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The control performance of a passive dynamic vibration absorber (DVA) is known to be sensitive to its frequency deviation. This study upgrades the conventional device and proposes an adaptive-passive variable frequency gas-spring DVA (APVF-GSDVA) for controlling the structural seismic response, while an adaptive control algorithm is developed that requires only a single input signal. The DVA’s vibration frequency is precisely modulated by adjusting the gas pressure in the gas-spring, aligning it with the inherent frequency of the multi-degree-of-freedom (MDOF) structure. The working principle and control algorithm of the APVF system is introduced and derived in detail, the corresponding gas-spring DVA and implementation are designed, and the configuration of the entire control system is realized. An adaptive variable frequency test scheme is designed and the frequency retuning function of the prototype APVF-GSDVA device installed on an MDOF structure is experimentally validated. The seismic response control effectiveness of the retuned DVA is demonstrated by comparing the detuned DVA, highlighting the necessity of implementing adaptive frequency adjustment of the gas-spring DVA. Experimental findings demonstrate that APVF-GSDVA accurately identifies the inherent frequency of the MDOF structure in ambient excitation, it then adjusts the pressure of the gas-spring according to the frequency-pressure relationship, optimally retuning the DVA. A retuned GSDVA can effectively suppress the structural seismic responses, compared to a detuned DVA, its control effectiveness on peak and RMS responses can be improved by a maximum of nearly 13.5% and 53.3% at a frequency deviation of 10%. Furthermore, results from two “detuning-retuning” test paths with distinct seismic excitations indicate that the retuned DVA exhibits superior control effectiveness, underscoring the significance of the adaptive frequency adjustment function in passive DVAs. [ABSTRACT FROM AUTHOR]

This paper investigates the control performance of a novel grounded inerter-based dynamic vibration absorber (GI-DVA) for random vibration reduction. First, the dynamics equations of the coupled system are written and the transfer function is obtained based on the Laplace transform. Then, assuming that the primary structure is under random white noise excitation, the displacement variance of the primary structure is calculated based on the exact definition of the H 2 norm, by solving the Lyapunov equation. By imposing that the partial derivatives of the response variance of the primary structure with respect to the system parameters are simultaneously equal to zero, the optimum design values of the H 2 optimized GI-DVA were derived numerically for given different mass ratio. It can be found that the optimal design parameters as the inerter-to-mass ratio, the stiffness ratio and the damping ratio increase, while the frequency ratio decreases with the increase in the mass ratio. Under the optimal conditions, the response analysis showed that the primary structure response controlled by the H 2 optimized GI-DVA can decrease with the increase in the mass ratio, but is less sensitive to large mass ratios, and can be robust to the mistuning on the optimum design parameters. Then, the control performance evaluation is first performed in the frequency domain, which reveal that the dynamic response reduction capacity of the H 2 optimized GI-DVA are significantly 62% and 48% superior to the H 2 optimized classic DVA (CDVA) and high-performance passive nontraditional inerter-based DVA (NIDVA-C4), respectively. Furthermore, for the root mean square response evaluation (H 2 performance), the H 2 optimized GI-DVA can provide significantly H 2 performance 58% and 50% than the H 2 optimized CDVA and NIDVA-C4, respectively. To obtain more realistic results, the time domain simulation is performed, which showed that the GI-DVA can provide significantly performance for random vibration reduction. [ABSTRACT FROM AUTHOR]

A novel lever-type stiffness-based grounded damping dynamic vibration absorber with grounded stiffness is presented in this paper, and the analytical design parameters are derived in detail. At the first, the equations of motion are established and the analytical solution of the primary structure displacement is obtained. It is found that with the introduction of grounded stiffness, the coupled system could be unstable and the stability condition is established. Then, the optimum stiffness ratio, the optimum damping ratio and the optimum grounded stiffness ratio are expressed as the function of mass ratio and lever ratio by minimizing the mean squared displacement response of the primary structure previously established. From the results analysis, the system stability is verified, and it is found that with the change in the lever ratio when the mass ratio is selected, there are three cases for the optimum grounded stiffness ratio, i.e., negative, zero and positive. Thus, for the vibration reduction of primary structure, the proposed dynamic vibration absorber (DVA) with positive grounded stiffness has the best control performance among the three cases. Compared with some typical designed DVAs under harmonic and random excitation, the results show that with the proposed optimum DVA the resonance amplitude and the frequency band of vibration reduction can greatly reduce and broadened, respectively, and the random vibration mitigation can be greatly increased. According to the existing literature, the proposed lever-type stiffness mechanism is justified, which means that the proposed DVA is practical and can be used in many engineering applications. [ABSTRACT FROM AUTHOR]

Dynamic vibration absorbers (DVAs) have been widely employed in vibration suppression applications for decades. While DVAs offer an effective solution, they are limited by the need for a high mass ratio between the DVA and the primary system to achieve significant vibration attenuation. To overcome this, researchers have introduced lever mechanisms, allowing for enhanced vibration suppression without increasing the mass ratio. However, levers, commonly used as amplification mechanisms, suffer from high inertia and limited amplification, particularly in larger applications. Another limitation is when DVAs are employed for energy harvesting as a secondary objective, they exhibit high sensitivity to system parameter variations, requiring extensive optimization. Various optimization techniques have been applied to DVAs for multiobjective optimization, including fixed-point theory, which is complex and requires intensive mathematical derivation, and simple metaheuristic techniques such as genetic algorithms (GA). This study proposes four novel DVAs using a hydraulic amplifier (HA) to address the limitations of traditional lever mechanisms and a mechanical inerter to improve the vibration damping. Also, multi-objective optimization was performed using particle swarm optimization (PSO) which is considered innovative in this application and compared with commonly used genetic algorithms (GA). The governing equations were derived using Newton's second law and solved numerically with the Runge-Kutta method. An AI-based approach was utilized for HA design. The results show that integrating HA and mechanical inerters significantly enhances vibration attenuation and broadens the frequency response. Additionally, the location of the mechanical inerter is critical in reducing vibration amplitude. Also, the multi-objective PSO outperforms GA in solution diversity and quality. The proposed integration of HA in DVAs offers potential applications across various engineering fields. [ABSTRACT FROM AUTHOR]

