Vibration Isolation Performance Research Articles

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.

Design and experiment of electromagnetic-hydraulic-rubber integrated vibration isolator

Low-frequency radiated noise, characterized by a distinctive “acoustic fingerprint” is generated when vibrations from marine machinery propagate through a ship’s hull into the ocean. This type of noise travels long distances with concentrated and stable energy, posing a significant threat to a ship’s acoustic stealth capabilities. Active-passive hybrid isolation is the primary method for reducing low-frequency radiated noise from ships; however, technical challenges remain, such as effectively integrating active and passive components, achieving high output force in a compact design, and addressing the poor linearity of actuator output at low frequencies. To address these issues, this paper presented an innovative electromagnetic-hydraulic-rubber integrated vibration isolator. Firstly, the study analyzed the dynamic characteristics of a two-degree-of-freedom isolation system and investigated the influence of active-passive hybrid vibration isolator parameters on control force and vibration reduction performance. Secondly, it was established that the magnetic circuit model and magnetic field strength expressions for the electromagnetic actuator using magnetic circuit analysis derive the analytical relationship between electromagnetic force, current amplitude, and frequency using the energy method. Subsequently, a mathematical model was developed for the rubber-hydraulic suspension component to examine its dynamic characteristics, hydraulic damping, and hydraulic force amplification transmission laws. Lastly, we organically combine the electromagnetic actuator with the rubber-hydraulic suspension and conduct a multi-physics joint simulation of the integrated vibration isolator using Comsol software to verify the effectiveness of the optimized design and vibration isolation control. Experimental research was carried out on the dynamic characteristics, output force properties, and fatigue characteristics of the integrated vibration isolator prototype. Results indicated that the established models and methods can achieve over 90% accuracy in predicting the performance of the electromagnetic actuator’s output force and exhibit good linearity within the 5–400 Hz range. The rubber-hydraulic suspension can achieve an amplification factor of up to 1.5 for the electromagnetic force while reducing the transmission of vibrations to the base. The research findings can enhance the low-frequency vibration isolation performance of marine machinery equipment and improve their acoustic stealth capabilities.

Origami-inspire quasi-zero stiffness structure for flexible low-frequency vibration isolation

As an emerging technology, origami exhibits rich nonlinear static and dynamic properties. However, simulating creases remains a key challenge hindering practice application, especially for volumetric (deformable) origami. Inspired by the bistable behavior and axial-rotational coupling mechanism of triangulated cylindrical origami (TCO), this paper proposes a novel combined truss-spring structure with additional inertial mechanism (TCTS-RIM) for low-frequency vibration isolation. Unlike pure TCO, the TCTS-RIM uses elastic linkages to simulate all creases and modifies crease positions, enhancing physical realization in engineering applications and offering tunable stiffness and inertia on demand. Static analysis shows the modified truss-spring structure in TCTS-RIM has superior quasi-linear negative stiffness compared to pure TCO, which enables a very wide quasi-zero stiffness (QZS) range via linear spring compensation. The wide QZS range for different loads can be realized by setting appropriate structural parameters. From system dynamic equations, nonlinear inertia, nonlinear quadratic force, and nonlinear damping due to RIM are identified and discussed. The Alternating frequency–time harmonic balance method is used to obtain the displacement transmissibility, and its parametric influencing investigations verify that the proposed TCTS-RIM has excellent low-frequency vibration isolation performance and rich tunability. Comparative discussions show the wide QZS range significantly reduces the resonance frequency, broadens the isolation frequency band, and yields superior dynamic performance versus pure TCO isolators. Moreover, equivalent mass, anti-resonance and softening behavior induced by the rotational inertia mechanism further enhance low-frequency vibration isolation performance. An experimental prototype is built, and experimental results validate the correctness of the theoretical analyses. This work presents a simple mechanical implementation of volumetric origami, which may progress the engineering applications of origami and provide a viable approach to low-frequency vibration control.

A3-DOF frog-inspired quasi-zero stiffness isolator and its vibration control performance

To pursue a nonlinear isolator with simpler structure, better load adaptability, and wider quasi-zero stiffness (QZS) region, a 3-DOF bionic vibration isolation device is proposed and analyzed inspired by the superior landing performance of the frog's leg structure. The mechanism's dynamical equation is established using Lagrange's principle. The dynamic model is validated using ADAMS simulation. The effects of spring stiffness and rod length on static mechanical characteristics are analyzed. The vibration attenuation performance of the structure is analyzed under independent three-directional excitation and three-directional coupled excitation. Compared with the typical X-shaped QZS isolator and the traditional QZS isolator, the designed structure's advantages is demonstrated. By tuning the parameters and building a control route based on variable-stiffness dielectric elastomer, optimization of the device's vibration isolation performance under coupled excitation was accomplished.

