshore container cranes that load/unload containers from a mega container ship to a smaller vessel is investigated. To withstand the harsh working conditions in the open sea, such as ship motions and winds, a 4-degrees-of-freedom control model consisting of plant uncertainties and known/unknown disturbances is newly developed. After decoupling the actuated (i.e., trolley displacements) and unactuated (i.e., swing angles) joint variables, a sliding surface that incorporates the decoupled dynamics is designed. Then, a new sliding-mode control (SMC) algorithm with two adaptation laws for switching- and equivalent-control inputs is developed. The asymptotic stability to the “real” sliding surface introduced in the decoupled (actuated, unactuated) state space is proven without a priori knowledge on the bounds of unknown disturbances. For the experiment, a three-dimensional crane mounted on a Steward platform to generate the ship motions is utilized. To verify the effectiveness of the proposed ASMC method, experimental results of the proposed method are compared with two representative works: the SMC presented by Ngo and Hong and the ASMC presented by Zhu and Khayati. The vibration suppression capability of the proposed method in the presence of ship motions, large initial swings, parameter uncertainties, and sudden disturbances is superior to the two compared methods. The developed algorithm can be used for a mobile harbor system as a new tool in the modern maritime industry.

Controlling the vibration and noise of a ballasted track using a dynamic vibration absorber with negative stiffness

In this study, a rail dynamic vibration absorber with negative stiffness is developed to reduce the vibration transmission and radiated noise from the rail components of a ballasted track. The compound models of the ballasted track system with and without the proposed dynamic vibration absorber and a traditional dynamic vibration absorber are constructed. A parametric study is performed to evaluate the effects of the design parameters of the proposed dynamic vibration absorber on the vibration and noise reduction of the track system in terms of the point receptance, the decay rate of rail vibration along the track, and the vibration energy level of the rail. Compared with the traditional dynamic vibration absorber, the proposed counterpart can work effectively over a broad frequency range around resonance. The efficiency of the dynamic vibration absorber can be improved by adjusting the design values of the active mass and damping coefficient. A comparison with the traditional dynamic vibration absorber shows that the vibration and noise suppression capability of the proposed one can be enhanced by increasing the value of the stiffness ratio. However, different from the traditional dynamic vibration absorber, the design parameters of the proposed one can also affect the decay rate and vibration energy at low-frequency regions. A discrete track with the proposed dynamic vibration absorber, which is arranged in continuous or discrete distribution along the rail, is illustrated to study the influences of the rail components on the decay rate and vibration energy level of rails. These calculated results could provide a theoretical basis for the design of the proposed dynamic vibration absorber in controlling the vibration and radiated noise from rails.

Structural control of a fixed offshore structure using a new developed tuned liquid column ball gas damper (TLCBGD)

Structural control of a system can be achieved by employing different control methods. The effectiveness of a control technique straightly depends on the performance of the control device. Among control devices, the tuned liquid column gas damper (TLCGD) has shown high vibration control capabilities. In this study, a newly developed damping system as a tuned liquid column ball gas damper (TLCBGD) system is introduced. The developed system is a combined version of a tuned liquid column ball damper (TLCBD) and a TLCGD system. The new damper is utilized on an offshore jacket platform and its qualification is studied under both regular and irregular wave incidences. The efficiency of the TLCBGD system is investigated numerically by implementing ball-tube ratio and gas pressure parameters. The effects of the ball-tube ratios and the gas pressure values on the vibration suppression capacity of the system are assessed through a parametric study. In comparison to a passive TLCGD system, the results revealed that the utilizing a TLCBGD system in the jacket platform improves the structural vibration suppression capability.

