The rapid development of high-speed railway networks requires advanced methods for analysing vibration and sound radiation characteristics of a fast rotating train wheel subject to a vertical harmonic wheel-rail force...The rapid development of high-speed railway networks requires advanced methods for analysing vibration and sound radiation characteristics of a fast rotating train wheel subject to a vertical harmonic wheel-rail force. In order to consider the rotation of the wheel and at the same time increase the computational efficiency, a procedure is adapted in this paper taking advantage of the axial symmetry of the wheel. In this procedure, a recently developed 2.5D finite element method, which can consider wheel rotation but only requires a 2D mesh over a cross section containing the wheel axis, is used to calculate the vibration response of the wheel. Then, the vibration response of the wheel is taken as acoustic boundary condition and the 2.5D acoustic boundary element method, which only requires a 1D mesh over the boundary of the above cross section, is utilised to calculate the sound radiation of the wheel. These 2.5D methods and relevant programs are validated by comparing results from this procedure with those from conventional 3D analyses using commercial software. The comparison also demonstrates that these 2.5D methods have a much higher computational efficiency. Using the 2.5D methods, we study the wheel rotation speed influences on the factors including the vertical receptance of the wheel at wheel-rail contact point, sound pressure level at a pre-defined standard measurement point, radiated sound power level, directivity of the radia- tion, and contribution of each part of the wheel. It can be concluded that the wheel rotation speed splits most peaks of the vertical receptance at the wheel-rail contact point, sound pressure levels at the field, and the sound power level of the wheel into two peaks. The directivity and power contribution of the wheel are also significantly changed by the wheel rotation speed. Therefore, the rotation of a train wheel should be taken into account when calculating its vibration and sound radiation.展开更多
The wheel-rail adhesion control for regenerative braking systems of high speed electric multiple unit trains is crucial to maintaining the stability,improving the adhesion utilization,and achieving deep energy recover...The wheel-rail adhesion control for regenerative braking systems of high speed electric multiple unit trains is crucial to maintaining the stability,improving the adhesion utilization,and achieving deep energy recovery.There remain technical challenges mainly because of the nonlinear,uncertain,and varying features of wheel-rail contact conditions.This research analyzes the torque transmitting behavior during regenerative braking,and proposes a novel methodology to detect the wheel-rail adhesion stability.Then,applications to the wheel slip prevention during braking are investigated,and the optimal slip ratio control scheme is proposed,which is based on a novel optimal reference generation of the slip ratio and a robust sliding mode control.The proposed methodology achieves the optimal braking performancewithoutthewheel-railcontactinformation.Numerical simulation results for uncertain slippery rails verify the effectiveness of the proposed methodology.展开更多
This paper studies the title problem including an analysis of the gyroscopic effects of the wheels of a rail-car travelling at high-speed around a level, horizontal curve. The analysis is based upon the fundamental pr...This paper studies the title problem including an analysis of the gyroscopic effects of the wheels of a rail-car travelling at high-speed around a level, horizontal curve. The analysis is based upon the fundamental principles of dynamics. The result is a design formula for the minimum curve radius needed to prevent derailment. Aside from the rail car geometric and physical properties, the minimum curve radius depends upon the square the train speed. An illustrative example shows that the wheel gyroscopic effect is destabilizing and additive to the centrifugal force derailment tendency. From a track design perspective, however, the gyroscopic effect is relatively small compared with the centrifugal force effect.展开更多