Research on the vibration isolation performance of a metal rubber-disc spring shock isolation device

In view of the fact that the vibration response of the laser-emitting telescope in the combination of artillery and light equipment cannot meet the target design requirements, this paper designs a new metal rubber-disc spring shock isolation device and conducts experimental research on its vibration isolation performance. The research is conducted from the frequency sweep test and the fixed frequency test. Through the vibration isolation performance test, it is found that the natural frequency of the metal rubber-disc spring shock isolation device is lower than that of the steel wire rope vibration isolator, and the frequency domain where vibration isolation occurs is wider, with better vibration isolation performance. In the fixed frequency test, the acceleration transfer rate of the metal rubber-disc spring composite vibration isolator is significantly better than that of the steel wire rope vibration isolator in the low-frequency range. As the excitation frequency increases, the difference between the acceleration transfer rate of the steel wire rope vibration isolator and the metal rubber-disc spring composite vibration isolator gradually shrinks, and finally converges.

Improvement of Commercial Vehicle Seat Suspension Employing a Mechatronic Inerter Element

To further improve the ride comfort of commercial vehicles, a seat ISD (Inerter–Spring–Damper) suspension utilizing a mechatronic inerter is proposed in this paper. Firstly, a five-DOF (degree-of-freedom) commercial vehicle seat ISD model was built. Then, the positive real network constraint conditions of a biquadratic impedance transfer function were determined, and the meta-heuristic intelligent optimization algorithm was used to solve the parameters. According to the solution, the impedance transfer function was obtained and the specific network structure was realized by network synthesis. Lastly, this study compares the vibration isolation performance of the mechatronic ISD suspension of the vehicle seat with that of a passive suspension. In comparison to passive seat suspension, the seat mechatronic ISD suspension reduces seat vibration transmissibility by 16.33% and vertical acceleration by 16.78%. Results indicate that the new suspension system can be an effective improvement in ride comfort.

Vibration Isolation Performance of a Constrained Damping Base for a High-Pressure Plunger Pump

Based on the effect of damped shear deformation on energy dissipation, a new constrained damping base for a polymer injection platform deck is proposed to reduce the excessive vibrations caused when multiple plunger pumps are jointly operated. A model for analyzing the vibration response of an I-beam-constrained damping base for a polymer injection platform with multiple plunger pumps was established using Abaqus 6.14 software and compared with rigid base and traditional rubber vibration isolators in terms of its vibration isolation performance. Furthermore, the effects of the damping material’s loss factor, the thickness of the damping layer, and the number of expansion layers on the vibration isolation characteristics of the constrained damping base were explored. This study shows that, with an increase in the damping material’s loss factor, the thickness of the damping layer and the number of extended layers, the vibration isolation performance of the constrained damping base is gradually enhanced. When the damping material’s loss factor is 1.0, the thickness of the damping layer is 20 mm, and the number of extended layers is 3, the constrained damping base’s vibration damping effect is optimized, and its vibration isolation rate becomes as high as 46.63%, which can significantly reduce the vibration response of the polymer injection platform.

Analysis and verification of vibration isolation performance of engine mount based on low-frequency approximation method

At present, most of the turbofan engine use the articulated link mount to connect the engine to the wing. The mechanical modeling, analysis and experimental research of articulated link mount are important means in the development of engine mount. In this paper, multibody dynamics method is used to establish the dynamic theory equation for a certain type of turbofan engine mount, and the low-frequency approximation method of the MNF file is proposed, which greatly improves the calculation speed on the basis of ensuring the calculation accuracy. In addition, a full-scale engine mounting system vibration isolation performance test platform was developed, and the vibration isolation efficiency of a certain type of engine mount at the high and low pressure rotor frequency was obtained. The results show that the simulation and test results agree well, the error is within 15% at the low-frequency, and 5% at the high-frequency. This work provides theoretical method and test evaluation means for the design and improvement of large passenger aircraft engine installation devices.

