Vibration Control Applications Research Articles

Bending-bending-torsion coupled wave propagation in thin-walled asymmetric metabeam: An analytical and experimental analysis

The primary focus of this paper is to analyze the impact of the periodic resonators on the wave dispersion phenomenon of a thin-walled asymmetric beam. An analytical framework has been developed to study the triply coupled flexural and torsional wave propagation in an asymmetric metabeam. The resonators are modeled as a beam with a lumped mass at the center and placed eccentrically from the shear center. Their periodicity allows them to generate a subwavelength attenuation band in the beam. The governing equations for the coupled bending-bending-torsion vibration of a metabeam having an asymmetric cross-section are considered for generating the dispersion phenomenon, including the warping effect. Applying the Bloch-Floquet principle, the dispersive characteristics of the asymmetric metabeam are obtained by using the transfer matrix method. The modal characteristics of an asymmetric beam without a resonator are computed using the spectral element method and are validated with previously published results. Subsequently, the attenuation band is investigated due to the presence of a resonator and followed by the transmittance spectrum to verify the suppression of the elastic waves in the attenuation band. The experimental analysis is carried out to validate the analytical framework by obtaining the modal frequencies from the frequency response function. The detailed parametric investigation reveals that the resonator’s position and characteristics significantly impact the occurrence of the band gap. A substantially wide attenuation band gap is attained by considering a continuous beam-mass resonator instead of a discrete spring-mass type resonator. This type of novel structure has the potential for the application of vibration control and acoustics.

Review on shear thickening fluid and its applications in vibration reduction

Abstract Shear thickening fluid (STF) is a nano-smart material that exhibits an instantaneous increase in viscosity when subjected to specific external loads. Notably, its viscosity response does not necessitate external energy input, making it widely applicable in vibration control, energy absorption, and vibration reduction. This paper first presents an introduction and analogy to the evolution of the thickening mechanism of STF. It then discusses factors that influence the rheological properties of STF, including the dispersed phase, dispersion medium, additives, and external environment. Furthermore, it explores various calculation models of STF in engineering applications, considering their advantages, disadvantages, and applicability. The paper later reviews the progress of STF utilization in vibration reduction and energy consumption, specifically focusing on improving mechanical properties in STF sandwich panels. Finally, it delves into the feasibility of STF application in vibration control by detailing the dynamic mechanical properties and applicability of vibration reduction equipment and calculation models based on STF.

Comparison of single and multi-coil self-powered MR damper subjected to cyclic and earthquake loading for structural vibration control

A promising solution for semi-active vibration control of different dynamic systems is to use magnetorheological (MR) dampers. In the present study, the investigation focuses on developing a novel single and multi-coil self-powered magnetorheological (MR) damper system using electromagnetic induction (EMI) for seismic mitigation. The conventional MR dampers, which rely on external power sources, can be unreliable and impractical in earthquake-prone locations. Thus, the EMI device connected to the MR damper can be used as an effective and alternative power source for the MR damper, results in a self-powered system. The proposed energy-harvesting system is an MR damper placed above the top of the piston. The coil is wound around the piston, and the outer casing with a ferrite magnet is fixed. As the mechanical energy of the piston is converted into electrical energy, its self-tuning capacity is a perfect fit for structural vibration control applications. The MR damper is subjected to cyclic and time-history loading. At a maximum amplitude of 15 mm, the damper generated 1767.8 N for cyclic loading and -1780 N for earthquake loading, the El Centro earthquake 1940 is considered for the study. By placing EMI, the mechanical energy is converted into electrical energy and powers the damper to avoid external power. The experimental results showcase enhanced damping forces and adaptability, thereby establishing it as an innovative and effective it can be alternative to conventional MR dampers for vibration control in future

Semi-active control for the seat car suspension system using MR elastomer isolator

The suspension system for the car seat is an important part of the vehicle that helps to increase comfort and reduce fatigue. The study of suspension systems using magnetorheological elastomer (MRE) has attracted researchers in recent years. MRE is an elastomer material such as rubber. The modulus of the material can change when a magnetic field is applied. In this study, an MRE-based isolator is first developed for a seat car suspension system. The characteristics of the isolator are investigated under the strength of the magnetic field. Based on Lyapunov theory and constraint force, the semi-active controller is then designed. Numerical simulations for the car seat dynamics system show that the developed isolator can reduce vibrations more when compared with the passive approach in the case of bump and random excitations. The results show significant potential for its application in vehicle seat vibration control.

