An experimental study of vibration reduction of a ballasted ladder track

2016 ◽  
Vol 231 (9) ◽  
pp. 1035-1047 ◽  
Author(s):  
Meng Ma ◽  
Weining Liu ◽  
Yulu Li ◽  
Weifeng Liu
Keyword(s):  
Laboratory Test ◽  
Vibration Reduction ◽  
Potential Effect ◽  
In Situ Experiment ◽  
Low Frequencies ◽  
Environmental Vibration ◽  
New Type ◽  
Reduction Effect ◽  
The Time Domain

The ballasted ladder track is a new type of longitudinal track. In this paper, to investigate its vibration reduction effect, both a laboratory test and in situ experiment were conducted. As the vibration sources, a newly designed drop weight impulse setup was employed in the laboratory test, and moving metro trains were employed in the in situ measurement. The vibration reduction effects of the ballasted track with ladder sleepers and regular concrete sleepers were compared. The results show that the ballasted ladder track can effectively decrease the peak value in the time domain and has the potential effect to control the environmental vibration in low frequencies. The shape of the sleeper can induce changes in the vibration field of the ballast.

Vibration Reduction Analysis of an Old Residential District under Vehicle Load

2014 ◽  
Vol 522-524 ◽  
pp. 1697-1702
Author(s):  
Bo Huang ◽  
Tang Dai Xia ◽  
Peng Fei He
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Vibration Reduction ◽  
Seismic Load ◽  
Far Field ◽  
Vehicle Load ◽  
Residential District ◽  
Bored Piles ◽  
Reduction Effect

Vibration phenomena on buildings in old residential district under non-seismic load are increasing. Given the vibration phenomenon on buildings in an typical old residential district under vehicle load, cast-in-situ bored piles in rows are suggested to reduce the vibration through analysis. Finite element method (FEM) is used to simulate vibration reduction effect of piles with different lengths. Considering analysis of the isolation of Rayleigh wave from far field and the result of FEM, 40 meter is the reasonable length of the vibration reduction piles. A vibration reduction solution is presented.

Influence of static preload on vibration reduction effect of floating slab tracks

2018 ◽  
Vol 25 (6) ◽  
pp. 1148-1163 ◽  
Author(s):  
Minghang Li ◽  
Meng Ma ◽  
Weining Liu ◽  
Bolong Jiang
Keyword(s):  
Vibration Reduction ◽  
Coupled Model ◽  
Mitigation Measures ◽  
Vehicle Body ◽  
Reference Case ◽  
Slab Track ◽  
Vibration Responses ◽  
Reduction Effect ◽  
Impact Vibration

To effectively reduce the railway vibration and its environmental impact, vibration mitigation measures are increasingly used. The vibration reduction effect of railway tracks is described quantitatively by insertion loss (IL). ILs obtained from in situ measurements under moving train loads and laboratory tests under artificial excitation differ significantly due to the different track loading state between these two methods. The differences of track loading state are induced by the moving effect of train passages and the preloads effect of vehicle masses, the latter of which is a significant factor to discuss in this paper. In order to study the static preload by vehicle masses influence on the vibration reduction effect in isolated tracks, the steel spring floating slab track and regular slab track, as a reference case, were compared. First, a theoretical simplified model was constructed, following which a finite–infinite element coupled model was built, which was calibrated by experimental test results. Impact loads were applied to both tracks with preloads using unsprung wheelsets or sprung vehicle-body masses, with the total mass varying from 0 t to 30 t. The results demonstrate that the increase in preload of unsprung mass makes the natural frequencies further reduced, and the peak IL value increased from 39 dB to 48 dB. The increase in preload has a significant effect on vibration responses below 5 Hz, and the application of the preload has different effects on the reduction effect in different frequency ranges.

Minimizing noise from metro viaduct railway lines by means of elastic mats and fully closed noise barriers

2018 ◽  
Vol 232 (6) ◽  
pp. 1828-1836 ◽  
Author(s):  
Caiyou Zhao ◽  
Wang Ping
Keyword(s):  
Noise Reduction ◽  
Vibration Energy ◽  
Rail Transit ◽  
In Situ Experiment ◽  
Noise Barriers ◽  
Transit Systems ◽  
Slab Track ◽  
Noise Barrier ◽  
Reduction Effect

An adverse effect of urban elevated rail transit systems is the associated noise, which has become a source of environmental complaints. In order to effectively address this problem, an in situ experiment has been conducted on the elevated sections of Hangzhou Metro Line 1 involving three cases: a 2.2 m vertical noise barrier with integrated bed track, a 2.2 m vertical noise barrier with an elastic mat floating slab track, and a 5.1 m fully enclosed noise barrier with an elastic mat floating slab track. The noise reduction effects of the elastic mats and the two kinds of noise barriers for metro viaduct railway lines were evaluated, and the mechanisms of these countermeasures were analysed. The results show that elastic mats can effectively reduce the transmission of wheel–rail vibration energy into the bridge, thus decreasing bridge-borne noise; meanwhile, the elastic mats could lead to an increase in wheel–rail noise. An excellent noise reduction effect was achieved in the area below and near the bottom of the bridge, while an increased noise effect was observed close to the area above and near the rail surface. The fully enclosed noise barrier controlled the propagation of wheel–rail noise more effectively than the vertical noise barriers, but no difference was found between these two kinds of noise barriers in controlling bridge-borne noise.

