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The vibrational response amplitudes reduction is investigated for the axially moving composite cantilever rectangular (AM-CCR) laminated plate subjected to the transverse and parametric excitation by using the nonlinear energy sink (NES). Three different NES installed methods which are one NES, two NESs in series and two NESs in parallel are compared for the vibration attenuation of the AM-CCR laminated plate. For the dynamic model of the AM-CCR laminated plate with transverse and parametric excitation, using the first-order shear deformation theory, the von Karman large deformation theory, Hamilton’s principle, and the Galerkin discrete technique, the ordinary differential motion equations of the system are obtained. The pseudo frequencies and the nonlinear vibrational behaviors are depicted for the AM-CCR laminated plate. The nonlinear dynamic motion equations are established for the AM-CCR laminated plate with one NES, two NESs in series and two NESs in parallel are derived, respectively. The comparisons are given for vibrational response amplitude attenuation of the different locations in which the NES is placed on the end of the plate under the various retractable velocities. In addition, the influences of the number and the series and parallel connections of the NESs on the vibrational response reduction of the AM-CCR laminated plate are studied by the simulation method. When the AM-CCR laminated plate contracts, the scheme attached NESs in series has the optimal effect of the vibration reduction. When the AM-CCR laminated plate extends, the scheme with NESs in parallel has better effectiveness for the vibrational response reduction [ABSTRACT FROM AUTHOR]

To improve the operational adaptability of high-speed trains, a control method is proposed to mitigate carbody lateral vibration by leveraging the dynamic vibration absorption effect of multi-suspended equipment. A comprehensive analysis of five typical wheel/rail contact relationships, closely related to vehicle operational status in the long-term service, is conducted and incorporated into the established rigid-flexible coupling dynamic model. Based on the proposed improved niche genetic algorithm (INGA), an objective function, which holistically assesses the vibration of the carbody and suspended equipment, is constructed to undertake the optimization analysis. The results show that the dynamic vibration absorption effect of the suspended equipment proves effective in controlling carbody lateral vibration, thereby enhancing operational adaptability. However, the improvement in vehicle performance varies under different operating conditions, influenced by the competitive relationship between multiple control objectives. While carbody lateral vibration performance could be further improved without considering equipment vibration tolerance, such improvements are limited, indicating that it is reasonable and necessary to consider equipment vibration tolerance in the research of carbody vibration control. This study furnishes valuable insights for improving the adaptability of high-speed train operations and provides ideas for further research on carbody vibration control using the suspended equipment. [ABSTRACT FROM AUTHOR]

The stability of the parametric resonance of a controlled stay cable with time delay is investigated. The in-plane nonlinear equations of motion are initially determined via the Hamilton principle. Then, utilizing the method of multiple scales, the modulation equations that govern the nonlinear dynamics are obtained. These equations are then utilized to investigate the effect of time delays on the amplitude and frequency-response behavior and, subsequently, on the stability of the parametric resonance of the controlled cable, that it is shown to depend on the excitation amplitude and the commensurability of the delayed-response frequency to the excitation frequency. The stability region of the parametric resonance is shifted, and the effects of control on the cable become worse by increasing time delay. The work plays a guiding role in the parametric design of the control system for stay cables. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Sandwich structures are widespread in engineering applications because of their advantageous mechanical properties. Recently, their acoustic performance has also been improved to enable attenuation of low-frequency vibrations induced by noisy environments. Here, we propose a new design of sandwich plates (SPs) featuring a metamaterial core with an actively tunable low-frequency bandgap. The core contains magnetorheological elastomer (MRE) resonators which are arranged periodically and enable controlling wave attenuation by an external magnetic field. We analytically estimate the sound transmission loss (STL) of the plate using the space harmonic expansion method. The low frequency sound insulation performance is also analyzed by the equivalent dynamic density method, and the accuracy of the obtained results is verified by finite-element simulations. Our results demonstrate that the STL of the proposed plate is enhanced compared with a typical SP analog, and the induced bandgap can be effectively tuned to desired frequencies. This study further advances the field of actively controlled acoustic metamaterials, and paves the way to their practical applications. [ABSTRACT FROM AUTHOR]

Seismically induced active earth pressure is one of the prime causes of the failure of retaining walls. As an alternative to the conventional ductility-based seismic design of an elastic retaining wall, this work explored the potential of a compliant tuned liquid damper (CTLD) for seismic vibration control of a cantilever retaining wall. The liquid (water) in CTLD sloshes with a certain phase difference to the motion of the wall to reduce vibration and dissipate the vibrational energy through wave breaking. A typical retaining wall geometry was adopted to ensure its static stability and safety against buckling under the weight of the CTLD. A single-degree-of-freedom (SDOF) reduced-order model of the retaining wall was derived from the finite-element-based modal analysis of the combined soil–wall system. Sun's model was adopted for the sloshing of liquid in the CTLD. The response time histories of interest were obtained by numerical integration of the equations of motion for the combined SDOF-CTLD system, solved iteratively for nonlinear sloshing. Selecting optimal parameters ensured the best efficiency (of response reduction) of the CTLD through a parametric study. A suite of input ground motions pertaining to varying hazard levels was employed to verify the effectiveness of vibration control. The average displacement and acceleration control efficiency varied from 13.95% to 50.04% and 13.51% to 53.21%, respectively, with the backfill soil type and damping. Considerable response reduction demonstrated the efficiency of the CTLD. The performance robustness was demonstrated through a parametric study. Practical Applications: Traditionally, retaining walls are designed to be safe from seismic activities incorporating the lateral earth pressure under earthquake conditions. In contrast, the present study recommends a vibration reduction technique using a compliant-tuned liquid damper (CTLD), in which the seismic demand of a cantilever retaining wall is reduced directly by reducing the shaking of the wall. The CTLD, which is made up of a long channel-like tank mounted along the top of the wall, reduces the vibration of the soil–wall system by controlling its acceleration and displacement. The seismic force transmission is reduced by applying the CTLD, leading to a more economical wall design. The robustness of the CTLD system is checked in terms of its efficiency by varying soil properties and tuning parameters, which are presented graphically and in tabular form. The use of CTLD for vibration control of cantilever retaining walls or other geotechnical structures in different settings can be decided based on these results. The CTLD tank that holds water can also serve additional water storage/supply purposes. [ABSTRACT FROM AUTHOR]

