scholarly journals Carbody vibrations of high-speed train caused by dynamic unbalance of underframe suspended equipment

2018 ◽  
Vol 10 (12) ◽  
pp. 168781401881896 ◽  
Author(s):  
Qunsheng Wang ◽  
Jing Zeng ◽  
Lai Wei ◽  
Bin Zhu
Keyword(s):  
Structural Damage ◽  
High Speed ◽  
Ride Comfort ◽  
Field Tests ◽  
Simulation Models ◽  
Mathematic Model ◽  
Dynamic Vibration Absorber ◽  
Elastic Suspension ◽  
Flexible Vibrations ◽  
Dynamic Unbalance

The effect of dynamic unbalance of the underframe suspended rotational equipment on the flexible vibrations of the carbody has become a major concern for high-speed trains. It is known from the field tests that the dynamic unbalance has a significant influence on carbody vibrations, especially the local flexible vibration, which leads to a decrease in the passenger ride comfort and may even cause structural damage to the carbody. A vertical mathematic model considering the carbody flexibility and the underframe suspended equipment is first set up, and then a three-dimensional dynamic model for a rigid–flexible coupled vehicle system is established. The effect mechanism of the dynamic unbalance on carbody flexible vibration is extensively studied, and the efficient measures to reduce the carbody flexible vibrations are proposed. The theoretical and simulation models are verified by comparing with a field test conducted on a newly designed high-speed railway. The results show that decreasing the unbalanced mass of the rotational equipment can reduce the carbody vibrations. Moreover, the use of elastic suspension for the underframe equipment can isolate the vibration transmission to the carbody. Both the theory of dynamic vibration absorber and dynamic unbalance should be considered to optimize reasonable suspension parameters, especially the suspension location and the suspension frequency.

Study on Ambulance Stretcher Vibration Isolation System

2012 ◽  
Vol 226-228 ◽  
pp. 324-327 ◽  
Author(s):  
Gong Yu Pan ◽  
Ying Zhang
Keyword(s):  
High Speed ◽  
Vibration Isolation ◽  
Ride Comfort ◽  
Angular Acceleration ◽  
Mathematic Model ◽  
Vertical Acceleration ◽  
Active System ◽  
Linear Quadratic ◽  
Isolation System ◽  
Vibration Isolation System

The ride comfort is one of the most important performances of the ambulance. In order to avoid patients' illness or injury to deteriorate during the transportation, the ambulance is required to hold smooth motion and high speed. Therefore, it is necessary to develop stretcher vibration isolation system to improve ambulance ride comfort. In this paper, a mathematic model of six degree freedom ambulance-stretcher-occupant system is established. Based on the theory of linear quadratic optimal control, the linear quadratic regulator (LQR) controller of active ambulance stretcher is designed. The simulation results indicate that the active system equipped with the optimal controller has better vibration reduction perfomance on vertical acceleration and pitch angular acceleration of the ambulance stretcher.

scholarly journals Decoupling Optimization Design of Under-Chassis Equipment Suspension System in High-Speed Trains

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Zhanghui Xia ◽  
Dao Gong ◽  
Jinsong Zhou ◽  
Wenjing Sun ◽  
Yu Sun
Keyword(s):  
Natural Frequency ◽  
High Speed ◽  
Optimization Design ◽  
Degrees Of Freedom ◽  
Vibration Mode ◽  
Ride Comfort ◽  
Vibration Damping ◽  
Dynamic Vibration Absorber ◽  
Damping Effect ◽  
High Speed Trains

The vibrations of high-speed trains may strongly affect the safety and ride comfort of passengers, which issue requires the damping optimization of under-chassis equipment (UCE). In this study, the natural frequency of UCE is determined via the dynamic vibration absorber theory. The performed investigation of UCE-car body system vibration behavior revealed that an eccentricity of UCE results in the coupling vibration in six degrees of freedom, which leads to significant changes in its vibration mode and frequency. Thus, the natural frequency of UCE deviates from the initially determined value, which implies that the vibration damping effect is weakened. In this study, two decoupling optimization design methods, namely, forward and inverse decoupling methods, are proposed to solve this problem. The analysis of results obtained proves the feasibility of the proposed methods, which yield favorable decoupling degrees for the UCE vibration modes and minimize the offset of the vibration mode frequency from the initial natural one. These methods are considered quite instrumental in the improvement of vibration damping effect for high-speed trains.

