Vibration Generation Mechanism Research Articles

Theoretical and Experimental Vibration Generation in a Coaxial Pulse-Tube Cryocooler

The microphonic noise induced by the vibration from cryocoolers has been found to cause energy resolution degradation in vibration-sensitive instruments. In this paper, theoretical and experimental research on the vibration generation mechanism of an aerospace-grade coaxial pulse-tube cryocooler (CPTC) is presented. Accordingly, suggestions for suppressing the vibration of the pulse-tube cryocooler are provided. A vibration model for the Oxford-type dual-opposed linear compressor is established, and the mechanism of vibration induced by the compressor is theoretically analyzed. A numerical simulation indicates that deviations in the compressor’s inductance coefficient, electromagnetic force coefficient, and flexure spring stiffness coefficient significantly affect the axial vibration of the compressor. The theoretical and experimental studies show that the high-order harmonic vibrations of the compressor are determined by both the resonance of the flexure springs and the high-order harmonics of the driving power supply. Through experiments and simulations, it is revealed that the dynamic gas pressure only induces vibration axially at the cold tip, while the radial vibration at the cold tip is determined by the heat head ‘s vibration and the structural response characteristics of the cold finger.

Vibration response analysis of boneless wiper-windshield system based on multi-body dynamics model

The vibration and noise generated by the boneless wiper-windshield system during its actual operation bother the occupants. Exploring the dynamic characteristics of the boneless wiper-windshield system is a prerequisite for understanding vibration and noise. In this paper, the dynamic characteristics of the boneless wiper-windshield system are investigated, and a rigid-flexible coupled multi-body dynamic model matching the real boneless wiper-windshield system is constructed. The friction characteristic of the dynamic model is studied through the wiper test bench experiment. The nonlinear dynamic response of the dynamic model is calculated with the Adams and results of the frictional vibration are well reproduced in real motions. The parallel analysis of the simulation calculation results and the real vehicle test results confirms the validity of the model. The results show that the vibration generation mechanism at the moments before and after the reversal can be explained by the instability of the wiper blades due to the negative friction characteristic. There are differences in the magnitude of the reversal impact force and the moment of reversal at each position of the wiper blade. The effect of the speed-gears on the system vibration is analyzed through the simulation results. The analysis method and simulation results in this article can provide reference for the research on vibration and noise control of boneless wiper systems.

Review on Vibration Monitoring and Its Application during Shield Tunnel Construction Period

With the rapid development of metro construction, shield machines inevitably have to traverse a variety of complex geological conditions, leading to the frequent occurrence of geological disasters, equipment failures, building vibration and other problems. Vibration, as an important feature of the shield tunneling process, has received more and more attention in recent years. This paper summarizes the relevant research progress of vibration monitoring during shield construction from 2015 to 2023. It analyzes the shield vibration generation mechanism, monitoring methods and application areas. Firstly, the shield vibration type is divided into mechanical vibration triggered by internal excitation and forced vibration triggered by external excitation, and the principles of vibration generated by shield main bearing, gearbox and disc cutter are discussed. Then, the commonly used vibration monitoring methods are outlined according to the installation location of the sensors (inside and outside of the shield). Finally, the applications of vibration signals in the diagnosis of shield faults, the identification of geologic conditions, and the evaluation of the current status of the interference with the buildings are summarized. This paper discusses the development trend of vibration monitoring during shield tunneling based on the current research situation and the current technology level, which provides valuable insights to enhance the safety and intelligence of shield construction.

Study on optimization of the dynamic performance of the robot bonnet polishing system

To solve the problem of processing quality degradation due to vibration in the robot bonnet polishing system (RBPS), the vibration generation mechanism of the polishing system is revealed based on the modal analysis and dynamic modeling of the RBPS. The modal analysis results showed that the operating frequency of the system is near the natural frequency, which makes the system susceptible to resonance. On the other hand, the forced vibration caused by the polishing force leads to high vibration at the end of the robot during the polishing process. In order to suppress the vibration generated by the polishing system and optimize the dynamic characteristics of the polishing system, a vibration suppression method to increase the damping ratio of the system was proposed. The experiments of SiC fixed point polishing were performed using both vibration suppression bonnet and original bonnet. The surfaces RMS and PV of the parts polished by the vibration suppression bonnet were generally better than those of the original bonnet. The vibration suppression bonnet has improved the convergence ratio of RMS and PV by 42.59% and 19.56% respectively over the original bonnet in the whole surface polishing experiments. The PSD analysis illustrated that the vibration suppression bonnet can better suppress the intermediate frequency errors. The effectiveness of the method in suppressing vibration and improving machining quality is demonstrated.

