Vibration Isolation Effect Research Articles

Study of the Micro-Vibration Response and Related Vibration Isolation of Complex Traffic Load-Induced Experimental Buildings

In view of the high-sensitivity vibration effect of precision instrument laboratory buildings under the influence of surrounding traffic loads, field micro-vibration tests under various working conditions were carried out based on actual projects. Combined with numerical simulation, measured data served as input loads to simulate the vibration effect of various traffic loads on the floor of a building structure, and the structural vibration laws under the comprehensive action of various loads were analyzed. The vibration isolation effect of the isolation ditch on the oblique orthogonal load was investigated according to the corresponding safety index. The results show that the main frequency components of the site vibration frequency caused by various traffic loads are approximately 25 Hz and that the root-mean-square speed value is stable below VC-E, which meets the design requirements. Under the comprehensive action of multiple loads, the site structure will produce a vibration amplification effect, which is obvious when all types of loads are distributed symmetrically and the curve distribution is controlled by load factors with large amplitudes. The isolation effect of a small isolation ditch is best when it is located close to the source and the building. The depth of the isolation ditch must be greater than the maximum depth of the source to achieve better results, and the width has little influence. The effect of a small isolation trench on vertical vibration is poor, and the oblique orthogonal triaxial load has a counteracting effect on the vertical component. Thus, additional structural vibration isolation measures are needed. The research results provide a reference for engineering vibration isolation, damping measures, and structural design.

Study of the properties and joint operation of resonant sound absorbers depending on their geometry and relative position

The research presented in the work focuses on a damper that utilizes an "intelligent" material called multilayer magnetorheological elastomer. These devices are of interest due to their ability to adjust the elastic properties, size, and shape of the working body by manipulating the external magnetic field. They also have a high load capacity. The effectiveness of the damper's vibration isolation is determined by its design, manufacturing technology, and the composition of the multilayer magnetorheological elastomer. The mechanical and magnetic hysteresis of the device allows for evaluating the controllability of the damper and its ability to absorb vibrations. Research results indicate the presence of a symmetric and narrow hysteresis loop, not exceeding 7 μm, within the operating range of control currents.

Digital Mechanical Metamaterial with Programmable Functionality.

Digitization has brought a new era to the world, liberating information from physical media. The material structure-property relation is high-dimensional and nonlinear, and the digitization of structure-property relations may bring unprecedented functional programmability and diversity. Here, a new concept of digital mechanical metamaterial (DMM) is presented, where property design is realized by programming the digital states of the DMM to decouple the design of the structure and property. Transforming the binary stable states of a curved beam to the digital bit, one unit cell of DMM manifests three distinct deformation responses under compression, i.e., compression-twist coupling (CTC), compression-shear coupling (CSC), and pure compression (PC). These deformation modes show notable differences in motion and stiffness, which, by digitally programming a series of DMM, can yield a spectrum of functionalities, including information encryption, stress-strain relation customization, energy absorption in cushioning, effective vibration isolation, and tunable force transmission. This study pioneers a versatile material design paradigm that provides much greater freedom for the property design of intelligent mechanical metamaterials.

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.

Broadband frequency vibration isolation in pipelines using BCC meta-lattice sandwich sleeves

Pipeline structures usually suffer from serious vibration problems due to pressure pulsation and fluid excitation, potentially compromising their structural stability and service life. In this paper, a lightweight body center cubic (BCC) meta-lattice sandwich sleeve is proposed to isolate vibrations in pipelines within a broadband frequency range. The vibration isolation is based on the concepts of the locally resonant metamaterials. An equivalent mass-spring model is conducted to theoretically predict frequency range and elucidate the generation mechanism of the band gap. In addition, an analytical methodology is also proposed to predict the equivalent stiffness of the BCC meta-lattice sleeves. The influence of geometric parameters and configuration layout of the meta-lattice on the flexural wave band gap is further investigated. Numerical studies and experimental tests are also conducted to validate the vibration isolation effectiveness, considering various pipe lengths and different numbers of meta-lattice units. The proposed design provides fundamental support for the design of lightweight vibration isolation structure for pipelines.

