Modelling of elastomeric elements of railway components, able to represent stiffness and damping characteristics in a wide frequency range, is fundamental for simulating the train–track dynamic interaction, covering issues such as rail deflection as well as transmitted forces and higher frequency phenomena such as short pitch corrugation. In this paper, a modified non-linear Zener model is adopted to represent the dependences of stiffness and damping of the rail fastening, made of elastomeric material, of a reference Embedded Rail System (ERS) on the static preload and frequency of its deformation. In order to obtain a reliable model, a proper laboratory test set-up is built, considering sensitivity and frequency response issues. The equivalent stiffness and damping of the elastomeric element are experimentally characterised with force-controlled mono-harmonic tests at different frequencies and under various static preloads. The parameters of the non-linear Zener model are identified by the experimental equivalent stiffness and damping. The identified model correctly reproduces the frequency- and preload-dependent dynamic properties of the elastomeric material. The model is verified to be able to predict the dynamic behaviour of the elastomeric element through the comparison between the numerically simulated and the experimentally measured reaction force to a given deformation time history. Time domain simulations with the model of the reference ERS demonstrate that the modelled frequency- and preload-dependent stiffness and damping of the elastomeric material make a clear difference in the transient and steady-state response of the system when distant frequency contributions are involved.

Rail corrugation growth is a major issue for railway infrastructure owners and operators determining extra costs due to an increased maintenance. Generally, rail corrugation leads to increased wear and vibration levels that eventually lead to degradation and damage of both railway track and vehicle components Aim of this work is to study, both from an experimental and from a numerical point of view, rail corrugation observed on the low-rail of a sharp curve (radius equal to 110 m) of an underground line. The causes of the corrugation may be found in the interaction between the track and the vehicle which is equipped with resilient wheels.

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.

Different methods are available to provide an estimation of the force exchanged at wheel-rail interface. Focussing on on-board systems generally the instrumented wheelset is the most used. Strain gauge bridges are typically applied on the axle and/or the wheel web to infer wheel-rail interaction forces generating a deformation field on the wheelset. It can be proved that the estimation of the lateral and vertical components of the contact forces on a generic wheelset results in a problem where six unknowns should be defined taking into account that the position of the contact points (even if unique) on the wheel affects the deformations measured both on the axle and/or on the wheel itself. Thus, at least six independent quantities must be measured in order to obtain a correct estimation of the contact force components. Other approaches rely on the instrumentation of the primary suspension in order to estimate at least the vertical component of the contact force. A hybrid method, that is combining the typical instrumented wheelset with the measurement of the deflection of the primary suspension, can be used if, for different reason, it is not possible to obtain six independent measurements related to the deformation of the wheelset. In the paper this hybrid approach will be presented as a means to overcome some problems in the instrumentation of the wheelset. The effectiveness of the proposed solution will be proved both on static and dynamic tests performed on a dedicated test-rig used for the calibration of the instrumented wheelset but also considering in-line test .