Mechanical Modelling of Static Hysteresis in Under Ballast Mats Using a Novel Rheological Approach

The objective of this work is to propose a novel mechanical model of under ballast mats (UBMs) that can replicate the phenomenon of energy dissipation under static loads. UBMs installed in the ballasted track structure can reduce the levels of vibration emitted by the railway system to the surrounding environment, affecting both people and the natural and built environment. A particular feature of UBM isolators is energy dissipation, which is manifested in load-deflection graphs in the form of so-called hysteresis loops. Notably, the hysteresis loop occurs not only under dynamic loads but also in the case of static loading. The constitutive equations of the UBM model will be formulated as a nonlinear set of ordinary differential equations. The parameters of the constitutive relations will be selected based on an optimization procedure to match the results of integrating the differential equations describing the theoretical model to the results of experimental tests of UBMs in the static range, in accordance with European standard EN 17282:2020-10.