Vibration Isolation System Research Articles

SH‐waves in a complex fluid composite structure with spring membrane imperfect interfaces

AbstractComplex fluids are of nobleness due to their unique mechanical responses to applied stress, which are different from simple fluids. Therefore, the current study encapsulated the behavior of SH‐wave in a complex fluid layer overlying a fiber‐reinforced half‐space with six different cases considered at the common interface. These cases involve various interface conditions, including perfect bonding, a spring layer, an infinitely thin membrane layer, loose bonding, a combined spring‐membrane layer, and a membrane layer with loose bonding. Precisely, the effect of loose bonding, membrane strength, and spring stiffness at the common interface on the propagation of SH (Shear Horizontal) wave is studied in detail. The problem is mathematically formulated for all the aforementioned six models followed by their solution with the aid of appropriate boundary conditions. Numerical computations are performed with a view to study the effect of stiffness of spring and membrane, as well as loose bonding at the common interface of the media. It is demonstrated that membrane strength impedes wave propagation, while increased spring stiffness supports it. Notably, the combined spring‐membrane interface has a more pronounced effect than a spring layer alone. The findings of this study may be utilized in the development of membrane technology, including the study of fluid membranes and it has significant importance in seismic engineering and vibration isolation systems.

Theoretical characteristics of a three-point Roberts linkage.

The Roberts linkage is recognized for enabling long-period pendulum motion in a compact format. Utilizing this characteristic, we are developing a three-point Roberts linkage for vibration isolation systems, with an eye toward its potential contribution to the development of next-generation interferometric gravitational wave antennas. In this article, we derived the equations to determine the essential parameters when using this linkage as a vibration isolation system, namely, the equivalent pendulum length and the relationship between translational motion of the center of mass and rigid body rotation, from size parameters. In addition, we analyzed the behavior in response to various errors.

Ultra-low frequency active vibration isolation system with quasi-zero stiffness characteristic using self-tuning filter-based feedforward control

Ultra-low frequency active vibration isolation system with quasi-zero stiffness characteristic using self-tuning filter-based feedforward control

Study on Dynamic Characteristics of Resilient Mount Under Preload.

Resilient mounts are essential for anti-vibration and shock absorption applications, making accurate predictions of their static and dynamic behaviors critical for effective design and mechanical performance. This study investigates static and dynamic characteristics of resilient mounts to predict their effects. Tension, compression, and shear tests were performed under quasi-static loading conditions to obtain stress-strain cycle curves. This study includes a review of the Yeoh hyperelastic model, which consists of three parameters, and discusses the calibration of these parameters to describe the hyperelastic material behavior. The parameters were validated through numerical analysis by comparing them with experimental results from quasi-static tests on the resilient mount. The dynamic behavior was further analyzed using modal analysis and frequency response simulations under various preload conditions. Results show that increasing preload significantly shifts the transmissibility curves and resonance peaks to lower frequencies. This study offers valuable insights into static and dynamic characteristics of resilient mounts, contributing to the design and optimization of vibration isolation systems for naval applications.

Chaotic band-gap modulation mechanism for nonlinear vibration isolation systems based on time-delay feedback control

Abstract Systems designed for nonlinear vibration isolation that incorporate chaotic states demonstrate superior capabilities in vibration attenuation, adeptly modulating the spectral constituents of vibrational noise. Yet, the challenge of eliciting low-amplitude chaotic dynamics and perpetuating these states across a diverse array of parameters remains formidable. This study proposes a pioneering strategy and technique for modulating the chaos band by incorporating a time-delayed feedback control mechanism within the framework of nonlinear vibration isolation systems.The investigation commences with an exhaustive analysis of the nonlinear dynamics, shedding light on the principles dictating the evolution of chaos. The study then advances to scrutinize the dynamics of systems with delays to elucidate the chaos-inducing processes engendered by feedback with temporal lags. Building upon the system’s responses, the chaotic performance and the effectiveness of the vibration isolation are crafted. Consequently, the time-delayed feedback control parameters are identified as pivotal design variables, which are then employed to dissect the control mechanisms influenced by the time-delayed feedback on the chaos band. Utilizing the delineated control mechanism, the nonlinear vibration isolation system is precipitously transitioned from a state of stable periodicity to one of chaos, fostering low-amplitude chaotic dynamics across an expansive parameter space, and in turn, resolving the previously stated challenge. Perhaps most significantly, the mechanism for attaining low-amplitude chaos introduced here paves the way for innovative methodologies in the active vibration isolation design of similar systems. Furthermore, it is anticipated to yield theoretical guidance for the manipulation of chaos bands and the formulation of active vibration isolation strategies within the domain of nonlinear vibration isolation systems.

