Passive Vibration Research Articles

Vibration suppression of a linear oscillator by a chain of nonlinear vibration absorbers with geometrically nonlinear damping

Nonlinear energy sink (NES) is a lightweight vibration absorber that is coupled to linear primary structure for passive vibration mitigation. In this work, we aim to investigate the effects of geometrically nonlinear damping on the capacity of multiple-degree-of-freedom (MDOF) NES to mitigate forced responses of the impulsively and harmonically loaded linear oscillator (LO). For the system under applied shock excitation, extensive simulation results show that the internal use of nonlinear damping enables the MDOF NES to rapidly and effectively absorb, transfer and dissipate the shock-induced energy for a broad range of initially imparted energies, particularly for the high or very high energy levels. The effectiveness of the optimized MDOF NES is further improved since the large-amplitude oscillations of the LO are reduced to a sufficiently low level during initial regime of motion. When the LO is subjected to harmonic excitations, the analytical study is performed to obtain the slow invariant manifold (SIM) by means of complexification-averaging (CX-A) method. The complex geometry of SIM reveals the energy transfer paths when the system reaches steady state. The global system behavior (strongly modulated response or periodic oscillation regimes) is analytically predicted by the singular points and ordinary equilibrium points, and a close match is achieved between theoretical analysis and numerical results. It is found that the proposed MDOF NES with nonlinear damping can eliminate the upper closed high-amplitude isolated branch, and the frequency bandwidth of multiple steady-state responses also decreases, the robustness and capacity of vibration attenuation by the proposed NES is dramatically enhanced. The findings in this work facilitate the design and broad applications in diverse engineering fields for the protection and safe operation of mechanical structures.

Fatigue Damage Mitigation for Welded Beam-to-Column Connections in Steel High-Rise Buildings Using Passive Vibration Control

To investigate the use of vibration control systems in fatigue damage mitigation for welded beam-to-column connections in steel high-rise buildings, cases of both a single connection under constant amplitude cyclic loading and multi-connections in a high-rise building under the stochastic wind, with and without the fluid viscous damper (VFD) and the tuned mass damper (TMD), are discussed respectively. The finite element analysis and the fatigue assessment are conducted so that the mitigation effect, the effect of technical parameters and the conditions of both high-cycle fatigue and low-cycle fatigue are all discussed. The results show that the VFD and the TMD systems are both effective in the mitigation of local fatigue damage along with the structural displacement for both cases. The VFD generally has a better mitigation effect than the TMD and it starts to take effect instantly with the external loading, but it causes a phase difference in structural responses, while the situation of the TMD is quite the opposite. The displacement and the local stress show similar and synchronous mitigation trends so that the damping systems can be designed based on either of them. The VFD should be designed with a smaller damping exponent and a larger damping coefficient in a braced installation form, while the TMD can be designed using the optimal parameters. The optimized VFD layout plan is that VFDs are placed between the two connections with large relative displacement and relative velocity on higher floors and these two connections with VFDs should be near to the targeted connection. The negative fatigue damage mitigation mainly stems from insufficient lateral support force so that the direct installation of VFDs may result in a negative fatigue damage mitigation effect in the connections with limited lateral support.

Lyapunov-Based Stability Analysis for Fluid Conveying System With Parallel Nonlinear Energy Sinks

In order to reduce the possibility of structural fatigue and increase the lifetime of conveying fluid pipe, transverse vibration must be effectively eliminated. In this work, using parallel nonlinear energy sinks (NESs), a passive vibration controller is proposed to dissipate the vibration energy of the conveying fluid pipe. A high-order model of the conveying fluid pipe-parallel NESs system, in the form of partial differential equation, is derived and then converted into a quadratic form model containing the gradient information of a convex function. Combining the energy disturbance technique and first order convexity characteristic, the exponential stability of the closed-loop system is proved, which addresses the effectiveness of the proposed parallel NESs. Then, numerical simulations are given to verify the theoretical results and to illustrate the advantages of parallel NESs comparing with single NES. Finally, the reliability of the proposed approach is preliminarily verified through experiment.

Assistant investigation of energy dissipation in non-obstructive particle damper based on a neural network using simulated annealing backpropagation

The particle damper has been widely used as an efficient passive vibration control device in recent years. The highly non-linear characteristic of the energy dissipation mechanism is essential for our increased understanding of non-obstructive particle damper (NOPD). To connect motion modes of the granular system and energy dissipation, we developed a neural network using simulated annealing backpropagation (SA-BP) to predict the loss factor of NOPD in this paper. The simulations based on the verified discrete element method (DEM) model are carried out, and the data is used to train and test the neural network. Based on the prediction of a well-trained neural network using SA-BP, the relationship between the loss factors and the rheology behaviors of the granular system is discussed. This paper effectively combines intelligent algorithms (SA-BP) and particle damping characteristics. The algorithm is expected to be further used as an auxiliary method for the experimental study of the granular system.

