scholarly journals Attenuation Law of Train-Induced Vibration Response of Subgrade in Beijing–Harbin Railway

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Ziyu Wang ◽  
Xianzhang Ling ◽  
Lina Wang ◽  
Yingying Zhao
Keyword(s):  
Field Experiments ◽  
Damping Ratio ◽  
Vibration Response ◽  
Vibration Level ◽  
Attenuation Curve ◽  
Vibration Acceleration ◽  
Negative Exponential Function ◽  
Attenuation Law ◽  
Vehicle Load ◽  
Environmental Vibration

To investigate environmental vibration in the case of railway subgrade in seasonally frozen regions, field experiments were conducted on the Beijing–Harbin railway subgrade of China in autumn and winter. Vibration acceleration and vibration level attenuation law were analysed based on monitoring results. Accordingly, the influence of the subgrade freeze-thaw states, vehicle load, train formation, and running speed on the subgrade surface environmental vibration was analysed. The vibration response of the subgrade decreased with an increase in the distance from the track. The attenuation curve of the vibration acceleration can be fitted using the negative exponential function, and the attenuation curve of the vibration level can be fitted using the linear function. Additionally, the subgrade vibration response during the frozen period was greater than that during the unfrozen period owing to increased strength and rigidity and decreased damping ratio after subgrade freezing, which increased the vibration response. Moreover, the vibration intensity of the subgrade increased with increase in the vehicle load and formation and decreased with an increase in the driving speed within a particular speed range. The findings of this study provide an objective basis for railway subgrade design and disaster assessment in cold regions of China.

Field Measurement and Numerical Simulation of Vibration Effect on Metro Depot Superstructure Caused by Passing Trains

2013 ◽  
Vol 303-306 ◽  
pp. 2893-2897
Author(s):  
Yu Bin Wu ◽  
Bin Zhang ◽  
Ying Hua Liu ◽  
Xian Hui Li
Keyword(s):  
Field Measurement ◽  
Element Model ◽  
Vibration Response ◽  
Vibration Level ◽  
Running Speed ◽  
3D Finite Element ◽  
Vibration Effect ◽  
Pull Out ◽  
Calculation Results ◽  
Environmental Vibration

In recent years, more attention had paid to the vibration and noise influence on nearby building caused by passing trains. The metro depot superstructure is directly built above the train garage, the vibration of superstructure is very serious when the trains get into or go out of the garage. In order to investigate the law of vibration influence on metro depot and superstructure, a field measurement has been carried out and a 3D finite element model of building-platform-column is established. The attenuation law and degree of environmental vibration influence is obtained by analyzing the measurement date and calculation results. The results show that the vibration response of superstructure is obvious, the vibration level is related with the running state of train. The vibration response is more serious when trains pull out of the garage than go into garage, because the running speed is faster when trains pull out of garage. The vibration intensity does not monotonically increase or monotonically reduce with the increasing of floor and it tends to change wave upon wave with the increasing of floor.

scholarly journals Vibration Response Characteristics and Application of Existing Railway Subgrade

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Junyun Zhang ◽  
Zhuoling He ◽  
Siyuan Chen ◽  
Le Zhang
Keyword(s):  
Vertical Vibration ◽  
Vibration Response ◽  
Disease Assessment ◽  
Horizontal Distance ◽  
Acceleration Response ◽  
Vibration Acceleration ◽  
Response Characteristics ◽  
Attenuation Law ◽  
Before And After ◽  
Research Studies

The existing conventional methods of subgrade disease assessment are not suitable for the existing lines. There are many research studies on the vibration response and attenuation law of the railway subgrade, but few research studies focus on the vibration response and attenuation law caused by the weak subgrade. In this study, vibration response tests were carried out at different positions and depths of the subgrade before and after reinforcement improvement. The results show that vibration response near the ballast is obvious, and it attenuates with the increase of the horizontal distance from the rail; the vibration acceleration response of the subgrade after reinforcement changes greatly; the vibration response curve of the reinforced section is spindle shaped, and the vertical vibration acceleration response attenuates obviously at the depth of 6.5 m, only about 10% to 30% of the surface; the vibration acceleration of the subgrade with reinforcement at the depth of 4.5 m attenuates to 60% of the surface; the vibration acceleration of the subgrade without reinforcement at the depth of 4.5 m attenuates to 50%–60% of the surface.