Low frequency vibration reduction bandgap characteristics and engineering application of phononic-like crystal metaconcrete material

Metaconcrete, as a new type of composite material with vibration attenuation characteristics, is formed by replacing traditional coarse aggregates with a heavy metal core wrapped with an elastic soft coating and mixing with cement mortar. However, due to the high bandgap frequency and narrow bandgap width, it is greatly limited in the engineering application of low frequency vibration control. In order to broaden the range and number of elastic wave bandgap of metaconcrete materials and solve the problem of low frequency vibration, a novel three-component cement-based phononic-like crystal model is proposed based on local resonance theory, and phononic-like crystal metaconcrete vibration reduction material is developed accordingly. Secondly, the band structure, bandgap mechanism, and frequency response function of the phononic-like crystal metaconcrete are calculated and analyzed, and indoor tests of the phononic-like crystal metaconcrete are conducted. Finally, a phononic-like crystal metaconcrete subway track bed is prepared using the developed phononic-like crystal metaconcrete material, and applied to the practical subway engineerings to solve the low frequency vibration problem generated during subway operation. The results show that the phononic-like crystal metaconcrete opens 6 low frequency bandgaps in the frequency range of 200 Hz, and the attenuation values are mostly above 10 dB in the frequency range of the bandgap, and the attenuation effect is good. Meanwhile, the on-site monitoring results show that the phononic-like crystal metaconcrete subway track bed has good low frequency vibration reduction effect in the 200 Hz frequency range. The maximum value of the one-third octave insertion loss of the tunnel wall is 13.22 dB, the maximum vertical Z-vibration level difference of the tunnel wall is 5.052 dB, and the maximum vertical frequency division vibration level difference of the tunnel wall is 5.926 dB. The maximum value of the vertical frequency division vibration level difference in the frequency range of 4–200 Hz is 13.87 dB, and the average value is 5.74 dB. The relevant research results of this paper provide a new technical approach to solve the problem of low frequency vibration in subway engineering and other engineering construction, breaking through the traditional vibration reduction control technology of civil engineering structures, and providing new idea and method for long-term vibration reduction and application of engineering structures.

Natural logarithm sliding mode control for vibration control application

This paper presents the control synthesis of a nonlinear sliding mode control, known as the “natural logarithm sliding mode control” (lnSMC), for a general n-th order system. The lnSMC offers a simple and straightforward design approach because it only requires tuning two design parameters. The first parameter has a physical meaning corresponding to the bounds of the state variables, which can be easily determined without a trial-and-error process. The second parameter is related to the controller’s feedback gains, which ensure that the system dynamics converged to the sliding surface. Lyapunov stability theory is used to analyze the closed-loop system and finite-time convergence stability. As a case study, the natural logarithm sliding mode controller is designed to suppress the vibration in a simple spring-mass system and an active suspension system. The simulation study shows that the proposed controllers have significant vibration suppression performance. Furthermore, the simulation study indicates that the sliding mode controller designed by using the natural logarithm sliding manifold outperforms the standard linear sliding manifold counterpart. In addition, due to the nature of the nonlinear switching function that creates boundary states, lnSMC has a huge potential to be applied in a wider area of vibration control.

Mechatronic design of a composite vibration isolation system

Composite materials have attracted researchers in vibration and noise control applications due to their significant dynamic characteristics such as high strength and high damping level. In this paper, a Glass Fiber Reinforced Composite material (GFRC) is presented as a vibration isolation system to control vibration levels in industry. In addition, the impact of integration of a mechatronic control system to improve the machining process and increase the control of vibration nature. A prototype of an industrial cam–follower machine is motorized, and the Frequency Response Function (FRF) is recorded using a B&K data acquisition analyzer at five rotational speeds. The transmitted vibrations to the machine foundation are estimated without any isolation system. Then, two optimized GFRC plates of optimum stacking sequences are used as an isolation system to reduce the transmitted vibration. The displacement transmissibility is calculated theoretically and experimentally. The results show that the use of GFRC plates as an isolator reduces the vibration level of the system by 98.46% and 98.5% for [90/90/90/0/0]s and [90/ ± 45/ ± 35/90/ ± 35]s GFRC configurations respectively.

