scholarly journals Studies on Frequency Response Characteristics of High-Speed Railway Train End Relationship Test System with Flexible Bases

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6147
Author(s):  
Zhiqiang Zhang ◽  
Dacheng Cong ◽  
Zhidong Yang ◽  
Yunfei Cai ◽  
Junwei Han
Keyword(s):  
Natural Frequency ◽  
High Speed ◽  
Parallel Robot ◽  
Test System ◽  
Design Criterion ◽  
Analytical Relationship ◽  
Test Accuracy ◽  
High Speed Railway ◽  
Characteristic Model ◽  
Response Characteristics

A train end relationship test system was installed with a Stewart parallel robot on the reaction bases perpendicular to the ground, to test the fatigue and durability of train end relationship components, such as the transfixion way of a high-speed railway train. The flexibility of the reaction bases affected the test accuracy of the train end relationship components within a test frequency band range. In this paper, a coupling characteristic model was established between the flexible bases and the parallel robot. Then, the analytical relationship was analyzed between the natural frequency of the bases and the natural frequency of the parallel robot. Moreover, a design criterion was proposed for the natural frequency of the reaction bases. It was considered that when the natural frequency of the bases was not less than five times the natural frequency of the parallel robot, the influence of the flexibility of the bases on the test accuracy can be ignored. The validity of the design criterion was verified by the simulation results.

A New Monitoring Method of Wheel/Rail Contact Forces Caused by Out-of-Round Railway Wheels

2012 ◽  
Vol 178-181 ◽  
pp. 1125-1130
Author(s):  
Zhi Chen Wang ◽  
Ying Song ◽  
Ying Ming Shen
Keyword(s):  
Traffic Safety ◽  
High Speed ◽  
Test System ◽  
Simulation Software ◽  
Contact Forces ◽  
Strain Gauges ◽  
Monitoring Method ◽  
High Speed Railway ◽  
Railway Traffic ◽  
Railway Wheels

Traditional methods of wheel-rail contact forces measurement all need strain gauges on wheel sets or rails. The shortcomings of strain gauges such as zero-drift, poor anti-interference property and instability of test system can’t meat wheel/rail force test requirements in high-speed railways. A method based on PVDF piezoelectric sensing technology is presented for the test of wheel/rail contact force. Firstly, on the basis of the theory of vehicle-track coupling dynamics and by means of simulation software ADAMS/Rail, a three-dimensional train-track simulation model is established. Secondly, the modes and characteristics of wheel/rail impact vibrations due to non-roundness of railway wheels are investigated in high-speed railway operation. The relationship between the range for acceptable roundness values and vehicle speed is determined. Finally, the view that it is of important significance to establish wheel/rail force real-time monitoring system is expanded, so that abnormal conditions caused by out-of-round wheels can be detected in time, to ensure high-speed railway traffic safety. The study is very important for enhancing the stability and economy signification of rail transmission.

Hydraulic System Design and Simulation of High-Speed Railway Dynamic Test System Excitation Device

2012 ◽  
Vol 271-272 ◽  
pp. 953-957
Author(s):  
Liang Cai Zeng ◽  
Fei Long Zheng ◽  
Yuan Wan ◽  
Qiang Hua Xi
Keyword(s):  
Hydraulic System ◽  
High Speed ◽  
Digital Simulation ◽  
Dynamic Test ◽  
Hydraulic Cylinder ◽  
High Amplitude ◽  
Test System ◽  
Excitation System ◽  
High Speed Railway ◽  
Exciting Frequency

The existing hydraulic excitation mode of valve controlled cylinder or pump controlled motor used in the excitation device of high-speed railway dynamic test system is difficult to meet the requirements of high exciting frequency, high exciting force and high amplitude. To solve these problems, the paper puts forward a bicyclic surface hydraulic cylinder, and designs the corresponding electro-hydraulic servo excitation system. According to the test system parameters，it establishes the mathematical model of the hydraulic system. It uses Matlab/Simulink to carry out theoretical analysis and digital simulation and uses PID Tuner to adjust the PID controller parameters. The simulation results show that the hydraulic excitation system designed meets the performance requirements of the high-speed railway dynamic test system excitation device.

scholarly journals Experimental Study on Electric Potential Response Characteristics of Gas-Bearing Coal During Deformation and Fracturing Process

Processes ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 72 ◽  
Author(s):  
Zhonghui Li ◽  
Yue Niu ◽  
Enyuan Wang ◽  
Lanbo Liu ◽  
Honghao Wang ◽  
...  
Keyword(s):  
Damage Evolution ◽  
High Speed ◽  
Electrical Potential ◽  
Test System ◽  
Stress Change ◽  
High Speed Photography ◽  
Response Characteristics ◽  
Fracturing Process ◽  
Erosion Effect ◽  
Gas Bearing

Coal mass is deformed and fractured under stress to generate electrical potential (EP) signals. The mechanical properties of coal change with the adsorption of gas. To investigate the EP response characteristics of gas-bearing coal during deformation and fracture, a test system to monitor multi-parameters of gas-bearing coal under load was designed. The results showed that abundant EP signals were generated during the loading process and the EP response corresponded well with the stress change and crack expansion, and validated this with the results from acoustic emission (AE) and high-speed photography. The higher stress level and the greater the sudden stress change led to the greater EP abnormal response. With the increase of gas pressure, the confining action and erosion effect are promoted, causing the damage evolution impacted and failure characteristics changes. As a result, the EP response is similar while the characteristics were promoted. The EP response was generated due to the charge separation caused by the friction effect etc. during the damage and deformation of the coal. Furthermore, the main factors of the EP response were different under diverse loading stages. The presence of gas promoted the EP effect. When the failure of the coal occurred, EP value rapidly rose to a maximum, which could be considered as an anomalous characteristic for monitoring the stability and revealing failure of gas-bearing coal. The research results are beneficial for further investigating the damage-evolution process of gas-bearing coal.