Modal characteristics and fluid–structure interaction vibration response of submerged impeller

2021 ◽  
pp. 107754632110036
Author(s):  
Shihui Huo ◽  
Hong Huang ◽  
Daoqiong Huang ◽  
Zhanyi Liu ◽  
Hui Chen
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Damping Ratio ◽  
Pure Water ◽  
Vibration Response ◽  
Modal Identification ◽  
Liquid Oxygen ◽  
Modal Characteristics ◽  
Oxygen Pump ◽  
Turbo Pump

Turbo pump is one of the elements with the most complex flow of liquid rocket engine, and as an important component of turbo pump, an impeller is the weak point affecting its reliability. In this study, a noncontact modal characteristic identification technique was proposed for the liquid oxygen pump impeller. Modal characteristics of the impeller under three different submerged media, air, pure water, and brine with same density as liquid oxygen, were tested based on the noncontact modal identification technology. Submersion state directly affects the modal frequencies and damping ratio. The transient vibration response characteristics of the impeller excited by the unsteady flow field was achieved combining with unsteady flow field analysis and transient dynamic analysis in the whole flow passage of the liquid oxygen pump. Vibration responses at different positions of the impeller show 10X and 20X frequencies, and the amplitude at the root of short blade is significant, which needs to be paid more attention in structural design and fatigue evaluation.

Effects of High-Speed Railway in Tunnel on Vibration Response of Upper Building

2013 ◽  
Vol 482 ◽  
pp. 155-162
Author(s):  
Si Hui Xu ◽  
Xiao Hui Zhang ◽  
Han Chen
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Reaction Force ◽  
Element Model ◽  
Vibration Response ◽  
Vibration Level ◽  
High Speed Railway ◽  
Proper Distance ◽  
Coupling Dynamic ◽  
Coupling Dynamic Model

In order to study the effects of high-speed railway in tunnel on vibration response of upper building, the Vehicle-Track-Tunnel-Soil-Building coupling dynamic model was established, and the reaction force of fasteners was used to transmit between Vehicle-Track coupling dynamic model and Tunnel-Soil-Building finite element model. According to modal analysis for typical section of building, sensitive frequency range and sensitive structure locations were obtained. In terms of two conditions, Tunnel-Building Integrated Structure and building are evaded from tunnel for some distance, 1/3 octave vibration level and VLZ vibration acceleration level for all measuring points were calculated to analyze the vibration response of building. The results are shown as follows: for Tunnel-Building Integrated Structure, the overall vibration level is high,which is above 65dB. 2-3dB will be reduced by decreasing speed and improving standard of track. when building is evaded from tunnel for some distance, with larger evaded distance, the vibration response is slighter. However, when evaded distance is above 30m, vibration may be amplified ,so its necessary to select proper distance. Vibration response of structure is most strong when 4 lines meet under building, so strict limitation on meeting condition of trains can effectively reduce vibration level.

Effect of Higher-Than-Rated-Speed Rotordynamic Modes on Rotor Balancing

2015 ◽  
Author(s):  
John J. Yu ◽  
Siddharth Ashar
Keyword(s):  
Critical Speed ◽  
Measured Data ◽  
Vibration Response ◽  
Vibration Level ◽  
Generator Rotor ◽  
Vibration Data ◽  
Unbalance Response ◽  
Nodal Points ◽  
Rotor Balancing