Vibration Analysis and Control of the Suspension System of the Drum Washing Machine by Applying SMA

The suspension system of the drum washing machine is the object of study. To reduce the vibration of drum washing machines during high-speed dehydration, a shape memory alloy is proposed to be used to make suspension spring. The spring stiffness can be controlled according to the characteristic that the elastic modulus of SMA varies with temperature to achieve damping effect. The mathematical model and multi-body dynamics simulation model are established for the suspension system of the drum washing machine, the vibration generation mechanism of the drum washing machine and the SMA active vibration control principle are analyzed, and the vibration control effect of the SMA suspension spring is studied for different speed simulations. The results show that the SMA variable stiffness suspension spring has a significant vibration control effect compared with the spring of general material.

Evaluation of Ground Vibration Resulting from a Heavy Vehicle Passing Over Transverse Rumble Strips: A Case Study in Kluang Road FT050

The transverse rumble strip (TRS) is one of the methods used to improve the driver's alertness to its driving and reduce their speed. However, the presence of a TRS causes unevenness on the road surface and may result in ground vibration when heavy vehicles passes it. This ground vibration may cause discomfort to the people living adjacent to the road. Therefore, there is a need to evaluate the level of ground vibration resulting from heavy vehicles passing over TRS especially on typical federal road in Malaysia which contains high percentage of fast-moving heavy vehicles. Ground vibration assessment study was conducted at federal road of Kluang-Batu Pahat Road (FT050) by using existing heavy vehicles in the traffic stream as study samples. ICP accelerometer and computer software Dewesoft7 have been used to measure and analyse the level of vibration generated. The results indicate heavy vehicles at a speed of 50 km/h, 33 km/h and 24km/h generate ground vibration level of 1.24 mm/s, 2.30 mm/s and 0.76 mm/s respectively. Other factors such as the weight of the heavy vehicles may involve in ground vibration generation mechanism as the results shown that there was no direct correlation between vehicle speed and level of ground vibration. All the generated ground vibration levels were found to be within the allowable limit set by Department of Environment Malaysia (DOE) standard guidelines.

Study of Transformer Core Vibration and Noise Generation Mechanism Induced by Magnetostriction of Grain-Oriented Silicon Steel Sheet

The problem of vibration and noise in the iron core of power transformers remains quite topical. Insofar as the state-of-the-art iron core and binding production adopt the lamination method and weft-free adhesive tape, respectively, the transformer core vibration is mainly attributed to the silicon steel sheet (SSS) magnetostriction. In this paper, based on the magnetostriction of grain-oriented SSS, an in-depth analysis of the vibration generation mechanism in the transformer core was performed. The SSS microstructure was observed, its magnetostrictive properties at different magnetic flux densities were tested, and a core-simulating four-corner iron core model was constructed to analyze the vibration characteristics. Modal, vibration, and noise tests were performed on an actual 110 kV transformer core under no-load conditions. The results show that the core vibration is related to SSS’s deformation mechanism. The vibration magnitude in different core parts varies due to the magnetostriction anisotropy. The vibration in vertical to the core plane is the largest, and its magnitude in the core center is lower than those at the seams in the same plane. The core vibration and noise exhibit a significant correlation, while modal characteristics strongly influence the core vibration and noise intensity.

Building vibration due to sonic boom—Results from simulations and field measurements

Sonic boom causing rattling and whole-body vibration in buildings can lead to human disturbance and annoyance. An overview of research on sonic boom vibration in the EU RUMBLE project is presented here. Numerical simulations are carried out for sets of buildings encompassing a variety of European building styles, and for different transmission situations such as with and without open windows. We calibrate the simulations with previous laboratory data and recorded sound and vibration data from field experiments in Tretyakov (Russia). We then use the simulation to understand how sensitive the vibrations are to various buildings and conditions. Moreover, correlations of sonic boom metrics to the measured and simulated vibrations are quantified. Two different types of vibration generation mechanisms are detected and analysed: The first one is floor vibrations being set up from the indoor sound transmitted from outdoor. The second is the horizontal motion of the whole building being set up by the outdoor sound at the lower overall resonance frequency of the building. It is found that both types of generation mechanisms can be important for sonic boom, and that they take place for different frequencies.

