The On-line Detection Research Of CWR Dynamic Response Under The Wheel-rail Force

Continuous welded rail(CWR) is widely applied in high-speed railway due to eliminating lots of rail joints, which have many advantages of stable travel, lower track maintenance and long service life. It has been confirmed that the safety of CWR is largely influenced by train dynamic load, which may skip the critical state, directly get into the inconsistent state from the consistent state. The signals of its dynamic strain and vibration acceleration include rich feature information, of which real-time collection and analysis have a guiding significance for research on instability of CWR. Combining simulating calculation with theoretical analysis or experiments, the paper is based on the monitoring system of wireless sensor network to realize real-time online measure of dynamic strain and vibration acceleration.In order to find rational installation site of dynamic strain sensor of CWR, the three-dimensional finite element model was built by the finite element software of Abaqus based on the CRTS I slab ballastless track, to analyze the vertical stress distribution of CWR effected by wheel-rail force, temperature force and the joint action of wheel-rail force and temperature force. A serious of load tests are performed on the wheel-rail force bedstand. As a result, the finding is fairly in accordance with the results of simulating calculation. Getting the longitudinal stress of rail in the model, the interaction relations of the rail longitudinal stress with wheel-rail force, temperature force, and the joint action of wheel-rail force and temperature force, are analyzed. The comparison between simulating results under the action of temperature force and the theoretical value is conducted. The results indicate that the longitudinal stress of simulation and the theoretical calculation agree pretty well. The von mises stress of CWR under the wheel-rail force is mainly located in a line region about45°to the horizontal line. And the maximum vertical stress is distributed in the upper part of the rail-web inside, except the contact area of rail-head and wheels. The vertical stress of the rail-web inside is more than the outside above the rail-foot. The longitudinal stress almost depend linearly on the wheel-rail force in the rail-web, and the relationship between the longitudinal stress and wheel-rail force is also quasi-linear. Meanwhile, the maximum vertical stress is in the rail-web down of the fastener withhold pitch, and the minimum vertical stress is in the middle of the rail cross. Wheel-rail force and temperature force are relatively independent in the change of the rail vertical and longitudinal stress. The measurement of vibration acceleration usually need an installation of accelerometers on the measured body. As for the bad condition of CWR, the common means of installing accelerometers is not applied in the long real-time measurement of vibration of CWR. A special fixture is used to install accelerometers on the railway to measure the vibration acceleration. However, the measured of railway vibration acceleration by the accelerometer in the special fixture installed is different from the value by direct installed accelerometers. In order to find the relationship of the above-mentioned, the model of vibration acceleration of railway is established, concluding the transfer function of the relationship between the accelerations measured in the rail and in the special fixture, which is verified by experiment. The results indicate that measured acceleration signal corresponding well with direct measurement results below the frequency of3.5kHz.