Practical engineering structures are subjected to hazardous seismic‐ and wind‐ induced vibrations during their lifetime. They should be designed based on capacity and serviceability targets. Similarly, the design of dynamic vibration absorbers (DVAs) should also meet multiple requirements. However, most current analytical approaches are based on a single‐target response and may lead to cumbersome expressions for complicated scenarios. To address these issues, concise solutions to negative‐stiffness inerter‐based DVAs are proposed in this paper. Firstly, a generic analytical optimization approach for H‐norm solutions considering different response targets of displacement, velocity, acceleration, and transmissibility, is established. Subsequently, the concise solutions are derived based on Taylor's expansion of these analytical solutions by ignoring higher‐order items of the equivalent mass ratio. Finally, the application scope and effectiveness of the proposed concise solutions are discussed. Consequently, the resulting concise solutions are proved to be located close to the pareto fronts of multi‐target optimization results. They have shown superior performances than conventional solutions in controlling the structural capacity and serviceability indicators of a practical five‐story steel frame case under dynamic wind and seismic hazards. Conclusively, the proposed concise solutions are simple in expression and reveal excellent multi‐target performances, which can provide guidance and insights for the optimal design of DVAs. [ABSTRACT FROM AUTHOR]

Abstract The research of rolling mill vibration theory has always been a scientific problem in the field of rolling forming, which is very important to the quality of sheet metal and the stable operation of equipment. The essence of rolling mill vibration is the transfer of energy, which is generated from inside and outside. Based on particle damping technology, a dynamic vibration absorber (DVA) is proposed to control the vertical vibration of roll in the rolling process from the point of energy transfer and dissipation. A nonlinear vibration equation for the DVA-roller system is solved by the incremental harmonic balance method. Based on the obtained solutions, the effects of the basic parameters of the DVA on the properties of vibration transmission are investigated by using the power flow method, which provides theoretical guidance for the selection of the basic parameters of the DVA. Furthermore, the influence of the parameters of the particles on the overall dissipation of energy of the particle group is analyzed in a more systematic way, which provides a reference for the selection of the material and diameter and other parameters of the particles in the practical application of the DVA. The effect of particle parameters on roll amplitude inhibition is studied by experiments. The experimental results agree with the theoretical analysis, which proves the correctness of the theoretical analysis and the feasibility of the particle damping absorber. This research proposes a particle damping absorber to absorb and dissipate the energy transfer in rolling process, which provides a new idea for nonlinear dynamic analysis and stability control of rolling mills, and has important guiding significance for practical production.

Abstract The acoustic black hole (ABH) structure exhibits remarkable energy focalization above a given cut-on frequency, offering potential for broadband vibration suppression in structures. However, its energy focusing properties diminish significantly below this cut-on frequency. Therefore, it is crucial to enhance the vibration attenuation capabilities of ABH structures within the low frequency range. This study presents a numerical investigation into the impact of thin-walled structures with embedded ABHs and distributed dynamic vibration absorbers (DVAs) on low frequency broadband vibration reduction. Initially, the focusing characteristics of the ABH thin-walled structure is analyzed, aiding in the attached position of DVAs. Furthermore, the influence of the design parameters and attached position of DVA on the broadband damping effect of the structure is explored. The findings indicate that DVAs designed for low frequencies can achieve significant vibration attenuation across the entire frequency spectrum, including low frequencies, when installed at specific focusing positions. When compared to the position with the maximum vibration response, while the attenuation of the low frequency common amplitude value is slightly reduced, greater vibration attenuation across the entire frequency band is achieved. This research offers valuable insights into optimizing the integration of DVAs with ABHs in thin-walled structures for enhanced broadband vibration attenuation.

Abstract Vibration quality is a vital indicator for assessing the progress of modern equipment. The dynamic vibration absorber (DVA) based on the acoustic black hole (ABH) feature is a new passive control method that manipulates waves. It offers efficient energy focalization and broad-spectrum vibration suppression, making it highly promising for applications in large equipment such as aircraft, trains, and ships. Despite previous advancements in ABH-DVA development, certain challenges remain, particularly in ensuring effective coupling with host structures during control. To address these issues, this study proposes a partitioned ABH-featured dynamic vibration absorber (PABH-DVA) with partitions in the radial direction of the disc. By employing a plate as the host structure, simulations and experiments were conducted, demonstrating that the PABH-DVA outperforms the original symmetric ABH-DVA in terms of damping performance. The study also calculated and compared the coupling coefficients of the two ABH-DVAs to uncover the mechanism behind the enhanced damping. Simulation results revealed that the PABH-DVA exhibits more coupled modes, occasionally with lower coupling coefficients than the symmetric ABH-DVA. The influence of frequency ratio and modal mass was further analyzed to explain the reasons behind the PABH-DVA's superior damping performance. Additionally, the study discussed the impact of the number of slits and their orientation. This research further explains the coupling mechanism between the ABH-DVA and the controlled structure, and provides new ideas for the further application of ABH in engineering.