As a burgeoning category of elastic metamaterials, 3D metastructures have garnered significant research attention for manipulating low-frequency acoustic and elastic waves. Bandgap engineering allows for the control of these waves across a subwavelength ultrawide frequency range. However, the manufacturing of these 3D structures poses a challenge, necessitating additional support materials for 3D-printed components, creating difficulties in mass production. In this study, we propose a novel lightweight 3D metastructure design that is easy to fabricate and provides a low-frequency subwavelength bandgap. We replaced conventional struts supporting heavy mass inclusions in typical designs with modified arch beams. This structural modification enables the easy and self-supporting manufacturing of 3D metastructure unit cells without the need for extra support material. Utilizing magnets and steel masses with bolts as hard inclusions, the magnet facilitates the quick assembly of the 3D metastructure, potentially facilitating mass manufacturing in practical applications. The wave dispersion and bandgap properties of the metastructure are investigated numerically, and experimental vibration tests are performed on the 3D-printed and assembled parts. The experimental results and numerical findings demonstrate robust vibration attenuation at low frequencies by the proposed 3D metastructure. The suggested, easy-to-fabricate 3D-metastructure design holds potential applications in low-frequency elastic-wave manipulation, including noise and vibration control. [ABSTRACT FROM AUTHOR]

The development of telescopes with large apertures is driven by the increasing demand for higher imaging resolution and coverage. Large membrane diffraction space telescopes are particularly attractive due to their lightweight nature, ease of folding and unfolding, and high-precision imaging capabilities. However, their substantial size and flexibility make them susceptible to long-duration, low-frequency vibrations during attitude maneuvers, which degrade attitude and imaging accuracy and risk instrument damage. Consequently, an urgent need exists for a high-precision integrated control scheme. In this paper, the integrated control of vibration and attitude in a large space telescope is studied using cable actuators and control moment gyroscopes (CMGs). Since cables can only withstand limited tension, the unilateral and constrained characteristics of the control input are taken into account during the control design process. Firstly, a rigid-flexible coupling dynamic model of the space telescope is established using the velocity variation principle with hybrid coordinates. Additionally, a two-body astrodynamic model is developed to assess the impact of gravity gradient torque. Next, combining the computational torque method and H∞ control theory, an integrated control scheme is proposed, which achieves vibration and attitude control during maneuvers. Then, this paper optimizes the cable actuator positions via the discrete particle swarm optimization (PSO) algorithm and plans various attitude maneuver paths. Finally, numerical simulations are adopted to demonstrate the effectiveness of the control scheme. The results show that this integrated control scheme swiftly suppresses structural vibrations during attitude maneuvers, enabling high-precision attitude control of the space telescope. • A vibration-attitude integrated control for a novel large membrane diffraction space telescope is studied • 3 types of attitude maneuver paths are planned for the two requirements of time optimal and minimum vibration excitation. [ABSTRACT FROM AUTHOR]

Low-frequency vibration is the core problem that hinders high-precision equipment's positioning accuracy and control accuracy. However, the response of a nonlinear electrical-mechanical coupling system is nonlinear and quite complicated under the ambient random vibrating environment. This paper presents a vibration suppression method through NARX (Nonlinear autoregressive with external input) neural network and its controller. The experiment platform is designed, and its dynamic model is obtained through system identification. The Neural network direct dynamic inverse control system is established, and the controller is designed. Both the simulation and experimental results show that the NARX identification and the controller can effectively achieve vibration suppression, and the experiment's highest vibration rejection ratio is 90.8%. The vibration suppression technology can be extensively applied to low-frequency vibration systems, such as aerospace equipment and high-precision equipment. [ABSTRACT FROM AUTHOR]

In multi-mass systems, torsional vibration is a common and annoying phenomenon. Effective vibration suppression and robustness to wide-range parameter variations are essential for a sound motion system. However, most control methods focus on the primary resonance mode, and the high-order resonance modes are not actively treated in the control design, resulting in the control bandwidth not being high enough and limiting the control performance. This paper proposes a novel two-stage design scheme to realize a wideband control to improve control performance. First, a hybrid uncertainty model is tailored for multi-mass systems, which uses an equivalent and uncertain spring constant to describe the variation of the primary mode and a dynamic uncertainty to cover the other resonance modes. This hybrid model strikes a better balance between the model conservatism and the feasibility of a less conservative design. Then, the passivity of the parameter uncertainty is utilized to conduct a phase compensation on the nominal system. After the phase compensation, all uncertainties are converted into norm-bounded ones, and the robust performance design is carried out. This method is applied to vehicle drivetrain benches, and its superiority is validated through simulation comparisons and experiments on two typical types of drivetrain benches. • Hybrid model for multi-mass systems characterizes primary resonance and other modes. • Two-stage design method with phase-shaping achieves high performance robust control. • The method is applied to drivetrain benches, outperforming the conventional methods. [ABSTRACT FROM AUTHOR]

Vibration is inevitable in operation of mechanical equipment, but severe vibrations will cause serious harm to wind turbines (WTs). This paper takes the drivetrain of 8 MW WT as the object, established a multi-body electromechanical coupling model of WT and verified the accuracy of the established model through the WT drivetrain in the laboratory. Subsequently, based on this model, time-frequency domain analysis was conducted on the vibration response of the WT drivetrain under different control strategies of the generator, and the influence of the generator control strategy on the vibration of the drivetrain was studied. The result shows that the generator control strategy has a significant impact on the vibration response amplitude of the drivetrain, but has a relatively small impact on the frequency component. Meanwhile, the sliding mode controller designed in this paper has good anti-interference ability, which can make the system quickly reach dynamic stability, and effectively suppress the vibration of the main components in the drivetrain. Under the new controller's control, the transverse vibration displacement of some parts of the WT drivetrain can be reduced by up to nearly 60 %. This paper provides new ideas and new methods for the active vibration reduction control of WT drivetrain. [ABSTRACT FROM AUTHOR]

