Periodic modelling solutions for railway track structures

Understanding dynamic track stiffness is crucial for addressing railway dynamics issues such as ground-borne noise, track dynamics, and rolling noise. This parameter is often analysed through its inverse, receptance, which is the ratio of the structure’s deformations to a unit force. Studies on receptance offers valuable information for assessing the track’s mechanical behaviour, developing control strategies, and optimising the design of new systems.
Despite its importance, most comprehensive studies on railway track components typically employ analytical approaches. While these methods simplify modelling, they often lack the complexity needed to accurately capture the structure’s response and cannot fully replicate 3D wave propagation effects. Although numerical approaches provides more flexibility, they are computationally intensive. Alternatively, periodic strategies, offer a promising solution by reducing computational effort while accurately modelling the structure’s behaviour. Thus, this research employs a periodic strategy to develop a computational tool for calculating the dynamic performance of ballasted railway track structures.
First, several modelling strategies for the track’s behaviour study are review and compared based on their ability to simulate different railway engineering problems. This comparison allowed for the selection of a periodic formulation, which can be coupled with perfectly matched layers to replicate wave propagation effects. Using this periodic approach, the model is refined for receptance applications by considering the effects of two common modelling assumptions: beam-on-elastic foundation and symmetry. The findings indicate that neglecting wave propagation in subgrade-earthwork layers results in errors of approximately 80% - 300% at frequencies below 200 Hz, and around 30% between 200 - 440 Hz. Additionally, assuming symmetry along the track centreline overlooks certain track bending modes, leading to errors of about 20% up to 1000 Hz. This new model facilitates a parametric study on ballasted track components, providing insights into their typical frequency ranges and enabling the formulation of new empirical equations.