Experimental characterization and performance improvement evaluation of an electromagnetic transducer utilizing a tuned inerter

This research reports on the experimental verification of an enhanced energy conversion device utilizing a tuned inerter called a tuned inertial mass electromagnetic transducer (TIMET). The TIMET consists of a motor, a rotational mass, and a tuning spring. The motor and the rotational mass are connected to a ball screw and the tuning spring interfaced to the ball screw is connected to the vibrating structure. Thus, vibration energy of the structure is absorbed as electrical energy by the motor. Moreover, the amplified inertial mass can be realized by rotating relatively small physical masses. Therefore, by designing the tuning spring stiffness and the inertial mass appropriately, the motor can rotate more effectively due to the resonance effect, leading to more effective energy generation. The authors designed a prototype of the TIMET and conducted tests to validate the effectiveness of the tuned inerter for electromagnetic transducers. Through excitation tests, the property of the hysteresis loops produced by the TIMET is investigated. Then a reliable analytical model is developed employing a curve fitting technique to simulate the behavior of the TIMET and to assess the power generation accurately. In addition, numerical simulation studies on a structure subjected to a seismic loading employing the developed model are conducted to show the advantages of the TIMET over a traditional electromagnetic transducer in both vibration suppression capability and energy harvesting efficiency.

Identification of beneficial mass-included inerter-based vibration suppression configurations

Vibration suppression capabilities of linear passive vibration absorbers, such as traditional tuned mass damper (TMD), and recently proposed inerter-based vibration absorbers, have been studied for multiple mechanical systems. In particular, significant performance advantages have been obtained with a specific device making use of both inerter and mass elements, namely the tuned mass damper inerter (TMDI). However, there are still countless mass-included inerter-based configurations that have not been studied, which can potentially provide more preferred dynamic properties. In this paper, an immittance-function-layout (IFL) is introduced, which can cover a large range of topological connection possibilities with both mass and inerter elements. With the recently proposed structural immittance format, a systematic approach is established to identify the most beneficial IFL type mass-included inerter-based configurations with pre-determined number of each element type. Vibration suppression performance with single-IFL type device and two parallel-connected IFLs (i.e. dual-IFL) type devices are investigated in this paper. Three optimal configurations are identified for mitigating the maximum inter-storey drift of an example 3-storey building model subjected to base excitation. With this 3-storey building model, results show that, for the optimum single-IFL configuration, the performance improvement is 7.3% compared with the optimum TMDI, and with identified beneficial dual-IFL configurations, up to 34.9% performance advantages are obtained. Furthermore, consistent performance gains are shown under real-life earthquake inputs and with a 10-storey building model using identified absorber configurations.

Using grounded nonlinear energy sinks to suppress lateral vibration in rotor systems

Abstract Modern rotating machineries require vibration suppression devices with simple structure and wide band effective vibration suppression frequency range, so a grounded nonlinear energy sink (GNES) with piecewise linear stiffness is developed to satisfy the requirements. Firstly, the structure and working principles of the GNES is explained. Then, the piecewise linear stiffness characteristic of elastic rods is analyzed and the dynamic equations for the rotor-GNES system are established, in which the rotor system is assumed to be either isotropic or anisotropic; numerical simulations are then carried out to study the vibration suppression effect of the GNES, and the wide-band vibration suppression capability of the GNES is assessed; comparison is made between the vibration suppression effect of the GNES and that of the dynamic vibration absorbers. Finally, experiments are carried out on a rotor-GNES system test platform to verify the suppression effects. The results show that the GNES is effective at suppressing vibrations in terms of both transient and steady-state vibrations within a rotor system. In the numerical simulation an optimal vibration suppression rate of 78% is achieved and in the test a rate of 68% is achieved.

Anomalous vibration suppression in a weak-value-emulated heterodyne roll interferometer.