Flow-Induced Vibration Analysis of Topside Piping at High Pressure

Flow-induced vibration (FIV) from high-velocity multiphase flow is a common source of vibration concern in process piping, potentially leading to fatigue failures and hydrocarbon leaks. A combination of computational fluid dynamics (CFD) and finite element (FE) modeling offers a potentially powerful tool for assessing and diagnosing multi-phase FIV problems in hydrocarbon-production piping systems. Global energy consultancy Xodus Group performed FIV studies on an Equinor-operated topside production system, carrying multiphase flow at high-pressure (approximately 69 bara) conditions, where significant vibration was measured. The study assessed different vibration-simulation methodologies, combining FE analysis with forcing functions based on both correlations and CFD simulations. The aim was to gain a better understanding of the accuracy and limitations of calculation methods typically used to assess fatigue. Calculating Multiphase FIV in Operational Pipework While CFD FIV modeling methods have been well validated against low-pressure water-airflow under laboratory conditions (Emmerson et al. 2016a and 2016b), little has been published to show how well these techniques perform for operational hydrocarbon-production systems. As these systems usually operate at higher pressures with complex, live hydrocarbon fluids and water, the process conditions are often not well defined. They typically incorporate sev-eral features that could complicate the vibration-generation mechanisms such as long upstream pipelines, chokes, and convoluted combinations of pipe bends with complex support arrangements. As part of the development of a new Energy Institute guidance document for subsea pipework, the project with Equinor was instigated following a joint industry project (JIP) established by Xodus, in collaboration with TNO and funded by six major operators, to improve techniques for estimating forcing functions in liquid-gas flows. Vibration measurements were taken at various locations on a section of piping carrying multiphase flow at high-pressure conditions (approximately 69 bara) (Fig. 1). The forces were applied in harmonic, transient, and fluid structural interaction (FSI) simulations (directly coupled FE and CFD). The topside piping arrangement consists of 16-in. schedule-100 piping, with a tee at the top of a riser section followed by six 90° and four 45° 1.5 R/D elbows and is reasonably well supported (as shown in Fig. 1). The measurements provided the vibration velocity of the piping structure, and frequency spectra analysis was performed for comparison with the structural-response simulations. The main locations of interest are V4 and V5 as the measured vibration was the highest here. The peak vibration velocity at V4 is 4.7 mm/s and this occurs at 5.1 Hz in the EW-Y direction (Fig. 2), while at V5 the peak is 6.4 mm/s at 5.2 Hz.

Deep Hole Drilling of Large-Diameter Titanium Alloy With a Novel Rotary Low-Frequency Vibration Device

Titanium alloy (Ti) has been widely used in aerospace industry due to excellent mechanical properties and the demands of Ti parts with a high length-to-diameter ratio and a large diameter are increasing. However, deep hole drilling of large-diameter Ti holes is usually both time-consuming and cost-consuming due to a series of problems such as unfavorable chip removal, helical structure on the hole surface, poor hole precision and severe tool wear. This paper reports on the cutting mechanism and experimental results of low-frequency vibration-assisted single-lip drilling (LFVASLD) of large-diameter Ti holes (O17mm) for the first time. In this paper, a novel rotary low-frequency vibration device was developed and the vibration generation mechanism was analyzed. Thereafter, the material removal mechanism of LFVASLD was established. Then, the comparative experiments between LFVASLD and conventional single-lip drilling (CSLD) of Ti were conducted. The experimental results show that, compared with CSLD, LFVASLD can significantly prolong the drilling depth by 9 times due to reduced tool wear and alleviate helical structure on the hole surface due to the separated cutting mode. Furthermore, the influence of drilling parameters in LFVASLD on hole quality were also investigated. It is concluded that, the LFVASLD method is suitable for deep hole drilling of large-diameter titanium alloy and the developed rotary low-frequency vibration device can be used as a machine tool accessory to significantly improve the processing capacity in the industrial practice.

