Vibration Isolation Design Research Articles

Vibration characteristics and isolation in vibration-sensitive areas under moving vehicle load

A precision instrument building is used to house various experimental equipments that are sensitive to ground vibrations. In order to research the characteristics of ground vibrations under the moving vehicle load, a field test of vibration was carried out. A coupling model of moving vehicle load-foundation soil-building structure was established to simulate vibration isolation measures and analyze the vibration isolation effect. The results indicate that the ground vibrations in the sensitive area caused by the moving vehicle load are mainly low frequency in the vertical direction, where the principal frequency is in the 3∼4 Hz range, consistent with the ground pulsation test. The horizontal vibration attenuates much faster than the vertical vibration. For the vibration isolation using the piles, factors including pile spacing, pile length and barrier width have a significant impact on the vibration isolation effect, while the number of pile rows and the material of piles have relatively little influence. Using the optimized vibration isolation plan, the vibration in the sensitive area caused by the moving vehicle load can be reduced by about 30∼50%. The research methods and conclusions of this paper can serve as a useful reference for the analysis of ground vibrations and vibration isolation design in vibration-sensitive areas.

Stability Design of Air Vibration Isolation Device for a High Power Density Main Engine

In order to improve the alignment stability of the air vibration isolation device of a high-powered main engine, we established a mechanical model for the air vibration isolation system and analyzed the alignment deviation of the device and the vibration decoupling conditions of the system. Additionally, an optimized design method for the dual-direction support of the air vibration isolators positioned symmetrically on the main engine was proposed. The resultant design showed that when compared to the conventional inclined support of air springs for the main engines onboard ships, the dual-direction support design proposed in this paper for air vibration isolation could eliminate the adverse effect of the output torque reaction on the alignment of the main engine and decouple the system to reduce the number of peaks in the frequency response of vertical force transmission. The optimized design could effectively improve the alignment performance of the device for tilted or swinging operating conditions and maintain the good alignment stability of the device when a single vertical support air spring fails. A single vertical support air spring failure mainly affects the stability of the main engine under the reaction of the output torque, especially the air springs arranged in the corner, while the air springs arranged in the middle have no effect. The optimized design could also improve the vibration isolation performance. This is important for the design of air spring vibration isolation devices for high power density main engines.

Vibration characteristics of innovative reentrant-chiral elastic metamaterials

In this work, an innovative two-dimensional (2D) hybrid auxetic elastic metamaterial (MODEL I) with reentrant triangular and chiral structures is proposed to open the broaden bandgap for vibration attenuation. Furthermore, the hybrid reentrant-chiral lattice with embedded resonators (MODEL II) shows multiple bandgaps at ultra-low frequency. Based on theoretical lumped mass-in-mass method and finite element method, the bandgap and longitudinal elastic wave attenuation are characterized. There is no complete bandgap in classical reentrant triangular lattice (MODEL 0), while the complete bandgaps width for MODEL I and II account for one forth of the concerned frequency range (0–4500 Hz). What more, the lower boundary of the first bandgap for MODEL II is 56% lower than that of MODEL I. The bandgap formation mechanisms are investigated by analyzing the mode shapes on the dispersion curves, and the frequency-dependent energy flow are studied through the iso-frequency contours, phase and group velocities. Finally, the longitudinal elastic wave attenuation of finite-size lattice of MODEL II illustrates ultra-wide vibration attenuation frequency range in the directional bandgaps. This research provides important clues and theoretical guidance for the design of vibration isolators, beam, plates and other renewed devices.

On wave transmission in saturated soil system separated by a nonlinear isolated layer

Nonlinearity is the basic property of materials, especially for dynamic responses under waves with large amplitudes such as seismic waves. In this study, wave propagation characteristics in 1D saturated soil system with a nonlinear isolated layer are investigated. Biot poroelasticity is employed to describe the constitutive relations and motion equations for saturated soils. The nonlinear dynamic responses are considered for the isolated layer. The perturbation method is utilized to solve the nonlinear wave equations in the isolated layer. The model is verified by degenerating it into a linear system. A parametric analysis for normalized displacement amplitude is conducted while considering and without considering the isolated layer’s nonlinearity. The results indicate that the isolated layer’s nonlinearity has a nonnegligible influence on wave transmission and cannot be ignored under certain circumstances, which can provide a meaningful guideline for investigating wave characteristics and vibration isolation designs with nonlinear materials in saturated soil.

