A new approach for the evaluation and the improvement of the metrological characteristics of an instrumented wheelset for the measure of wheel–rail contact forces

The actual European regulations for the acceptance of railway vehicles prescribe the measurement of not only accelerations but also contact forces exchanged at wheel–rail interface, in order to assess the level of running safety, track loading and vibration behaviour. It is important to point out that the standards do not prescribe any specific method to measure forces, or define the measurement of forces. The aim of this paper is to investigate the metrological properties of a dynamometric wheelset in order to determine the associated measurement uncertainty and to verify its readiness in the range of frequencies where the force analysis must be performed. With reference to a specific instrumented wheelset, a method for increasing the accuracy of the measure when critical running conditions (i.e. large values of the derailment coefficient Y/Q) are detected is proposed. The proposed method can be applied to any instrumented wheelset, but it is particularly effective on non-conventional wheelsets, where only few measurements are available and the classical methods cause large estimation errors.