The research of rolling mill vibration theory has always been a scientific problem in the field of rolling forming, which is very important to the quality of sheet metal and the stable operation of equipment. The essence of rolling mill vibration is the transfer of energy, which is generated from inside and outside. Based on particle damping technology, a dynamic vibration absorber (DVA) is proposed to control the vertical vibration of roll in the rolling process from the point of energy transfer and dissipation. A nonlinear vibration equation for the DVA-roller system is solved by the incremental harmonic balance method. Based on the obtained solutions, the effects of the basic parameters of the DVA on the properties of vibration transmission are investigated by using the power flow method, which provides theoretical guidance for the selection of the basic parameters of the DVA. Furthermore, the influence of the parameters of the particles on the overall dissipation of energy of the particle group is analyzed in a more systematic way, which provides a reference for the selection of the material and diameter and other parameters of the particles in the practical application of the DVA. The effect of particle parameters on roll amplitude inhibition is studied by experiments. The experimental results agree with the theoretical analysis, which proves the correctness of the theoretical analysis and the feasibility of the particle damping absorber. This research proposes a particle damping absorber to absorb and dissipate the energy transfer in rolling process, which provides a new idea for nonlinear dynamic analysis and stability control of rolling mills, and has important guiding significance for practical production. [ABSTRACT FROM AUTHOR]

The traction motors installed on the bogie frame of high-speed trains are of adverse effect on the bogie hunting stability. Utilising the elastic-suspended motors as dynamic vibration absorbers can increase the hunting critical speed. However, the vibration and dynamic stress of the motor system will be aggravated compared to the rigid motor suspension. In this work, the hunting stability and dynamic stress of a high-speed bogie with elastic-suspended motors are studied. Firstly, the DVA mechanism of hunting stability for a bogie with elastic-suspended motors is conducted by the eigenvalue method. Increasing the critical speed by the elastic motor suspension will sacrifice the motor vibrations and stresses. Secondly, the rigid-flexible coupled dynamic model of the vehicle and motor system is developed to give insight into the consequent effects on dynamic stress. Finally, some countermeasures, e.g. wheel-rail conicity control and motor suspension optimisation, are proposed to suppress the dynamic stress of the motor hanger system. One effective manner to suppress the dynamic stress of the motor hanger system is to improve the hunting stability by limiting the wheel-rail conicity. Another one is to lower the lateral stiffness of the motor suspension and increase the damping ratio of the motor damper. [ABSTRACT FROM AUTHOR]

In engineering practice, dynamic vibration absorber is an effective method to control vibration of beam structure. The mathematical model of beam coupled with spring–mass systems under elastic edge constraints is established in this paper. In addition to Fourier cosine series, supplementary sine functions are introduced to represent the displacement function of the beam. The spring–mass system is considered by increasing degrees of freedom when constructing the mass matrix and stiffness matrix. The efficiency of solving equivalent mass is greatly improved in the comparison with FEM, which is important when designing dynamic vibration absorber. Subsequently, we conduct parametric analysis of the control effect about the dynamic vibration absorber based on the current mathematical model. The procedure of designing distributed dynamic vibration absorber of beam structure under various boundary condition is also presented. To verify the validity of the current mathematical model and design procedure, a cantilever beam experiment was conducted. The findings presented in the current research may be useful for researchers in the process of multi-line spectrum vibration control of beam structure. [ABSTRACT FROM AUTHOR]

The acoustic black hole (ABH) structure exhibits remarkable energy focalization above a given cut-on frequency, offering potential for broadband vibration suppression in structures. However, its energy focusing properties diminish significantly below this cut-on frequency. Therefore, it is crucial to enhance the vibration attenuation capabilities of ABH structures within the low frequency range. This study presents a numerical investigation into the impact of thin-walled structures with embedded ABHs and distributed dynamic vibration absorbers (DVAs) on low frequency broadband vibration reduction. Initially, the focusing characteristics of the ABH thin-walled structure is analyzed, aiding in the attached position of DVAs. Furthermore, the influence of the design parameters and attached position of DVA on the broadband damping effect of the structure is explored. The findings indicate that DVAs designed for low frequencies can achieve significant vibration attenuation across the entire frequency spectrum, including low frequencies, when installed at specific focusing positions. When compared to the position with the maximum vibration response, while the attenuation of the low frequency common amplitude value is slightly reduced, greater vibration attenuation across the entire frequency band is achieved. This research offers valuable insights into optimizing the integration of DVAs with ABHs in thin-walled structures for enhanced broadband vibration attenuation. [ABSTRACT FROM AUTHOR]

The dynamic vibration absorber with inerter and grounded stiffness (IG-DVA) is used to control a two-scale system subject to a weak periodic perturbation. The vibration suppression effect is remarkable. The amplitude of the main system coupled with absorber is significantly reduced, and the high frequency vibration completely disappears. First, through the slow-fast analysis and stability theory, it is found that the stability of the autonomous system exerts a notable regulating effect on the vibration response of the non-autonomous system. After adding the dynamic vibrator absorber, the center in the autonomous system changes to an asymptotically stable focus, consequently suppressing the vibration in the non-autonomous system. Further research reveals that the parameters of the absorber affect the real parts of the eigenvalues of the autonomous system, thereby regulating the stability of the system. Transitioning from a qualitative standpoint to a quantitative approach, a comparison of the solutions before and after the introduction of the dynamic absorber reveals that, when the grounded stiffness ratio and the mass ratio of the dynamic absorber are not equal, the high-frequency part in the analytical solution disappears. As a result, this leads to a reduction in the amplitude of the trajectory, achieving a vibration reduction effect. [ABSTRACT FROM AUTHOR]

