Vibration Isolation Design Research Articles

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.

Vibration Suppression and Isolation for Rapeseed Grain Cleaning Loss Sensor

Rapeseed cleaning loss is an important factor to weigh rapeseed combine harvester performance. With the development of sensor technology, establishing a rapeseed cleaning loss monitoring system can be interesting and necessary. However, the rapeseed combine harvester made in China is always with larger vibration, which is not beneficial for sensor monitoring accuracy. Experiment results indicate that inertia force from vibrating sieve unbalanced motion has the greatest influence on the monitoring accuracy of the sensor in its installation position. To reduce the effect of vibration on monitoring accuracy of the sensor, the vibration absorption and isolation structure for cleaning loss sensor has been designed. Moreover, the vibration isolation design was performed on the basis of vibration suppression. The vibration isolation rubber was designed to isolate the vibration at the joint of the sensor with the frame. The experimental results shown that the above design can reduce the vibration disturbance and highlight the grain collision signal greatly, which is beneficial for improving the sensor discrimination ability.

Simulation and experiment research of vibration characteristic on star compressor

Aiming at the vibration defects of star compressor, simulation and experiment are carried out to investigate the compressor. By drilling holes in the valve stem, the pressure changes of each cylinder are measured without damaging the cylinder block. The dynamic model of crank-connecting rod mechanism is established. After the measured cylinder pressure loaded on the dynamic model, the force acting on the main motion pair is obtained. The finite element model of the compressor is established for the first time, the force of the motion pair is loaded on the finite element model by MPC coupling method, and the vibration acceleration of the machine base is tested. The result shows that the main modal shapes between 50-150 Hz are body deformation, modal shapes between 150-200 Hz are base deformation, the simulation acceleration of the base is higher than that of the experiment, and the main working frequency and frequency doubling can correspond. The conclusions provide reference for vibration isolation design of star compressor.

Study on dynamic characteristics of horizontal suspension in engineering vehicle seat based on rolling vibration isolation principle

The low frequency horizontal vibration of engineering vehicles is a part of multidimensional vibration, which causes driver's occupational disease. Therefore, the design of low frequency horizontal vibration isolation is of great significance. The principle of rolling vibration isolation is applied to seat suspension for low frequency horizontal vibration isolation in this paper. The natural frequency characteristic model of horizontal suspension and the seat-human system dynamics model with horizontal suspension based on the Lagrangian equation are established. The dynamic characteristics of rolling horizontal suspension are studied on account of the established models. Results show that this horizontal suspension can achieve very low natural frequency so as to isolate the low frequency vibration in horizontal direction by the matching design of the rollers and concave dimensions. The vibration isolation characteristics of the front and back seat–human system are improved with the reduction of the rollers’ radius. The vibration isolation characteristic of the front and back seat - human system increases with the increase of the concave surfaces’ radius.

Numerical Analysis of Pipeline Vibration Characteristics in Large Pumping Stations

This paper focuses on the high frequency vibration of the pipeline structure during operation of the large cascade pumping station. In order to explore its causes and inherent vibration characteristics, this paper takes #1 pressure pipeline of No.7 pump of Gansu Province Jingdian Project as the research object. The principle of additional mass method is used to establish a simplified fluid-solid coupling simulation model, and then the model is used to carry out numerical simulation test on the pipeline under different unit opening and closing conditions. After analyzing the numerical results of the simulation, the vibration mode and displacement deformation law are discovered and compared with the DASP field monitoring results. The results show that: under four representative working conditions, the vibration deformation of the pressure pipeline mainly occurs in the elbow section and the connecting section of the large and small tubes; the amplitude of the vibration mode increases with the increase of the modal order; furthermore, the water outlet pipe that is not easily vibrated in the high-order mode is gradually vibrated and deformed; in addition, the numerical simulation results are in good agreement with the field test results. This research can provide reference for the optimization design of pipeline vibration isolation and vibration reduction, and also provide a theoretical basis for the subsequent research on pipeline structural damage diagnosis and its safe operation.