A three-dimensional (3-D) wheel-rail rolling contact model with a wheel fiat was built using commercial software Hypermesh, and the dynamic finite element simulation was conducted using LS-DYNA 3D/explicit code. Inf...A three-dimensional (3-D) wheel-rail rolling contact model with a wheel fiat was built using commercial software Hypermesh, and the dynamic finite element simulation was conducted using LS-DYNA 3D/explicit code. Influences of the train speed, flat length and axle load on the vertical wheel-rail impact response were discussed, respectively. The results show that the maximum vertical wheel-rail impact force induced by the wheel flat is higher than that generated by the perfect wheel, and these two dynamic impact forces are much greater than the static axle load. Besides, the maximum von Mises equivalent stress and maximum equivalent plastic strain are observed on the wheel-rail contact surface, and both of them as well as the maximum wheel-rail impact force are sensitive to train speed, fiat length and axle load.展开更多
Gearbox, as the crucial transmission equipment of high-speed train drive system, bears mainly the impact of wheel-rail excitation during its application, resulting in fatigue failure of the housing structure. In order...Gearbox, as the crucial transmission equipment of high-speed train drive system, bears mainly the impact of wheel-rail excitation during its application, resulting in fatigue failure of the housing structure. In order to analyze the vibration characteristics of the high-speed train gearbox housing, a test had been performed under operating condition on Wuhan-Guangzhou High-Speed Railway, where a host of vibration characteristics of different parts of housing had been obtained, and vibration signals had also been comparatively analyzed using acceleration amplitude spectrum and equivalent acceleration amplitude method. The result showed that the vibration level of the measuring point A on the joint part of the gearbox housing and axle bearing block was higher than that of the measuring point B on the upper part of the gearbox housing, both horizontally and vertically. And there existed attenuation during the transmission process of vibration from point A to Point B. Further, when a train was moving at a high speed, the gearbox vibration at the head carriage was better than that at the tail carriage. In addition, when a train slowed down from 300 km/h to 200 km/h, the horizontal equivalent acceleration amplitude dropped by 58% while the vertical one declined by 62%. Equivalent acceleration amplitude method was used to identify the vibration relations among different parts of housing, and the validity and applicability of this method were verified by data analysis. The study provided reference to ensure the operating safety of high-speed train drive system and design of new housing structure.展开更多
To study the curving performance of trains, 1D and 3D dynamic models of trains were built using nu- merical methods. The 1D model was composed of 210 simple wagons, each allowed only longitudinal motion; whereas the 3...To study the curving performance of trains, 1D and 3D dynamic models of trains were built using nu- merical methods. The 1D model was composed of 210 simple wagons, each allowed only longitudinal motion; whereas the 3D model included three complicated wagons for which longitudinal, lateral, and vertical degrees of freedom were considered. Combined with the calculated results from the 1D model under braking conditions, the behavior of draft gears and brake shoes were added to the 3D model. The assessment of the curving performance of trains was focused on making comparisons between idling and braking conditions. The results indicated the following: when a train brakes on a curved track, the wheel-rail lateral force and derailment factor are greater than under idling conditions. Because the yawing movement of the wheelset is limited by brake shoes, the zone of wheel contact along the wheel tread is wider than under idling conditions. Furthermore, as the curvature becomes tighter, the traction ratio shows a nonlinear increasing trend, whether under idling or braking conditions. By increasing the brake shoe pressure, train steering becomes more difficult.展开更多
第七届全国大学生工程训练综合能力竞赛智能+赛道基于机器视觉的智能物流搬运机器人,对OpenMV4视觉模块进行研究,应用该模块进行二维码、不同颜色物料等多种目标的识别,信息经过模块上STM32F427微控制器的处理,与Arduino Mega 2560板通...第七届全国大学生工程训练综合能力竞赛智能+赛道基于机器视觉的智能物流搬运机器人,对OpenMV4视觉模块进行研究,应用该模块进行二维码、不同颜色物料等多种目标的识别,信息经过模块上STM32F427微控制器的处理,与Arduino Mega 2560板通信,机器人识别场地上的三个区域,用PID算法驱动麦克纳姆轮机器人的四个直流电机旋转并且定位机器人,通过PCA9685模块的I2C通信协议,发送PWM脉冲信号给机械臂上的四个关节舵机,使智能物流搬运机器人对场地上的物料进行自动搬运。实验证明其可以较为精确地完成各项搬运任务。展开更多
