Vibration Transmission Characteristics Research Articles

Field Measurement and Research on Environmental Vibration due to Subway Systems: A Case Study in Eastern China

With the rapid development of subway systems, the negative environmental impacts of vibration induced by subways has gradually become a research hotspot. For the purpose of developing predictive models of vibration and designing effective vibration mitigation systems, continuous field dynamic measurements were conducted simultaneously in a subway tunnel, ground, and building in eastern China, the most prosperous region in China. The characteristics of vibration transmission and attenuation induced by subway were analyzed by statistical analysis of large amounts of measurement data. The results showed that most prominent and visible attenuation of vibration is from the track to the ballast bed in the tunnel, where the ground-borne vibration would quickly decrease exponentially with distance. The results also showed that the measured attenuation value of indoor vibration was approximate 0.76 dB on average between each floor. Moreover, the decay ratio of the vibration increased with the increase in the frequency range. Based on these findings, construction gauge of 20–25 m outside of the tunnel is recommended. In addition, reducing the vibration source excitation intensity is the most effective vibration isolation method, especially by track structural transformation.

Multi-body dynamic simulation and vibration transmission characteristics of dual-rotor system for aeroengine with rubbing coupling faults

In this paper, a dual-rotor system multi-body dynamic model with rubbing coupling faults is established for practical aero-engine. In the model, the rubbing fault simulation method is introduced, the coupling effect between the internal and external rotor is considered. The numerical simulations of rotor vibration are accomplished by the utilization of multi-body dynamic platform, where the simulation model consists of discs unbalances and local rub-impact between discs and casing shells. The time-domain responses, the frequency spectra and the shaft-center trajectories of dual-rotor with different unbalance and different rubbing positions are obtained. The vibration and its transmission characteristics of the inner and outer rotors are calculated. Finally, the simulation results are compared with the measured vibration of a dual rotor tester with rubbing fault. The simulation results are consistent with the measured results, which confirms the feasibility of the established model and the multi-body dynamics simulation method in this paper. The application of multi-body dynamics simulation method in aero-engine can deepen the understanding of the internal operation nature and laws of aero-engine, reduce the repetition of physical tests, greatly improve the efficiency and quality of development, accelerate the research and manufacture process.

Seismic Response and Vibration Transmission Characteristics of Laminated Rubber Bearings with Single Disorder

AbstractThe characteristic receptance method of analyzing the free wave propagation of a finite monocoupled periodic system with a single disorder is applied to study the vibration transmission thr...

The random vibration and force transmission characteristics of the elastic propeller-shafting system induced by inflow turbulence

Random vibration and force transmission characteristics of an elastic propeller-shafting system induced by the inflow turbulence are analytically studied. Both the propeller blades and the shafting are simplified as three-dimensional elastic beam, which are connected by lumped spring elements. Based on the Timoshenko beam theory, an analytical model considering both the longitudinal and transverse responses of the propeller-shafting system is developed. The random pressure spectrum induced by inflow turbulence is computed by the correlation method and is mapped onto the blades as exciting source. By virtue of the frequency response function matrix, the random vibration characteristics of the propeller-shafting system and forces transmitted through different bearings are obtained. Analytical results show that the elasticity of the propeller blades cannot be neglected and the bending modes of the propeller blades amplify both the longitudinal and transverse transmitted forces. The longitudinal force transmission is mainly controlled by the propeller elasticity and the longitudinal stiffness of the thrust bearing, while the frequency and magnitude of the transverse force is mainly controlled by the bending modes of the shafting and the system elasticity, respectively.

Effect of Hammer Impact on Wave Propagation Characteristics of Soil

Wave transmission through soil due to dynamic load causes many problems to civil engineers craving safe construction. In this article, a laboratory model study is conducted to investigate the vibration propagation characteristics of soil due to the falling masses at different depths. Different types of impact, soils, and relative densities are used to study the characteristics of vibration transmission and energy dissipation. It was found that the increase in relative density and decrease in the depth causes an increase in the Peak Particle Acceleration and wave velocity of soil. An attempt is also made to determine the dynamic properties of soil using wave velocity ratios. A simple laboratory arrangement discussed here can be used to predict the wave propagation in soil reasonably and can determine its elastic constants. From the studies, it was revealed that the wave travel in soil and the peak particle acceleration depends on many factors like density, particle gradation, impact energy, etc.

Exploring Vibration Transmission Rule of an Artificial Spider Web for Potential Application in Invulnerability of Wireless Sensor Network.