The lever or the lever-type mechanism can achieve an inertia amplification effect by appropriately calibrating its structural configuration, and it is also proven to be one of the most cost-effective solution for the inerter realization compared with other mechanical devices. Benefitting from this property, the present paper adopted a new type of tuned lever inerter-like mass damper (TLIMD) for attenuating stochastic load-induced structure dynamic responses. A set of closed-form formulae for the TLIMD optimal parameters are developed by the use of H2 norm optimization criterion, wherein the structure's inherent damping is explicitly accounted for. It is theoretically demonstrated that the TLIMD optimal parameters are mainly dominated by three critical parameters, i.e., the damper mass ratio, the lever length ratio (known as the inertia amplification ratio) and also the host structural damping. The proposed formulae for the TLIMD optimization are validated through the seismic analysis, where two classic inerter-based dampers (i.e., the tuned mass damper inerter (TMDI) and the tuned inerter damper (TID)) optimized by the numerical technique are included in the discussion. It is found that the TLIMD has a superior advantage in reducing the structure responses and also exhibits stronger robustness for the detuning condition than the classic inerter-based dampers. Furthermore, the increase in the damper mass ratio and the lever length ratio can be beneficial for enhancing its performance. [ABSTRACT FROM AUTHOR]

In recent years, vibration control utilizing smart materials has garnered considerable attention. In this paper, we aim to achieve vibration suppression of a plate structure with a tail-fin shape by employing piezoelectric actuators—one of the smart materials. The plate structure is rigorously modeled based on the Kirchhoff–Love plate theory, while the piezoelectric actuators are formulated in accordance with the Prandtl–Ishlinskii model. This research proposed a control system that addresses the interference effects arising during vibration control by dividing multiple piezoelectric elements into two groups and implementing MIMO control. The efficacy of the proposed control method was validated through simulations and experiments. [ABSTRACT FROM AUTHOR]

A vibration-reducing boring bar with variable damping is proposed as a solution to the issue of poor stability of boring bars during boring machining. This will enhance the stability of boring machining. Firstly, this article places a variable-damping vibration absorber in the cavity at the front end of the boring bar. An excitation coil, a mass block, and a cantilever beam make up the vibration absorber structure. It contributes to damping adjustment by adjusting the excitation coil's energizing voltage, which alters the damping force on the mass block. On this basis, establish a dynamic model and analyze the damping and magnetic field of the variable-damping vibration absorber. Simultaneously building a vibration-damping boring bar system platform based on LabVIEW to monitor and control the vibration status of the boring bar. Finally, the feasibility of the vibration-damping boring bar was verified through performance testing of the vibration absorber and boring experiments. The results showed that the maximum vibration acceleration of the vibration-damping boring bar decreased by about 34.7%. It has been proven that the variable-damping vibration reduction boring bar has a good vibration reduction effect. [ABSTRACT FROM AUTHOR]

The characteristics of low damping and closely spaced natural frequencies make stay cables susceptible to wind-induced vibrations. This work proposed a novel damping device consisting of tuned mass damper (TMD) and rigid cross-tie (RCT) to mitigate the vibration of stay cables effectively. Two adjacent stay cables interconnected with RCTs can provide installation locations for TMDs, thus making the novel TMD-RCT control system feasible. Experimental control tests were carried out on a two-cable model of adjacent stay cables built in laboratory, where one TMD was designed based on the fundamental vibration mode of the stay cable. The effects of CT stiffness, number of RCTs, mass ratio, and installation position on the vibration reduction effect of the device were studied. To validate the efficacy of the proposed TMD-RCT device in vibration mitigation of stay cables under different loading cases, simulation tests and corresponding control performance evaluation were conducted. [ABSTRACT FROM AUTHOR]

Summary: In 2005, Moon proposed to equip tall buildings with movable façades to improve structural performance. Previous studies showed that, although this could be very effective in mitigating wind‐induced vibrations, its applicability is limited, as façades tend to exhibit excessive relative displacements. To solve this issue, two improvements are proposed in this work. First, the original idea of a monolithic façade is generalized to a Multiblock Movable Façade (MMF) where the external building skin is segmented into several independent blocks. Second, a friction slider equipped with bumpers is used to realize a dissipative connection capable of limiting the displacements of the façade. To evaluate the applicability of these ideas, the case study of a 209m tall building (the Isozaki tower in Milan, Italy) is considered. Dissipative sliders are modeled as nonlinear hysteretic elements incorporated into a finite element model of the building. Numerical simulations of the dynamical effects of wind‐actions are carried out to compare the performances of the building with and without MMF. The results show that the actions transmitted to the building by the façade can be tuned by properly setting the characteristics of the MMF system to achieve satisfactory performance in terms of maximum displacements and accelerations. [ABSTRACT FROM AUTHOR]

An overall investigation of the electromagnetic force, vibration, and average torque of the Interior Permanent Magnet Synchronous Motors (IPMSM) in the dq model for electric propulsion ships is carried out, and the electromagnetic vibration characteristics of the PMSM under the vector control strategy is explored. Firstly, the space and frequency characteristics of the electromagnetic force of the dq model motor are derived using the Maxwell stress tensor method, and the influence of the dq‐axes magnetic field on the electromagnetic force under different loads is discussed in detail. Secondly, the finite element method is used to verify the influence of dq‐axes currents on motor electromagnetic force, vibration, and average torque. Finally, the experiments are conducted on an 8‐pole 48‐slot IPMSM, and the results are consistent with the theoretical analysis and simulation results. The results indicate that the electromagnetic vibration of the PMSM for electric propulsion ships increases with the increase of the current iq and decreases with the increase of the current id. The electromagnetic vibration of the motor can be reduced by selecting the appropriate dq‐axes current under the output torque constraint. [ABSTRACT FROM AUTHOR]