Design and Vibration Isolation Investigation of a Load-Adjustable Quasi-Zero Stiffness Isolator

Quasi-zero Stiffness (QZS) isolators offer significant advantages in low-frequency vibration isolation. Nonetheless, the complexity of the structure and the limited load adaptability hinder the practical application of such isolators. Therefore, this paper proposes a novel load-adjustable QZS isolator based on a compliant mechanism. By integrating the positive stiffness of the curved beam and the negative one of the inclined beam, a comprehensive design strategy for the QZS flexible beam is introduced. The optimal geometric parameters of the structure are determined using a genetic algorithm, and the finite element simulations are employed to numerically validate the QZS characteristics of the structure as well as the low-frequency vibration isolation performance. Leveraging the same structural design and a kind of temperature-sensitive materials-Thermoplastic Polyurethane (TPU), a unit cell of load-adjustable QZS isolator controlled by electric heating is developed and fabricated via 3D printing. Static and dynamic tests are conducted to explore the QZS platform characteristics and vibration isolation performance of the isolator subjected to various voltage inputs. The results demonstrate that the QZS characteristics of the isolator can be effectively regulated by adjusting the input voltage, ensuring effective low-frequency vibration isolation under different loads. Moreover, the incorporation of serial and parallel arrangements of unit cells could further enhance the range of load adjustability. This study offers novel insights into the design of load-adjustable QZS isolators.

Nonlinear static and dynamic response of a metastructure exhibiting quasi-zero-stiffness characteristics for vibration control: an experimental validation

This work introduces a novel metastructure designed for quasi-zero-stiffness (QZS) properties based on the High Static and Low Dynamic Stiffness mechanism. The metastructure consists of four-unit cells arranged in parallel, each incorporating inclined beams and semicircular arches. Under vertical compression, the inclined beams exhibit buckling and snap-through behavior, contributing negative stiffness, while the semicircular arches provide positive stiffness through bending-dominated behavior. The design procedure to achieve QZS is established and validated through finite element analysis and experimental investigations. The static analysis confirms a QZS region for specific displacement. Dynamic behavior is analyzed using a nonlinear dynamic equation solved using the Harmonic Balance Method, validated experimentally with transmissibility curves showing sudden jump down with effective vibration isolation. Parametric studies with varied payload masses and excitation amplitudes further verify the ability to of metastructure to attenuate vibrations effectively in low-frequency ranges.

Investigation of the vibration isolation effect of composite vibration isolation walls on ground surface vibrations in deep tunnels of suburban railways

To investigate the vibration isolation effect of composite vibration isolation walls on surface vibrations in suburban railway deep tunnels under various influencing factors, an integrated numerical model of the train was initially developed. This model solved the wheel-rail interaction force and was applied to a three-dimensional volume coupling model of the track soil. Subsequently, the model's reliability was validated through comparison with measured data. Afterward, the vibration isolation effects of various types of EPS material vibration isolation walls were examined, with a focus on exploring the impact of thickness, material proportion, and relative positioning of the materials within the vibration isolation wall composed of EPS material and concrete. Research indicates that with an increase in the burial depth of a single material vibration isolation wall, its effective vibration isolation frequency range gradually widens. When the burial depth of the vibration isolation wall exceeds the tunnel burial depth, the vibration isolation effect is optimal. Composite vibration isolation walls, with thicknesses smaller than single-material vibration isolation walls, exhibit superior vibration isolation effects compared to their single-material counterparts. The effective vibration isolation frequency band of composite vibration isolation walls differs from that of single-material vibration isolation walls. Using the optimal-size vibration isolation wall of a single material as a composite vibration isolation wall enhances the vibration isolation effect of peak acceleration in the frequency domain by 16.58% and peak velocity by 16.95%. Moreover, frequency domain peak displacement experiences a 30.73% improvement in the vibration isolation effect.

A locally resonant metamaterial and its application in vibration isolation: Experimental and numerical investigations

AbstractVibration isolation metamaterial barrier has been extensively studied in mitigating the damage induced by vibration, while a deeper understanding of the vibration isolation characteristics based on laboratory experiments is still lacking. In this work, a locally resonant metamaterial barrier is proposed, and a large‐scale laboratory experiment was first designed to investigate the isolation mechanism of the proposed metamaterial barrier. The metamaterial vibration isolation barrier is assembled by arraying 5 × 5 resonators. To better explain the observations in experiments and unveil the underlying isolation mechanism, COMSOL Multiphysics was also employed to simulate the laboratory experiment. Subsequently, the vibration isolation effect is quantitatively analyzed by analyzing the acceleration amplitude reduction spectrum (ARS) of the ground surface. The vibration isolation mechanism is discussed by monitoring the acceleration field around the metamaterial barrier. The results indicate that two significant locally resonant attenuation domains are observed, which are induced by the first‐order and second‐order vertical resonance frequencies of the metamaterial. Another experimental scheme that simultaneously monitored the acceleration of the mass block and the bottom of resonators was implemented to investigate vibration in the resonator. The vibration energy distribution on the mass block and the bottom of the resonator is found to depend significantly on the vibration frequency. When the frequency is lower than a certain frequency, the locally resonant is dominant. Otherwise, the geometric scattering is dominant. The vibration isolation mechanism of the locally resonance metamaterial was investigated by laboratory experiments and provided an effective solving path for isolating the low‐frequency vibration.