Research of Vibration Characteristics of Ship Propeller-shaft Longitudinal Two-stage Vibration Isolation System

Aiming at the vibration control problem of ship propeller-shaft system, this paper put forward a design approach of ship propeller-shaft longitudinal two-stage vibration isolation system and its dynamic characteristics are studied. The vibration mathematical model of ship propeller-shaft longitudinal two-stage vibration isolation system is established. The influence of mass ratio, stiffness ratio and damping ratio of two-stage vibration isolation system is studied. The design is optimized taking a ship propeller-shaft system as an example. The results show that the ship propeller-shaft longitudinal two-stage vibration isolation system which is optimized has better isolation effect than the single-stage vibration isolation system. The research results have important reference value for ship propeller-shaft longitudinal vibration isolation design.

Developing student imagination and career interest through a STEM project using 3D printing with repetitive modeling

ABSTRACT Over the past few years, digital fabrication has been utilized in technology laboratories to emphasize hands-on learning processes in technology and engineering education. Recent studies indicate that hands-on activities can help students connect with science, technology, engineering, and mathematics (STEM) disciplines and develop key skills required in the 21st century. However, some argue that introducing 3D printing technology in schools could reduce pragmatic engagement and cause affective loss of hands-on interests. To explore the use of 3D printing machines in technology and engineering education, this research developed a STEM-based vibration isolator activity using a 3D printer and repetitive modeling. A nonequivalent control group design was employed in this research, and 192 Taiwanese high school students participated in this study. The conclusions are: (1) repetitive modeling in the STEM-based design activity enhanced student imagination; (2) repetitive modeling was effective in developing high school students’ interest in technology and engineering careers; and (3) repetitive modeling, engineering design, and “conceiving imagination” were significant predictors of the students’ final products. These results suggest a benefit to high school technology education of using 3D printers in a STEM-based vibration isolator design activity with repetitive modeling.

Design and co-optimization of a laminated isolation bearing based on magnetorheological elastomer

Magnetorheological elastomer (MRE) base isolation is regarded as one of the most promising candidates in adaptive base isolation filed for civil structure. The field is rapidly evolving with significant technological advancements, while MRE device developing remains a spotlight of interest, essential for the future developments of MRE control system. Other than previous research in MRE device developing, which lacks a theoretical design combining the requirements of applied object, meanwhile, which only focus on the magnetic-controllable range without an integrated performance optimization. This report presents an efficient design and optimization of MRE isolation bearing (MRE-IB) according to the requirements of a scaled frame structure, by simultaneously considering the superior magnetic-controllable performance, low power consumption and fast current response time as the optimization objectives. After an efficient design, co-simulation and optimization, the optimized MRE-IB is manufactured and evaluated. The evaluated results verify the validity and reliability of the proposed optimization method. Besides the intrinsic importance of providing theoretical foundation and reference value for the design and optimization of MRE vibration isolators, this study can also conduce to the efficient design and optimization of other MRE devices, such as MRE absorbers, MRE buffers, and so on.