scholarly journals Semi-Active Vibration Control Based on a Smart Exciter with an Optimized Electrical Shunt Circuit

2021 ◽  
Vol 11 (20) ◽  
pp. 9404
Author(s):  
Yi Wang ◽  
Thomas Kletschkowski
Keyword(s):  
Vibration Control ◽  
Active Vibration Control ◽  
Vibration Reduction ◽  
Structural Vibration ◽  
Simulation Framework ◽  
Structural Vibrations ◽  
New Type ◽  
Active Vibration ◽  
Reduction Effect ◽  
Shunt Circuit

A smart exciter coupled to cabin panels can be used as a new type of loudspeaker for emergency announcements in the aircraft cabin. The same device can also be used as a semi-active vibration control system which is effective in reducing the amplitude of structural vibration. The objective of this paper is to investigate the potential of vibration reduction using a smart exciter in combination with an optimized resistive-inductive shunt circuit, which serves as an absorbing network. First, the vibration reduction effect has been analyzed numerically using a simulation framework realized with COMSOL and MATLAB/Simulink. In a second step, the reduction effect of the smart exciter together with a resistive-inductive shunt circuit, which is produced by the Center of Applied Aeronautical Research (Zentrum für Angewandte Luftfahrtforschung GmbH, Hamburg, Germany), has been investigated experimentally. The results presented here prove that the smart exciter together with a resistive-inductive shunt can be highly effective in reducing structural vibrations.

scholarly journals From small wrinkles to Schallamach waves during rubber friction: In situ experiment and 3D simulation

2021 ◽  
Vol 96 ◽  
pp. 107084
Author(s):  
Cui Zhibo ◽  
Su Zhaoqian ◽  
Hou Dandan ◽  
Li Genzong ◽  
Wu Jian ◽  
...  
Keyword(s):  
3D Simulation ◽  
In Situ Experiment ◽  
Rubber Friction

scholarly journals In-situ monitoring for liquid metal jetting using a millimeter-wave impedance diagnostic

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tammy Chang ◽  
Saptarshi Mukherjee ◽  
Nicholas N. Watkins ◽  
David M. Stobbe ◽  
Owen Mays ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Millimeter Wave ◽  
Manufacturing Systems ◽  
Wave Impedance ◽  
In Situ Monitoring ◽  
Full Wave ◽  
Drop On Demand ◽  
The Time Domain ◽  
Metal Droplets

AbstractThis article presents a millimeter-wave diagnostic for the in-situ monitoring of liquid metal jetting additive manufacturing systems. The diagnostic leverages a T-junction waveguide device to monitor impedance changes due to jetted metal droplets in real time. An analytical formulation for the time-domain T-junction operation is presented and supported with a quasi-static full-wave electromagnetic simulation model. The approach is evaluated experimentally with metallic spheres of known diameters ranging from 0.79 to 3.18 mm. It is then demonstrated in a custom drop-on-demand liquid metal jetting system where effective droplet diameters ranging from 0.8 to 1.6 mm are detected. Experimental results demonstrate that this approach can provide information about droplet size, timing, and motion by monitoring a single parameter, the reflection coefficient amplitude at the input port. These results show the promise of the impedance diagnostic as a reliable in-situ characterization method for metal droplets in an advanced manufacturing system.

scholarly journals Digital Image Correlation for Evaluation of Cracks in Reinforced Concrete Bridge Slabs

2021 ◽  
Vol 6 (7) ◽  
pp. 99
Author(s):  
Christian Overgaard Christensen ◽  
Jacob Wittrup Schmidt ◽  
Philip Skov Halding ◽  
Medha Kapoor ◽  
Per Goltermann
Keyword(s):  
Reinforced Concrete ◽  
Digital Image Correlation ◽  
Crack Initiation ◽  
Laboratory Test ◽  
Digital Image ◽  
Crack Detection ◽  
Image Correlation ◽  
In Situ Tests ◽  
Stop Criterion

In proof-loading of concrete slab bridges, advanced monitoring methods are required for identification of stop criteria. In this study, Two-Dimensional Digital Image Correlation (2D DIC) is investigated as one of the governing measurement methods for crack detection and evaluation. The investigations are deemed to provide valuable information about DIC capabilities under different environmental conditions and to evaluate the capabilities in relation to stop criterion verifications. Three Overturned T-beam (OT) Reinforced Concrete (RC) slabs are used for the assessment. Of these, two are in situ strips (0.55 × 3.6 × 9.0 m) cut from a full-scale OT-slab bridge with a span of 9 m and one is a downscaled slab tested under laboratory conditions (0.37 × 1.7 × 8.4 m). The 2D DIC results includes full-field plots, investigation of the time of crack detection and monitoring of crack widths. Grey-level transformation was used for the in situ tests to ensure sufficient readability and results comparable to the laboratory test. Crack initiation for the laboratory test (with speckle pattern) and in situ tests (plain concrete surface) were detected at intervals of approximately 0.1 mm to 0.3 mm and 0.2 mm to 0.3 mm, respectively. Consequently, the paper evaluates a more qualitative approach to DIC test results, where crack indications and crack detection can be used as a stop criterion. It was furthermore identified that crack initiation was reached at high load levels, implying the importance of a target load.

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