A negative stiffness dynamic base absorber for seismic retrofitting of residential buildings

In this study, a negative stiffness-based passive vibration absorber is developed and implemented as a seismic retrofitting measure for typical reinforced concrete (RC) residential buildings. The device, namely, the extended KDamper for retrofitting (EKD-R), is introduced at the base of the structure, between the foundation level and the first story of the building. The design of the EKD-R device and the selection of its properties are undertaken by incorporating a harmony search (HS) algorithm that provides optimized parameters for the mechanism, following constraints and limitations imposed by the examined structural system. Nonlinearities due to the plastic behavior of the structural members and soil–structure interaction (SSI) effects are modeled and taken into consideration during the process. Subsequently, a realistic case study of a benchmark three-story RC building is examined, and the performance of the EKD-R system is assessed. The building superstructure is designed according to Eurocodes. The structure–foundation system, along with the EKD-R, is explicitly modeled using finite elements (FE) that may realistically capture structural nonlinearities and SSI effects. The HS algorithm is employed, and optimized EKD-R components are obtained and implemented in the benchmark structure. Finally, a series of recorded real ground motions are selected, and nonlinear time-history dynamic analyses are conducted aiming to assess the behavior of the controlled system. Results indicate the beneficial role of the novel dynamic absorber, hence rendering the concept a compelling seismic retrofitting technology.

Damping performance of particle dampers with different granular materials and their mixtures

A particle damper is a passive vibration control technology that utilizes the high damping properties of granular materials for reducing the vibration amplitude of a structure over a wide frequency range. Energy dissipation of particle damper is a highly nonlinear and complex physical phenomenon [1]. Previous studies have shown that the damping mechanism of a particle damper depends on several factors, like particle size and shape, granular material, filling ratio, and the number of particles [2–5]. Out of these parameters, the type of granular material used in the particle damper plays a major role in reducing the vibration amplitude of a mechanical structure. Therefore, the current contribution aims to investigate the influence of 20 different granular materials on vibration attenuation. The granular materials under investigation are subdivided into two major groups, namely: soft particles, like rubber granulate, and hard particles, like steel balls. Furthermore, this paper proposes a hybrid particle damper in which two different types of granular material mixtures are used, i.e. a particle damper in which for instance soft particles are mixed with hard particles. Moreover, in this contribution, fine particles, like rubber powder are mixed with hard granular materials like lead shot, which can be seen as an extension of the fine particle impact damper concept [6]. The humidity-dependent behavior of particle dampers is also another important issue, which is addressed in this paper. To investigate the vibration attenuation efficiency of all the granular materials and their mixtures including the humidity-dependent behavior, a laser scanning vibrometer device is used. Generally, the relationship between the vibration response and the granular material mass is rarely addressed in the literature, which can restrict the industrial application of particle dampers. Hence, the additional mass of the granular material is also a focus of this paper. The experimental investigation shows that the vibration response of the test specimen is significantly lower for particles with lower densities in the low-frequency range. Furthermore, an excellent damping efficiency can be also observed for the particle damper with a granular material mixture. The results obtained in this study are not restricted to any special structure and can be implemented in several industrial applications, where vibration and noise attenuation plays a major role, like automotive, aerospace, wind turbine, medical technology, mining, etc.

Characteristics of passive vibration control for exponential non-viscous damping system: Vibration isolator and absorber

Materials or structures made of polymers or composites often exhibit non-viscous damping behavior. The non-viscous damping forces that depend on the history velocity can be expressed by the exponential non-viscous damping model. Some polymer or composite materials can be used as damping materials for kinetic energy absorption in the dynamic systems. Vibration isolator and absorber are usually considered for shock absorption. In this study, transfer ratios of vibration isolator and absorber with exponential non-viscous damping system are derived by using the Laplace transform. The dimensionless amplitude of vibration absorber with exponential non-viscous damping is derived too. Compared to viscous damping system, transfer ratio and dimensionless amplitude of exponential non-viscous damping system are influenced by the ratio of the relaxation parameter and natural frequency or the frequency of the external load. With the non-viscous damping material used in vibration control, the ratio is therefore a non-negligible factor which should be considered in analysis.