An effective secondary suspension system for isolating the high-frequency vibrations of suspended monorail vehicle running on a flexible track beam

ABSTRACT Secondary suspension system is a core component of a suspended monorail vehicle (SMV), which plays a vital role in suppressing the car-body vibrations. This article aims to investigate the vibration isolation performance of an external secondary system (ESSS) for the SMV. Firstly, the structural features and mechanical mechanism of the ESSS are elaborated, which are compared with those of an existing internal secondary suspension system (ISSS) in the SMV. Then, an effective analysis method for the vehicle-track beam interaction of the suspended monorail system (SMS) is established based on the rigid-flexible coupling dynamics theory, in which the main modal information of the track beam is considered. Furtherly, applying the established analysis method, the vehicle-track beam vibrational responses between the ISSS and ESSS are compared under the local irregularity of beam-end junction and random track irregularity, and the superiorities of adopting the ESSS are revealed. Finally, by comprehensively considering the vehicle-track beam vibrational responses, several crucial parameters of the ESSS are selected appropriately. Results show that the ESSS has a significant advantage in isolating the high-frequency vibrations of the SMV compared with the existing used ISSS; simultaneously, it could also effectively decrease the track beam vibration. To guarantee good vehicle riding comfort, the vertical stiffness and damping with the ESSS are recommended to be 0.05∼0.2 MN/m and 10∼30 kN·s/m, respectively. Highlights ➢ Structural features and mechanical mechanisms of an effective ESSS for the SMV are introduced. ➢ A high-efficiency analysis method for vehicle-track beam interaction of the SMS is established. ➢ By a comparison with the commonly used IEEE, the advantages and significance of the ESSS are revealed ➢ Several crucial design parameters of the SMV with ESSS are selected appropriately.

Environmental Microvibration Analysis Method for Vibration Isolation Research in High-Precision Laboratories

Environmental microvibrations, often originating from unidentified sources, pose a significant challenge for predicting and controlling their complex wave fields, potentially leading to measurement errors of sensitive instruments in high-precision laboratories and impacting the accuracy of experimental outcomes. Therefore, investigating effective control measures for environmental microvibrations under passive conditions is key to addressing such engineering issues. This paper presents a finite element analysis method tailored to address environmental microvibrations in the absence of apparent sources. This method involves obtaining the vibration time history at specific ground surface points through field measurements and combining the Rayleigh wave velocity attenuation character with depth at the center frequencies of one-third octave bands within the 1–100 Hz frequency range; the vibration time history at any depth in the soil is calculated. These calculated vibrations are then applied as input loads to the corresponding nodes on one boundary of the foundation–soil model, serving as the source of environmental microvibrations. The predicted results are compared with measured data and the empirical point source input method, indicating that this approach is more precise and efficient, providing valuable reference for the prediction and analysis of environmental microvibrations. In addition, utilizing this method, the study examines the effects of pile foundation parameters such as the pile length, burial depth, and concrete baseplate thickness on the vibration isolation performance of environmental microvibrations, providing guidance for designing pile foundation isolation.

Multi-directional vibration isolation performances of a scissor-like structure with nonlinear hybrid spring stiffness

Multi-directional vibration isolation performances of a scissor-like structure with nonlinear hybrid spring stiffness

Experimental Study on Reutilization of Waste Rubber Chips with Sheetpiles as a Coupled-Wave Barrier to Reduce Ground-Borne Vibrations

Abstract Purpose Environmental and man-made vibrations due to various sources have become an environmental issue in recent years. Wave barriers such as open and in-filled trenches have been commonly used in the mitigation of these vibrations. Even though the open trench has exhibited better performance than the others, it may not be applicable or feasible in many cases. Therefore, soft and stiff barriers have been used for the same purpose. The present study aims to reveal the vibration isolation performance of not only single barriers such as rubber chips in-filled trenches and sheetpiles but also a novel barrier, rubber chips-sheetpile coupled barriers. Methods Rubber chips and sheetpiles were employed as soft and stiff wave barriers, respectively. The screening effectiveness of rubber chips, sheetpiles and their coupled form was examined through comprehensive field tests. Vibrations having frequencies in the range of 10–80 Hz were generated by a state-of-the-art mobile seismic shaker and measured by highly sensitive acceleration and velocity pickups in the absence and presence of these wave barriers. The effectiveness of the wave barriers was quantitatively determined. Results and conclusion While the sheetpile was more effective than rubber chips at low frequencies, the case was vice versa at higher frequencies. However, the coupled wave barrier outperformed other barriers in each case. If one barrier could not provide the required amount of isolation or is only effective within a limited range of frequency, using a coupled barrier with the installation of the other may significantly provide better vibration isolation.

Mechanical characteristics analysis of high dimensional vibration isolation systems based on high-static-low-dynamic stiffness technology.