This paper presents an active vibration control methodology to suppress the vibration of a square laminated composite plate. The plate undergoes large deflection, where the dynamics of the system is nonlinear. The main layer of the composite plate is made of a graphite/epoxy composite (T300/976) with angle orientations of [-45/45/-45/45], with a total thickness of 1mm, in addition to two piezoelectric layers of type PZT G1195 N, each with a thickness of 0.1 mm. The two piezoelectric layers cover the entire area of the upper and lower surfaces of the laminated composite plate where the upper layer senses vibration and feeds it back to the controller, whereas the lower layer acts as an actuator which receives a voltage signal from the controller. The proposed control method involved using a Proportional-Integral-Derivative (PID) controller with a gain scheduling strategy where the system nonlinearity is addressed by changing the controller parameters momentarily, with optimal tuned parameters selected according to the dynamic characteristics during the vibration of the plate. The numerical model of the laminated composite plate is formulated using the finite element method (FEM) for large deflection vibrating composite plates. The controller performance was tested by simulating the vibration of the plate under the action of the controller for four cases with different vibration modes, and the results showed the effectiveness of the proposed PID controller with gain scheduling strategy. [ABSTRACT FROM AUTHOR]

The paper partially covered Active Constrained Layer Damping (ACLD) cantilever beams' dynamic modeling, active vibration control, and parameter optimization techniques as the main topic of this research. The dynamic model of the viscoelastic sandwich beam is created by merging the finite element approach with the Golla Hughes McTavish (GHM) model. The governing equation is constructed based on Hamilton's principle. After the joint reduction of physical space and state space, the model is modified to comply with the demands of active control. The control parameters are optimized based on the Kalman filter and genetic algorithm. The effect of various ACLD coverage architectures and excitation signals on the system's vibration is investigated. According to the research, the genetic algorithm's optimization iteration can quickly find the best solution while achieving accurate model tracking, increasing the effectiveness and precision of active control. The Kalman filter can effectively suppress the impact of vibration and noise exposure to random excitation on the system. [ABSTRACT FROM AUTHOR]

This article introduces an advanced nonlinear controller designed for optimizing the performance of a single‐link robot arm featuring a flexible joint. The proposed nonlinear control strategy incorporates a Proportional‐Integral (PI) controller in conjunction with a nonlinear velocity feedback component, aimed at providing effective nonlinear damping and suppressing vibrations. To validate the controller's performance, extensive simulations are conducted utilizing machine learning techniques within the Python environment. The performance of the proposed nonlinear damping controller is benchmarked against a conventional linear cascaded P‐PI control structure, with both controllers fine‐tuned using the Nelder‐Mead algorithm. Simulation results demonstrate that the nonlinear damping controller yields substantial improvements in the dynamic behavior of the robot axis arm, showcasing superior step and sinusoidal position tracking performance, along with active vibration damping capabilities. This research contributes valuable insights into the enhanced nonlinear control strategies for flexible‐joint robot arms, offering promising advancements in their overall dynamic performance. [ABSTRACT FROM AUTHOR]

Several types of acoustic metamaterials composed of resonant units have been developed to achieve low-frequency bandgaps. In most of these structures, bandgaps are determined by their geometric configurations and material properties. This paper presents a frequency-displacement feedback control method for vibration suppression in a sandwich-like acoustic metamaterial plate. The band structure is theoretically derived using the Hamilton principle and validated by comparing the theoretical calculation results with the finite element simulation results. In this method, the feedback voltage is related to the displacement of a resonator and the excitation frequency. By applying a feedback voltage on the piezoelectric fiber-reinforced composite (PFRC) layers attached to a cantilever-mass resonator, the natural frequency of the resonator can be adjusted. It ensures that the bandgap moves in a frequency-dependent manner to keep the excitation frequency within the bandgap. Based on this frequency-displacement feedback control strategy, the bandgap of the metamaterial plate can be effectively adjusted, and the vibration of the metamaterial plate can be significantly suppressed. [ABSTRACT FROM AUTHOR]

Broadband vibration attenuation is a challenging task in engineering since it is difficult to achieve low-frequency and broadband vibration control simultaneously. To solve this problem, this paper designs a piezoelectric meta-beam with unidirectional electric circuits, exhibiting promising broadband attenuation capabilities. An analytical model in a closed form for achieving the solution of unidirectional vibration transmission of the designed meta-beam is developed based on the state-space transfer function method. The method can analyze the forward and backward vibration transmission of the piezoelectric meta-beam in a unified manner, providing reliable dynamics solutions of the beam. The analytical results indicate that the meta-beam effectively reduces the unidirectional vibration across a broad low-frequency range, which is also verified by the solutions obtained from finite element analyses. The designed meta-beam and the proposed analytical method facilitate a comprehensive investigation into the distinctive unidirectional transmission behavior and superb broadband vibration attenuation performance. [ABSTRACT FROM AUTHOR]

This paper addresses the traveling wave vibration control of rotating functionally graded material (FGM) conical shells via piezoelectric actuator and sensor pairs. Considering the circumferential initial stresses and Coriolis forces induced by rotation, as well as arbitrary boundary conditions, the electromechanically coupled governing equations of the rotating FGM conical shell with piezoelectric patches are established using the Lagrange equation. The model validation is carried out through a comparative analysis with existing literature. Base on the model, the linear–quadratic regulator controller is designed to suppress the traveling wave vibrations of rotating FGM conical shells considering the participation of multi-vibration modes in the dynamic responses. To evaluate the performance of the controller, free and forced vibrations of rotating FGM conical shells with different rotational speeds, material compositions and excitation positions are investigated in detail. Additionally, five typical piezoelectric sensors/actuators distributions are presented and the effects of piezoelectric patch layout on the control efficiency are discussed. [ABSTRACT FROM AUTHOR]

In previous studies, structure vibration control mainly focused on integer-order systems or commensurate fractional-order (FO) dynamics systems. In this paper, we propose an adaptive radial basis function (RBF) neural network feedback (ARBF-FK) controller for FO building structure vibration systems with viscoelastic (VE) dampers, uncertain structure parameters and unknown seismic waves. Firstly, use a FO multi-order state space description for FO building structural vibration systems. Then, the design of the ideal feedback controller is based on the stability theory of FO multi-order systems. Moreover, to reduce the cost and facilitate the practical implementation of the control, unknown earthquake seismic waves is approximated by a RBF neural network, the ARBF-FK controller is proposed. In addition, to guarantee the stability of the closed-loop control system and avoid falling into local optimum, network weights are adapted by the FO Lyapunov stability theory instead of gradient descent algorithms. Finally, the convergence rate of the system is analyzed and perform various tests on the ARBF-FK controller. The simulation results demonstrate that the ARBF-FK controller has superior performance and is very robust to control FO building structure vibration systems with uncertain structure parameters and unknown external earthquake excitation. • A FO multi-order state space description method of FO building vibration systems is constructed. • An online adaptive ARBF-FK robust control strategy for FO building vibration systems is proposed. • Adaptive weights of neural networks are derived using the FO Lyapunov theory. [ABSTRACT FROM AUTHOR]

