论文部分内容阅读
Railway transportation is continuing to grow due to its relative merits such as high safety,predictable punctuality and large capacity.With the ongoing increases in speed and growth in traffic intensity,one kind of railway noise,curve squeal,is becoming more prominent.Field tests found that the sound pressure level of curve squeal is normally 30 dB higher than that of normal rolling noise.Curve squeal is associated with excessive lateral crabbing at the contact patch of wheel/rail interface.When a bogie negotiates a curve of a track,there is a misalignment between the rolling velocity and the wheel velocity; namely angle of attack,leading to a lateral sliding velocity of the wheel across the top of rail.The sound pressure level of wheel squeal has been shown to increase with angle of attack and rolling speed in both field and laboratory tests.To investigate this,a simplified analytical vibration model in the time domain is integrated with nonlinear rolling contact theory developed for wheel squeal.This model is used to simulate the vibration velocity of a test rig wheel at different rolling speeds and angles of attack.The simulated vibration velocities correlate well in the trend with the recorded sound pressure levels of wheel squeal in laboratory tests.Lateral creepage and force at various angles of attack and rolling speeds in the rolling contact are simulated.A rolling contact two disc test rig has been developed to investigate squeal noise.A novel method to introduce the angle of attack between two wheels is developed for this test rig.The contact forces between two wheels can be measured with Fiber Bragg Grating(FBG)on the bracket of the test rig.The squeal noise is measured with a microphone,which is 35 cm above the ground and 10 cm away from the contact point of the wheels.The test results show that the sound pressure levels of squeal noise increase with the yaw angle between the two wheels of the test rig.The FBG installed on the bracket of the test rig can measure contact force between two wheels,and the friction coefficient in rolling contact is measured and presented in this paper,providing more detailed investigation about the generation mechanism of wheel squeal.