Vibration performance improvement of D/G-set employing inerter-rubber vibration isolator

This paper investigated the benefits of vibration performance of diesel generator set (D/G-set) employing a kind of novel anti-vibration structure known as an inerter-rubber vibration isolator. We designed this vibration isolator in parallel with a rubber-part and a ball-screw inerter. Based on the inerter-rubber vibration isolator, the vibration system of an existing D/G-set (5DK-20) was built, and then the natural frequencies and vibration intensity of this D/G-set were analysed. The results show that the natural frequencies and the vibration intensity were both reduced employing inerter-rubber vibration isolators. Moreover, the anti-vibration performance of this D/G-set can be improved by more than 30% when the inertance-mass ratio is greater than 0.5. Therefore, the anti-vibration performance of the D/G-set can be significantly improved employing inerter-rubber vibration isolator. This work provides a new direction for vibration isolation design of power machinery, especially for the marine high-power low-speed D/G-set, which has practical engineering significance.

Development of Hybrid Vibration Isolator by Inertial-Type Actuator and Wire Mesh Mount

Hybrid-type mounts have been frequently developed as combining active vibration control techniques to predesigned passive mounts in order to increase equipment precision and to provide sufficient performance in extreme environments. Among various passive vibration isolation materials, wire mesh is regarded as a good candidate for reducing vibration due to its moderate material price, ease of machining, and long life cycle, without significant deterioration induced by aging or environmental effects. However, research on design, including wire mesh material, as a mount material, and the application of active control technology to its performance have rarely been conducted. In this paper, the method and procedure of an active hybrid mount design using a wire mesh material and inertial mass type actuator are proposed. Prior to designing a passive wire mesh isolator, the static and dynamic elastic modulus of wire mesh materials were experimentally extracted using simple shaped cylindrical specimens, and their characteristics relating to vibration isolator design were examined. From the experimental results of the simple shape specimens, density was determined to be the most important design factor, and the procedure for designing the passive component of the hybrid mount was proposed with density as the design factor. In addition, a procedure for designing an inertial mass type active vibration reduction device using a piezo actuator is also proposed with the goal of vibration reduction in equipment with periodic operation frequency, such as motors and pumps, and the vibration reduction effectiveness of the hybrid mount system was examined by simple two- and three-degree-of-freedom systems.

Vibration Protection of Historical Buildings Located near the Lines of Urban Rail Transport

Besides the underground, the second common type of public transport is the tram. Tram lines in Moscow city center, as well as in other cities in Russia, are being renovated and reconstructed. Vibration of the railway track travels through the ground to the foundation of buildings adjacent to tram lines, causing high vibration and structure-borne noise levels inside them. The article presents result of a vibration isolation system analysis and design for a building, located in 37m of the two-lanes tram line. Prior to design procedure, field measurements were made and vibration levels inside the building were recorded. The vibration isolation system design included calculation of soil pressure on the isolation pad and subsequent estimation of the elastomeric pad dynamic modulus. Using this data, the eigenfrequecny of vibration isolation system was derived and its efficiency calculated. After the system maintenance, measurements were made to check the system’s performance. During the measurements acceleration of isolated part of the building and the ground surface were synchronously measured and transfer function derived.

Vibration isolation with high thermal conductance for a cryogen-free dilution refrigerator.

We present the design and implementation of a mechanical low-pass filter vibration isolation used to reduce the vibrational noise in a cryogen-free dilution refrigerator operated at 10 mK, intended for scanning probe techniques. We discuss the design guidelines necessary to meet the competing requirements of having a low mechanical stiffness in combination with a high thermal conductance. We demonstrate the effectiveness of our approach by measuring the vibrational noise levels of an ultrasoft mechanical resonator positioned above a superconducting quantum interference device. Starting from a cryostat base temperature of 8 mK, the vibration isolation can be cooled to 10.5 mK, with a cooling power of 113 µW at 100 mK. We use the low vibrations and low temperature to demonstrate an effective cantilever temperature of less than 20 mK. This results in a force sensitivity of less than 500 zN/Hz and an integrated frequency noise as low as 0.4 mHz in a 1 Hz measurement bandwidth.