铁道客车轮对上的不平衡质量影响列车运行安全及速度的进一步提升,轮对安装前需要精确检测不平衡质量并进行动平衡处理。本文提出自适应小波消噪、MUSIC(Multiple Signal Classification)谱估计、相关分析法相结合的方法,实现铁道客车...铁道客车轮对上的不平衡质量影响列车运行安全及速度的进一步提升,轮对安装前需要精确检测不平衡质量并进行动平衡处理。本文提出自适应小波消噪、MUSIC(Multiple Signal Classification)谱估计、相关分析法相结合的方法,实现铁道客车轮对动平衡振动信号特征的提取。通过Labview软件与MATLAB混合编程实现软件开发,并搭建铁道客车轮对动平衡测试平台进行实验验证,实验验证结果表明,经过降噪和采样分辨率的控制,可以克服现场噪声及频率干扰问题,提取的信号幅值及相位具有较高的精度,可实现轮对上不平衡质量及位置的准确探测。展开更多
基金the support to this work from the Ministry of Science and Technology of China (2016YFE0205200)China Railway (2015Z003-B)Scientific Research Foundation of State Key Laboratory of Traction Power (2017TPL_T01)
文摘The rapid development of high-speed railway networks requires advanced methods for analysing vibration and sound radiation characteristics of a fast rotating train wheel subject to a vertical harmonic wheel-rail force. In order to consider the rotation of the wheel and at the same time increase the computational efficiency, a procedure is adapted in this paper taking advantage of the axial symmetry of the wheel. In this procedure, a recently developed 2.5D finite element method, which can consider wheel rotation but only requires a 2D mesh over a cross section containing the wheel axis, is used to calculate the vibration response of the wheel. Then, the vibration response of the wheel is taken as acoustic boundary condition and the 2.5D acoustic boundary element method, which only requires a 1D mesh over the boundary of the above cross section, is utilised to calculate the sound radiation of the wheel. These 2.5D methods and relevant programs are validated by comparing results from this procedure with those from conventional 3D analyses using commercial software. The comparison also demonstrates that these 2.5D methods have a much higher computational efficiency. Using the 2.5D methods, we study the wheel rotation speed influences on the factors including the vertical receptance of the wheel at wheel-rail contact point, sound pressure level at a pre-defined standard measurement point, radiated sound power level, directivity of the radia- tion, and contribution of each part of the wheel. It can be concluded that the wheel rotation speed splits most peaks of the vertical receptance at the wheel-rail contact point, sound pressure levels at the field, and the sound power level of the wheel into two peaks. The directivity and power contribution of the wheel are also significantly changed by the wheel rotation speed. Therefore, the rotation of a train wheel should be taken into account when calculating its vibration and sound radiation.
基金supported by the National Natural Science Foundation of China(Grant 51305437)Guangdong Innovative Research Team Program of China(Grant201001D0104648280)
文摘The wheel-rail adhesion control for regenerative braking systems of high speed electric multiple unit trains is crucial to maintaining the stability,improving the adhesion utilization,and achieving deep energy recovery.There remain technical challenges mainly because of the nonlinear,uncertain,and varying features of wheel-rail contact conditions.This research analyzes the torque transmitting behavior during regenerative braking,and proposes a novel methodology to detect the wheel-rail adhesion stability.Then,applications to the wheel slip prevention during braking are investigated,and the optimal slip ratio control scheme is proposed,which is based on a novel optimal reference generation of the slip ratio and a robust sliding mode control.The proposed methodology achieves the optimal braking performancewithoutthewheel-railcontactinformation.Numerical simulation results for uncertain slippery rails verify the effectiveness of the proposed methodology.
文摘This paper studies the title problem including an analysis of the gyroscopic effects of the wheels of a rail-car travelling at high-speed around a level, horizontal curve. The analysis is based upon the fundamental principles of dynamics. The result is a design formula for the minimum curve radius needed to prevent derailment. Aside from the rail car geometric and physical properties, the minimum curve radius depends upon the square the train speed. An illustrative example shows that the wheel gyroscopic effect is destabilizing and additive to the centrifugal force derailment tendency. From a track design perspective, however, the gyroscopic effect is relatively small compared with the centrifugal force effect.