A passive self-tuning vibration neutraliser using nonlinear coupling between the degrees of freedom

Vibration neutralisers are widely used to suppress vibration of a host structure subject to external excitation at a specific frequency. When attached to a structure, they create a notch filter in the frequency response, reducing the vibration levels considerably. An inherent limitation is related to the narrow frequency range in which they are effective. Over the years, there have been different attempts to make the vibration absorber more robust. These include using active and semi-active control strategies to change the tuning frequency, using piezoelectric elements with shunt circuits, electromagnetic actuators, servo motors, and even exploring nonlinear effects. In many cases, there is a need for an external power source to modify the characteristics of the system. This paper concerns a passive vibration neutraliser that can adapt automatically to one of two frequencies corresponding to the frequency of an external harmonic force. Importantly, it does this without the need for an external power source. The device consists of a beam-like neutraliser that is attached to the host structure at its centre through a roller bearing. The stiffness element is a rectangular beam that can rotate in the bearing, changing the stiffness it presents to the direction of excitation. The paper describes an experimental study into such a device, and an analytical model is proposed that qualitatively captures the time-domain behaviour of the experimental device. A possible mechanism by which the device self-tunes to either of the two frequencies of excitation is discussed. Supplementary material is also provided to show the device in operation.

Modeling and optimization of multiple tuned mass dampers for a barge-type floating offshore wind turbine

Significant structural responses pose potential hazards to the safe operation of floating offshore wind turbines (FOWTs). To effectively mitigate the motion of FOWTs using conventional passive vibration control methods such as tuned mass damper (TMD) and multiple tuned mass damper (MTMD), an optimization method for TMD and MTMD in a barge-type FOWT is proposed in this study. A simplified dynamic model of a barge FOWT with MTMD, which includes the tower first bending and floating platform degrees of freedom (DOFs), in addition to the simplified DOF of the MTMD, is derived. The corresponding fully coupled numerical model is established using the updated simulation tool FAST-SC. Subsequently, the unknown parameters and accuracy of the simplified dynamic model are validated via comparison with the results of the coupled numerical model. Moreover, an optimization method is proposed based on the simplified dynamic model considering the prominent coupling effects of FOWT and computational expense, and the GA algorithm is used for TMD and MTMD optimization. Furthermore, the effectiveness of the optimized TMDs and MTMD is evaluated based on the reduction in the coupled responses of the barge FOWT under the selected environmental conditions. Compared with the optimized TMD in the nacelle, the optimized TMD in the platform and MTMD are proven to be more feasible for vibration mitigation under complex environmental loads. Moreover, an improved steady output is obtained using the optimized vibration control methods, in addition to the excellent mitigation effects on structural responses.

Exact augmented perpetual manifolds as a tool for the determination of similar rigid body modes: Corollary for determining backbone curves of autonomous systems

Perpetual points in mathematics have been defined recently, and their significance in describing the dynamics of systems is ongoing research. In mechanical engineering, the perpetual points of linear unforced mechanical systems are associated with rigid body motions, and they form the perpetual manifolds. The systems that admit perpetual manifolds of rigid body motions are called perpetual mechanical systems. The concept of perpetual manifolds has been extended to the exact augmented perpetual manifolds, whereas all the accelerations are equal but not necessarily zero. A theorem defines the conditions of external forces that lead to rigid body motion of externally forced mechanical systems. Herein, based on this theorem, a corollary is proven that, through a very simple framework, defines specifications to mechanical systems resulting in the existence of rigid body similar modes and can serve as a tool in the nonlinear normal modes (NNMs) theory for the determination of their backbone curves of dissipative mechanical systems. Further, on these, backbone curves can be used for passive vibration control design of N-degree-of-freedom (dof) mechanical systems. The verification of the theory has been done with the design of a 5-dof nonlinear perpetual mechanical system with three types of boundaries, linear, nonlinear smooth, and nonsmooth boundaries. The numerical simulations results are in excellent agreement with the theory. Although 5-dof mechanical systems have been examined, the corollary is valid for N-degree-of freedom systems. The corollary provides a simplified framework for the design of mechanical systems to admit rigid body modes for systems with a general configuration that is not obvious using traditional techniques. This work is rather significant in mechanical engineering because it provides a new tool firstly for determining similar NNMs of dissipative mechanical systems and secondly for the design of passive vibration control devices.