It has been challenging to predict the peak spatial accelerations of tall buildings experiencing wind-induced motion. Frequency domain solution techniques using modal analysis are typically employed for wind tunnel studies, in which it is necessary to combine the modal responses statistically to estimate the peak spatial responses. An improved solution technique is presented that treats the determination of the peak accelerations as an optimization problem with a closed-form solution. The peak X, Y, and torsional accelerations are solved using matrix multiplication of the modal response covariance matrix and mode shapes. The peak resultant acceleration is determined by solving an eigenvalue problem. The proposed solution method accommodates correlation between modal responses, which existing methodologies have neglected. A case study is presented in which significant correlation exists between a building's modal responses due to a strong across-wind loading exciting two modes simultaneously. A tuned mass damper (TMD) is incorporated into the building design to reduce wind-induced motions. The TMD transfers energy between structural modes of vibration and increases the correlation between modes considerably. Neglecting modal correlation effects results in a considerable overestimation of some spatial responses and a considerable underestimation of other spatial responses. While a bidirectional TMD decreased the modal responses by a similar amount, due to the strengthened modal correlation not all directions of motion were decreased as much as would be expected if the correlation was not present. It is therefore necessary that DVA systems designed for tall buildings properly account for modal correlation. [ABSTRACT FROM AUTHOR]

Polygonal wheels are a widespread problem in the railway industry. Oscillation phenomena appearing at the wheelset may provide an environment where the wheel polygonization is promoted essentially. The flexibility of the wheelset was highlighted as an important influence on these phenomena in curves with a small radius of curvature at trams in recent studies. A dynamic vibration absorber applied on the wheelset may reduce oscillations at the wheelset significantly and is studied as a potential mitigation measure of wheel polygonization. A basic system model, representing a wheelset with non-driven independently rotating wheels, is used to investigate the mechanism and performance of this passive remedy. Influences of different parameter combinations of the absorber are discussed systematically. The efficiency of the dynamic vibration absorber is analysed further with a more detailed multibody system model of a two-axle tram bogie. Results reveal that an adequately tuned absorber might significantly reduce the possible development and further evolution of predominant polygonal orders. Additionally, basic guidelines for the design of the dynamic vibration absorber applied at the wheelset are pointed out. [ABSTRACT FROM AUTHOR]

Vibration quality is a vital indicator for assessing the progress of modern equipment. The dynamic vibration absorber (DVA) based on the acoustic black hole (ABH) feature is a new passive control method that manipulates waves. It offers efficient energy focalization and broad-spectrum vibration suppression, making it highly promising for applications in large equipment such as aircraft, trains, and ships. Despite previous advancements in ABH-DVA development, certain challenges remain, particularly in ensuring effective coupling with host structures during control. To address these issues, this study proposes a partitioned ABH-featured dynamic vibration absorber (PABH-DVA) with partitions in the radial direction of the disc. By employing a plate as the host structure, simulations and experiments were conducted, demonstrating that the PABH-DVA outperforms the original symmetric ABH-DVA in terms of damping performance. The study also calculated and compared the coupling coefficients of the two ABH-DVAs to uncover the mechanism behind the enhanced damping. Simulation results revealed that the PABH-DVA exhibits more coupled modes, occasionally with lower coupling coefficients than the symmetric ABH-DVA. The influence of frequency ratio and modal mass was further analyzed to explain the reasons behind the PABH-DVA's superior damping performance. Additionally, the study discussed the impact of the number of slits and their orientation. This research further explains the coupling mechanism between the ABH-DVA and the controlled structure, and provides new ideas for the further application of ABH in engineering. [ABSTRACT FROM AUTHOR]

Compared to the two-stage linear vibration isolator (TLVI), the two-stage quasi-zero stiffness (TQZS) system offers superior vibration isolation performance, making it a promising candidate for vibration isolation of precision instrument. However, the TQZS system exhibits a significant vibration amplitude due to its low dynamic stiffness. In this paper, a coupled (TQZS-UDVA) system consisting of a TQZS system and a dynamic vibration absorber (DVA) attached to the upper stage of the TQZS system is presented. The harmonic balance method is employed to obtain approximate analytical solution. The effects of system parameters on dynamic behavior and isolation performance are studied in detail. Five performance indexes are proposed, and based on these indexes, the damping and tuning stiffness of DVA are optimized. The results indicate that the integration of DVA effectively mitigates the vibration amplitude and extends the isolation frequency band, without compromising high-frequency performance. [ABSTRACT FROM AUTHOR]

The tuned mass damper (TMD) is a classical device interesting for reducing deformations between DOFs without physically connecting them. However, it has a practical limit due to the increase in mass required for improving its performance. A building mass damper (BMD) uses mode coupling to make the upper substructure of a chain-like structure behave as a TMD for the lower substructure, which avoids adding mass to the structure. Unfortunately, near-uniform chain-like structures require isolation of the upper substructure for tuning the BMD, making it impractical for retrofitting existing structures since it is an in-series intervention. This paper proposes and evaluates using an inerter, instead of isolating the upper substructure, to control vibrations through mode coupling in a chain-like structure. From an analytical and numerical study, it was found a significant reduction of lower substructure deformations by implementing solely an inerter and a damper in the upper substructure. The inerter-based approach showed similar performance to the classical BMD with the advantage of being an in-parallel intervention. Therefore, this approach constitutes a practical retrofit to improve the dynamic behavior of existing structures with excessive deformations in a lower substructure whose functionality or esthetics would be compromised if control devices were installed in it. [ABSTRACT FROM AUTHOR]