Numerical and experimental studies on the car body flexible vibration reduction due to the effect of car body-mounted equipment

2016 ◽  
Vol 232 (1) ◽  
pp. 103-120 ◽  
Author(s):  
Caihong Huang ◽  
Jing Zeng ◽  
Guangbing Luo ◽  
Huailong Shi
Keyword(s):  
High Speed ◽  
Ride Comfort ◽  
Numerical Study ◽  
Experimental Studies ◽  
Vibration Absorber ◽  
Response Analysis ◽  
Dynamic Vibration Absorber ◽  
Vibration Absorption ◽  
Car Body ◽  
Dynamic Vibration

To study the effect of car body-mounted equipment on the car body flexible vibration, a vertical rigid-flexible coupling model of a high-speed vehicle is established, which includes a flexible car body, rigid bodies for two bogie frames, four wheelsets, and the car body-mounted equipment. The car body is approximated by an elastic beam, with dimensions selected to give similar mass and vertical bending frequency to an existing car body. Model validation is then carried out by comparing results from numerical simulation and on-track test. Using frequency response analysis and ride comfort analysis, parametric studies are undertaken in order to investigate the respective effect of equipment mounting systems on the car body flexible vibration and ride comfort perceived by the passenger. It is found that the equipment behaves as a dynamic vibration absorber on account of its elastic connections to the car body. The stiffness, damping, mass, and installing position of the equipment have a significant influence on the car body flexible vibration. The optimal parameters of the dynamic vibration absorber are given, which can contribute much to the vibration absorption of the car body flexible vibration. Finally, extensive tests on a high-speed test vehicle are conducted to represent a part of results obtained in the numerical study, including modal tests on the car body, component tests on rubber springs used in the equipment mounting systems, and roller rig tests on the vibration absorption performance of the equipment. It is shown that the car body flexible vibration can be effectively suppressed by reasonably suspending the car body-mounted equipment.

Case study: Prediction and field tests of railway noise and effects of a low-height noise barrier

2020 ◽  
Vol 68 (4) ◽  
pp. 303-314
Author(s):  
Yuna Park ◽  
Hyo-In Koh ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
...  
Keyword(s):  
High Speed ◽  
Field Tests ◽  
Residential Areas ◽  
Railway Systems ◽  
Railway Noise ◽  
Sound Levels ◽  
Noise Barrier ◽  
The Difference ◽  
Reduction Effect ◽  
The Impact

Railway noise is calculated to predict the impact of new or reconstructed railway tracks on nearby residential areas. The results are used to prepare adequate counter- measures, and the calculation results are directly related to the cost of the action plans. The calculated values were used to produce noise maps for each area of inter- est. The Schall 03 2012 is one of the most frequently used methods for the production of noise maps. The latest version was released in 2012 and uses various input para- meters associated with the latest rail vehicles and track systems in Germany. This version has not been sufficiently used in South Korea, and there is a lack of standard guidelines and a precise manual for Korean railway systems. Thus, it is not clear what input parameters will match specific local cases. This study investigates the modeling procedure for Korean railway systems and the differences between calcu- lated railway sound levels and measured values obtained using the Schall 03 2012 model. Depending on the location of sound receivers, the difference between the cal- culated and measured values was within approximately 4 dB for various train types. In the case of high-speed trains, the value was approximately 7 dB. A noise-reducing measure was also modeled. The noise reduction effect of a low-height noise barrier system was predicted and evaluated for operating railway sites within the frame- work of a national research project in Korea. The comparison of calculated and measured values showed differences within 2.5 dB.