Nonlinear characteristics of a multi-degree-of-freedom spur gear system with bending-torsional coupling vibration

Abstract The paper deals with bending-torsion coupling response of spur gear system due to its complex excitations. Based on the Bartelmus model, a multi-degrees-of-freedom lumped parameter dynamic model of a one-stage gear system, which includes gear mesh stiffness fluctuations, transmission errors, gear backlash and torque loads, is established. Considering the misalignment of gear root circle and base circle, an improved mesh stiffness model is applied to calculate the time-varying mesh stiffness by simplifying the gear tooth as a cantilever beam on the root circle. Based on these equations of gear system, the dynamic orbits of the bending-torsion coupling system are observed using bifurcation diagrams plotted with the frequency ratio and torsional stiffness as control parameters. Meanwhile the dynamic properties of the gear system are identified from the time domain response diagrams, phase plane diagrams, Poincare maps and amplitude-frequency spectrums of the gear system. The numerical results show that the system exhibits a diverse range of periodic, sub-harmonic, and chaotic motion with the coupling effects of bending and torsional vibrations. The results provide us a further understanding about vibration generation mechanisms and work status of the spur gear system.

Nonlinear dynamic analysis of rigid rotor supported by gas foil bearings: Effects of gas film and foil structure on subsynchronous vibrations

Abstract Highly nonlinear subsynchronous vibrations are the main causing factors of failure in gas foil bearing (GFB)-rotor systems. Thus, investigating the vibration generation mechanisms and the relationship between subsynchronous vibrations and GFBs is necessary to ensure the healthy operation of rotor systems. In this study, an integrated nonlinear dynamic model with the consideration of shaft motion, unsteady gas film, and deformations of foil structure is established to investigate the effect of gas film and foil structure on system subsynchronous response. One test rig of GFB-rotor system is developed for model comparison. High agreement is shown between the prediction and test data, especially in the frequency domain. The nonlinear dynamic response is analyzed using waterfall plots, operation deflection shapes, journal orbits, Poincare maps, and fast Fourier transforms. The parameter studies reveal that subsynchronous vibrations are highly related to gas film and foil structure. Subsynchronous vibrations can be adjusted by parameters such as bump stiffness, nominal clearance, and static loads. Therefore, gas foil bearing parameters should be carefully adjusted by system manufacturers to achieve the best rotordynamic performance.

Study on elucidation of combustion vibration generation mechanism and deterrence method

Study on elucidation of combustion vibration generation mechanism and deterrence method

Torsional vibration signal analysis as a diagnostic tool for planetary gear fault detection

Abstract This paper aims to investigate the effectiveness of using the torsional vibration signal as a diagnostic tool for planetary gearbox faults detection. The traditional approach for condition monitoring of the planetary gear uses a stationary transducer mounted on the ring gear casing to measure all the vibration data when the planet gears pass by with the rotation of the carrier arm. However, the time variant vibration transfer paths between the stationary transducer and the rotating planet gear modulate the resultant vibration spectra and make it complex. Torsional vibration signals are theoretically free from this modulation effect and therefore, it is expected to be much easier and more effective to diagnose planetary gear faults using the fault diagnostic information extracted from the torsional vibration. In this paper, a 20 degree of freedom planetary gear lumped-parameter model was developed to obtain the gear dynamic response. In the model, the gear mesh stiffness variations are the main internal vibration generation mechanism and the finite element models were developed for calculation of the sun-planet and ring-planet gear mesh stiffnesses. Gear faults on different components were created in the finite element models to calculate the resultant gear mesh stiffnesses, which were incorporated into the planetary gear model later on to obtain the faulted vibration signal. Some advanced signal processing techniques were utilized to analyses the fault diagnostic results from the torsional vibration. It was found that the planetary gear torsional vibration not only successfully detected the gear fault, but also had the potential to indicate the location of the gear fault. As a result, the planetary gear torsional vibration can be considered an effective alternative approach for planetary gear condition monitoring.