Wave propagation analysis for three typical box girders: Dominant wave modes and their applications

Because of the prevalent application of bridges in transportation, problems such as vibration and noise of bridges, especially in densely populated urban areas, are increasingly arousing concerns. The vibro-acoustic behaviors of bridges are important for vibration and noise control. Although these vibro-acoustic behaviors have been reported and discussed in several studies in terms of modal analysis, this study focuses on the probe into the vibration properties of three typical box girders (BGs) from the wave motion perspective: concrete, steel–concrete composite, and steel BGs. The dispersion characteristics and mode shapes of waves propagating in BGs are identified using the wave finite element method (WFEM). This calculation method combines the finite element method (FEM) with the Bloch–Floquet theorem, and it is validated by the existing literature and FEM. The wave propagation characteristics of the three typical BGs are then compared to analyze their similarities and differences in vibration. Furthermore, the contribution of each wave mode to the whole vibration and the local vibration of BGs is determined; consequently, the important vibration mechanism can be identified and ranked in different frequency bands. Lastly, some feasible application of vibration control for BGs is given in the light of the vibration mechanism. The study results provide theoretical and practicable foundation of vibration control for BG bridges in urban rail trafficsystems

An adaptive feedforward method in active vibration control for the propulsion shafting system

This paper proposes a new adaptive feedforward control method for the rejection of multiple periodic disturbances in the propulsion shafting system. The active vibration control scheme of the propulsion shafting system is established by employing the equivalent-input-disturbance principle which reduces the complexity of the control system in applications. The adaptive control algorithm is designed by taking the scale transformation procedure and the frequency-tracking technique into consideration. The scale transformation normalizes the iso-surface of the optimization function by the frequency response characteristics of the control channel, which immensely improves the convergence rate of the control algorithm for multi-harmonic disturbance. Moreover, the adaptive controller tracks the fluctuating frequencies in a direct method, enhancing the efficiency and robustness of the algorithm for eliminating time-varying disturbances. Finally, numerical simulation and experimental validation are carried out to show that the proposed method has good performance on the application of the active vibration control of the propulsion shafting system.

Vibration isolator using graded reinforced double-leaf acoustic black holes - theory and experiment

The acoustic black hole (ABH) has aroused great interest and shown high potential of application in broadband vibration control using a lightweight structure. Yet conventional ABHs still suffer from intrinsic weak structural stiffness and poor broadband low-frequency performance. Besides, there is a lack of effective computational methods for the design of complex or composite ABH structures with practically required properties. In this paper, the vibration isolation of a beam with embedded graded reinforced double-leaf ABH (GRD-ABH) structures is investigated, focusing on improving both broadband low-frequency vibration isolation performance and the structural stiffness. The multibody system transfer matrix method (MSTMM) is proposed to model and simulate the compound ABH beam, which is treated as a multibody system with complex topology. Both the free and forced vibration analysis of the GRD-ABH are conducted and the results are compared with the finite element method (FEM), thus validating the correctness and high computation efficiency of the MSTMM. The results show that the GRD-ABH beam can simultaneously enhance a broadband low-frequency vibration isolation effect and the structural stiffness compared with the conventional periodic reinforced double-leaf ABH beam. The experiment further verified the correctness of the MSTMM and the effectiveness of the vibration isolation effect of the proposed GRD-ABH beam. The proposed theoretical approach and the graded reinforced double-leaf design provide the basis for solving the vibration isolation problem of more complex ABH structures.

Piezoelectric Actuators Placement Using Genetic Algorithm and Active Vibration Control of Smart Plane Frame Structure

A Genetic Algorithm-based optimisation scheme is presented to find the optimum actuator elements infinite element analysis for active vibration control applications. The dynamic strain data is used to reduce the size of search domain for the actuators placement problem. A modal velocity, feedback control is employed to estimate the active damping of piezoelectric actuators. The structural damping index is taken as a fitness function; which directly reflects the status of active damping effect for a given piezoelectric actuator set. Modal preference is attempted by assigning a different weighting factor in the fitness function for desired modes to have better controllability. As an illustration, a 20-member smart plane frame is modeled with d3I based extension-bending piezoelectric actuators using 2-D piezoelectric Timoshenko beam element. It is shown that the vibration of first four elastic modes is actively controlled with optimally, selected four piezoelectric actuators.

IDENTIFICATION OF CHATTER VIBRATIONS AND ACTIVE VIBRATION CONTROL BY USING THE SLIDING MODE CONTROLLER ON DRY TURNING OF TITANIUM ALLOY (TI6AL4V)

In recent years, with the development of sensor technologies, communication platforms, cyber-physical systems, storage technologies, internet applications and controller infrastructures, the way has been opened to produce competitive products with high quality and low cost. In turning, which is one of the important processes of machining, chatter vibrations are among the biggest problems affecting product quality, productivity and cost. There are many techniques proposed to reduce chatter vibrations for which the exact cause cannot be determined. In this study, an active vibration control based on the Sliding Mode Control (SMC) has been implemented in order to reduce and eliminate chatter vibration, which is undesirable for the turning process. In this context, three-axis acceleration data were collected from the cutting tool during the turning of Ti6Al4V. Finite Impulse Response (FIR) filtering, Fast Fourier Transform (FFT) analysis and integral process were carried out in order to use the raw acceleration data collected over the system in control. The system is modeled mathematically and an active control block diagram is created. It is observed that chattering decreased significantly after the application of active vibration control. The surface quality formed by the amplitude of the graph obtained after active control has been compared and verified with the data obtained from the actual manufacturing result.