Significant similarities exist between a spider web and wireless sensor network in terms of topology. Combining the unique advantages of the spider web in nature, such as invulnerability and robustness, with communication technology of a wireless sensor network presents high research value and broad development prospects. In this paper, a sort of a spiral artificial spider web based on 3D printing and its associated vibration testing device is proposed, which is used to study the transmission rule of vibration information of the spider web under given excitation conditions. It provides useful inspiration for establishment of an invulnerable communication rule of wireless sensor network. In order to investigate vibration transmission characteristics of the artificial spider web, vibration images are recorded and analyzed by a high-speed photography system, and vibration intensity is characterized by use of peak-to-peak value. Furthermore, vibration performance of the artificial spider web is studied under conditions of integrity and destruction, respectively. Our test observation reveals the vibration transmission rule of the unique structure of the spider web, providing a novel analysis method for improving invulnerability of the wireless sensor network.

Vibration characteristics of damping pad floating slab on the long-span steel truss cable-stayed bridge in urban rail transit

With the development of urban rail transit, long-span steel truss cable-stayed bridges have become increasingly favored. Therefore, train-induced bridge-borne vibration and noise are occurring more often. The damping pad floating slab (DPFS) has been widely used as an effective vibration damping track structure; however, there is a lack of research on the vibration mechanism and effects of the DPFS for long-span steel truss cable-stayed bridges. This study focuses on the steel truss cable-stayed bridge in urban rail transit. First, the theoretical model of the train-track-bridge coupling interaction is established in the frequency-domain (the track structure is DPFS, and the interaction of multiple wheels is considered). Using this model, the wheel–rail dynamic force, force transmission rate of the track, and the force transmitted to the bridge are calculated. Then, the vibration prediction model of the long-span steel truss cable-stayed bridge is established using the plate-beam finite element (FE) method and statistical energy method. The force transmitted to the bridge is applied to the vibration prediction model to obtain the vibration transmission characteristics of the typical plate of the bridge. The prediction model is verified by comparing the obtained results with the field test of a long-span steel truss cable-stayed bridge, and the damping mechanism of DPFS track is discussed. Finally, the force transmitted to the bridge is calculated based on the embedded-sleeper (ES) track structure (the ES has no vibration damping facilities). The values of the overall vibration level are calculated from the prediction models using ES and DPFS, and the vibration reduction effect of DPFS is studied by comparison with the ES.

전달경로해석을 이용한 드럼세탁기의 기여도 평가 프로세스 정립

Transfer paths are complex and difficult to analyze. The characteristics of vibration and noise transmission are also complex and various vibrations and noise sources are correlated. In this study, we experimentally investigated the noise and vibration transmission mechanisms of a drum-type washing machine. In addition, we analyzed the transfer path and coherence using the multi-dimensional spectral analysis approach designed to remove correlations by implementing coherence and frequency response functions to the operating status. Finally, we estimated the contributions of individual components to the output noise radiated by structural vibrations.

Investigation on vibration source and transmission characteristics in power transformers

The tank vibration of power transformers comes from alternating forces acting on the core and windings. It is meaningful to study the vibration sources and the transmission characteristics in transformers for interpreting the constitution of the tank vibration specifically. This paper experimentally investigates the coupling between the winding vibration and the core vibration, as well as the vibration transmission characteristics on a single phase power transformer the winding vibration coupled with the core vibration has a broader frequency band than the responses caused by the electromagnetic force. For transmission characteristics, the oil-borne transmission is the main path for the winding vibration, while the structure-borne transmission highly depends on the modal characteristics of the tank. This work improves the understanding of the relationship between the internal vibrations and the tank responses.

Characteristics of wave propagation, vibration transmission and acoustic emission in fluid-filled coaxial periodic shells

The wave propagation, vibration transmission and acoustic emission characteristics in the two coaxial shells containing fluid are studied. A finite element method (FEM) is utilized to conduct the investigation. Elastic band gaps (BGs) are generated in this coaxial shell system with either light or heavy fluid loading if the cylindrical shell walls are design to be periodic structure. For light fluid loading, BGs of the fluid-filled coaxial shell system are almost the same as those for the inner and outer shells in vacuum. Because the coupling effect of the annular light fluid is so weak that it can be neglected; thus, the inner and outer shell may behave independently. In terms of heavy fluid loading, the confined annular fluid region acts as an effective energy transmission medium that links the two shell motion together. The “hydrodynamic” mass induced by the annular-fluid can be far larger than its actual mass when the annular gap is sufficient narrow. As a result, the fluid inertial loading on the other shell can be quite enormous, rendering the central frequencies of BGs for the coaxial periodic shell system notably decreased. The BG formation mechanism may be attributed to (i) phenomenon of interference of waves reflected by these repeated “periodicity cells”, (ii) cut-off frequencies and (iii) hybrid vibration motion modes of different shell sections, according to various circumferential modes and frequency ranges. The acoustic pressure in the narrow annular region is extremely high, if the filling fluid is dense. However, when the harmonic frequency is located at the BG, the acoustic pressure becomes weaker and weaker along the axial direction of the shell; in contrast, if frequency is in the wave pass bands, the acoustic pressure levels will remain as strong as at the front end of the shell throughout the shell.