• A novel method is proposed to suppress the torsional vibration of high-damped rotors. • A high-damped rotor is replaced approximately by an equivalent undamped rotor using the WDE. • Two closed-form expressions for a suitable system of springs and viscous dampers are proposed to design an optimal DVA. • The torsional vibration of the high-damped rotor is significantly reduced by attached an optimal DVA. In the rotating systems, the torsional vibration of damped rotors usually appears and induces the imbalance of systems. The dynamic vibration absorber (DVA) is used for reducing the torsional vibration of damped rotors. Recent researches have shown that traditional methods are suitable for reducing the torsional vibration of weak damped rotors. However, the traditional methods will cause significant errors for high-damped rotors. Therefore, a novel method is proposed to suppress the torsional vibration of high-damped rotors using a dynamic vibration absorber based on Weighted Dual Estimation (WDE) of equivalent linearization techniques. The high-damped rotor is replaced approximately by an equivalent undamped rotor based on the WDE of equivalent linearization techniques. Two closed-form expressions for a suitable system of springs and viscous dampers of the optimal DVA are determined to suppress the torsional vibration of high-damped rotors. The numerical analysis results show that the torsional vibration of the high-damped rotor has surprisingly reduced at the resonant frequency region by using the optimal DVA. The proposed expressions for a suitable system of springs and viscous dampers of the optimal DVA are reliable for suppressing the torsional vibration of a highly damped rotor. [ABSTRACT FROM AUTHOR]

The Fluid Dynamic Vibration Absorber (FDVA) is a dynamic vibration absorber where the inductance is gained by translated fluid mass and the capacitance by coil springs. Due to the hydraulic transmission, the FDVA is a lightweight component compared to other dynamic vibration absorbers. As shown in this paper, the FDVA reduces the wheel load fluctuation of a passenger car. After optimisation, the FDVA is integrated into a damper's piston rod. Experiments in a quarter-car test rig show the benefit of the integrated FDVA compared to a standard damper. Excited by a stochastic road profile, the measured benefit with FDVA is $ 3.5\% $ 3.5 % more comfort and $ 4.3\% $ 4.3 % less wheel load fluctuation. [ABSTRACT FROM AUTHOR]

Improving the control performance of dynamic vibration absorbers has recently been effective by introducing a grounded negative stiffness device. However, the negative stiffness structure is unstable and difficult to achieve in engineering practice , and its major drawback is that it amplif ies the vibration response of the primary system at low frequency region. Meanwhile, some mechanical devices can be combined to make the DVA work even better with a grounded positive stiffness. For this purpose, this paper combines for the first time the control effect of the inerter device and grounded positive stiffness into a three-element DVA model in order to better improve vibration reduction of an undamped primary system under excitation. First, the dynamic equation of motion of the system is written according to Newton 's second law. Then, the steady-state displacement response of the primary system under harmonic excitation is calculated. In order to minimize the resonant response of the primary system around its natural frequency, the extended fixed point theory is applied. Thus, the optimized parameters such as the tuning frequency ratio, the stiffness ratio , and the approximate damping ratio are determined as a function of mass ratio and inerter – mass ratio. From the results analysis, it was found that the inerter – mass ratio has a better working range to guarantee the stability of the coupled system. Then , study on the effect of inerter – mass ratio on the primary system response is carried out. It can be seen that increasing the inerter – mass ratio in the optimal working range can reduce the response of the primary system beyond its uncontrolled static response. However, it is necessary to avoid the situation where the inerter – mass ratio is very large because it can lead to unrealistic optimal parameters. Finally, comparison with other DVA models is show n under harmonic and random excitation of the primary system. It is found that the proposed DVA model in this paper has high control performance and can be used in many engineering practice s. [ABSTRACT FROM AUTHOR]

Dynamic vibration absorbers (DVAs) have been widely employed in vibration suppression applications for decades. While DVAs offer an effective solution, they are limited by the need for a high mass ratio between the DVA and the primary system to achieve significant vibration attenuation. To overcome this, researchers have introduced lever mechanisms, allowing for enhanced vibration suppression without increasing the mass ratio. However, levers, commonly used as amplification mechanisms, suffer from high inertia and limited amplification, particularly in larger applications. Another limitation is when DVAs are employed for energy harvesting as a secondary objective, they exhibit high sensitivity to system parameter variations, requiring extensive optimization. Various optimization techniques have been applied to DVAs for multi-objective optimization, including fixed-point theory, which is complex and requires intensive mathematical derivation, and simple metaheuristic techniques such as genetic algorithms (GA). This study proposes four novel DVAs using a hydraulic amplifier (HA) to address the limitations of traditional lever mechanisms and a mechanical inerter to improve the vibration damping. Also, multi-objective optimization was performed using particle swarm optimization (PSO) which is considered innovative in this application and compared with commonly used genetic algorithms (GA). The governing equations were derived using Newton’s second law and solved numerically with the Runge-Kutta method. An AI-based approach was utilized for HA design. The results show that integrating HA and mechanical inerters significantly enhances vibration attenuation and broadens the frequency response. Additionally, the location of the mechanical inerter is critical in reducing vibration amplitude. Also, the multi-objective PSO outperforms GA in solution diversity and quality. The proposed integration of HA in DVAs offers potential applications across various engineering fields.