The spur planetary gear torsional stiffness and its crack sensitivity under quasi-static conditions

Abstract The sun–planet and ring–planet tooth mesh stiffness variations and the resulting transmission errors are the main internal vibration generation mechanisms for planetary gear systems. This paper presents the results of torsional stiffness analysis of involute spur planetary gear systems in mesh using finite element methods. A planetary gear model with three planet gears and fixed ring gear and its subsystem models have been developed to study the subsystem and overall torsional stiffnesses. Based on the analysis of torsional mesh stiffness, predictive models for single branch sun–planet–ring and overall planetary gear torsional stiffnesses have been proposed. A crack coefficient was introduced to the sun–planet and ring–planet meshes to predict the effect and sensitivity of changes to the overall torsional mesh stiffness. The resulting mesh stiffness crack sensitivity of the overall gear system was analysed under quasi-static conditions. It was found that the carrier arm stiffness has great influence on the crack sensitivity while the overall stiffness was most sensitive to the crack on the sun–planet mesh.

Fatigue Life Assessment of Traffic-Signal Support Structures from an Analytical Approach and Long-Term Vibration Monitoring Data

AbstractWind-induced, large-amplitude vibrations of traffic-signal support structures are frequently observed. Such vibrations can result in a large number of stress cycles and substantial fatigue damage. This paper presents the characteristics of wind-induced vibration of a traffic-signal support structure observed in a long-term, full-scale measurement project, which are used as a basis to understand the vibration generation mechanism. Based on the measured structural response, conditional on mean wind speed, wind direction, and turbulence intensity, the fatigue damage is evaluated using a closed-form spectral method with consideration of narrowband, non-Gaussian response characteristics. The uncertainty in the structural response under given wind conditions is quantified and included in the fatigue damage evaluation. The effectiveness and accuracy of the proposed approach are illustrated by comparing the results of the spectral method with that from the time-domain rainflow counting method based on the...

剛体円環モデルを用いた農用タイヤのパラメータ同定

The objective of this study is to clarify the vibration generation mechanism of agricultural machinery caused by the interaction between the tire lugs and the road surface. It is important to investigate the lug excitation force occurring on a rolling agricultural tire in order to clarify the vibration generation mechanism. In our previous study, it is confirmed that the dynamic behavior of rolling tire is influenced by the vibration characteristics of the tire and only the rigid modes can affect the rolling tire behavior. Therefore, we modeled the tire as a circular rigid ring supported on an elastic foundation with a contact patch slip model in order to estimate the lug excitation force. An important aspect of tire modelling is the identification of the tire model parameters. In this research, the tire wheel system is modeled as a circular rigid ring connected to the wheel through the tire sidewalls with a contact patch slip model. As for an agricultural tire, the out-of-plane dynamics is also important because of cross-stich lugs. This model can describe not only the in-plane tire dynamics but also out-of-plane tire dynamics. The equations of motion of the dynamic tire model are derived and the equations of motion are rearranged to describe the in-plane and the out-of-plane dynamics. From the rearranged equations of motion, frequency equations are derived separately and calculation procedure for obtaining the natural frequencies of the rigid ring model is formulated. Furthermore, the model parameters are identified by minimizing the difference between measured and calculated natural frequencies using Downhill Simplex method. The natural frequencies and natural modes predicted by the calculation using the identified model parameters show good agreement with those obtained experimentally.

Some Aspects of Bearing Noise Generation

Problem of ball bearing and roller bearing noise generation is important in present technology level, and its solution stands in front for a new machine designer. New materials of bearings create new problems of bearing noise generation, so research of noise and vibration generation mechanism in necessary. Problem of lubrication gives significant influence to vibration and noise generation in bearings, so in common task of bearing work vibration is quite complex and requires experimental verification of theoretical ideas. This paper is intended to cover noise generation mechanism of ceramic bearings in comparison to steel ones and evaluate influence of bearing lubricant with different properties. There are presented design of experimental workbenches, experimental research procedure and results from research. Experimental results material is presented graphically and numerically. Finally, conclusion on problem and results of experimental research are made.

Mathematical model approach of hydrodynamic vibration generation mechanisms of heat-exchange tube bundles

A mathematical model approach has been proposed and the modified method of discrete vortices has been applied to calculate the plane-parallel separation flow of bodies with irregular shapes. These methods were applied to investigate the generation of hydrodynamic vibration mechanisms of tube bundles in heat-exchange apparatuses.