Design and Vibration Isolation Performance of Truss‐Type CFRP Raft Frame

Traditional raft frame is single in the form of materials and structures. To give full play to its vibration isolation performance, a truss‐type CFRP (carbon fiber‐reinforced plastics) raft frame was designed and prepared. Based on the composite material mechanics and damping strain energy model, a method combining the finite element simulation and experiment was used to calculate the damping of the designed CFRP truss structure. The modal harmonic response analysis of CFRP truss structure was carried out by virtue of the ABAQUS finite element software to explore the influence of structure parameters on the vibration transmission characteristics of CFRP truss structure and provide reference for the design of a truss‐type CFRP raft frame. The truss‐type CFRP floating raft vibration isolation platform was established. Given different excitation sources, the truss‐type CFRP raft frame designed in this paper was demonstrated to have good vibration isolation effect in most frequency bands by analyzing the acceleration‐vibration level differences.

Vibration propagation identification of rotor-bearing-casing system using spatiotemporal graphical modeling

Casing vibration is usually applied for diagnosing faults of rotor-system in aero-engine, while the transmission mechanism of the vibration from the inner source to the outer casing is rarely discussed and the vibration propagation characteristics have not been quantitatively evaluated. This work presents a data-driven spatiotemporal graphical modeling approach, spatiotemporal pattern network (STPN), to estimate the vibration propagation characteristics by exploring the causal dependency between the measurements. The proposed STPN model with information based metric is further applied to ascertain the most sensitive position on the casing for diagnosing the faults of the rotor system. Numerical simulation and experiments on a test rig are carried out to validate the proposed approach. The results show that the proposed approach is capable of determining the vibration transmission characteristics from the inner rotor system to the outer casing and can be applied in sensitivity analysis to ascertain the best sensor location on the casing.

Dynamic Analysis of Umbilical Cables for Maglev Vibration Isolation Systems

Umbilical cables are the only paths that transmit vibration from the base to the upper platform in a maglev vibration isolation platform. The geometry properties and the vibration transmission characteristics of umbilical cables are crucial for the isolation performance of maglev vibration isolation platforms. The dynamic model of umbilical cables is studied comprehensively based on the nonlinear mechanics of a thin elastic rod, and the model is solved according to a differential quadrature method. A case about a cantilever cable is solved to verify the accuracy, efficiency, and convergence of the solution. The method to obtain an equivalent dynamic model of umbilical cables is analyzed, and the relationship between the excitation parameters and the disturbing forces/moments is obtained, which can be applied in the overall dynamic analysis of maglev vibration isolation systems. Experiments are carried out to verify the dynamic model, the numerical solution, and the equivalent dynamic model. To understand the applicability of the equivalent dynamic model, disturbing forces and moments caused by different frequencies, different amplitudes, and different initial configurations are compared; and the transmission characteristics of umbilical cables are obtained. The research has an important significance on the dynamic analysis of umbilical cables for maglev vibration isolation systems, and the method in establishing an equivalent dynamic model of umbilical cables is applicable.

Study on vibration transfer characteristics of acoustic supermaterial plate structure

The problem of low frequency vibration and noise control is a huge challenge in the engineering environment. The bandgap characteristics of phononic crystals can suppress the propagation of acoustic waves and provide a new solution for low-frequency vibration and noise control. In this paper, an acoustic supermaterial structure plate is proposed. By the finite element calculation, two band gaps of 71Hz∼120Hz and 315Hz∼400Hz are obtained. Finite element method is used to analyze the variation of the transverse and longitudinal periodic number of the acoustic supermaterial plate, and the relationship between the vibration transmission characteristics and the band gap is obtained. The research shows that the number of original cells of acoustic metamaterial structural plates is at least 8.

A study of modeling experiments of the vibration behavior of elevated railway box girder

Based on the model similarity theory, this article deduces the model similarity relationship of the elevated railway box girder at the elastic stage and designs a 1/10 box girder scale model by adopting a 32 m simply-supported box girder bridge from the Beijing–Shanghai Railway as the prototype. It then verifies the validity of the model design and the dynamic similarity between the 1/10 model and the prototype through constraint mode and free mode experiments on the 1/10 scale model, together with transient finite element calculation. The dynamic calculation model is utilized here for the analysis of the errors occurring in the production of the model, and the effect of the model structure simplification on the box girder mode frequency and vibration response. Finally, the article studies the vibration transmissibility characteristics between the plates and along the longitudinal direction by means of model testing. It also discusses the effect of different bridge support stiffness on the box girder vibration. The results presented in this paper can provide a method for forecasting and evaluating the existing or plan-to-build high speed railway environment vibration.

