基于超声波的轮轨接触斑及应力检测系统研究

Research on ultrasonic-based wheel-rail contact patch and stress detection system

针对目前轮轨接触斑及接触应力分布难以有效检测的问题,基于接触面的准静态弹簧模型与超声波反射法,设计一种适用于静态轮轨接触状态检测的系统。系统采用水浸式点聚焦超声探头进行检测,主要由机械结构部分、超声波激励采集系统和接触斑及应力分析显示系统组成。机械结构部分包括轮轨加载机构和两轴扫描机构,分别实现对轮轨的固定与加载,以及夹持超声探头进行平面扫描运动;超声波激励采集系统实现对扫描机构的运动控制以及超声波信号的激励、采集和传输,并与接触斑及应力分析显示系统通过以太网通信,实现命令接收与超声波数据的上传;接触斑及应力分析显示系统实现超声数据的接收与处理,并实时显示和存储检测结果。利用所搭建的检测系统首先进行标定实验,建立超声声压反射系数与接触应力之间的关系,然后进行轮轨接触斑与应力分布检测实验,获得了20~70 kN载荷下车轮试件与钢轨的接触斑及应力分布云图,最后采用3次样条插值处理优化了检测效果。实验结果表明:所提出的检测方法与系统能够有效检测静态轮轨接触斑几何形状与接触应力的分布情况,反映真实的轮轨接触状态。对于轮轨的优化设计、寿命预测和轨道维护等研究都具有重要作用和意义。

Aiming at the problem that it is difficult to effectively detect wheel-rail contact patch and contact stress distribution,a system suitable for static wheel-rail contact state detection was designed according to the quasi-static spring model of the contact surface and ultrasonic pulse reflection method.The system used a water-immersed spot focusing ultrasonic probe for detection,which was mainly composed of mechanical parts,ultrasonic excitation,and acquisition system,contact patch and stress analysis display system.The mechanical parts included a wheel-rail loading mechanism and a two-axis scanning mechanism,which respectively realized the fixation and loading of the wheel-rail,and the planar scanning movement of clamping the ultrasonic probe.The ultrasonic excitation and acquisition system realized the motion control of the scanning mechanism,and the excitation,acquisition and transmission of ultrasonic data and the reception of corresponding command.The contact patch and stress analysis display system realized the reception and processing of ultrasonic data,as well as the real-time display and storage of test results.Before the tests,the calibration experiment was carried out to establish the relationship between the ultrasonic sound pressure reflection coefficient and the contact stress.Then the wheel-rail contact patch and stress distribution detection experiment was done,and the contact patch and stress distribution image of the wheel-rail specimen under 20~70 kN load were obtained.Finally,cubic spline interpolation was used to optimize the results.The experimental results show that the proposed detection method and designed system can effectively detect the static wheel-rail contact patch geometry and its contact stress distribution,reflecting the real wheel-rail contact state.It is of great significance for wheel-rail optimization design,lifetime prediction and track maintenance.