Active vibration isolation support platform for double crystal monochromator

The quality of the beamline at a synchrotron light source is directly related to the performance of the double crystal monochromator. This paper presents a designed active vibration isolation support platform for the double-crystal monochromator to meet the higher stability demands of advancing synchrotron light sources. The platform has good decoupling characteristics through the redundant structure of eight actuators mixed with active and passive. A vibration isolation control scheme is designed based on distributed degrees of freedom and a feed-forward feedback composite control scheme to ensure high stiffness of the support platform while achieving full-band vibration isolation. Finally, constructed a verification platform for an active vibration isolation system and verified the effectiveness of the proposed control method through experiments. With the designed active vibration isolation algorithm, the system can achieve full-band vibration isolation within the 1–100 Hz bandwidth.

Development of vibration isolation system for halls and report on sound insulation and vibration experiment

Rubber and polyurethane have been widely used as vibration isolation materials in halls and studios. In this project, we have developed a floor-mounted coil spring vibration isolator with improved vibration isolation and sound insulation characteristics, while keeping the installation height equivalent or lower than rubber and polyurethane. In this paper, we evaluate the vibration isolation performance of the developed device by measuring vibration transmission loss, and confirm that the device can suppress surging, which is a weak point of metal springs, while achieving a low natural frequency. The sound transmission loss measurement also confirmed that the floating slab incorporating the device has sufficient sound insulation performance, and these results indicate that the device can be applied to acoustic spaces such as concert halls, where quietness is required.

Study of Systems of Active Vibration Protection of Navigation Instrument Equipment

Assessment of the influence of vibration isolator parameters on the distribution of the system’s natural frequencies is a significant task in the design of vibration isolation systems. The root method was used to determine the natural frequencies of the controlled vibration isolator. For a certain feedback structure of a controlled electrodynamic type vibration isolator, the need for a consistent selection of parameters has been justified. A mathematical solution has been proposed for the approximate determination of the roots of the characteristic equation of the controlled vibration isolator, which enables the analytical assessment of the influence of the vibration isolator parameters on the distribution of its natural frequencies. The research has been conducted in relative parameters, which makes it possible to generalize the results. The specificity of the inertial dynamic vibration isolator, which in some cases is associated with the implementation of anti-resonance conditions, can lead to the fact that resonant frequencies can occur on both sides of the tuning frequency of the vibration isolator. The use of an elastic suspension on flat springs to protect navigation equipment from vibration allows reduction in the intensity of translational vibration, while not changing the orientation of the device relative to the Earth. The implementation of an elastic suspension according to the scheme of the inverted pendulum allows an increase in the effectiveness of vibration isolation, under the conditions of a controlled change of the vibration isolator parameters and due to the use of feedback. The results of this research can be used in precision systems, such as vibration isolators, laser processing equipment, ultraprecision measurements or medical devices.

A quasi-zero-stiffness vibration isolator inspired by Kresling origami

Vibration isolators are widely used to mitigate undesirable vibrations in engineering systems and structures, but low-frequency vibration isolation remains a challenge. Origami-inspired structures, with their tunable stiffness and transformative capabilities, offer potential for vibration isolation. Inspired by conical Kresling origami, this study proposes a quasi-zero-stiffness vibration isolation system. Static analysis of the origami structure reveals that the system exhibits near-zero dynamic stiffness at the static equilibrium position, while maintaining static stiffness during the load-bearing process. The amplitude-frequency characteristic formula and vibration transmissibility formula are derived using the harmonic balance method. The effects of varying damping ratios and excitation amplitudes on the amplitude-frequency and transmissibility curves are examined. It is shown that the vibration isolation range increases with the number of layers. A comparison of the system's response to harmonic vibrations under different compressive deformations highlights the effectiveness of the origami quasi-zero-stiffness system as a vibration attenuator. Compared to existing quasi-zero-stiffness dampers, the origami-inspired system features a wider isolation frequency band, a lower initial isolation frequency, and reduced vibration transmissibility, demonstrating superior isolation performance, particularly at low frequencies.

Investigation of dynamic characteristics of a vibration isolation system for impact resistance of the marine container

ABSTRACT To achieve impact load resistance for the marine container, the paper designs a novel vibration isolation system. The dynamic characteristics of the system are experimentally investigated to verify the mathematical model. Based on the model, the vibration isolation rate is predicted under different conditions and its sensitivity to different influencing factors is investigated. The system is optimally designed for multiple parameters using adaptive particle swarm optimization (APSO). The results show that the vibration isolation system temporarily enters the pressure building displacement stage which does not affect the properties of the system. The model calculations coincide with the test results by more than 97%, except for the pressure building displacement stage. The predictions of vibration isolation rate are more than 80% and the sensitivity to excitation direction, load mass, system frequency and damping ratio is significant. The optimal system can meet the design requirements of engineering applications.