We experimentally validate the vibration suppression capabilities of a weak-value-like protocol. The phase-sensitive heterodyne technique exhibits advantageous characteristics of a weak measurement including anomalous amplification in sensitivity and technical noise suppression. It does not, however, leverage the entanglement between the system and meter to amplify the signal of interest, as is typical in a weak measurement. In this formalism, we demonstrate an amplification in sensitivity to the roll angle of over 700 times. High precision roll experiments anchor numerical simulations to show that the interferometer outperforms standard interferometry by a factor of 500 in terms of peak-to-peak noise amplitude. During the measurement of a rolling stage, technical noise - primarily in the form of vibrations - is substantially attenuated. This is the first demonstration of vibration suppression capabilities that are inherent to the light from a metrology instrument instead of achieved via mechanical damping. The emulation presented in this work also identifies an avenue to achieve anomalous amplification outside of the standard weak measurement protocol.

Dynamic Behavior of a Simple Rolling Seismic Isolator with a Position Restoring Device

Herein, the behavior of a rolling type seismic isolation system with a position restoring device (PRD) is investigated, for alleviating problems such as rapid convergence and position restoration. The equation of motion is derived by modeling the behavior of the seismic isolation system, and the seismic characteristics according to the design variables of the PRD are investigated through numerical analysis. The vibration characteristics of the equation of motion show nonlinearity and depend on different variables. Numerical analysis was performed by using the fourth and fifth order Runge–Kutta method, and the vibration characteristics were analyzed with respect to the design parameters in the rolling type seismic isolation system with PRD, and compared to a model without PRD. In the model with PRD, numerical results show that the vibration suppression capability of the earthquake and the position restoration after disturbance are improved compared to those of the model without PRD. In addition, the rolling type seismic isolation system had nonlinear characteristics at specific frequencies, where the response increases suddenly and harmonics occur. This phenomenon can be controlled by the ratio of mass to stiffness and the damping coefficient, showing that the mount system can be designed to avoid resonance through optimal design.

Adaptive positive position feedback control with a feedforward compensator of a magnetostrictive beam for vibration suppression

In this paper, a Fe–Ga alloy magnetostrictive beam is designed as an actuator to restrain the vibration of a supported mass. Dynamic modeling of the system based on the transfer matrix method of multibody system is first shown, and then a hybrid controller is developed to achieve vibration control. The proposed vibration controller combines a multi-mode adaptive positive position feedback (APPF) with a feedforward compensator. In the APPF control, an adaptive natural frequency estimator based on the recursive least-square method is developed to be used. In the feedforward compensator, the hysteresis of the magnetostrictive beam is linearized based on a Bouc–Wen model. The further remarkable vibration suppression capability of the proposed hybrid controller is demonstrated experimentally and compared with the positive position feedback controller. Experiment results show that the proposed controller is applicable to the magnetostrictive beam for improving vibration control effectiveness.

Optimal design of a beam-based dynamic vibration absorber using fixed-points theory

The addition of a dynamic vibration absorber (DVA) to a vibrating structure could provide an economic solution for vibration suppressions if the absorber is properly designed and located onto the structure. A common design of the DVA is a sprung mass because of its simple structure and low cost. However, the vibration suppression performance of this kind of DVA is limited by the ratio between the absorber mass and the mass of the primary structure. In this paper, a beam-based DVA (beam DVA) is proposed and optimized for minimizing the resonant vibration of a general structure. The vibration suppression performance of the proposed beam DVA depends on the mass ratio, the flexural rigidity and length of the beam. In comparison with the traditional sprung mass DVA, the proposed beam DVA shows more flexibility in vibration control design because it has more design parameters. With proper design, the beam DVA's vibration suppression capability can outperform that of the traditional DVA under the same mass constraint. The general approach is illustrated using a benchmark cantilever beam as an example. The receptance theory is introduced to model the compound system consisting of the host beam and the attached beam-based DVA. The model is validated through comparisons with the results from Abaqus as well as the Transfer Matrix method (TMM) method. Fixed-points theory is then employed to derive the analytical expressions for the optimum tuning ratio and damping ratio of the proposed beam absorber. A design guideline is then presented to choose the parameters of the beam absorber. Comparisons are finally presented between the beam absorber and the traditional DVA in terms of the vibration suppression effect. It is shown that the proposed beam absorber can outperform the traditional DVA by following this proposed guideline.