Vibration characteristics and vibration isolation design of oil-immersed power transformer

Transformer vibration and noise has become a prominent problem in power grid construction and operation. Firstly, on the basis of expounding the vibration mechanism of iron core and winding, the transmission path of vibration and noise of transformer is analyzed. Secondly, it is pointed out that it is not cost-effective to control transformer vibration and noise only from the selection of core and winding materials, manufacturing process and structural optimization. It is necessary to start from the transmission path of transformer sound and vibration, and adopt auxiliary vibration reduction and noise reduction measures such as vibration isolation of the body to reduce the transmission of vibration of the body to the oil tank wall, foundation and adjacent structures. Then, the design method of oil immersed power transformer body vibration isolation is discussed, and the relevant parameters such as frequency ratio, damping ratio and the arrangement of vibration isolation support are proposed. The reasonable vibration isolation design of transformer body can achieve remarkable vibration isolation effect and the vibration isolation efficiency can reach more than 96%. Finally, the vertical design stiffness of 81 kinds of oil immersed power transformer vibration isolation layers with 4 voltage levels of 10 kV, 35 kV, 110 kV and 220 kV are calculated. Taking a typical 110 kV transformer as an example, the corresponding vibration isolation design scheme is proposed. The research provides a good reference for the vibration isolation design of transformer body in the future.

The analysis and design of nonlinear vibration isolators under both displacement and force excitations

In this study, a novel criterion known as the comprehensive transmissibility is proposed to estimate the isolation performance of nonlinear isolation systems under complex loading excitations. A combined quasi-zero-stiffness (QZS) isolator is enumerated, and the comprehensive performance of other common isolator systems and the existing QZS system is analyzed. Based on the normalized differential equations of the isolation system, the isolation performances of different isolation systems are studied by using the comprehensive transmissibility criterion, showing that the combined QZS isolator has better isolation performance than others. In addition, the output frequency response function (OFRF) representation of the comprehensive transmissibility is derived, and the optimal design of the QZS isolation system is developed by using the OFRF. The simulation results demonstrate that the design can meet the requirements of the vibration isolator with both the force and displacement excitations and is promised to be applied to the design of nonlinear isolation systems in engineering practice. To solve the issue of the analysis and design of nonlinear vibration isolation systems under multi-excitation, a new criterion known as comprehensive transmissibility is proposed. Based on the comprehensive transmissibility, the isolation performance of the combined vibration isolation system is analyzed, and the output frequency response function (OFRF) method is applied to conduct the design of the isolation system.

4D printed zero Poisson's ratio metamaterial with switching function of mechanical and vibration isolation performance

The unusual properties of mechanical metamaterials are determined by the configuration of artificial periodic structures. However, the mechanical performance of conventional metamaterials is irreversible and cannot perceive and respond to the changes in the environment. In present study, a zero Poisson's ratio metamaterial with intelligent switching mechanical properties and vibration isolation effect is proposed. Based on a 4D printing method of shape memory polymer, this metamaterial is created that can sense temperature changes and switch mechanical properties. The macroscopic deformation and the morphology change of the metamaterial during compression tests are analyzed using experimental and finite element methods. The irregular buckling distortion of the metamaterial is eliminated by cylindrical design, and controllable and adjustable local deformation and stress-strain curve are achieved based on microstructure gradient design. Subsequently, this work focused on the vibration isolation performance of metamaterials, and found fascinating shock absorption performance. Compared with traditional linear spring, this metamaterial spring can effectively reduce the vibration amplitude of certain frequency bands before reaching the resonance peak, which provides a new realization method for low-frequency vibration isolation design.

A dynamic reconfigurable nonlinear energy sink

Traditional nonlinear energy absorbers, such as the nonlinear energy sink (NES) and negative stiffness vibration isolators, are not configurable. Therefore, when their structures have been fabricated, their performances cannot be tunable in real time, which prevents the application of these devices over a wider range external forcing amplitude. In this paper, we present a novel energy absorber that essentially offers nonlinearity and a time-dependent inertial mass. The newly designed mass is engineered using a three-body system, which consists of a primary mass and two additional masses that rotate along a circular orbit and offer an additional degree of freedom for dynamic modulation of the absorber. The resonant frequency can be modulated dynamically by using the angular velocity to trigger a controlled target energy transfer (TET). In particular, it is found that the maximum energy absorption limit can be overcome and that a much lower threshold for triggering of TET is supported. These results provide a new framework for the design of nonlinear vibration isolators and absorbers.