基金supported by the National Natural Science Foundation of China (Grant No. 51475392)the Fundamental Research Funds for the Central Universities (Grant No. 2682015RC09)the Research Fund of State Key Laboratory of Traction Power (Grant No. 2015TPL_T02)
文摘A three-dimensional (3-D) wheel-rail rolling contact model with a wheel fiat was built using commercial software Hypermesh, and the dynamic finite element simulation was conducted using LS-DYNA 3D/explicit code. Influences of the train speed, flat length and axle load on the vertical wheel-rail impact response were discussed, respectively. The results show that the maximum vertical wheel-rail impact force induced by the wheel flat is higher than that generated by the perfect wheel, and these two dynamic impact forces are much greater than the static axle load. Besides, the maximum von Mises equivalent stress and maximum equivalent plastic strain are observed on the wheel-rail contact surface, and both of them as well as the maximum wheel-rail impact force are sensitive to train speed, fiat length and axle load.
文摘Gearbox, as the crucial transmission equipment of high-speed train drive system, bears mainly the impact of wheel-rail excitation during its application, resulting in fatigue failure of the housing structure. In order to analyze the vibration characteristics of the high-speed train gearbox housing, a test had been performed under operating condition on Wuhan-Guangzhou High-Speed Railway, where a host of vibration characteristics of different parts of housing had been obtained, and vibration signals had also been comparatively analyzed using acceleration amplitude spectrum and equivalent acceleration amplitude method. The result showed that the vibration level of the measuring point A on the joint part of the gearbox housing and axle bearing block was higher than that of the measuring point B on the upper part of the gearbox housing, both horizontally and vertically. And there existed attenuation during the transmission process of vibration from point A to Point B. Further, when a train was moving at a high speed, the gearbox vibration at the head carriage was better than that at the tail carriage. In addition, when a train slowed down from 300 km/h to 200 km/h, the horizontal equivalent acceleration amplitude dropped by 58% while the vertical one declined by 62%. Equivalent acceleration amplitude method was used to identify the vibration relations among different parts of housing, and the validity and applicability of this method were verified by data analysis. The study provided reference to ensure the operating safety of high-speed train drive system and design of new housing structure.
文摘To study the curving performance of trains, 1D and 3D dynamic models of trains were built using nu- merical methods. The 1D model was composed of 210 simple wagons, each allowed only longitudinal motion; whereas the 3D model included three complicated wagons for which longitudinal, lateral, and vertical degrees of freedom were considered. Combined with the calculated results from the 1D model under braking conditions, the behavior of draft gears and brake shoes were added to the 3D model. The assessment of the curving performance of trains was focused on making comparisons between idling and braking conditions. The results indicated the following: when a train brakes on a curved track, the wheel-rail lateral force and derailment factor are greater than under idling conditions. Because the yawing movement of the wheelset is limited by brake shoes, the zone of wheel contact along the wheel tread is wider than under idling conditions. Furthermore, as the curvature becomes tighter, the traction ratio shows a nonlinear increasing trend, whether under idling or braking conditions. By increasing the brake shoe pressure, train steering becomes more difficult.
文摘第七届全国大学生工程训练综合能力竞赛智能+赛道基于机器视觉的智能物流搬运机器人,对OpenMV4视觉模块进行研究,应用该模块进行二维码、不同颜色物料等多种目标的识别,信息经过模块上STM32F427微控制器的处理,与Arduino Mega 2560板通信,机器人识别场地上的三个区域,用PID算法驱动麦克纳姆轮机器人的四个直流电机旋转并且定位机器人,通过PCA9685模块的I2C通信协议,发送PWM脉冲信号给机械臂上的四个关节舵机,使智能物流搬运机器人对场地上的物料进行自动搬运。实验证明其可以较为精确地完成各项搬运任务。
文摘铁道客车轮对上的不平衡质量影响列车运行安全及速度的进一步提升,轮对安装前需要精确检测不平衡质量并进行动平衡处理。本文提出自适应小波消噪、MUSIC(Multiple Signal Classification)谱估计、相关分析法相结合的方法,实现铁道客车轮对动平衡振动信号特征的提取。通过Labview软件与MATLAB混合编程实现软件开发,并搭建铁道客车轮对动平衡测试平台进行实验验证,实验验证结果表明,经过降噪和采样分辨率的控制,可以克服现场噪声及频率干扰问题,提取的信号幅值及相位具有较高的精度,可实现轮对上不平衡质量及位置的准确探测。