Large floating raft vibration isolation systems (FRVISs) based on high-static-low-dynamic stiffness (HSLDS) technology offer excellent low frequency vibration isolation performance with broad application prospects. However, the design process for these complex high-dimensional coupled nonlinear systems remains poorly developed, particularly when applied for ocean-going vessels that experience rolling and pitching motions. The present work addresses this issue by establishing a six-degree-of-freedom HSLDS vibration isolation model for FRVISs composed of eight isolators, and the model is applied to fully analyze the swing stability and multidimensional vibration isolation performance of these systems. The influence of nonlinearity on the mechanical properties of the vibration isolators is analyzed more clearly by assuming that each vibration isolator realizes nonlinear HSLDS characteristics in the z direction and linear characteristics in the x and y directions. The results demonstrate that the swing displacement responses of the system are greatly reduced under weak nonlinearity, which reflects the high static stiffness and high static stability characteristics of an HSLDS system. The multidimensional vibration isolation performance of the system is evaluated according to the impacts of nonlinearity, the installation height Hz of the isolators, and the relative position Dr of the two middle isolators. The results of analysis demonstrate that applying a value of Hz = 0 produces the best vibration isolation performance overall under strong nonlinearity by avoiding unnecessary secondary peaks in the force transmission rate under harmonic mechanical excitation and ensuring a maximum high-frequency vibration isolation effect. However, applying a weak nonlinearity is better than a strong nonlinearity if Hz is not zero. In contrast, Dr has little effect on the vibration isolation effect of the raft in the x, y, and z directions. Therefore, an equidistant installation with Dr = 0.5 would be considered ideal from the standpoint of installation stability.

A novel adjustable magnetorheological fluid gradient material of low frequency vibration isolation: a theoretical and experimental study

In this paper, a novel adjustable magnetorheological fluid (MRF) gradient material for low-frequency control is proposed, and the vibration isolation performance of this gradient material is investigated theoretically and experimentally. The gradient material has an excellent ability to control the sound waves and vibrations. However, the currently prepared gradient material does not have the parameter adjustability. At the same time, the MRF can change its material parameters according to the external magnetic field. After applying the traveling magnetic field (TMF) to the MRF with continuously varying and adjustable magnetic induction strength, its material parameters will also be continuously varying and adjustable to constitute an adjustable gradient material. In order to investigate the vibration transfer characteristics of this adjustable gradient material, this paper establishes a micro-mechanical model of MRF and theoretically investigates and numerically calculates the mechanical impedance and vibration transfer characteristics of the adjustable gradient material through the machine-electric analogy theory. At the same time, experimental research was conducted by building an experimental platform to conduct experiments. The results show that the novel adjustable gradient material composed of a TMF and MRF has a good vibration suppression effect in the low-frequency range (10 ∼ 60 Hz) with the vibration level difference of up to 30 dB or more, which has a broad application prospect in the field of vibration control.

Design and vibration characteristics of sandwich constrained damping gasket for diaphragm air pump

There are certain problems of vibration reduction and isolation relevant to the working stability of diaphragm air pumps. To make the diaphragm air pump meet the use requirements, a sandwich-constrained damping gasket is designed and prepared in this paper. The research focuses on examining the impact of varying damping layer thickness on the efficacy of damping gaskets in reducing and isolating vibrations. Meanwhile, with the increase of the damping layer thickness, the total vibration severity of the diaphragm air pump body continues to increase, indicating a weakened performance of vibration reduction, while the vibration isolation performance is gradually improved.

Biomimetic dual-phase ceramic lattice architectures with enhanced mechanical and vibration isolation performances

Ceramic materials have broad application prospects for impact/perforation protection purposes due to their high strength, high hardness, and other characteristics. Nevertheless, the high brittleness, susceptibility to fracture, and difficulty in processing and forming limit the popularization of ceramic components. This paper proposed a novel silica gel-filled dual-phase ceramic lattice meta-structure based on a biomimetic biphasic design method to achieve the improvement of mechanical properties. Two configurations of dual-phase body-centered cubic (BCC) and face-centered cubic (FCC) ceramic lattice structures were designed and fabricated through DLP-based additive manufacturing and simple filling technology. Quasi-static compression and dynamic vibration testing were conducted. Comparisons between single-phase and dual-phase ceramic lattices were performed from the perspective of compression strength, fracture toughness, and vibration level difference. It was demonstrated that the addition of soft silica gel reduced the stress concentration at the connection of the lattice rod and effectively inhibited the crack propagation. The dual-phase BCC lattice structure exhibited a 3 times increase in toughness and a 4.2 times increase in compressive strength relative to the single-phase design. The toughness and compressive strength of the dual-phase FCC ceramic lattice were increased by 1.4 times. The introduction of the soft silica gel achieved a significant vibration isolation in the pre-resonance frequency band between 1000 Hz to 3000 Hz. This study provides a reliable method for constructing biomimetic dual-phase meta-structures with both load-bearing capacity and low-frequency vibration isolation capacity.

