Rail Defects: Wave Wear

Testing method
①Visual inspection and assisted 1m electronic ruler measurement.

② Install the sensor on the rail inspection vehicle and use the string method or inertia method to measure; the string method uses the rail tread shape obtained by the sensor, and measures the line connecting the two measuring points of the rail as the measuring chord, with the middle measuring point reaching The positive vector of the chord is used as the measurement value of rail corrugation wear; the inertial method calculates the corrugation value by calculating the acceleration value to the displacement.

cause
The causes of rail corrugation wear are relatively complex. The causes of corrugation can generally be summarized into two categories: dynamic cause theory and non-dynamic cause theory.

① The dynamic cause is that the vibration of the wheel-rail system produces corrugation. The vibrations causing corrugation can be divided into three categories: self-excitation, resonance and feedback vibration. The corrugation wavelength is associated with one or several vibration forms in the wheel-rail system.

② Non-dynamic causes believe that even if the wheel-rail force is a constant value, corrugation will occur due to uneven plastic flow or wear, and the wavelength of corrugation is random. The corrugation on the curve is generally believed to be caused by the different turning radii of the wheelsets.

development results
Rail corrugation will cause intense vibrations of trains and track structures, produce noise, affect passenger comfort, and increase the maintenance workload and costs of the railway maintenance department.
The formation and development of rail corrugation not only affects the service life of locomotives, vehicles and track structures, severe rail corrugation can lead to train derailment accidents.

Approach
① Corrugation can be processed by grinding (or milling): the grinding plan should be determined according to the degree of surface damage and wheel-rail contact. After grinding, the damage should be ensured to be eliminated. Before grinding, the condition of the rails in the area to be grinded should be investigated. Use rails. Profile meter or profile template measurement, based on the surface condition of the rail, rail damage and wheel-rail contact, a polishing plan is formulated based on the designed profile. During the grinding process of large-scale road maintenance machinery, the results after grinding should be measured and analyzed in a timely manner, and the grinding plan should be adjusted to ensure that the grinding is in place according to the designed profile.

For surface damage of rail sections, milling and grinding operations should be used. The quality of rail grinding operations should comply with the acceptance standards for rail grinding operations.
② In serious cases, the rail should be replaced.

Precaution
The mechanisms of corrugation formation are different, and the control measures taken are also different. The main methods to control corrugation of curved rails on heavy-duty lines include rail grinding, rail lubrication, wheel-rail friction coefficient adjustment, increasing the hardness of curved rail materials to improve their wear resistance, and replacing rails.

In addition, in addition to using the above-mentioned similar methods, the factors that induce corrugation can also be eliminated by changing and optimizing the track structural characteristics, such as reducing track irregularities, increasing track elasticity, using optimal fastener vibration damping stiffness and Sleeper distance, study the relationship between speed, wheel-rail roughness excitation and sensitivity of track resonance characteristics, etc.