Novel Phononic-Like Crystal Wave Barrier Structure for Vibration Isolation

As an efficient, environmentally friendly, and economical urban public transportation tool, the subway has significant advantages compared to other urban public transportation tools and plays an irreplaceable role in the urban rail transit system. While the subway brings many conveniences to people, its operation has also brought a series of problems to urban development and residents’ lives, especially the vibration and noise problems generated by the subway have become unavoidable and urgent problems to be solved. The traditional wave barriers have a certain effect on attenuating and suppressing the vibration generated by the subway, but it has shortcomings in terms of the width and quantity of elastic wave bandgap (BG), so its application in low-frequency vibration reduction and isolation of subway systems is greatly limited. In order to broaden the elastic BG width and quantity of the wave barrier, this paper designs a novel phononic-like crystal subway wave barrier (PLCSWB) for subway vibration isolation based on locally resonant theory. Firstly, the dispersion curves of the novel PLCSWB are calculated using the improved plane wave expansion method and finite element method (FEM), and compared with the dispersion curves of traditional phononic crystal (PC) wave barriers. Secondly, the frequency response function of the novel PLCSWB is calculated using FEM to evaluate its attenuation effect on vibration, and the energy distribution characteristics at its BG boundary are analyzed. Then, the main factors affecting the BG of the novel PLCSWB are analyzed, and a spring–mass system equivalent model of the novel PLCSWB is established to theoretically estimate its BG range. Finally, the vibration data of the tunnel wall monitored on site are used to analyze and verify the vibration isolation effect of the novel PLCSWB. The results show that the novel PLCSWB opens five low-frequency BGs in the 200[Formula: see text]Hz frequency band, which increased the total width of the opened BGs by 49% compared to traditional PC wave barriers. In the frequency range of the BG, the attenuation value of the novel PLCSWB to vibration is mostly above 30[Formula: see text]dB, and the energy distribution inside the structure is mainly concentrated in the primitive cell that controls the BG, indicating good attenuation and control effects on vibration. The main factors affecting the BG of the novel PLCSWB are the density of the scatterer material, the elastic modulus, and the thickness of the wrapping layer material. Moreover, during subway operation, the novel PLCSWB has a good attenuation effect on the vibration transmitted from the tunnel wall to the soil. Among them, the maximum vibration acceleration amplitude of the novel PLCSWB with nine rows is reduced by 47%, and the vibration isolation performance is remarkable. The relevant research results of this paper provide a novel approach and method for the study of subway vibration reduction and isolation, and can also provide specific references for the design and development of wave barriers.

Research on compressive behavior of thick rubber bearings for mitigating train-induced structural vibration

The challenge of mitigating train-induced vibrations and ensuring seismic safety in buildings has led to increased interest in thick rubber bearings. This study examined 15 full-scale thick rubber bearings, analyzing the influence of rubber material and shape factors on their vertical mechanical performance through experimental research and numerical simulations. In addition, taking practical engineering as the object, the vertical isolation effect and seismic safety of seismic and vibration dual control bearings with thick rubber bearings as vertical isolation components were studied. The results show that thick rubber bearings have lower vertical stiffness than traditional bearings and exhibit stronger non-linearity. Variations in the thickness of rubber layers during manufacturing minimally affect the overall vertical performance of the bearings. The overall vertical performance of thick rubber bearings can be extrapolated from the performance of single-layer rubber. In response to train-induced vibrations, the seismic and vibration dual control bearings with thick rubber bearings as vertical isolation components achieve effective vibration isolation. In the case of seismic loads, the seismic and vibration dual control bearings show good seismic safety. The findings of this study are valuable for the performance research of thick rubber bearings and for the seismic and vibration dual control design.

