Rail and wheel surface irregularities are the main source of rolling noise. One of the main causes for wheel surface roughness is tread braking. Wheels braked by the most common tread brakes—cast iron blocks—have high roughness levels and, as usual, corrugation with wavelength of 30–100 mm. The Brite Euram research project EUROSABOT deals with new solutions for tread brakes, which would lower the roughness level, prevent the buildup of periodic roughness, and consequently reduce the rolling noise, and at the same time would follow the safety requirements of railway operation. Field measurements, discussed in detail by Stefan Buehler in a companion presentation, in parallel with laboratory studies has distinguished that the interaction of thermo-elastic and vibrational instabilities is the main reason for corrugation generation. Computer simulations describing simultaneously thermodynamical, structural, and acoustic processes of the braking operation have proved to be unpractical for parametric studies and, instead, several simplified models are used. These models have shown that the main parameters affecting roughness growth are Young’s modulus and coefficient of thermal expansion of the block material and damping of the system.
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