It was surprisingly reported that a generator rotor could not be balanced to an acceptable vibration level by weights at two balance planes at the drive end (DE) and the non-drive end (NDE) fan rings. Both real measured vibration data and rotordynamic calculations indicate that the rotor at rated speed of 3600 rpm appears to run just above the 2nd critical speed (couple or conical mode). However, couple weights (same weights placed at both DE and NDE with 180-degree-out-of-phase) have little effect on 1X vibration response. A third balance plane had to be utilized to effectively reduce vibration. This paper uses measured data and rotordynamic modelling to explain these findings. It is found that the 4th mode could affect synchronous vibration response at rated speed significantly besides the 3rd mode. The two fan ring balance planes appear to be near the nodal points of the 4th mode, which explains ineffectiveness of the couple weights to vibration response at rated speed in the field. Measured data from real machines including influence vectors are presented from third balance planes such as the coupling and the exciter ends, besides the fan ring wheels. The 3rd and 4th rotordynamic modes are also given along with unbalance response studies.

A STUDY OF THE INFLUENCE OF FRICTION FORCES ON THE TRANSMISSION OF SOIL VIBRATION ON GAS PIPELINES

Tribologia ◽  
2017 ◽  
Vol 272 (2) ◽  
pp. 49-58 ◽  
Author(s):  
Wacław GAWĘDZKI ◽  
Jerzy TARNOWSKI
Keyword(s):  
Friction Force ◽  
Field Experiments ◽  
Tensile Force ◽  
Variable Parameter ◽  
Gas Pipeline ◽  
Vibration Acceleration ◽  
Friction Forces ◽  
Acceleration Signal ◽  
Acceleration Signals ◽  
Pipe Vibration

The article presents the influence of friction force values during the contact of a gas pipeline with sand pack on the transmission of soil vibrations on a tested pipe section. Field experiments were carried out on standard gas pipeline insulations subjected to dynamic interactions. The load sources comprised artificially generated soil vibrations with an impulsive character. Within the course of experiments, soil and pipe vibration acceleration signals were registered for different values of friction forces in its contact with the soil. The value of friction forces being a variable parameter during experiments were applied by the change of values of the tension static force of the gas pipeline section. The analysis of the registered soil and pipe vibration acceleration signals were conducted based on the time-domain signal decomposition method, Hilbert-Huang Transform (HHT). This method enables one to decompose the non-stationary vibration acceleration signal into narrowband components. For each component, a course of instantaneous values for frequency and amplitude was specified. The dependence of the pipe vibration acceleration amplitude on the pipe tensile force and friction force of the pipe in the contact with the soil was demonstrated.

Experimental Evaluation of Vibration Effects Induced by Planed Railway Line on Surrounding Historic Tower

2014 ◽  
Vol 501-504 ◽  
pp. 861-866
Author(s):  
Yuan Tian ◽  
Nan Zhang ◽  
Wei Guo Yang ◽  
Jia Ming Niu
Keyword(s):  
Field Experiments ◽  
Dominant Frequency ◽  
Vibration Velocity ◽  
Vibration Source ◽  
Vibration Level ◽  
Frequency Range ◽  
Structural Vibrations ◽  
Upward Trend ◽  
Railway Line ◽  
Different Types

Using field experiments, the vibration effects of historic tower induced by planed railway line are estimated. The vibrations include the construction vibration and the traffic-induced vibration. The results show that the blasting construction leads to the significant increase in vertical velocity and acceleration. There is no difference between the background vibration of field and foundation of tower. Different types of the sites soil around the tower cause little change. Each measurement time showed an upward trend of vibration level with the increase of frequency. The closer the tower is to the vibration source, the larger the structural vibrations would be. The dominant frequency range for highway-induced vibration is 10-20Hz. For train-induced vibration, the dominant frequency range is more than 40Hz. Surface waves will result in amplification phenomenon of vibration velocity of ancient structures within a certain range.

scholarly journals Vibration Response Characteristics of the Cross Tunnel Structure

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Jinxing Lai ◽  
Kaiyun Wang ◽  
Junling Qiu ◽  
Fangyuan Niu ◽  
Junbao Wang ◽  
...  
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Time History ◽  
Element Model ◽  
Vibration Response ◽  
Shield Tunnel ◽  
Tunnel Structure ◽  
Response Characteristics ◽  
Vehicle Load ◽  
Metro Tunnel