An optimal control method of internal resonances for vibration isolation system using an aperiodic isolator

An optimal control method of internal resonances for vibration isolation system using an aperiodic isolator

Active Composite Control of Disturbance Compensation for Vibration Isolation System with Uncertainty

The pointing and positioning accuracy of precision instruments in aerospace are often disturbed by low-frequency vibrations. An active/passive vibration isolation system is a feasible solution to suppress low-frequency vibrations. However, the vibration isolation performance of the active control strategy is seriously affected by the uncertainty of the system and the difficulty to meet the higher requirements of new-generation equipment. This paper proposes an active composite control (ACC) strategy for vibration isolation systems with uncertainty. The proposed ACC integrates feedforward control based on known systems and feedback control based on the Kalman filter for systems with uncertainty. Further, the derivation and stability analyses of the proposed ACC algorithm are provided, and the influence of system uncertainty on vibration isolation performance based on the proposed ACC is analyzed. Experimental verification is conducted and the experimental results confirm that the proposed ACC can effectively realize the low-frequency and wide-band vibration isolation for the system with uncertainty. Starting from 30 Hz, the vibration isolation performance of the proposed ACC with uncertainty is significantly improved than that of the ACC completely based on a deterministic system model.

Nonlinear interactions of an n-layer X-shape low-frequency vibration isolator equipped with a nonlinear vibration absorber at 1:1 internal resonance: analytical and numerical investigations

This work addresses, for the first time, the nonlinear dynamics of an n− layers bioinspired X− shape low-frequency vibration isolation system equipped with a nonlinear vibration absorber. The comprehensive mathematical model governing the two-degree-of-freedom system has been derived using Lagrangian mechanics. The method of averaging was applied to obtain an accurate analytical solution for the derived mathematical model. Utilizing the established analytical solution, the dynamical characteristics of the X− shape vibration isolator have been explored both as a single-degree-of-freedom system and after coupling with the proposed vibration absorber, as a two-degree-of-freedom system. The influence of different system parameters, including the number of structure layers, the initial inclination angle, the X− shape rod length, and the absorber stiffness and damping coefficients, on the vibration isolation performance has been investigated. The main findings indicate that while the single-degree-of-freedom X− shape low-frequency vibration isolator performs well in eliminating low-frequency vibration excitations, it exhibits strong vibration levels when the base excitation frequency exceeds the structure's natural frequency. Additionally, it was found that coupling a highly damped linear vibration absorber to the X− shape isolator not only eliminates the strong oscillations of the structure when subjected to high-frequency base excitations but also enhances the structure's low-frequency vibration isolation performance. Moreover, it was reported that integrating a nonlinear vibration absorber with either soft or hard spring characteristics instead of a linear one may degrade the vibration isolation performance of the structure rather than enhance it. Finally, numerical validation of all the analytical results was performed, which showed excellent correspondence with the analytical findings.

A semi-active adaptive pneumatic vibration isolator based on frequency response analysis and nonlinear control

In this work, an adaptive nonlinear error feedback controller based on fuzzy state observer is proposed to a novel rubber pneumatic vibration isolator (PVI) system. First, a novel rubber PVI system is designed and developed. Harmonic balance method is applied to establish the dynamic model of the PVI system, so as to analyze the frequency response characteristics of the system. Second, to improve the PVI performance in low-frequency vibration, a nonlinear state error feedback control system based on fuzzy state observer is designed for the active PVI system. Furthermore, the experiment system is established. Finally, through the experimental comparison under 5 Hz, 7 Hz, 20 Hz, and 40 Hz, an adaptive PVI strategy is proposed. The experimental results demonstrate that the adaptive PVI shows better performance in vibration isolation.

Dynamic characteristics of nonlinear vibration isolator for gas turbine

AbstractIn this study, a theoretical model of the vibration isolation system of the gas turbine is developed and numerically solved. A simplified finite element (FE) model was also established to determine the response under the shock load. The results of the FE model are used to verify the effectiveness of the theoretical model and the numerical solution. The influence of isolator stiffness, vibration isolator damping, and vibration isolator nonlinear stiffness coefficient on the shock response of the vibration isolation system is studied using the controlled‐variable method. These parameters (stiffness, damping, and nonlinear coefficient) enter into the shock resistance design of gas turbine vibration isolators.

