Acoutic Specification of Composite Brake-Blocks for Railway vehicles

Invited paper

Fabien Letourneaux

SYSTRA - Innovation Directorate

Wednesday 3 june, 2015, 16:20 - 16:40

0.1 London (90)

The reduction of the rolling noise produced by freight wagons is one of the major challenges of the railway sector to develop the freight traffic. In that context, the development of new types of brake blocks (made of composite material) which tend to smooth the wheel tread and then to drastically reduce the rolling noise excitation have been developed. This paper presents an acoustic acceptance procedure which is to be included within the general approval procedure of these composite brake blocks issued by UIC (UIC leaflet 541-4) currently under revision. The acoustic acceptance procedure comprises 3 steps: 1. It first relies on the measurement of wheel acoustic roughnesses which are representative of the brake block to be assessed. 2. These wheel acoustic roughnesses are then used to derive a Single Index which aims at comparing the wheel roughness of the new brake blocks to a reference wheel roughness. 3. Last, the compliance of the new brake block is examined, based on the sign of this Single Index The originality of the procedure is that it only requires the measurement of wheel roughness and make use of a virtual TSI compliant pass-by test to derive a relevant acceptance criterion. Input data (wheel and rail roughness, pass-by noise) coming from a TSI compliant reference test case measured within the frame of the NICOBB project are used to carry out the calculation step. It results in a very simple procedure easy to handle by non-expert people but nevertheless rather robust and accurate to sort out the noisy and quiet brake blocks. In the full paper this acoustic acceptance procedure will be deeply detailed. Example of applications on different existing LL and K blocks will be supplied and will demonstrate the effectiveness of the method.

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