Simulation calculation and research of double layer metal rubber vibration isolator

Marine diesel units will produce certain vibration and noise at work, which will affect the normal operation of machinery and crew’s physical and mental health. It is a common solution to equip diesel units with vibration isolators, so it is very necessary to optimize the design of vibration isolators. Based on diesel engine set with double layer metal rubber vibration isolator, for example, to establish the geometric model of the vibration isolator with Solidworks, and importing it into the finite element software called ANSYS Workbench to make simulation calculation, get the vibration isolator in forward loading, reverse load and radial load displacement nephogram under three working conditions and stress nephogram, get the maximum double metal rubber vibration isolator deformation, the maximum stress value and the location of maximum stress. The results show that the maximum stress of the double layer metal rubber isolator is less than the yield limit of the material, which meets the work requirements. The stress concentration is easy to occur in the center of the bottom base of the vibration isolator, that is, fatigue failure is easy to occur. Under the condition of radial loading, the maximum deformation of the case is large. The maximum deformation and stress of the improved case are significantly reduced, which is of guiding significance to the optimal design of the vibration isolator.

Attributes of a Vibration Isolator Design with Stiffness Nonlinearities

Attributes of a Vibration Isolator Design with Stiffness Nonlinearities

Beneficial stiffness design of a high-static-low-dynamic-stiffness vibration isolator based on static and dynamic analysis

A high-static-low-dynamic-stiffness (HSLDS) isolator has good application prospects in low-frequency vibration and micro-vibration isolation. The nonlinear stiffness of the vibration isolation system strongly influences its dynamic responses and vibration isolation performance. In this paper, for a HSLDS isolator model, a stiffness range parameter d and a static equilibrium position stiffness Ksep are introduced to indicate the different stiffnesses of the nonlinear isolator. The averaging method is employed to solve the nonlinear dynamic equation of the proposed system at steady state for each excitation frequency. The effects of the parameters d and Ksep on the dynamic responses and isolation effectiveness of the HSLDS isolator are clearly analysed. The results show that an increase in d and a reduction in Ksep improve the isolation performance of the system. Considering the application of the HSLDS isolator in micro-vibration environments, the beneficial stiffness design under various excitation amplitudes and damping conditions is discussed on the basis of the limited maximum response amplitude. Several useful guidelines for the stiffness design of the HSLDS isolator are developed, which help to improve the vibration isolation performance of the system. The results provide useful insight for the design, analysis and application of HSLDS vibration isolators.

Analysis of the non-resonance of nonlinear vibration isolation system with dry friction

We studied the properties of cubic nonlinear systems with dry friction damping on the prospect of ‘non-resonance’. An approximate method was used to get the frequency-response function. And the critical dry friction which ensures no displacement transmissibility amplified in whole frequency range was determined through the frequency-response function. We also researched those characters which may influence the effect of the non-resonance in this system, and proved those results by empirical experiments. The above conclusions have a theoretical significance for the design of nonlinear vibration isolators.

Vibration isolation design for periodically stiffened shells by the wave finite element method

Periodically stiffened shell structures are widely used due to their excellent specific strength, in particular for aeronautical and astronautical components. This paper presents an improved Wave Finite Element Method (FEM) that can be employed to predict the band-gap characteristics of stiffened shell structures efficiently. An aero-engine casing, which is a typical periodically stiffened shell structure, was employed to verify the validation and efficiency of the Wave FEM. Good agreement has been found between the Wave FEM and the classical FEM for different boundary conditions. One effective wave selection method based on the Wave FEM has thus been put forward to filter the radial modes of a shell structure. Furthermore, an optimisation strategy by the combination of the Wave FEM and genetic algorithm was presented for periodically stiffened shell structures. The optimal out-of-plane band gap and the mass of the whole structure can be achieved by the optimisation strategy under an aerodynamic load. Results also indicate that geometric parameters of stiffeners can be properly selected that the out-of-plane vibration attenuates significantly in the frequency band of interest. This study can provide valuable references for designing the band gaps of vibration isolation.