Influence of contact condition between flexible plate and passive pivot support on machining vibration

A passive support with a pivot mechanism was previously designed for increasing damping of the vibration modes of a flexible structure. Here, to investigate the influence of the contact conditions between the pivot support and a flexible plate, the contact area is discretised into line contacts using metal rollers. The effect of contact stiffness is also investigated using additional plastic rings. Impact hammering tests are conducted and measured dynamic compliances are compared. Machining tests are subsequently performed to confirm vibration suppression. The line contacts are found to exhibit good vibration suppression capability in both the vibration and machining tests.

Characteristic analysis of vibration isolation system based on high-static-low-dynamic stiffness

The purpose of this study is to investigate the characteristics of vibration isolation system with a single degree-of-freedom (SDOF) and a two-degree-of-freedom (2DOF) respectively based on the high-static-low-dynamic-stiffness (HSLDS). This model consists of a simple configuration connecting a vertical spring and a pair of oblique springs. The restoring force of the isolation system is approximated to linear and cubic stiffness by applying the Maclaurin series expansion. The dynamic equations of the SDOF and 2DOF are established for the harmonic force excitation. The frequency-amplitude response equation of the SDOF is obtained by employing the harmonic balance method (HBM) and is demonstrated in the classical Runge-Kutta method. The solution stability is ensured by applying the Floquet theory. Effects on the frequency response curves (FRCs) for the damping ratio and excitation amplitude are explored and discussed. The force transmissibility (FT) is defined to evaluate the vibration suppression capability. Effects on the FT of the SDOF and 2DOF for the excitation amplitude, mass ratio, and damping ratio are investigated. An experimental investigation of the SDOF is carried out to evaluate the actual attenuation performance in comparison with the equivalent linear system (ELS). The simulation and experimental results show that the HSLDS system with harmonic force excitation demonstrates hardening stiffness with multi-valued solutions. The occurrence of jump phenomenon is observed and explained by the stiffness variation. The system response and resonance frequency are affected by the excitation amplitude and damping ratio. The HSLDS system outperforms the ELS in a low frequency range if an appropriate mass is mounted. It is excited by a proper force and owns a suitable damper, which offers a theoretical guidance for the design and application of a novel HSLDS isolator.

Multidimensional Trajectories Generation with Vibration Suppression Capabilities: the Role of Exponential B-splines

In this paper, exponential B-spline trajectories are presented and discussed. They are generated by means of a chain of filters characterized by a truncated exponential impulse response. If properly tuned, the filters applied to a vibrating plant are able to cancel the oscillations and in this sense the resulting splines are optimized with respect to the problem of vibrations suppression. Different types of exponential B-spline are illustrated, with one or more exponential filters in the chain, and the procedure for the interpolation of a given set of desired via-points, with a proper choice of the control points, is shown. As a matter of fact, exponential B-splines, generated by means of dynamic filters, combine the vibration suppression capability of input shapers and smoothing filters with the possibility of exactly interpolating some via-points. The advantages of these curves are experimental proved by considering the motion of a spherical pendulum connected to the flange of an industrial robot.

Dynamic properties of an axially moving sandwich beam with magnetorheological fluid core

Dynamic properties and vibration suppression capabilities of an axially moving sandwich beam with a magnetorheological fluid core were investigated in this study. The stress–strain relationship for the magnetorheological fluid was described by a complex shear modulus using linear viscoelasticity theory. First, the dynamic model of an axially moving magnetorheological fluid beam was derived based on Hamilton’s principle. Then, the natural frequency of the sandwich beam for the first mode was determined. Later, the effects of the speed of the axial movement, axial force, applied magnetic field, skin–core thickness ratio, and their combination on the dynamic properties of the sandwich beam with a magnetorheological fluid core were investigated. It was found that these parameters have significant effects on the dynamic properties of the sandwich beam. Moreover, the results indicate that the active control ability of magnetic field has been influenced by the axial force, moving speed, and increasing skin–core thickness ratio.