To explore the application of tuned mass damper (TMD) for controlling vibrations in rail box girder structures, a scaled model system for vehicle-rail-bridge coupling vibrations with a geometric similarity ratio of 10:1 is designed and manufactured based on the high-speed electric multiple units and CRTS-II plate ballastless-track-box girder structure, and the vibration damping effect of TMD on the roof plate and wing plate of box girder under different working conditions is analyzed, including different mass ratios, different positions and different installation quantities. The results show that the vibration damping effect when the TMD mass ratio is 0.02 is better than the vibration damping effect when the mass ratio is 0.01, and TMD with a larger mass ratio can be preferred under the condition of considering structural safety and economy; different TMD installation positions have different damping effects on the components of the box girder, and the vibration response at the installation of TMD plates is significantly suppressed; the vibration damping effect of installing two TMDs on the box girder structure is significantly better than that of installing one TMD, and its damping range is also improved. The research conclusion can provide a reference for the damping design of elevated rail box girder structure. [ABSTRACT FROM AUTHOR]

Main objective of this research to eliminate the resonant vibrations and stabilize the unstable motion of a self-excited structure through the implementation of an innovative active control strategy. The control strategy coupling the self-excited structure with a second-order filter, which feedback gain λ and control gain β , as well as a first-order filter, which feedback gain δ and control gain γ. The coupling of the second-order filter to establish an energy bridge between the structure and the filter to pump out the structure's vibration energy to the filter. In contrast, the primary purpose of coupling the first-order filter to stabilize the closed loop by adjusting the damping of the system using the control keys δ and γ. Accordingly, the mathematical model of the proposed control system formulated, incorporating the closed-loop time delay τ. An analytical solution for the system model obtained, and a nonlinear algebraic system for the steady-state dynamics of the controlled structure extracted. The system's bifurcation characteristics analyzed in the form of stability charts and response curves. Additionally, the system's full response simulated numerically. Findings the high performance of the introduced controller in eliminating the structure's resonant vibrations and stabilizing non-resonant unstable motion. In addition, analytical and numerical investigations revealed that the frequency band within which the second-order filter can absorb the structure's resonant oscillation relies on the algebraic product of β and λ. Furthermore, it was found that the equivalent damping of the system depends on the algebraic product of γ and δ , which can be employed to stabilize the negatively damped self-excited systems. Finally, it reported that although the loop delay can potentially degrade vibration control performance, the time-delay stability margin is nonlinearly proportional to the product of γ and δ. This finding that increasing the value of γ × δ can compensate for the adverse effects of loop delay on both system stability and vibration suppression efficiency. [ABSTRACT FROM AUTHOR]

This paper addresses the robust vibration control problem for a gantry crane system which is governed by a partial differential equation. The control objectives are to transport the cargo from the initial position to the desired position and suppress the vibration of the cable and payload in the presence of boundary disturbance. To achieve the objectives, a sliding-mode controller is proposed by repressing the boundary disturbance. By using the operator semigroup theory, the well-posedness of the closed-loop system is guaranteed. The asymptotic stability of the closed-loop system is proven by using the extended LaSalle's invariance principle. Both numerical simulations and experiments are provided to illustrate the effectiveness of the proposed boundary control method. [ABSTRACT FROM AUTHOR]

Researchers in the field of vibration control have shown increasing interest in magneto-rheological dampers (MRDs) in recent years. Conventional flow-mode MRDs typically employ a gas chamber as an accumulator to accommodate volume changes and promote fluid communication. However, this approach introduces manufacturing complexities and raises production costs. To overcome these challenges, we propose a novel configuration for flow-mode MRDs that replaces the accumulator with a structural constraint. This modification leads to a more compact and cost-effective MRD solution suitable for engineering applications. This paper presents an introduction, followed by the configuration and design of the novel MRD for a case study involving a vehicle suspension system. To enhance output performance, we optimize the significant geometry of the damper using the finite element method (FEM), taking into account the damping force, off-state force, and inductive time constant of the damper. Based on the optimal simulation results, we provide a detailed design of the optimized flow-mode MRD without an accumulator for prototype fabrication. To assess the practical performance of the proposed MRD prototype, we conducted experiments on a test rig and engaged in comprehensive discussions based on the obtained results. [ABSTRACT FROM AUTHOR]

An inerter system, based on electromechanical similarity theory and vibration mitigation and isolation technology, represents a category of vibration damping systems. These systems typically improve damping performance by increasing mass or inertia, a method often found to be inefficient, leading to inadequate damping and limited applicability in real-world engineering scenarios. The lightweight inerter system (LwIS) introduced herein offers a more flexible and efficient means of altering structural inertia. Initially, this paper establishes the motion control equations for LwIS, followed by a stochastic analysis to derive the analytical expression for the root mean square displacement under Gaussian white noise excitation. A parametric analysis of LwIS is subsequently conducted, developing a displacement-based parametric strategy. Design examples for single-degree-of-freedom (SDOF) engineering structures under various requirements are provided, demonstrating the validity of LwIS’s optimal parameters through responses to simple harmonic excitation and seismic impacts. The findings indicate that the optimization approach of LwIS, unlike traditional methods, simultaneously addresses the displacement performance of the primary structure and the deformation efficiency of the damping element, thereby facilitating comprehensive optimization. Four optimal design parameters for LwIS are identified, underscoring its applicability to stochastic excitation and a broader range of load cases, thus enhancing its practicality in engineering contexts. LwIS’s design philosophy aims to improve deformation efficiency through an increased deformation enhancement coefficient in the damping element, enhancing damping performance, controlling seismic responses, and achieving superior energy dissipation. The optimal parameters, smaller in value, maximize the potential of the inerter system, aligning with the dual objectives of performance optimization and lightweight design, consequently reducing engineering costs. [ABSTRACT FROM AUTHOR]