Transmissibility of Bending Vibration of an Elastic Beam

This paper proposes an isolation transmissibility for the bending vibration of elastic beams. At both ends, the elastic beam is considered with vertical spring support and free to rotate. The geometric nonlinearity is considered. In order to implement the Galerkin method, the natural modes and frequencies of the bending vibration of the beam are analyzed. In addition, for the first time, the elastic continuum supported by boundary springs is solved by direct numerical method, such as the finite difference method (FDM). Moreover, the detailed procedure of FDM processing boundary conditions and initial conditions is presented. Two numerical approaches are compared to illustrate the correctness of the results. By demonstrating the significant impact, the necessity of elastic support at the boundaries to the vibration isolation of elastic continua is explained. Compared with the vibration transmission with one-term Galerkin truncation, it is proved that it is necessary to consider the high-order bending vibration modes when studying the force transmission of the elastic continua. Furthermore, the numerical examples illustrate that the influences of the system parameters on the bending vibration isolation. This study opens up the research on the vibration isolation of elastic continua, which is of profound significance to the analysis and design of vibration isolation for a wide range of practical engineering applications.

Vibration isolation design using lattice structures fabricated by additive manufacturing

Vibration isolation design using lattice structures fabricated by additive manufacturing

Vibration Characteristics Analysis of Convalescent‐Wheelchair Robots Equipped with Dynamic Absorbers

To provide a theoretical guidance for the vibration isolation design, the vibration responses characteristics for the convalescent‐wheelchair robot with DA (dynamic absorber) undergoing the random road were revealed. Firstly, the vibration model of the convalescent‐wheelchair system with DA was created. The frequency response functions of the road excitation velocity to the convalescent acceleration, the wheelchair body acceleration, and the tire dynamic deflection were deduced. Then, the numerical calculation method of the PSD (power spectral density) and the RMS (root mean square) responses were proposed. Thirdly, the vibration isolation performances of the wheelchair robot with DA and without DA were compared. Finally, the sensitivity analysis of the vibration responses to the mass ratios, the damping ratios, and the natural frequencies was carried out to reveal the effects of the parameters on the vibration responses. The results show that the DA can partly suppress the vibration of the convalescent and the wheelchair body, especially in the resonance area of the wheelchair body. However, the DA cannot successfully improve the tire contact behavior.

Magnetorheological elastomer vibration isolation of tunable three-dimensional locally resonant acoustic metamaterial

Magnetorheological elastomers (MREs) are used as cladding in three-dimensional locally resonant acoustic metamaterial (LRAM) cores. The metamaterial units are combined into a vibration isolator. Two types of LRAMs, namely, cubic and spherical kernels, are constructed. The finite element method is used to analyze the elastic band structures, transmittances, and vibration modes of the incident elastic waves. Results show that the central position and width of the LRAM elastic bandgap can be controlled by the application of an external magnetic field; furthermore, they can be adjusted by changing the MRE cladding thickness. These methods contribute to the design of metamaterial MRE vibration isolators.

The OVAL experiment: a new experiment to measure vacuum magnetic birefringence using high repetition pulsed magnets

A new experiment to measure vacuum magnetic birefringence (VMB), the OVAL experiment, is reported. We developed an original pulsed magnet that has a high repetition rate and applies the strongest magnetic field among VMB experiments. The vibration isolation design and feedback system enable the direct combination of the magnet with a Fabry-P\'erot cavity. To ensure the searching potential, a calibration measurement with dilute nitrogen gas and a prototype search for vacuum magnetic birefringence are performed. Based on the results, a strategy to observe vacuum magnetic birefringence is reported.

Sound isolation of large transformers mounted on raised floors

Transformers for substation service mounted on elevated floors often cause spurious sound to be transmitted to the spaces below it. Magnetostriction vibration of the massive iron core at 120 Hz and its harmonics drives the supporting floor to emit sound into the spaces below. Contemporary vibration isolation design fails to prescribe the proper isolation method since the mass of that transformer considerably exceeds that of the participating mass of the concrete floor. A vibration isolation paradigm is proposed of a two-body system in inertial space; the participating mass of the concrete floor being the second active body; the virtual mass of the pair along with the spring stiffness determines the resonance frequency. The ratio of that resonant frequency to that to be isolated is a measure of the expected isolation. For good isolation, the resonant frequency should be 1/10th that of the vibration to be isolated. The floor participating mass is approximated as a square one-half wavelength of the thin conc...