Analytical approach to suppress the vibration of spur gear pair using particle damping technique

Vibration and noise have annihilated effect on the mechanical systems. These two are main adverse parameters leading to many undesirable effects lead to fatigue and failure of the machine decreased reliability, energy losses and degraded performance. Vibration damping is reactive vibration control method. Passive and active damping techniques are used to reduce the resonant vibrations. Theory of energy dissipation mechanism is followed by particle damping and is one of the passive vibration control technology. Particle damping, an impact mass is attached contains number of particles. The dissipation of loss of vibrational energy will occur due to impact, friction and change of energy. Damping is an effect of reducing, preventing its oscillations. Particle impact dampers are used to decrease the undesirable vibration in automobile industries, robots aerospace industries, gear box, etc. like engineering applications. This paper focused on the particle damping technology to reduce the vibrations generated in transmission spur gear. The model is developed which have cavity or holes in which particle dampers are present; it decide the relation between friction coefficient of the particles at constant rotational speed, various particle size. In present research damping particle of different sizes are selected to study the effect on damping using modal analysis. We found that, at the low or minimum speed, small and edgeless particles have good damping impact and at fast speed, more unpleasant and irregular particles are even better. It is observed that, the particle size and damping effect are directly proportional. This reduces the noise and harshness in system and ultimately improves the quality performance and life of the gearbox.

Mitigation of subway-induced low-frequency vibrations using a wave impeding block

The effective control of low-frequency vibrations induced by subway operation remains a problem, but wave impeding blocks (WIBs) have the potential to solve this issue. To investigate the vibration isolation behavior of WIB under subway loading, this study established a coupled track-tunnel-ground-WIB model using the two-and-a-half dimensional finite element method (2.5D FE). The effect of bedrock on wave propagation was first revealed by analyzing the eigenfrequencies of the soil layer with a tunnel. It was found that the bedrock reduced ground-borne vibrations with a frequency lower than the cut-off frequency of the soil layer. Based on this observation, the vibration isolation behavior of the WIB with different locations, embedding depths, material types, and dimension parameters was analyzed in detail. The WIB located beneath the tunnel invert (near-field active vibration isolation) exhibits a completely different behavior than that beneath the ground surface (far-field passive vibration isolation). The former can reduce ground vibrations in the entire ground surface, whereas the latter only works in a limited region directly above the WIB. The far-field vibration isolation effect is not sensitive to the vibration frequency and embedding depth, but the WIB dimension and rigidity have a significant impact. The near-field vibration isolation effect is most significantly influenced by the embedding depth, followed by the material property and dimension parameter. The WIB installed beneath the tunnel invert with a thinner embedding depth and stiffer rigidity more effectively isolates low-frequency vibrations induced by the subway.

Implementation of Active and Passive Vibration Control of Flexible Smart Composite Manipulators with Genetic Algorithm

Implementation of Active and Passive Vibration Control of Flexible Smart Composite Manipulators with Genetic Algorithm

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

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

Control of pendulum oscillations by Tuned Liquid Dampers

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

Recent Advances in Quasi-Zero Stiffness Vibration Isolation Systems: An Overview and Future Possibilities

In recent decades, quasi-zero stiffness (QZS) vibration isolation systems with nonlinear characteristics have aroused widespread attention and strong research interest due to their enormous potential in low-frequency vibration isolation. This work comprehensively reviews recent research on QZS vibration isolators with a focus on the principle, structural design, and vibration isolation performance of various types of QZS vibration isolators. The negative-stiffness mechanism falls into two categories by different realization methods: passive and active/semi-active negative-stiffness mechanisms. Representative design, performance analysis, and practical application are elaborated for each category. The results show that passive vibration isolation systems have excellent low-frequency vibration isolation performance under specific payload and design parameters, whereas active/semi-active vibration isolation systems can better adapt to different environmental conditions. Finally, the development trends and challenges of QZS vibration isolators are summarized, and the solved and unsolved problems are highlighted. This review aims to give a comprehensive understanding of the QZS vibration isolation mechanism. It also provides guidance on designing new QZS vibration isolators for improving their vibration isolation performance and engineering applicability.

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

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

A tunable fiber Fabry-Perot cavity for hybrid optomechanics stabilized at 4 K.

We describe an apparatus for the implementation of hybrid optomechanical systems at 4K. The platform is based on a high-finesse, micrometer-scale fiber Fabry-Perot cavity, which can be widely tuned using piezoelectric positioners. A mechanical resonator can be positioned within the cavity in the object-in-the-middle configuration by a second set of positioners. A high level of stability is achieved without sacrificing either performance or tunability, through the combination of a stiff mechanical design, passive vibration isolation, and an active Pound-Drever-Hall feedback lock incorporating a reconfigurable digital filter. The stability of the cavity length is demonstrated to be better than a few picometers over many hours both at room temperature and at 4K.

Vibration Control of Functionally Graded Panels using Parallel Resonators

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

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

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