Stochastic vibration suppression analysis of an optimal bounded controlled sandwich beam with MR visco-elastomer core

To control the stochastic vibration of a vibration-sensitive instrument supported on a beam, the beam is designed as a sandwich structure with magneto-rheological visco-elastomer (MRVE) core. The MRVE has dynamic properties such as stiffness and damping adjustable by applied magnetic fields. To achieve better vibration control effectiveness, the optimal bounded parametric control for the MRVE sandwich beam with supported mass under stochastic and deterministic support motion excitations is proposed, and the stochastic and shock vibration suppression capability of the optimally controlled beam with multi-mode coupling is studied. The dynamic behavior of MRVE core is described by the visco-elastic Kelvin-Voigt model with a controllable parameter dependent on applied magnetic fields, and the parameter is considered as an active bounded control. The partial differential equations for horizontal and vertical coupling motions of the sandwich beam are obtained and converted into the multi-mode coupling vibration equations with the bounded nonlinear parametric control according to the Galerkin method. The vibration equations and corresponding performance index construct the optimal bounded parametric control problem. Then the dynamical programming equation for the control problem is derived based on the dynamical programming principle. The optimal bounded parametric control law is obtained by solving the programming equation with the bounded control constraint. The controlled vibration responses of the MRVE sandwich beam under stochastic and shock excitations are obtained by substituting the optimal bounded control into the vibration equations and solving them. The further remarkable vibration suppression capability of the optimal bounded control compared with the passive control and the influence of the control parameters on the stochastic vibration suppression effectiveness are illustrated with numerical results. The proposed optimal bounded parametric control strategy is applicable to smart visco-elastic composite structures under deterministic and stochastic excitations for improving vibration control effectiveness.

A General Framework for Designing SISO-Based Motion Controller With Multiple Sensor Feedback

This paper proposes N-degree-of-freedom (N-DoF) control for single-input and single-output based systems. This method relaxes the water-bed effect, which limits the capacity to suppress disturbances and noise using multiple sensors. The system's design procedure for the control system and nominal stability conditions are introduced. N-DoF control is then compared with classical two-DoF control and with Kalman filter using simulations and experiments of motor systems with an encoder and an accelerometer. The results indicate that N-DoF control achieves an enhanced disturbance and an oscillation suppressing performance simultaneously. Moreover, N-DoF control is applied to two-mass systems and verified by using numerical simulation. The characteristics are introduced and compared with several conventional approaches. The results suggest that N-DoF control incorporates all the characteristics of the other methods, and its disturbance and vibration suppression capability is demonstrated.

On Vibration Suppression and Energy Dissipation Using Tuned Mass Particle Damper

Particle damping has the promising potential for attenuating unwanted vibrations in harsh environments especially under high temperatures where conventional damping materials would not be functional. Nevertheless, a limitation of simple particle damper (PD) configuration is that the damping effect is insignificant if the local displacement/acceleration is low. In this research, we investigate the performance of a tuned mass particle damper (TMPD) in which the particle damping mechanism is integrated into a tuned mass damper (TMD) configuration. The essential idea is to combine the respective advantages of these two damping concepts and in particular to utilize the tuned mass damper configuration as a motion magnifier to amplify the energy dissipation capability of particle damper when the local displacement/acceleration of the host structure is low. We formulate a first-principle-based dynamic model of the integrated system and analyze the particle motion by using the discrete element method (DEM). We perform systematic parametric studies to elucidate the damping effect and energy dissipation mechanism of a TMPD. We demonstrate that a TMPD can provide significant vibration suppression capability, essentially outperforming conventional particle damper.