Three-dimensional phononic crystals with self-similar structures

Acoustic metamaterials have the advantages of designability, strong pertinency, small size and good effect, and have good application value in solving the problem of sound insulation and noise reduction. Phononic crystals with wide bandgap and multi-bandgap can inhibit elastic wave propagation to some extent. In this study, a three-dimensional phononic crystal model with self-similar properties is designed by using fractal method. First, an initial unit is constructed, then the arm of the initial unit is replaced with the structure itself to form a self-similar structure. The self-similar model can block sound waves in the wide band and multi-band range. By changing the structure shape and size of phononic crystal, the sound wave blocking in different frequency range is also studied. At the same time of continuous optimization of the structure, the variation rules of the model band structure under different parameters are summarized. To find the good parameters of broadband and multi-band sound wave blocking, so as to achieve the effect of vibration isolation and noise reduction. The finite element method is used to simulate the vibration of the model to verify the existence of elastic wave bandgap. Phononic crystals have a good prospect in the field of sound insulation and noise reduction.

Generative quasi-zero stiffness paradigm for vibration isolation by constraining the constant force with hardening boundaries

Quasi-zero stiffness (QZS) isolators are widely used to mitigate the low-frequency vibration. This paper proposes a new QZS paradigm for vibration isolation utilizing constant force with hardening boundaries (CFHB). Different from the conventional parallel connection of positive and negative stiffness elements, the CFHB directly exhibits the QZS characteristic which is generated when the uniform magnetic field is converted to a non-uniform one. Therefore, it avoids complex assembly and material deformation, and eschews the reliability issues related to stiffness combination. Concretely, the radially magnetized shaft has a uniform area in the middle part which can be distorted by a coaxial sleeve made of high permeability material. A constant magnetic force is generated in this process. Two hardening boundaries formed by two pair of repulsive magnets are applied to constrain the QZS stroke and maintains the working position. The shaft's magnetic field is studied to clarify the filed distribution, and the distortion by the sleeve is simulated by finite element analysis (FEA). The force-displacement relationship of the case study is proven to be continuous and fitted by a polynomial form. The influence of dimension parameters on the performance of vibration isolator is systematically investigated to guide the design. Dynamic differential equation considering Coulomb damping and viscous damping is established and solved applying the Runge-Kutta Method (RKM) to obtain the vibration response. A prototype is fabricated to experimentally validate its performance, demonstrating the QZS properties in quasi-static calibration and the vibration isolation effect under the frequency sweep and periodic excitations. The generative QZS offers a new paradigm with a simple structure, suggesting its substantial potential for practical deployment.

Low-frequency and broadband vibration absorption of a metamaterial plate with acoustic black hole resonators

Acoustic metamaterials with bandgap properties can lead to effective vibration attenuation in a targeted frequency range. In this paper, a novel locally resonant metamaterial plate is proposed, connected with acoustic black hole (ABH) resonators. The structure is shown to achieve low-frequency and broadband vibration absorption. The proposed microunit design consists of three parts: the ABH resonator, supporting beams as the connector, and the frame (FC-ABH). The modal characteristics of the microunit and the dispersion relation of the infinite periodic FC-ABH structure are calculated by both Gaussian expansion method and finite element method. By the effects of flexural wave absorption of ABH coupled with the local resonance mechanism, a low-frequency and broad vibration attenuation band can be generated. When the damping of materials is included, the attenuation band can be further widened, with relative bandwidth measured by the experiment up to 0.93. The results of numerical simulations and experimental tests demonstrate that the finite periodic FC-ABH can act as an effective vibration absorber and isolator. The proposed structure may provide new ideas for the design and application of broadband vibration mitigation metadevices.

Double roller negative stiffness mechanism seat suspension optimization design and vibration analysis

To further improve the vibration isolation performance of automobile seat suspension and the riding comfort of automobiles, this paper uses the double roller negative stiffness mechanism (NSM) to calculate the seat suspension with quasi-zero stiffness (QZS) characteristics. The influence of the structural parameters on the QZS characteristics is simulated and analyzed, and the structural parameters are optimized by the orthogonal design method. The effectiveness of the optimization was verified by analyzing the dynamic response of the seat suspension system. The results show that the natural frequency of the vibration isolation system of the seat suspension decreases, the vibration isolation band widens after the introduction of the double roller NSM, and the vibration isolation effect is improved under low-frequency excitation.