Research on Structural Design of Coal Crusher House in Thermal Power Plant

This paper takes the specific characteristics of pulverized coal room in thermal power plant as the starting point，firstly, this paper analyzes the process layout and structure selection, and then the structural design and vibration design requirements of coal crusher house are introduced in this paper. Finally, based on the engineering example, a new structure form of vibration isolation design is creatively proposed, which provides a new design idea for the practical engineering design

Elastic Wave Propagation in Lattice Metamaterials with Koch Fractal

In this study, the wave propagation properties of lattice metamaterials with Koch fractal structures are investigated in terms of band structures and directional wave propagation. The analytical models of lattice metamaterials are established using the finite element method, and the dispersion relation is solved using the Bloch’s theorem. The band structures of the lattice metamaterials with different numbers of iterations are studied, and the group velocities at a selected frequency are calculated to analyze the directional wave propagation characteristics. Furthermore, dynamic responses of the finite structures are calculated using commercial finite element software to verify the band gaps and directional wave propagation behaviors in the lattice metamaterials. The results show that multiple and low band gaps are present in the lattice materials with various geometric parameters of the Koch fractal, and the position of the lowest band gap decreases as the number of iterations increases. The results indicate the potential applications of lattice metamaterials with Koch fractals for vibration isolation and multi-functional design.

The Design and Analysis of a Novel Passive Quasi-Zero Stiffness Vibration Isolator

This project aims to design a novel passive quasi-zero stiffness vibration isolator (QZS-VI) and analyze the static and dynamic mechanical properties of the QZS-VI. First, a novel combination of V-shaped lever, plate spring and cross-shaped structure (VL-PS-CS) vibration isolation platform is designed, and a nonlinear QZS-VI is built by parallel connecting VL-PS-CS and coil spring. Second, the static and dynamic modeling of QZS-VI are derived considering the geometrical nonlinearity of V-shaped lever and the large deflection of plate spring, and the average method is applied to obtain the displacement transmissibility. Third, the effects of different structural parameters (e.g., the lengths of long arm and short arm of V-shaped lever, the assembly angle between two arms, the thickness of plate spring) on the static mechanical and equivalent nonlinear friction properties of QZS-VI are thoroughly investigated. Finally, the vibration isolation performance of the designed QZS-VI is compared with another QZS-VI of buckled beam mechanism and traditional linear vibration isolator. The QZS-VI with VL-PS-CS fully explores the nonlinear advantages of plate spring and V-shaped lever and can achieve excellent high static and low dynamic stiffness and nonlinear friction properties. The superior static mechanical properties and nonlinear friction of QZS-VI can be tuned with different structural parameters. The designed QZS-VI exhibits much smaller resonant frequency, lower peak value and more stability property at the peak frequency than other isolators due to its special nonlinear friction and stiffness properties. The designed QZS-VI is practical, novel and suitable for low-frequency vibration isolation. The innovative structure provides novel insights into the design of passive vibration isolators and has great potential for application in engineering practice.

Band gaps and vibration transfer characteristics of one-dimensional triangular arrangement of elastic metamaterials

In this paper, three one-dimensional elastic metamaterials (EMs) coupled with triangular arranged resonators are proposed for broadband elastic vibration suppression and the vibration characteristics of these three models (MODELS II, III, and IV) are compared with the classical EM MODEL I. Firstly, the dispersion curves of the proposed models are studied based on Bloch’s theorem. This shows that the starting frequency of the first band gap for MODEL II, MODEL III, and MODEL IV is 8.8%, 54%, and 15% lower than that of MODEL I, respectively. The total band gap width of MODEL IV (α = 60°) is 2.89 times that of MODEL II (α = 60°), 1.59 times that of MODEL III (α = 60°), and 4.3 times that of MODEL I, specifically. The effect of the parameters and configuration of the system on the band gap features is discussed. The spring stiffness ratio has the greatest influence on the band gap behavior, and the optimal parameters of a low-frequency vibration isolation design are obtained accordingly. Finally, the wave propagation characteristics of the EM system composed of finite unit cells show great agreement with the band gap structure of an infinite lattice structure predicted by Bloch’s theorem. This research will provide important clues and theoretical guidance for the design of vibration isolators, plates, beams, and other renewed devices.