Human–Structure Interaction (HSI) can significantly influence the dynamic characteristics of pedestrian footbridges, particularly those distinguished by their lightness and slenderness. This study examines the performance of Tuned Mass Dampers (TMD) and Semi-Active Tuned Mass Dampers (STMD) on pedestrian footbridges when their modal parameters change due to the influence of HSI. For this purpose, a 30 m long simply-supported footbridge with linear mass values ranging from 200kg/m to 2000kg/m and a fundamental frequency varying from 1Hz to 5Hz has been considered. In addition, several pedestrian streams with different pedestrian densities have been used to assess the structural dynamic response. The analysis highlights that structural lightness and slenderness are critical factors in determining whether the incorporation of an HSI model is relevant to accurately predict the dynamic performance of the structure. The findings indicate that while TMDs can become ineffective due to shifts in natural frequencies caused by HSI, resulting in a degradation of vibration reduction from 70–75% to 40–45%, STMDs demonstrate a robust capability to adjust and cope with these frequency changes, maintaining a higher average vibration reduction of around 55–60%. Consequently, STMDs emerge as a necessary solution for very slender structures where HSI significantly alters the global frequency response. This study highlights the importance of considering HSI in the design and implementation of damping solutions to ensure optimal functionality and user comfort on lightweight pedestrian bridges. [ABSTRACT FROM AUTHOR]

The response amplification technology, which enhances the efficiency of shock absorption apparatuses, has been widely applied in the field of shock absorption control for engineering structures. Researchers have proposed and verified through numerical analysis and experiments more structural forms of this technology as applicable. The functions are also more comprehensive, such as increased utilization rate of structural space and economy. The development of its theoretical foundation has progressed from constant solutions based on small deformations to solutions that reflect the time-varying characteristics of the amplification factor of the brace-damping system. Simultaneously, the influencing factors of the amplification factor have been analyzed in detail to provide better theoretical guidance for engineering practice. This paper provides a detailed discussion on the research overview of the response amplification technology and the influencing factors of the amplification factor. The conclusion introduces the significance of using this technology, comprehensively analyzes the deficiencies and limitations of existing response amplification technology, and points out the research and development direction, with the expectation of providing ideas for further development. [ABSTRACT FROM AUTHOR]

High-temperature superconducting pinning maglev technology has great potential for high-speed transportation due to its passive stability and friction-free characteristics. However, at high speeds, the weak damping characteristics of the system make it challenging to attenuate system vibrations caused by external excitation effectively. An electromagnetic shunt damper can be added to the high-temperature superconducting vehicle system to address this challenge. However, due to the complexity of the high-temperature superconducting vehicle system and external excitation, it is challenging to determine the optimal electromagnetic shunt damper parameters through analytical calculation. This study proposes a method for optimizing electromagnetic shunt damper parameters based on the NSGA-II multi-objective optimization algorithm. The high-temperature superconducting vehicle dynamic simulation model with electromagnetic shunt damper is established, and the dynamic simulation is carried out according to the actual operation conditions. Taking the dynamic indexes as the objectives, the optimal electromagnetic shunt damper parameters are then selected within a reasonable range based on dynamic indexes used as objectives in the NSGA-II algorithm. The effectiveness of the optimization method is verified through simulations and experiments on a levitation model vehicle with electromagnetic shunt damper under random vibration conditions. Finally, the optimized electromagnetic shunt damper parameters are applied to an engineering high-speed high-temperature superconducting pinning maglev vehicle through simulation. The calculation results demonstrate that various performance indexes are improved after optimization. This optimization design provides a reference for applying electromagnetic shunt damper in high-temperature superconducting pinning maglev vehicles. [ABSTRACT FROM AUTHOR]

The aeroengine bracket is a vital connector, which plays a key role in supporting and transmitting loads. In this paper, a bracket with variable stiffness for vibration control of aeroengine accessory is designed. Firstly, the topology optimization for the initial model of the aeroengine bracket is carried out, and the quality of the bracket was reduced by 84.78% while meeting the strength requirements. After that, part of the material of the bracket was replaced by shape memory alloy (SMA) to design the bracket with variable stiffness. It is found that with the increase in temperature, the stiffness of the designed bracket with variable stiffness increases by about 36%, and maximum von Mises stress and deformation of the bracket have decreased. Finally, the integrated modeling of aeroengine casing-bracket-accessory is carried out. Under single and coupled fault frequencies, the amplitude of the accessory is reduced by 57.5% and 63.1%, respectively. The frequency sweep at different temperatures shows that as the temperature increases, the resonance frequency changed from 74.6 Hz to 89.1 Hz and the resonance peak amplitude decreased by 17.7%. [ABSTRACT FROM AUTHOR]

This study focuses on the vibration control effect of the spring vibration isolation system (SVIS) on a super high-rise building located on the subway (BLS) and the transmission mechanism of vibration in super high-rise BLS. Firstly, the 1:35 scale shaking table test model of super high-rise BLS is designed, the rationality of the shaking table test model is verified, and the shaking table test is implemented. Secondly, the finite element model (FEM) is established and verified based on the results of the shaking table test. Finally, based on verified FEM, the vibration control effect of SVIS on super high-rise BLS and the vibration transmission mechanism of super high-rise BLS is analyzed. The results show that the vibration response of the BLS show amplification trend along the height direction. The amplification of vibration response of BLS is effectively controlled by SVIS. The higher the floor, the greater the reduction coefficient, and the better the control effect. The reduction coefficient above 10F is mainly distributed above 0.80 due to the SVIS. The BLS equipped with the SVIS maintains the degree of Z -direction vibration and 1/3 octave vibration acceleration level that is within the limits stipulated by the specifications. The first-order vertical frequency of BLS equipped with the SVIS is adjusted from 65 Hz to 8 Hz, far from the favorable frequency range of the subway wave. [ABSTRACT FROM AUTHOR]