Three‐magnet‐ring quasi‐zero stiffness isolator for low‐frequency vibration isolation

AbstractA three‐magnet‐ring quasi‐zero stiffness (QZS‐TMR) isolator is designed to solve the problem of low‐frequency vibration isolation in the vertical direction of precision equipment. QZS‐TMR has both positive and negative stiffness structures. The positive stiffness structure consists of two mutually repelling magnetic rings and the negative stiffness structure consists of two magnetic rings nested within each other. By modulating the relative distance between positive and negative stiffness structures, the isolator can have QZS characteristics. Compared with other QZS isolators, the QZS‐TMR is compact and easy to manufacture. In addition, the working load of QZS‐TMR can be flexibly adjusted by varying the radial widths of the inner magnetic ring. In this paper, the static analysis of QZS‐TMR is carried out to guide the design, and the low‐frequency vibration isolation performance is studied. In addition, the experimental prototype of QZS‐TMR is designed and manufactured. The static and vibration isolation experiments are carried out on the prototype. The results show that the initial vibration isolation frequency of the experimental prototype is about 4 Hz. The results show an excellent low‐frequency vibration isolation effect, which is consistent with the theoretical research. This paper introduces a new approach to the design of the QZS isolator.

The study on mechanical properties of the vibration isolator

First of all, the working principle of vibration reduction of the vibration isolator is briefly introduced. The vibration isolator adopts the design ideal of no formant and adopts a damping locking mechanism in the resonance region to solve the problem of vibration amplification of the system. The purpose of vibration attenuation is to use small damping in the attenuation region. Then, through the numerical simulation calculation method, it can be obtained that the isolator has a good vibration isolation effect under different effects of shock and impact, and the effective rate is about 90%, which fully guarantees the structural safety of the test equipment. Finally, according to an example, a model is established to study the influence of equipment weight and center of gravity design deviation on the natural frequency and natural frequency point vibration transmission efficiency of the equipment. Through analysis, it can be found that in the case of no abnormality of the equipment, the frequency is changed in the range of 1∼160 Hz, and the ratio of the system response to excitation is not more than 2, which meets the design requirements.

Design of hyperbolic quasi-zero stiffness metastructures coupled with nonlinear stiffness for low-frequency vibration isolation

Quasi-zero stiffness (QZS) metastructures with simple structures exhibit a high low-frequency vibration isolation performance, but the bearing capacity and working regions are limited due to the linear positive stiffness elements. In this study, a novel hyperbolic QZS metastructure coupled with nonlinear stiffness is designed by combining a pair of cosine-shaped beams and arc-shaped beams for low-frequency vibration isolation. Finite element models (FEM) and experimental analysis are utilized to examine the static characteristics of the metastructure, revealing a wide QZS region and significant load-bearing capacity. The metastructure can achieve effective vibration isolation properties through reasonably designing the unit cells. The influence of geometrical parameters on the QZS region is investigated to optimize and realize desirable QZS features. The dynamic equation and response of the vibration isolation system are determined using the harmonic balance method. Moreover, the corresponding displacement transmissibility is confirmed by numerical simulation. The results of the dynamic sweep frequency experiment further verify the validity of the theoretical analysis model. The hyperbolic QZS metastructure system possesses good vibration isolation performance due to the introduction and compensation of a nonlinear positive stiffness arc beam element. The proposed hyperbolic QZS metastructure provides a significant route for the stiffness compensation of metastructures.

Vibration Isolation and Launch Performance Enhancement of the Spacecraft In-Orbit Launch Design Using the Nonlinear Dynamic Feature

This paper proposes a new spacecraft in-orbit launch design using a nonlinear configuration to utilize nonlinear dynamics for the enhancement of vibration isolation and launch performance. The in-orbit launch device has four springs, where the stroke directions of two springs are perpendicular to the launch direction so as to produce nonlinearity with negative stiffness for enhancing the launch velocity. The other two springs are designed to counterbalance the above negative stiffness when the launch outlet is shut down, leading to quasi-zero dynamic stiffness for vibration isolation enhancement. The dynamic equations of the in-orbit launch device for both the on- and off-launch are presented. Then the performance enhancement of both the vibration isolation and launch performance is thoroughly investigated via comparative study and parametric study. The resonance peak is reduced by 4.16 dB, the effective vibration isolation bandwidth is increased by 57%, and the launch speed is increased 1.64 times. This validates the performance improvement of the new launch device design and presents a useful guideline for application.

Study of a damper based on a multilayer magnetorheological elastomer

The research presented in the work focuses on a damper that utilizes an "intelligent" material called multilayer magnetorheological elastomer. These devices are of interest due to their ability to adjust the elastic properties, size, and shape of the working body by manipulating the external magnetic field. They also have a high load capacity. The effectiveness of the damper's vibration isolation is determined by its design, manufacturing technology, and the composition of the multilayer magnetorheological elastomer. The mechanical and magnetic hysteresis of the device allows for evaluating the controllability of the damper and its ability to absorb vibrations. Research results indicate the presence of a symmetric and narrow hysteresis loop, not exceeding 7 μm, within the operating range of control currents.