This paper presents an advanced vertical control system using active suspension to stabilize the vertical motion of an in-wheel motor-driven electric vehicle. The design of the control system and conceptualization were carried out by mathematical modeling with integration with the quarter car model. A novel active suspension is developed through the model-based design to control the vehicles to move smoothly and continuously. Even though experimental validation is an effective and more accurate method to evaluate the control system, it is important to reduce the dependency on physical testing. Thus, a reliable simulation framework would be beneficial in the vehicle development process. In this paper, the hydraulic system is designed and simulated by using the Simcenter Amesim. For the dynamic vibration absorber, we are seeking to design a skyhook control to control the damping force by an electric damper, whereas the spring stiffness can be switched by opening and closing the fluid passage to the gas chamber. In the spring stiffness control, the stiff suspension can reach a ratio of 1.3 compared to the soft suspension. The objective of this research work was realized with the proposed simulation framework to test the effectiveness of suspension control system to improve ride and handling in a four in-wheel motor-driven electric vehicle.

Structural vibration has always been a major concern in the engineering field. A dynamic vibration absorber in the form of contacts with adjustable stiffness (CDVA) offers effective vibration suppression and can improve conventional dynamic vibration absorbers with high sensitivity to frequency deviation and difficulty in adjusting the frequency. In this research, first, based on the theoretical model of the contact between a rubber ball and an inner cone, the feasibility of changing the axial contact state to change the structure's natural frequency was verified using an ANSYS simulation. A theoretical model of the static contact stiffness between the ball and the inner cone was constructed using Hertzian contact theory and Hooke's law, and a theoretical model of the cubic nonlinear elastic restoring force was used to characterize the stiffness properties of the rubber ball during compressive rebound. The steady-state frequency response equations of the main vibration structure were derived using the averaging method in conjunction with the two-degree-of-freedom dynamics model, and the stability of the solutions to the frequency response equations was obtained in conjunction with the stability determination criterion. Then, the impact of the CDVA's design parameters on the nonlinear dynamic response of the primary vibration structure was simulated and analyzed. The resulting findings can serve as guidance for designing dynamic vibration absorber parameters. Based on the principles of ball-inner cone contact, a dynamic vibration absorber structure was proposed. A design test was conducted to verify the correctness of the contact stiffness model, and an experimental study was carried out to investigate the law of change in the dynamic stiffness and damping of the principle structure of CDVA under dynamic excitation conditions. Finally, the vibration test platform of the solidly supported beam structure was constructed, and vibration suppression tests of the CDVA in different compression states were conducted to investigate the tunability and feasibility of CDVA vibration suppression. The results showed that the dynamic vibration absorber had good vibration absorption characteristics and could be used for single-mode vibration suppression of multimodal main structures. [ABSTRACT FROM AUTHOR]

Purpose: This paper propose a grounded-type DVA attached to a damped primary system, which can effectively suppress the vibration amplitudes by introducing a lever, focusing on the optimal design of the novel DVA. It can be utilized to the simplified model of a damped spacecraft or stay cable of cable-stayed bridges. Methods: The design of DVA considers H ∞ and H 2 optimization criteria, and defines performance indicators separately. In the H ∞ optimization, we couple generalized fixed-point theory (GFPT) and perturbation method (PM) with particle swarm optimization (PSO) algorithm to minimize the maximum amplitude amplification factor of primary system, so that the amplitudes at two fixed points are close to the same horizontal line. Nevertheless, in the H 2 optimization, the GFPT and PM are combined with Newton's method to minimize the power input to primary system. Results: The numerical results indicate the consistency and effectiveness of the two optimization criteria. Compared with other classical models, the effects of different grounded stiffness ratios on the amplitude frequency responses, time histories, and vibration energies of the primary system subjected to harmonic excitation and random excitation, respectively, as well as the vibration reduction effect, are studied. Conclusions: Numerical simulations display with the positive grounded stiffness, the proposed DVA outperform the existing DVAs with same mass, damping, and stiffness under the harmonic excitation and random excitation. The results can provide theoretical and computational guidance for the optimal design of DVA. [ABSTRACT FROM AUTHOR]

The quasi-zero stiffness (QZS) system, as a typical high-static-low-dynamic-stiffness (HSLDS) system, is able to realize low frequency vibration isolation by introducing nonlinear negative stiffness. However, the nonlinearity of the system may result in a serious deterioration of the isolation performance under large amplitude excitation. In this paper, an inerter-based combined vibration isolation (IBCVI) system is proposed to overcome this problem. The IBCVI system consists of a QZS system and an inerter-based linear dynamic vibration absorber (IBDVA). The harmonic balance method is employed to obtain amplitude–frequency response of the IBCVI system, and the mechanism of IBDVA on vibration isolation system is revealed. Then the effects of system parameters on control performance are studied in detail. The results of the comparison with other models show that the presented model performs smaller vibration amplitude and wider isolation frequency band. This research provides a new insight into vibration isolation under large amplitude excitation from the perspective of vibration absorption. [ABSTRACT FROM AUTHOR]

This article investigates the parameter optimization problem for a novel inerter-based dynamic vibration absorber (IDVA) system with a grounded negative stiffness spring, which can be applied to many vibration control systems, such as building vibrations, bridge vibrations, vehicle suspensions, etc. The passive mechanical network in the IDVA system of this article is the parallel connection of a passive spring and a three-element damper-spring-inerter series network. First, the motion equations of the IDVA system are established based on Newton's second law, and the transfer function in the dimensionless form is derived. Then, the H ∞ optimization problem is formulated for the given values of the mass ratio and negative stiffness ratio. Since it is found that the frequency response curves of this system pass through four fixed points that are independent of the damping ratio, the extended fixed-point method is adopted to optimize the system. Then, the analytical solutions of the optimal parameter values in terms of the mass ratio and negative stiffness ratio are derived, and the necessary and sufficient condition for the IDVA system with optimal parameter values to be stable is obtained by the Hurwitz criterion. Compared with other four optimal DVAs in the existing literature, the optimal IDVA system with a grounded negative stiffness spring can provide better H ∞ performance, and the numerical examples illustrate that the system can provide better time-domain performances under random excitations. [ABSTRACT FROM AUTHOR]