Optimum design of electromechanical vibration isolators

Conventional vibration isolators have been used for a long time to isolate a receiver from a source of disturbance. Probably, the most popular example of vibration isolators can be found in automotive suspensions. In vehicles, the spring and damper elements are used to damp road vibration and also to maintain drive handling stability. In this process, the mechanical energy is converted into heat and dissipated in the damper element. The idea of recovering part of the energy has become an attractive topic among researchers over the last three decades. In this context, this study investigates the possibility of replacing the damper element with an electrical circuit coupled to the mechanic system using a permanent magnet/coil transducer. Different electrical circuit configurations are analyzed to study the influence of damping on the mechanical system. Expressions to obtain critical damping and optimum damping to reduce the maximum peak in the frequency response are developed and presented in tabular form for ease of reference. The methodology is then applied to a two-degree-of-freedom system representing a quarter-vehicle suspension model. The results show that coupled electrical circuits can be used to replace fluid dampers in the design of vibration isolators without performance loss.

Design and experimental investigation of ultra-low frequency vibration isolation during neonatal transport

To resolve the tough issue of ultra-low frequency vibration isolation during neonatal transport, a new incubator with quasi-zero-stiffness (QZS) isolators is proposed. In the new incubator, the infant housing unit is supported by the QZS isolators to mitigate mechanical vibration being transmitted from the ambulance floor to the infant. Each of the QZS isolators is devised by combining a pair of permanent magnet rings and a coil spring, and the design parameters are realized by the equivalent magnetic charge method. Both the prototypes of the QZS isolator and incubator are manufactured, and their vibration isolation performances are tested. The results show that the QZS isolator can fulfil vibration isolation from 2 Hz, and the incubator with four such QZS isolators is effective from 3.2 Hz under the designated payload. Most importantly, the acceleration response of the infant model in the housing unit is much lower than the base excitation, when the incubator is driven by a random base excitation with frequency bandwidth from 2 Hz to 15 Hz.

Обоснование конструкции виброизоляторов с дискретно изменяемой жесткостью

Обоснование конструкции виброизоляторов с дискретно изменяемой жесткостью

巡天制冷模块隔振解锁装置设计与分析

巡天制冷模块隔振解锁装置设计与分析

Vibration in the building with machines on the floors

في الوقت الحاضر ، مع تقدم العلم ، ظهرت مواد بناء ذات خصائص ميكانيكية عالية (قوة عالية ، عالية التخميد وضوء .. إلخ) وأنظمة عزل اهتزاز متطورة. كما أنه مصحوب بتطوير أساليب التحليل والتصميم الإنشائي والازدهار المدرك للبرمجيات والإلكترونيات كلها ساهمت بشكل كبير في الدراسة المتعمقة للمباني الاهتزازية الأكثر شمولاً من سابقاتها وفي نفس الوقت تلبية متطلبات التصميم المدني - بنيان.في حالة وجود آلات مثبتة على الأرض ، توجد معضلة تتمثل في حل متزامن لمشكلة عزل الاهتزاز النشط والسلبي. يجب أن يأخذ النهج المعقد لتصميم عزل اهتزازات الآلات في الاعتبار مسار انتقال الاهتزاز في المبنى ؛ من المصدر إلى الأجسام الحساسة للاهتزاز. يمكن تحديد العلاقات بين الإشارات في نظام "الآلات الدقيقة - بناء الآلات الديناميكية" بناءً على النموذج المبني من عناصر محدودة صلبة. بناءً على معادلات حركة النظام ، تم تحديد هيكله الديناميكي ووظائف نقل الأنظمة الفرعية والاقتران المتقاطع بين الأنظمة الفرعية. تم فحص تأثير هذه الوصلات على وظيفة النقل التي تصف العلاقة بين إزاحة الآلة الدقيقة والقوى المتولدة في الآلة الديناميكية.