Mitigating jacket offshore platform vibration under wave loadings utilising nonlinear energy sinks

ABSTRACT The random vibrations of jacket offshore platforms caused by wave loadings can reduce the service life and fatigue failure of the offshore platforms. The nonlinear energy sink (NES) has great application potential because of its lightweight, high robustness and wide frequency band of vibration attenuation. The NES is introduced to mitigate the vibrations of the jacket offshore platform as a passive control device under wave loadings. The dynamic model of jacket platforms is developed with the NES system. The optimal parameters of the NES system are obtained by exhaustive search method. The results show that the NES system can effectively mitigate the responses of the deck level of jacket platforms under different wave states. The NES system could reduce the response under various deck's mass and stiffness of jacket platforms. The present study proves the feasibility of the NES system in the application of vibration control for marine structures.

Investigation of broadband damping and damping mechanism of quadrangular star-shaped ligament heterostructure

In this paper, a single-phase quadrangular star-shaped ligamentous heterostructure is constructed, and a two-phase structure is formed by attaching a resonator at the center of the structure. The lattice theory and finite element modeling are combined to analyze the band structure of the two structures, and the additional resonator at the center of the structure improves the bandgap range. Based on this, the bandgap can be widened and reduced by adjusting the resonator size. In the structural vibration modal analysis, it is explained that the coupling of traveling wave and vibration can open the omnidirectional bandgap, which provides guidance for the subsequent structural optimization. In addition, the relationship between bandgap opening and directional propagation of elastic waves is verified by a comprehensive analysis of group velocity, phase velocity, and other means. Finally, the transmission characteristics and stress distribution of the structure within the finite period structure are investigated, and it is further verified that the structure has a strong attenuation capability to vibration. This structure has good vibration isolation capability in a wide frequency range and has potential for application in complex vibration control.

Effect of training on the cyclic behaviour of SMA wire

Shape memory alloys (SMAs) are a new generation of smart metallic materials with numerous unique and widely applicable characteristics. With their superelasticity and ability to dissipate energy under cyclic loading, SMAs are an excellent choice for passive vibration energy dissipation systems. However, due to functional fatigue, the energy dissipation and re-centring capacity of virgin SMA dwindles at a decreasing rate during cyclic loading and eventually reaches a stable level. Since for vibration control applications stable mechanical properties with predictable responses to vibrational forces are preferred, preloading SMA wires for mechanical training is proposed to overcome this drawback. Nevertheless, the effect of training conditions on the mechanical behaviour of SMA wires has only been investigated in a few studies. To fill this research gap, the influence of different training parameters, such as strain amplitude, frequency, number of cycles and prestrain, on the mechanical behaviour of SMA wires is examined. The results show that while a sufficient number of cycles and certain level of strain amplitude are required to reach a stable stress–strain relation, training frequency is the most important parameter for eliminating residual strain.

Tunable elastic wave modulation via local phase dispersion measurements of a piezoelectric metasurface with signal correlation enhancement

Tunable piezoelectric metasurfaces have been proposed as a means of adaptively steering incident elastic waves for various applications in vibration mitigation and control. Bonding piezoelectric material to thin structures introduces electromechanical coupling, enabling structural dynamics to be altered via tunable electric shunts connected across each unit cell. For example, by carefully calibrating the inductive shunts, it is possible to implement the discrete phase shifts necessary for gradient-based waveguiding behaviors. However, experimental validations of localized phase shifting are challenging due to the narrow bandgap of local resonators, resulting in poor transmission of incident waves and high sensitivity to transient noise. These factors, in combination with the difficulties in experimental circuitry synthesis, can lead to significant variability of data acquired within the bandgap operating region. This paper presents a systematic approach for extracting localized phase shifts by taking advantage of the inherent correlation between the incident and transmitted wavefronts. During this procedure, matched filtering greatly reduces noise in the transmitted signal when operating in or near bandgap frequencies. Experimental results demonstrate phase shifts as large as −170° within the locally resonant bandgap, with an average 28% reduction in error relative to a direct time domain measurement of phase, enabling effective comparison of the dispersive behavior with corresponding analytical and finite element models. In addition to demonstrating the tunable waveguide characteristics of a piezoelectric metasurface, this technique can easily be extended to validate localized phase shifting of other elastic waveguiding metasurfaces.