It is well known that the tunnel structure will lose its function under the long-term repeated function of the vibration effect. A prime example is the Xi’an cross tunnel structure (CTS) of Metro Line 2 and the Yongningmen tunnel, where the vibration response of the tunnel vehicle load and metro train load to the structure of shield tunnel was analyzed by applying the three-dimensional (3D) dynamic finite element model. The effect of the train running was simulated by applying the time-history curves of vibration force of the track induced by wheel axles, using the fitted formulas for vehicle and train vibration load. The characteristics and the spreading rules of vibration response of metro tunnel structure were researched from the perspectives of acceleration, velocity, displacement, and stress. It was found that vehicle load only affects the metro tunnel within 14 m from the centre, and the influence decreases gradually from vault to spandrel, haunch, and springing. The high-speed driving effect of the train can be divided into the close period, the rising period, the stable period, the declining period, and the leaving period. The stress at haunch should be carefully considered. The research results presented for this case study provide theoretical support for the safety of vibration response of Metro Line 2 structure.

scholarly journals Evaluation of Road Service Performance Based on Human Perception of Vibration While Driving Vehicle

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Wenbo Shi ◽  
Ming Li ◽  
Jingxuan Guo ◽  
Kaixuan Zhai
Keyword(s):  
Human Perception ◽  
Service Performance ◽  
Road Maintenance ◽  
Vibration Level ◽  
Vibration Acceleration ◽  
The Road ◽  
Vibration Data ◽  
Road Condition ◽  
Road Condition Monitoring ◽  
On The Road

Road surface monitoring is a significant issue in providing smooth road infrastructure for vehicles, and the key to road condition monitoring is to detect road potholes that affect driving comfort and transportation safety. This paper presents a simple, efficient, and accurate way to evaluate road service performance based on the acquisition of road vibration data by vibration sensors installed in vehicles. Inspired by the discrete fast Fourier transform, the vibration acceleration is processed, and the RMS value of vibration acceleration at 1/2 octave is calculated, after which the road vibration level is calculated. The vibration level is optimized according to the human body’s sensitivity to different frequencies of vibration, resulting in road service performance indicators that can reflect the human body’s real feelings. According to the road service performance index values on the road grading, combined with GPS data on the electronic map color block labeling, the results obtained for the road condition warning, road maintenance, driver route selection have an important significance.

scholarly journals Pengaruh bahan kampas rem terhadap respon getaran pada sistem rem cakram

2017 ◽  
Vol 12 (1) ◽  
pp. 1
Author(s):  
Muhammad Mushlih Elhafid ◽  
Didik Djoko Susilo ◽  
Purwadi Joko Widodo
Keyword(s):  
Damping Ratio ◽  
Pressure Variation ◽  
Vibration Response ◽  
Brake System ◽  
Disc Brake ◽  
Brake Pad ◽  
Brake Pads ◽  
Braking System ◽  
Analysis Experiment ◽  
Disc Rotation

This study aims to determine the effect of brake pads material to the vibration response of disc brake system on many variety of braking conditions. The variations of brake pads material on this research such as metallic, non-asbes and ceramic. The variations of braking operation such as speed of disc rotation and braking pressure. Each brake pads material tested by variation of disc rotation 425, 637, 850, 1062 rpm and pressure variation 0,5 bar, 1 bar, 1,5 bar. Furthermore, the dynamic characteristics of brake pad had been tested by using the method of Modal Analysis Experiment. The results showed that the type of brake pad materials, disc rotation and braking pressure affect to vibration response of disc brake system. Increasing speed of disc rotation and braking pressure will increase the excitation force causing value amplitude of vibration in the braking system increases. Usage of brake pad ceramic also showed the lowest amplitude of vibration for all variations of disc rotation and braking pressure. Because the ceramic brake pad have the lowest natural frequency, then the value of the damping ratio is high, so that decreasing amplitude of vibration that occurs in the braking system.

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