This article presents a novel approach to impact regulation of nonlinear vibrational responses in a beam flutter system subjected to harmonic excitation. This study introduces the use of a Nonlinear Integral Positive Position Feedback (NIPPF) controller for this purpose. This technique models the system as a three-degree-of-freedom nonlinear system representing the beam flutter, coupled with a first-order and a second-order filter representing the NIPPF controller. By applying perturbation analysis to the linearized system model, the authors obtain analytical solutions for the autonomous system with the controller. This study aims to reduce vibration amplitudes in a nonlinear dynamic system, specifically when 1:1 internal resonance occurs. The Routh–Hurwitz criterion is utilized to evaluate the system's stability. Furthermore, the frequency–response curves (FRCs) exhibit symmetry across a range of parameter values. The findings highlight that the effectiveness of vibration suppression is directly related to the product of the NIPPF control signal after comparing with different controllers. Numerical simulations, conducted using the fourth-order Runge–Kutta method, validate the analytical solutions and demonstrate the system's amplitude response. The strong correlation between the analytical and numerical results highlights the accuracy and dependability of the proposed method. [ABSTRACT FROM AUTHOR]

Passively tuned mass dampers (TMDs) are known to effectively mitigate the vibration of wind turbines. However, existing literature predominantly examines their application in damping vibrations of the tower or platform, overlooking the potential benefits of installing TMDs on the turbine blades themselves. This study investigates the impact of wind and wave loads on TMD damping effectiveness and proposes a comprehensive damping strategy involving TMDs installed in both the nacelle and the blades. The design optimized the mass and stiffness of these TMDs to enhance their performance. Results indicate that, as wind speeds increased from 12 m/s to 24 m/s, the power spectral density at the tower's natural frequency (0.22 Hz) more than doubled. Notably, TMDs exhibited robust vibration damping capabilities under high wind speeds. Specifically, at wind speeds of 24 m/s, TMDs reduced anterior–posterior and lateral displacement at the tower top by 61.2% and 166.8%, respectively, when two TMDs were combined. Conversely, the study found that TMDs did not significantly improve vibration damping at lower to moderate wind speeds. This research underscores the importance of optimizing TMDs for high wind conditions to ensure wind turbine stability and mitigate potential vibration-related risks effectively under varying environmental loads, including wind and waves. It offers valuable insights for the refined design and deployment of TMDs in wind energy applications. [ABSTRACT FROM AUTHOR]

This article introduces a novel regenerative suspension system designed for active seat suspension, to reduce vibrations while recovering energy. The system employs a four-quadrant electric actuator operation model and utilizes a brushless DC motor as an actuator and an energy harvester. This motor, a permanent magnet synchronous type, transforms DC into three-phase AC power, serving dual purposes of vibration energy recovery and active power generation. The system's advanced vibration control is achieved through the switching of MOSFET transistors, ensuring the suspension system meets operational criteria that contrast with traditional vibro-isolation systems, thereby reducing the negative effects of mechanical vibrations on the human body, while also lowering energy consumption. Comparative studies of the regenerative system dynamics against passive and active systems under random vibrations demonstrated its effectiveness. This research assessed the system's performance through power spectral density and transmissibility functions, highlighting its potential to enhance energy efficiency and the psychophysical well-being of individuals subjected to mechanical vibrations. The effectiveness of the energy regeneration process under the chosen early excitation vibrations was investigated. Measurements of the motor torque in the active mode and during regenerative braking mode, and the corresponding phase currents of the motor, are presented. [ABSTRACT FROM AUTHOR]

In this paper, an innovative hamburger-shaped eddy current damper (HSECD) is presented to mitigate the responses of civil structures subjected to wind excitations. The damper's capacity to dissipate energy is significantly enhanced through a two-phase configuration of permanent magnets (PMs) and two transmission devices: a ball-screw assembly and a bevel gear group. The improved eddy current damper (ECD) solves the problem that the low damping density of traditional ECDs hinders their application to the field of vibration control for civil structures. First, the construction details of this novel HSECD are elaborated, and its principle is discussed through theoretical analysis and numerical simulation. Subsequently, a prototype of the HSECD was fabricated, and cyclic tensile–compressive tests were conducted to investigate its mechanical performance. Furthermore, the temperature effect on the damper's maximum output force was analyzed, and more than 10% performance degradation was detected in tests with a continuous loading of 1,250 s, while the damper performance quickly reached a steady state after a certain decline. A theoretical model of the HSECD was then established to simulate its hysteretic characteristics, and the accuracy was verified by comparing it with the test data, where their energy error was only 1.9%. Finally, the application of the HSECD to both a single-degree-of-freedom (SDOF) simplified system and a jacking engineering system demonstrates its excellent control performance because the reduction ratios of their peak displacement were as high as 31.1% and 40.9%, respectively. These results highlight the significant practical value of the HSECD in mitigating the wind-induced vibrations for engineering structures. [ABSTRACT FROM AUTHOR]

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Active disturbance rejection control (ADRC) is considerably applied due to its advantage of focusing on merely dominant parameters. Research on flexible systems frequently confronting perplexing disturbances can utilize this method to simplify irrelevant items as a single variable. In this paper, we focused on vibration control problems in flexible systems with the application of ADRC and constructed a second‐order system model under the guideline of fundamental principles of ADRC and an innovative algorithm for tuning feedforward compensation ADRC. During the simulation, we discussed three cases in which each solely one parameter varies while others are kept invariant. Time, open‐loop frequency, and close‐loop frequency responses were respectively analyzed in all cases as to determine the stability of the system. According to the simulation results, we arrived at the conclusion: we should choose the specification of a flexible system within an intermediate range and evade from critical system parameters to procure stability and efficiency. [ABSTRACT FROM AUTHOR]