Narrowing longitudinally coupled prefabricated slab track maintenance duration with field data analysis of slab deformation under high temperature

2021 ◽  
pp. 095440972098626
Author(s):  
Zai-Wei Li ◽  
Xiao-Zhou Liu ◽  
Hong-Yao Lu ◽  
Yue-Lei He
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Ride Comfort ◽  
Cost Effective ◽  
Periodic Variation ◽  
Longitudinal Force ◽  
Distribution Analysis ◽  
High Speed Rail ◽  
Track Maintenance ◽  
Slab Track

The deformation of longitudinally coupled prefabricated slab track (LCPST) due to high temperature may lead to a reduction in ride comfort and safety in high-speed rail (HSR) operation. It is thus critical to understand and track the development of such defects. This study develops an online monitoring system to analyze LCPST deformation at different slab depths under various temperatures. The trackside system, powered by solar energy with STM8L core that is ultra-low in energy consumption, is used to collect data of LCPST deformation and temperature level uninterruptedly. With canonical correlation analysis, it is found that LCPST deformation presents similar periodic variation to yearly temperature fluctuation and large longitudinal force may be generated as heat accumulates in summer, thereby causing track defects. Then the distribution of temperature and deformation data is categorized based on fuzzy c-means clustering. Through the distribution analysis, it is suggested that slab inspection can be shortened to 6 hours, i.e. from 10:00 am to 4:00 pm, reducing 14.3% track inspection workload from the current practice. The price of workload reduction is only a 2% chance of missed detection of slab deformation. The finding of this research can be used to enhance LCPST monitoring efficiency and reduce interruption to HSR operation, which is an essential step in promoting reliable and cost-effective track service.

Investigation of a loess-mudstone landslide and the induced structural damage in a high-speed railway tunnel

2020 ◽  
Vol 79 (5) ◽  
pp. 2201-2212
Author(s):  
Shunhua Zhou ◽  
Zhiyao Tian ◽  
Honggui Di ◽  
Peijun Guo ◽  
Longlong Fu
Keyword(s):  
Structural Damage ◽  
High Speed ◽  
Railway Tunnel ◽  
High Speed Railway

Kinematic Analysis and Simulation on Parallel Vibration Reduction Seat

2011 ◽  
Vol 464 ◽  
pp. 195-198
Author(s):  
Qi Zhi Yang ◽  
Guo Quan Huang ◽  
Chen Long ◽  
Xiao Bing Zhu
Keyword(s):  
Ride Comfort ◽  
Vibration Reduction ◽  
Simulation Models ◽  
Vibration System ◽  
Good Effort ◽  
Seat Suspension ◽  
Vehicle System ◽  
Adams Software ◽  
Seat Vibration ◽  
Vehicle Seat

Vibration of vehicle system is a typical vibration of multi-degree freedom. The damping performance of multi-degree freedom seat suspension is important to ride comfort of vehicle occupants. Based on the multi-dimensional movement principle of parallel mechanism, it is built a new vehicle seat with 3-DOF suspension. It is Established a kinematics model and then analyzed the theory of the displacement of the parallel vehicle seat system. Finally, using ADAMS software to build the simulation models of seat suspension, it is showed that the seat vibration system has a good effort on vibration reduction.

Association Between Match Activity, Endurance Levels and Maturity in Youth Football Players

2019 ◽  
Vol 40 (09) ◽  
pp. 576-584 ◽  
Author(s):  
Lorenzo Francini ◽  
Ermanno Rampinini ◽  
Andrea Bosio ◽  
Darragh Connolly ◽  
Domenico Carlomagno ◽  
...  
Keyword(s):  
High Speed ◽  
Perceived Exertion ◽  
Field Tests ◽  
Work Rate ◽  
Height Velocity ◽  
Aerobic Performance ◽  
Football Players ◽  
Youth Football ◽  
Match Rate ◽  
Very High

AbstractThe aim of the study was to examine the associations between maximal and submaximal field tests with match physical activity and biological maturation in youth football players. Sixty-eight youth football players (U14, U15, U16, U17) performed maximal and submaximal field endurance tests. Biological maturity was estimated calculating the distance from peak height velocity (Y-PHV). Physical match activities were tracked using GPS units and players’ post-match rate of perceived exertion (RPE) was recorded. Mainly moderate associations were found between field tests and match activities. Large correlations were found between Yo-Yo Intermittent Recovery test level 1, distance covered at high and very high-speed running, the quantity of very high and maximal metabolic power running. Small to moderate associations between match activities and Y-PHV were observed. The magnitude of correlation between match activities and field tests increased from moderate to large when matches with an RPE>5 were considered. The results provide further evidence of the association between young football players’ aerobic performance and match work rate. Submaximal field tests demonstrate ecological validity and may constitute a practical alternative to performing maximal tests. Maturation was found to have a moderate effect on youth players’ match work rate.

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