Sector Project "BB - Wheel interaction" - WP1/Activity 1.2: "Numerical investigation of wheel dimensioning braking load cases: Constant power vs locked brake simulation"

“Brake Block-Wheel Interaction” is a sector project involving brake block manufacturers, entities in charge of the maintenance of wagons, railway undertakings, UIC staff, universities, wagon keepers, and wheel and brake block manufacturers.

Its goal is to define the appropriate conditions for managing brake block/wheel interaction, avoiding safety risks and restrictions in the use of tread-braked wheels, improving the reliability of the system, and improving and harmonising rules to prevent approaches based on individual experience.

The sector project is structured around three major work packages:

·  WP1 Analysis of the state-of- the-art, calculations, and tests specifications

·  WP2 Calculations, laboratory, and field tests

·  WP3 Summary of the results

WP1 is divided into four activities:

·  Activity 1.1 Influence of operational conditions on wheel design

·  Activity 1.2 Wheel design worst-case scenario assessment

·  Activity 1.3 Braking heterogeneity assessment

·  Activity 1.4 Brake block characteristics – impact on energy distribution

In the report written by the Expert Team in charge of WP1/Activity 1.2, specifications for numerical simulations and bench tests were provided that were potentially to be conducted as part of WP2. The present report details numerical simulations in line with one of those specifications, with the aim of finding the braking load case that constitutes the thermomechanically most severe load case for wheels, considering:

1) The wheel design load in EN 13979-1 [5] (wheel requirements)

2) The load case stemming from the TSI requirements when also considering a stop at the end of a descent (brake system requirements)

3) The load cases that result from the fixed brakes testing of brake blocks in UIC Leaflet 541-4 (brake block requirements)

For the third load case, brake power records for all of the brake block tests in the WP1 report of Activity 1.2 [3] were assessed. It can be noted that power variations stemming from the Wildenrath line tests were not investigated in the present report.