Design of hybrid controller for broadband vibration isolation with active negative stiffness and ground-hook

This paper presents a novel hybrid control strategy that integrates active negative stiffness (ANS) with the ground-hook principle, aiming to enhance the vibration isolation system’s performance across both low and high-frequency ranges. Firstly, to improve vibration isolation performance, this study analyzes the existing ANS model. It identifies key factors affecting ANS stability and proposes a control parameter adjustment scheme based on stability conditions. This approach effectively refines ANS control theory and provides theoretical support for the application of ANS by ensuring stability. Secondly, addressing the limitations of ANS in high-frequency vibration isolation, this study proposes targeted solutions based on the ground-hook principle. While ANS excels in low-frequency isolation, this work tackles its shortcomings to enhance high-frequency vibration isolation. These solutions include the implementation of relative velocity feedback (RVFB) control and absolute velocity feedforward (AVFF) control to enhance high-frequency vibration isolation performance, and AVFF exhibits superior advantages over RVFB. Furthermore, the stability of different control strategies is analyzed. The findings reveal that sky-hook significantly enhances the control stability margin of the ANS loop, while RVFB decreases it, with AVFF having a minimal impact. Finally, comprehensive experiments validate a significant enhancement in both low and high-frequency vibration isolation performance, providing robust evidence for the practical engineering application of the vibration isolation system.

Vibration control and transmission mechanism of super high-rise building located on subway based on spring vibration isolation system

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.

Study of the Vibration Isolation Properties of a Pneumatic Suspension System for the Seat of a Working Machine with Adjustable Stiffness

This paper presents a study of the vibration isolation properties of pneumatic suspension systems for work machinery seats, with a particular focus on adjustable stiffness. It highlights the contribution that semi-active seat suspension systems make to vibration reduction, ultimately leading to improved passenger comfort levels and increased safety for vehicle users. The primary objectives of the research were twofold: firstly, to identify the key parameters of the apneumatic vibration isolation system; and secondly, to evaluate its performance in improving vibration damping. This entailed the development of a mathematical model that would foreground the movement through simulations based on different initial pressures, thus enabling the accurate prediction of real-life scenarios concerning the vibration-damping characteristics of the seating system, taking into account the different design options available for working machine technology applied at the test bed level, of which the pneumatic isolator is an integral component. In the cognitive process, the verification and validation of the formulated theoretical model play an important role. This approach enables the behaviour of the actual system to be inferred from the results of simulation studies, thus allowing the design of an appropriate vibration control system. By simulating different air bellow pressures, the characteristics of the seat suspension system can be assessed. This study provides valuable insights into optimising the vibration-damping capability of the air suspension system.

Stair‐Stepping Mechanical Metamaterials with Programmable Load Plateaus

AbstractMaterials with target load plateaus offer the potential for developing innovative vibration suppression and isolation systems for applications such as satellite platforms, submarines, and electric vehicles. However, implementing these materials can pose significant challenges. In this study, stair‐stepping mechanical metamaterials with programmable load plateaus are presented, which are created via a three‐level (unit, module, and 3D object) construction strategy. The strategy inspired by the inverse design concept achieves tunability in the number and properties of load plateaus within the force–displacement profiles of the metamaterials. This approach even yields appealing stair‐stepping response patterns, as validated by experiments and finite element simulations. Promisingly, programming the unit from its initial configuration to a “zero stiffness” configuration enables these metamaterials excellent vibration isolation performance. Furthermore, two reversible methods are proposed for switching among various unit configurations, namely shape memory programming and supporting payload. This innovative design strategy for programmable load plateaus opens up new possibilities for creating metamaterials with customized force–displacement responses. It also provides opportunities to incorporate multimodal vibration isolation capabilities into precision devices.

SINGLE-DEGREE-OF-FREEDOM VIBRATION ISOLATION SYSTEM WITH ONE ADDITIONAL SUPPORT

Vibration isolation is one of the most effective methods for reducing vibration levels of supporting structures when installing vibroactive equipment (active vibration isolation) or vibration levels of vibro-sensitive objects relative to foundation vibration levels (passive vibration isolation). Damping devices utilizing high-speed fluid flow through apertures have found wide applications in shock vibration isolation and vibration isolation systems in aerospace and defense sectors. Recent research has led to the development of viscous fluid dampers (VFDs) for use in civil engineering, particularly in earthquake-prone areas. Scientists conducted experiments aimed at determining the ability of viscous fluid dampers to reduce damages and displacements of structures without increasing stresses. Mathematical models have been developed and are applied in vibration isolation systems. When vibroactive equipment is installed on building and structure support systems, vibrations with sufficiently high vibration parameters may occur, potentially leading to loss of load-bearing capacity. In such cases, vibration isolation is considered one of the most effective methods for reducing these vibration levels. In this study, a calculation method has been developed, and calculation dependencies and algorithms for calculating vibration protection systems with nonlinear characteristics (additional support connections, viscous fluid damper) have been derived for both single-degree-of-freedom and two-degree-of-freedom systems. The research involved an analysis of normative and scientific-technical literature on the subject: types, structural solutions, calculation, and analysis of vibration protection systems. The main method selected was based on the use of transfer functions of linear systems (the non-traditional "normal form" method). Calculations were performed using computer mathematics systems- Matlab.