In this paper, the possibility of harvesting energy from the vibrations of a plate is analyzed. The harvester takes the form of a cantilever dynamic vibration absorber equipped with a piezoelectric layer and tuned by means of a tip mass to the first mode of vibration of the plate. A mathematical model of the coupled system composed of the plate and the harvester is presented. The validity of the proposed harvester is proved by means of simulations carried out with the modal expansions approach. Simulation results highlighting the effects of harvester tuning and location are presented as well. Then, the validity of the harvester is confirmed by experimental tests carried out both with a concentrated impulsive load and with a distributed pressure load. Simulations and experimental tests are performed on the cantilever piezoelectric dynamic vibration absorber and on the same piezoelectric layer directly bonded to the plate surface. Results show an improvement in terms of generated voltage when the proposed novel device is used in place of the simple layer. [ABSTRACT FROM AUTHOR]

Purpose: This paper is concerned with the H∞ optimization design of passive and active dynamic vibration absorbers (DVAs) attached to an undamped or damped primary system. Methods: The proposed optimization method is an efficient non-smooth H∞-synthesis algorithm that is utilized to solve structured H∞-synthesis in control engineering. This method can conveniently achieve the optimal design for the amplitude magnification factors of both the absolute and the relative displacements of a DVA using the proposed dual H∞ design, and implement co-design of H∞-optimal proportional-integral-differential controllers and passive parameters of an active DVA. Results: Two active DVAs and two variant passive DVAs reported in the literature are taken as examples for design improvement. The optimization results indicate that the proposed method has significant advantages over the conventional fixed-points-theory-based methods and many numerical global optimization methods. Conclusions: The proposed H∞ optimization design yields much better vibration suppression result for proportional-integral-differential control based active DVAs and variant passive DVAs with complicated structures. It is directly based on their equations of motion in state-space forms, and explicit formulations of various amplitude magnification factors, such as those on the absolute and the relative displacements and active force, need not be derived in the MATLAB environment. A possible situation of occurrence of large amplitude of the relative displacement in DVAs rarely considered in the literature can be handled by using the proposed dual H∞ design. [ABSTRACT FROM AUTHOR]

This paper describes the construction of the numerical model of a passive damping device called eMDVA (embedded Mass Dynamic Vibration Absorber) and experimental investigation of the eMDVA's multi-modal damping effect for elastic vibrations of a plate-like structure. The eMDVA consists of a ball-like mass embedded in a viscoelastic medium; and the mass can vibrate in every direction. When the thickness of the viscoelastic medium differs in the X, Y, and Z directions, the ball-like mass has different natural frequencies for every vibration direction. An appropriate numerical model that can predict these natural frequencies correctly is needed to design the eMDVA; in particular, defining the viscoelastic properties is an important and challenging subject. In this work, the Prony series is used to express the viscoelastic material, and the setting process of the coefficients in the Prony series is studied. It has been shown that using a sufficient number of terms in the Prony series and using sufficient measurement data to define their coefficient leads to good results in expressing the viscoelastic material. Using the constructed viscoelastic model, vibration characteristics of the eMDVA, such as the change of the natural frequencies versus the viscoelastic material's shape change and frequency response characteristics, are investigated numerically using a commercial finite element software Ansys. After that, an eMDVA is produced and applied to a plate-like elastic structure. A series of excitation tests are conducted, and the multi-mode vibration reduction effect by the eMDVA has been demonstrated.

Purposes In order to suppress the vertical vibration of the mill during rolling process, a multi-degree-of-freedom particle damping absorber (PDA) combined with dynamic vibration absorber and particle damping technology for vertical vibration control of the roll is propsed. Besides, the vibration transfer and energy dissipation behavior of the coupled Roll-PDA system is in vestigated. Methods A four-degree-of-freedom vertical vibration model of the coupled system is established, and the steady-state solution of the system is obtained by using the Incremental Harmonic Balance Method (IHBM).The influence law of the stiffness coefficients and damping coefficients in the PDA on the power flows is investigated. Findings The results show that, for different external excitation frequencies, the flow direction of the roll vibration energy of the rolls can be changed by controlling the PDA parameters. In addition, the effect of particle parameters on the vibration energy dissipation behavior of particle groups is analyzed by using PFC3D software simulation, and the results show that the smaller the particle size and the larger the filling rate, the better the particle group energy consumption effect.