In response to limitations in vibration suppression performance of traditional linear tuned mass damper due to energy threshold constraints and narrow vibration bands, this study proposes a magnetic tri-stable NES (MTNES) formed by combining a linear spring and magnets. Compared to the conventional nonlinear energy sink (NES), the magnetic tri-stable NES (MTNES) incorporates magnetism to enhance the nonlinear stiffness. Firstly, the mechanism of the MTNES is introduced in this study, which reveals the existence of the three stable points in the system. Subsequently, the equations of motion of the coupled system with MTNES attached to the cantilever beam are derived, and the optimal parameter combination for MTNES is determined using a global optimization method. Furthermore, the influence of MTNES parameter variations on vibration suppression efficiency is studied through parameter analysis. Then, the restoring force of the MTNES is simplified into polynomial form, and the system response is analyzed using the harmonic balance method and Runge–Kutta method. Finally, experimental studies on the coupled system are conducted. The results indicate that MTNES can effectively suppress the resonance of the host structure within a wide frequency band, with the highest vibration suppression rate of up to 66% under strong modulated response. Additionally, the results of numerical calculations and theoretical analysis are in good agreement with that of the experiment. [ABSTRACT FROM AUTHOR]

Civil engineering structures are susceptible to collapsing when exposed to severe vibrations. Therefore, it is essential to protect them from undesirable vibrations triggered by natural calamities like earthquakes or strong winds. This paper proposes an innovative semi-active Magnetorheological (MR) inerter system with a compact structure for seismic protection. The inerter system consists of four rubber bearings and the semi-active MR inerter. The inertance of the semi-active MR inerter can be switched according to different working scenarios. This unique operating principle enhances the adaptability of the system. To assess the performance of the proposed inerter system, a scaled three-storey building was constructed following scaling laws. Four scaled earthquake signals with different dominant frequencies were used as ground motion excitations. An inertance switch controller based on short-time Fourier transformation (STFT) methodology was built to determine the desired inertance of the inerter. Both the simulation and experimental results indicated that the proposed semi-active MR inerter system provides superior vibration mitigation capacity over the passive inerter systems. Specifically, the employment of the semi-active MR inerter effectively reduces the acceleration responses of the structures under different seismic excitations. [ABSTRACT FROM AUTHOR]

This article describes an innovative technical solution developed by the authors that can be used to improve the quality, reliability, safety, and service life of hydraulic units. The problems of vibration control are discussed. Phase-chronometric diagnostics are proposed. The possibilities of significantly increasing the accuracy of hydraulic unit operation control are presented. [ABSTRACT FROM AUTHOR]

Vibration is inevitable in operation of mechanical equipment, but severe vibrations will cause serious harm to wind turbines (WTs). This paper takes the drivetrain of 8 MW WT as the object, established a multi-body electromechanical coupling model of WT and verified the accuracy of the established model through the WT drivetrain in the laboratory. Subsequently, based on this model, time-frequency domain analysis was conducted on the vibration response of the WT drivetrain under different control strategies of the generator, and the influence of the generator control strategy on the vibration of the drivetrain was studied. The result shows that the generator control strategy has a significant impact on the vibration response amplitude of the drivetrain, but has a relatively small impact on the frequency component. Meanwhile, the sliding mode controller designed in this paper has good anti-interference ability, which can make the system quickly reach dynamic stability, and effectively suppress the vibration of the main components in the drivetrain. Under the new controller’s control, the transverse vibration displacement of some parts of the WT drivetrain can be reduced by up to nearly 60 %. This paper provides new ideas and new methods for the active vibration reduction control of WT drivetrain.

Abstract An overall investigation of the electromagnetic force, vibration, and average torque of the Interior Permanent Magnet Synchronous Motors (IPMSM) in the dq model for electric propulsion ships is carried out, and the electromagnetic vibration characteristics of the PMSM under the vector control strategy is explored. Firstly, the space and frequency characteristics of the electromagnetic force of the dq model motor are derived using the Maxwell stress tensor method, and the influence of the dq‐axes magnetic field on the electromagnetic force under different loads is discussed in detail. Secondly, the finite element method is used to verify the influence of dq‐axes currents on motor electromagnetic force, vibration, and average torque. Finally, the experiments are conducted on an 8‐pole 48‐slot IPMSM, and the results are consistent with the theoretical analysis and simulation results. The results indicate that the electromagnetic vibration of the PMSM for electric propulsion ships increases with the increase of the current iq and decreases with the increase of the current id. The electromagnetic vibration of the motor can be reduced by selecting the appropriate dq‐axes current under the output torque constraint.

Precision research and technological equipment, as a rule, is not able to provide its specification characteristics without a high-quality vibration protection system. Active vibration control of an object is provided with the help of an additional source of movement, an actuator. The most promising high accuracy actuators are based on smart materials, such as materials with shape memory, piezoelectric and magnetostrictive materials, electro- and magnetic active fluids and elastomers. Dielectric elastomer is one of the types of electroactive polymers. Actuators based on a dielectric elastomer show high performance in terms of accuracy and speed and operate due to the controllable deformation of the elastomer under the action of a high voltage electric field. The paper provides a comparison of actuators based on sheet and thin film control electrodes. The influence of the quality of the polymer surface and the type of electrodes on the travel range of the actuator and maximum amplitude of vibrations the system can suppress on the basis of a dielectric elastomer is estimated. The formation of the electrode by magnetron sputtering in vacuum makes it possible to create a thin-film layer of copper that covers the elastomer, despite the developed surface. The effect of ion treatment of an elastomer before coating on the quality of the formed electrode is considered. After the ion treatment, the surface of the elastomer acquires a more uniform regular structure. A thin-film electrode layer is formed according to the topology of the elastomer to an accomplished standard.

Abstract This article introduces an advanced nonlinear controller designed for optimizing the performance of a single‐link robot arm featuring a flexible joint. The proposed nonlinear control strategy incorporates a Proportional‐Integral (PI) controller in conjunction with a nonlinear velocity feedback component, aimed at providing effective nonlinear damping and suppressing vibrations. To validate the controller's performance, extensive simulations are conducted utilizing machine learning techniques within the Python environment. The performance of the proposed nonlinear damping controller is benchmarked against a conventional linear cascaded P‐PI control structure, with both controllers fine‐tuned using the Nelder‐Mead algorithm. Simulation results demonstrate that the nonlinear damping controller yields substantial improvements in the dynamic behavior of the robot axis arm, showcasing superior step and sinusoidal position tracking performance, along with active vibration damping capabilities. This research contributes valuable insights into the enhanced nonlinear control strategies for flexible‐joint robot arms, offering promising advancements in their overall dynamic performance.