Metasurface-guided flexural waves and their manipulations

Elastic metasurfaces, being the subject of much attention and discussion, are first designed by phase modulation and now are also considered as a kind of structures with subwavelength size, e.g., layer structures in 3D space or strip structures in 2D space. However, most of elastic metasurfaces, especially those with phase gradient subunits, cannot support elastic wave propagations along them. In this research, we construct non-resonant metasurfaces with an array of slots in plates and explore a unique form of flexural waves propagating along and decaying exponentially with the increasing of the distance from the metasurfaces, which are called metasurface-guided flexural waves. A theoretical framework is established to solve the dispersion relations of these waves by coupling high-order diffraction and waveguide modes. On the basis of this framework, we design three metasurfaces for rainbow reflection, mode conversion and topological interface state, which are realized and verified by finite element simulations and experiments. Our work provides a new idea for the manipulation of flexural waves in plates, which may have wide potential applications in vibration control, structural health monitoring and acoustic device design.

A model for near-perfect transmission through lossy media with acoustic sources

Acoustic metamaterials exhibit effective material properties not found in naturally occurring media, and, as such, have received considerable attention for their potential applications in noise and vibration control, diagnostic imaging, and nonreciprocal transmission. Complementary acoustic metamaterials have been proposed as a means of compensating for the high impedance mismatches of aberrating layers that disrupt the acoustic field and hence distort acoustic images. More recently, a complementary acoustic metamaterial featuring active components was shown in principal to compensate for both the impedance mismatch and energy attenuation of lossy materials, but a physical realization of the concept has not yet been implemented. Here, we present results from a one-dimensional acoustic model showing how a plane wave incident on a lossy material can be augmented by point monopole and dipole sources to allow for near perfect transmission, thus rendering the lossy medium acoustically transparent. We present general expressions for source magnitudes that are dimensionless with respect to frequency, material thickness, and the background medium. We show that these results are consistent with three-dimensional finite element simulations, where the appropriate monopolar and dipolar forces are generated using finite dimensional velocity sources with real loudspeaker characteristics mounted in an acoustic waveguide.

Characterization of elastic topological states using dynamic mode decomposition

Elastic topological states have been receiving increased attention in numerous scientific and engineering fields due to their defect-immune nature, resulting in applications of vibration control and information processing. Here, we present the data-driven discovery of elastic topological states using dynamic mode decomposition (DMD). The DMD spectrum and DMD modes are retrieved from the propagation of the relevant states along the topological boundary, where their nature is learned by DMD. Applications such as classification and synthesis of wave propagation can be achieved by the underlying characteristics from DMD. We demonstrate the classification between topological and traditional metamaterials using DMD modes. Moreover, the model enabled by the DMD modes realizes the synthesis of topological state propagation along the given interface. Our approach to characterizing topological states using DMD can pave the way towards data-driven discovery of topological phenomena in material physics and more broadly lattice systems.

A Hybrid Damper with Tunable Particle Impact Damping and Coulomb Friction

A particle impact damper (PID) dissipates the vibration energy of a structure through impacts within the damper. The PID is not commonly used in practice mainly because of its low damping-to-mass ratio and the difficulty in achieving its optimal design due to its nonlinear characteristics. In contrast, a Coulomb friction damper (FD) can offer a higher damping force-to-mass ratio than other dampers, but it is also difficult to be controlled precisely due to its nonlinear characteristics and excessive frequency sensitivity regarding the resonant frequency. This paper examines a hybrid damper by combining a particle impact damper and a Coulomb friction damper (PID + FD) theoretically and experimentally. A theoretical model of the proposed damper is developed and tested numerically on a single-degree-of-freedom (SDOF) structure. The predicted results are validated by experimental tests on a prototype of the proposed damper. The damping force provided by the FD in the prototype can be varied by adjusting the normal force applied through a compression spring, while the vibration energy dissipation by the PID can be varied by changing the cavity size of the PID. A parametric analysis of the proposed hybrid damper has been performed. The proposed hybrid damper can reduce the maximum vibration amplitude of the SDOF primary structure by 66% and 43% compared with using the FD and PID only. The proposed damper is found to be effective over a wide range of excitation frequencies. Furthermore, the proposed hybrid damper achieves a similar vibration suppression performance to the traditional tuned mass damper (TMD) of a similar mass ratio. The proposed damper does not require an optimally tuned natural frequency and damping, unlike the TMD, and therefore it does not have the detuning problem associated with the TMD. In addition, the performance of the proposed damper is tested and compared with the TMD for random earthquake excitation data. Consequently, the proposed hybrid damper may be a simpler and better alternative to the TMD in passive vibration control applications.