Nonlinear dynamic analysis of a unilateral vibration vehicle system with structural nonlinearity under harmonic excitation

Abstract In this paper, the nonlinear dynamics and vibration transmission characteristics of a multi-body dynamic model are investigated to examine the performance of a unilateral vibration vehicle system. The nonlinear equation of motion, considering the suspension and tyre characterized by quadratic and cubic nonlinearities, is deduced by Lagrange's equation. Based on the dynamic equation, the nonlinear dynamic behaviors of the vibration system are investigated more precisely by bifurcation diagram, the largest Lyapunov exponent and 3-D frequency spectrum with the effects of external excitation amplitude, tyre nonlinearity and inclined angle. The numerical analysis indicates that the vibration system exhibits a wide variety of rich and interesting dynamic behaviors, namely different motion states and jump discontinuity are observed, and the different routes to chaotic motion via period-doubling bifurcation, inverse period-doubling bifurcation, Hopf bifurcation and saddle-node bifurcation are presented depending on the different system parameters.

Vibration transmission analysis of nonlinear floating raft isolation system with magneto-rheological damper

The vibration transmission characteristics of a three-degree of freedom nonlinear floating raft isolation system are studied in order to analyze the influence of magneto-rheological damper on primary resonance attenuation. A revised Bingham model verified by experiment is adopted to describe the nonlinear magneto-rheological damping force, and the dissipated energy based on the model is given which is more than general viscous damper. Then, the approximately analytic solution for primary resonance of floating raft isolation system is obtained by means of averaging method, and it is compared with numerical integration solution. Force transmissibility is proposed to evaluate the effectiveness of magneto-rheological damper. The influences of magneto-rheological damper parameters on force transmissibility are also investigated. The results show that force transmissibility decreases as the increase of viscous damping coefficient of magneto-rheological damper and zero-force velocity. The influence of control force is the same with in the first and third resonance frequency but has opposite effect in the second one. The results obtained from this work are benefit to control vibration transmission of rotating machine.

Vibration Transmission Characteristics of a Quasi-zero Stiffness Torsional Isolator

Vibration Transmission Characteristics of a Quasi-zero Stiffness Torsional Isolator

Finite Element Analysis and Experimental Study on Elbow Vibration Transmission Characteristics

Pipeline system vibration is one of the significant factors leading to the vibration and noise of vessel. Elbow is widely used in the pipeline system. However, the researches about vibration of elbow are little, and there is no systematic study. In this research, we firstly analysed the relationship between elbow vibration transmission characteristics and bending radius by ABAQUS finite element simulation. Then, we conducted the further vibration test to observe the vibration transmission characteristics of different elbows which have the same diameter and different bending radius under different flow velocity. The results of simulation calculation and experiment both showed that the vibration acceleration levels of the pipeline system decreased with the increase of bending radius of the elbow, which was beneficial to reduce the transmission of vibration in the pipeline system. The results could be used as reference for further studies and designs for the low noise installation of pipeline system.

Dynamic modelling of a rotor-bearing-housing system including a localized fault

An in-depth understanding of the dynamic characteristics through rotor-bearing-housing systems is very valuable for fault detection and diagnosis applications of rotating machines such as high-speed spindle, roll mill, gearbox, engines, etc. A new vibration model of a rotor-bearing-housing system considering the rotor compliance, elastic interface between the housing and outer race, housing compliance, and time-dependent excitations introduced by a localized fault on the inner and outer races of an inherent ball bearing is proposed in this work. An analytical method for calculating the time-dependent excitations including the time-dependent displacement excitation and contact stiffness coefficient between the ball and fault edges is presented. Differences between vibration responses of a rotor-bearing-housing system from the proposed model and the previous model without the rotor compliance in the literature are discussed. The presented model is used to discuss the influences of all the rotor compliance, housing compliance, and fault sizes on the races of the inherent ball bearing on the vibration responses and vibration transmission characteristics through the rotor-bearing-housing system, which cannot be formulated by the current dynamic models in the listed references. An experimental study is introduced to validate the presented model. The results show that the rotor compliance and time-dependent contact stiffness coefficient caused by the fault have great influence on the dynamic characteristics through the rotor-bearing-housing system. It also seems that the developed method can provide a new vibration modelling method for the vibration analysis for a rotor-bearing-housing system with and without the faults.