scholarly journals An Accurate Measurement Method for Tension Force of Short Cable by Additional Mass Block

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Shuichang Li ◽  
Longlin Wang ◽  
Hua Wang ◽  
Peihua Shi ◽  
Riyan Lan ◽  
...  
Keyword(s):  
Natural Frequency ◽  
Force Measurement ◽  
Ritz Method ◽  
Added Mass ◽  
Short Length ◽  
Effective Length ◽  
Tension Force ◽  
Analytical Relationship ◽  
Test Accuracy ◽  
Additional Mass

The equivalent effective length parameter is introduced into the vibration equation of short cable; that is, the boundary condition that affects the test accuracy of short cable force is equivalent to the calculated length of cable. By attaching an additional mass block to the cable, new parameters are introduced to identify the tension force. Vibration differential equations are established for cable with and without addition mass block, taking new parameters into account, such as equivalent effective length and added mass. By solving the equations using the RITZ method, the analytical relationship between the natural frequency of cable and equivalent effective length before and after a mass block is added can be developed. It can also develop an analytical method to identify the equivalent effective length depending on whether the added mass block is attached. Then, tension force of short length cable can be evaluated by measuring its natural frequency based on equivalent effective length. The method is verified by field tests. The tests results indicate the new method mentioned in this paper is going to largely improve the accuracy of tension force measurement of short length cable.

The design of a 2-dof novel flexible parallel robot

Robotica ◽  
2006 ◽  
Vol 24 (5) ◽  
pp. 603-604
Author(s):  
Yongjie Zhao ◽  
Tian Huang ◽  
Zhiyong Yang
Keyword(s):  
Natural Frequency ◽  
Fundamental Frequency ◽  
High Speed ◽  
Parallel Robot ◽  
Total Weight ◽  
Structure Modification ◽  
Orthogonal Direction ◽  
Low Speed

This paper addresses the design of a 2-dof novel flexible parallel robot that maximizes the fundamental frequency of vibration under a specified total weight constraint. In order to enhance the natural frequency of the robot in the direction Z, structure modification of the robot is made based on the initial project. The proposed robot is suitable for the application that requires high-speed motion in a plane and step-by-step, or relatively low speed on the orthogonal direction.

scholarly journals Response Characteristics of Cross Tunnel Lining under Dynamic Train Load

2020 ◽  
Vol 10 (12) ◽  
pp. 4406 ◽  
Author(s):  
Ang Wang ◽  
Chenghua Shi ◽  
Chenyang Zhao ◽  
E Deng ◽  
Weichao Yang ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Stress Level ◽  
High Speed ◽  
Tunnel Lining ◽  
Static Stress ◽  
Railway Tunnel ◽  
High Speed Railway ◽  
Response Characteristics ◽  
Stress Levels ◽  
Long Time

The crossing area is a vulnerable component of the interchange high-speed railway tunnel because of the high-static stress level and the long-term dynamic train load in the operation period. Although attention has been paid to this problem, the response characteristics of high-speed railway tunnel lining at the cross position under the dynamic train load may still need further research as very little investigation is available on this issue at present. In this paper, the initial stress state and dynamic response characteristics of tunnel lining were studied using the three-dimensional finite element method. Furthermore, the damage evolutionary characteristics of the tunnel inverted arch under dynamic and initial static loads were researched using a set of self-developed indoor fatigue test devices. The size of the test box is 400 × 300 × 250 mm (length × width × height). Numerical simulation results indicate that the displacement and stress levels of tunnel lining are very high at the cross position. The stress increment of tunnel lining due to the dynamic train load is more likely to induce a break in the tunnel lining at this position. The indoor fatigue tests reveal that the change of structural strain increment amplitude and strain ratio is obvious when the dynamic load stress level is higher. It is better for dynamic stress levels not to exceed 0.6 times of structural tensile strength to avoid the tunnel lining being damaged in the long-time service period. The initial static load has an influence on the tunnel inverted arch, and the static stress level should be lower than 0.65 times of structural tensile strength to ensure the tunnel has long-time serviceability. This paper provides a reference for the future design of new cross tunnels and the operation safety evaluation and disease regulation of existing high-speed railway tunnels.

Optimized Design of the Structure of High-Speed Railway Bearing Test Rig

2012 ◽  
Vol 479-481 ◽  
pp. 1442-1445
Author(s):  
Xian Zhao Jia ◽  
Yong Jian Yu ◽  
Hong Bin Liu
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
High Speed ◽  
Dynamic Performance ◽  
Element Model ◽  
Optimized Design ◽  
Test Rig ◽  
Element Analysis ◽  
High Speed Railway ◽  
Main Spindle

This paper establishes the finite element model of main spindle in the test rig for high-speed railway bearing. Utilizing the finite element analysis software ANSYS, the modal analysis for spindle is carried on. Preliminary determination is that spindle resonance occurs. Structural optimization is carried out by increasing first natural frequency and reducing weight of main spindle in order to avoid resonance. The results showed that the position of support bearings is determined. The first natural frequency is increased by reducing spindle weight. The dynamic performance of the spindle is improved, avoiding the resonance region effectively.

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