Hybrid Electric Vehicle Powertrain Mounting System Optimization Based on Cross-Industry Standard Process for Data Mining

The meticulously engineered powertrain mounting system of hybrid electric vehicles plays a critical role in minimizing vehicle vibrations and noise, thereby enhancing the longevity of vital powertrain components. However, developing and designing such a system demands substantial time and financial investments due to intricate analysis and modeling requirements. To tackle this challenge, this study integrates data mining technology into the design and optimization processes of the powertrain mount system. The research focuses on the powertrain mounting system of a transverse four-cylinder hybrid electric vehicle, employing the CRISP-DM (Cross-Industry Standard Process for Data Mining) methodology to establish a data-mining prediction model for mounting stiffness. This model utilizes three data mining algorithms—Multi-SVR, MRTs, and MLPR—to assess their predictive accuracy concerning mounting system stiffness estimation. A comparative analysis reveals that the MRTs algorithm outperforms others as the most effective prediction model. The proposed predictive model elucidates the quantifiable correlation between vibration isolation performance and installation stiffness, overcoming complexities associated with traditional modeling approaches. Applying this model in powertrain mounting system design showcases the efficacy of the CRISP-DM-based approach, significantly enhancing design efficiency without compromising prediction accuracy.

Low-frequency forbidden band characteristics of metamaterials based on combined resonant units

With a view to increasing the width of the local resonant band gaps and obtaining damping at low-frequency, a metamaterial structure with multiple resonant units and an adjustable band gap is proposed. The single-unit structure of the metamaterial consists of a main system and three resonant units. Simultaneously, the energy band structure and frequency response characteristics of the metamaterial are investigated with the finite element method and the dispersion equation. Further, the effects of natural frequency, mass of resonant units, mass ratio, and stiffness ratio on the energy band structure are demonstrated. Also, the effect of damping on the band gap in the metamaterial structure is examined. The low-frequency vibration isolation performance of the structure is verified on experimental platform. In conclusion, the designed metamaterial structure provides three adjustable band gaps in the low-frequency range with good vibration damping.

Analytical optimization and performance evaluation of non-traditional tuned mass damper for stochastic base excited structures considering dual solutions

Compared with traditional tuned mass damper (TMD), non-traditional tuned mass damper (NTMD) has higher damping efficiency in some conditions. Nevertheless, the analytical optimization problem of NTMD has not been well solved; especially, multiple optimal solutions are not discussed. In this study, the closed-form optimal expressions of the NTMD using tuning stiffness are derived based on H 2 norm optimization. And the vibration mitigation performance of the NTMD is evaluated considering dual-solutions situation subjected to typical ground motion and impulse excitation. Different from solving the unique optimal frequency ratio, there exist two sets of optimal stiffness and damping ratio derived using tuned spring elements for given mass ratio, and the effective mass ratio is also limited as 1/3. The vibration mitigation or isolation performance and robustness of H 2 optimized NTMD with higher stiffness ratio are far superior to NTMD with lower stiffness ratio. NTMD using larger optimal tuning stiffness ratio also can be seen as an optimized form of Maxwell model using additional mass. Hence, using a large stiffness, namely, a large frequency ratio to design NTMD is recommended, which is different from traditional TMD. The case of NTMD with large stiffness can be adopted when the demands of practical engineering are not met using the optimal parameters of small stiffness. And a compromise scheme can also be provided, which are the combination with a larger mass ratio but is less than the maximum limit value 1/3 and a not very large stiffness ratio but is exceeded 0.5 according to demands of practical engineering.

Micro-vibration control of spaceborne payload with smart parallel struts

Currently, the observation resolution of Earth observation satellites and space telescopes is progressively increasing. However, vibrations induced by solar panel vibrations, control torque gyroscopic reaction forces, and internal satellite noise significantly impede the observation accuracy of space-borne precision optical payloads. To mitigate the impact of vibrations on precision payload, it is necessary to incorporate isolation devices into the transmission path between the payload and spacecraft bus. This paper aims to design a six-degree-of-freedom parallel struts for active control of vibration in sensitive payloads. An optical payload isolation system is constructed using a Gough-Stewart parallel configuration with flexible hinges. The dynamic model of the system is established by the Newton-Euler method. The dynamic characteristics and response of the isolation system are analyzed. Then the active controller is designed based on the Fuzzy Auto-Disturbance Rejection Control strategy, and the effectiveness of the controller is simulated and compared with the fuzzy Proportion Integration Differentiation (PID) control algorithm. The results show that the active parallel struts exhibit excellent vibration isolation performance and possess strong robustness, which provides a theoretical reference for further space applications.