The vibration isolation and absorption technologies for ship mechanical systems were reviewed, such as the concept, the application background, and the research status of floating raft vibration isolation systems and dynamic vibration absorbers. Meanwhile, the concept and development of passive control and active control were also analyzed. The smart materials and new structural forms were summarized. The concept, the working condition and the development of control components such as the quasi-zero stiffness vibration isolator, the acoustic black hole structure, the intelligent material actuator, and the active and semi-active dynamic vibration absorbers, were considered, and the control strategies of the active control were discussed. Besides, the theoretical and numerical methods for modelling, calculating and testing mechanical damping systems were also surveyed. At last, the development trend of the ship mechanical vibration reduction and isolation system was envisioned and portrayed. [ABSTRACT FROM AUTHOR]

Hybrid vibration absorbers (HVAs) are an effective solution for vibration mitigation. They combine the passive vibration absorption mechanism of tuned mass dampers (TMDs) with feedback-controlled actuators, similar to active mass dampers. This enables them to overcome the performance of both systems in terms of vibration mitigation effectiveness and energy consumption, respectively. This study evaluates the vibration suppression capabilities of an HVA against self-excited oscillations. A single-degree-of-freedom host system encompassing a negative damping term is considered. First, the possibility of enhancing the stability properties of an optimally tuned TMD through a feedback controller is evaluated. The analysis shows that this approach cannot improve the absorber's performance. Subsequently, simultaneous optimization of all the HVA parameters is considered. Our results reveal that this approach significantly enhances the system's performance. All analysis is carried out analytically without resorting to approximations. Finally, the absorber is numerically applied to suppress friction-induced vibrations and galloping instabilities. [ABSTRACT FROM AUTHOR]

This article is devoted to the development of a dynamic vibration absorber as a system in which an air spring moves between guides of a given shape perpendicular to their axis of symmetry. The shape of the guides is determined from the condition that the characteristic of the dynamic absorber is linear, which is equivalent to a spring with a given stiffness. The main disadvantage of most modern dynamic absorbers is that they are effective when operating only at a certain frequency of the driving force acting on a protected object. With a small change in this frequency, the amplitude of the protected object can increase many times over. This article proves that, by changing the designed pressure in the air spring of the proposed absorber, it is possible to get a given stiffness, at which it is effective at different frequencies of the driving force. [ABSTRACT FROM AUTHOR]

Two kinds of periodic composite pipes with support or dynamic vibration absorber are designed based on the theory of phononic crystals. Axial vibration and band gaps of composite fluid-filled pipe are calculated by using transfer matrix method and Bloch wave theory. The present fluid–structure interaction model and frequency domain calculation method are validated by comparing the velocity of fluid from a FEM model. The results show that the stop bands frequency of velocity responses are in good agreement with band gap. Longer length of a single cell decreases the beginning frequency and width of both two kinds' band gaps. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the realm of precision engineering, particularly in deep hole boring processes, tool vibration emerges as a critical determinant of machining performance. This investigation elucidates the genesis of self-excited vibrations within deep hole boring operations and delineates the underlying mechanisms of cutting tool vibration. A focal point of this study is the optimal alignment of the boring bar to mitigate vibrational impacts, thereby enhancing surface finish quality and extending tool longevity. Central to this analysis is the employment of a Dynamic Vibration Absorber (DVA) aimed at attenuating cutting tool vibration. The deployment of DVA necessitates precise identification of modal parameters, namely the equivalent stiffness (K) and mass (M) of the cutting tool. This research juxtaposes various scholarly methodologies to amalgamate theoretical calculations with simulation approaches, thereby acquiring accurate modal parameters. Utilizing Matlab software, the vibration amplitude of the boring bar under varying spring stiffness scenarios was examined. Results indicate a direct correlation between increased stiffness and reduced amplitude, particularly when the frequency ratio g ranges between 0.5 and 1.1. Consequently, a stiffer DVA configuration is posited as more effective in vibration reduction. Furthermore, the study conducted frequency sweep experiments on a damping boring bar, utilizing a vibration excitation platform. These experiments revealed the existence of an optimal stiffness value for the DVA, thereby underscoring the significance of stiffness matching in vibration mitigation strategies. [ABSTRACT FROM AUTHOR]

A magnetorheological (MR) damper is effective and economical for miscellaneous applications in automotive, mechanical, civil, and relative fields. A parameter tuning methodology independent of manual trial-and-error has received much technical interest for controlling vibrations. The present work contributes mathematical and Simulink modeling followed by MR damper design and development for vibration optimization of the single degree of freedom system. A Simulink model of an MR damper is performed on the mathematical model for vibration control, and the MR damper's tuning parameters are experimentally investigated to control the resonance frequency. Theoretical simulated results and its experimental verification show that increasing current raises the force to control the resonance frequency in an MR damper. The present approach provides a concise and improved platform for dynamic vibration absorber in the current potential market and the highly interested control community for the development of the distinctive attributes of the MR Damper. [ABSTRACT FROM AUTHOR]

Chatter is one of the major issues that cause undesirable effects limiting machining productivity. Passive control devices, such as tuned mass dampers (TMDs), have been widely employed to increase machining stability by suppressing chatter. More recently, inerter-based devices have been developed for a wide variety of engineering vibration mitigation applications. However, no experimental study for the application of inerters to the machining stability problem has yet been conducted. This article presents an implementation of an inerter-based dynamic vibration absorber (IDVA) to the problem of chatter stability, for the first time. For this, it employs the IDVA with a pivoted-bar inerter developed in the study by Dogan et al. (2022, "Design, Testing and Analysis of a Pivoted-Bar Inerter Device Used as a Vibration Absorber, Mechanical Systems and Signal Processing," 171, p. 108893) to mitigate the chatter effect under cutting forces in milling. Due to the nature of machining stability, the optimal design parameters for the IDVA are numerically obtained by considering the real part of the frequency response function (FRF), which enables the absolute stability limit in a single degree-of-freedom (SDOF) to be maximized for a milling operation. Chatter performance is experimentally validated through milling trials using the prototype IDVA and a flexible workpiece. The experimental results show that the IDVA provides more than 15% improvement in the absolute stability limit compared to a classical TMD. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Vibration, Measurement & Diagnosis is the property of Nanjing Hangkong Daxue and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)