Analyse der Constraints dans les roues de chemin de fer par methode ultrasonore - Contribution an an concept de securite

In order to evaluate the stress states in rims of monoblock railroad wheels, automated ultrasonic set-ups (UER) have built. 19 of these set-ups are already underindustrial use; several thousands of wheels have been tested. The set-up takes advantage of an electromagentic ultrasonic transducer which generates the ultrasound in the material so that non coupling is needed. This transducer together with a set-up for the automated data acquisition and evaluation enables the determination of the principal stress difference along a radial trace with a spatial sampling distance of 1mm. The profile of the difference of the stresses along the circumferential (tan) and radial (rad) direction of the wheel along the height of the rim gives strong evidences concerning the stress state.