A wheel-rail contact formulation for analyzing the train-structure nonlinear interaction that takes into account the wheel and rail geometry is proposed. Most of the existing methods treat the contact forces as external forces, whereas the present formulation uses a finite element to model the behavior in the contact interface, based on Hertz's theory and Kalker's laws. The equations of motion are complemented with constraint equations that relate the displacements of the vehicle and structure, being the complete system solved directly using an optimized algorithm. The formulation is validated with experimental data from a test performed on a rolling stock plant.

A new method for the dynamic analysis of the vertical vehicle-structure interaction is presented. The vehicle and structure systems can be discretized with various types of finite elements and may have any degree of complexity. The equations of both systems are complemented with additional compatibility equations to ensure contact between the vehicles and the structure. The equations of motion and the compatibility equations form a single system that is solved directly, thus avoiding the iterative procedure used by other authors to satisfy the compatibility between the vehicle and structure. For large structural systems the proposed method is usually more efficient than those that frequently update and factorize the system matrix. Some numerical examples have shown that the proposed formulation is accurate and efficient.

This article presents an accurate, efficient and stable algorithm to analyze the nonlinear vertical vehicle-structure interaction. The governing equilibrium equations of the vehicle and structure are complemented with additional constraint equations that relate the displacements of the vehicle with the corresponding displacements of the structure. These equations form a single system, with displacements and contact forces as unknowns, that is solved using an optimized block factorization algorithm. Due to the nonlinear nature of contact, an incremental formulation based on the Newton method is adopted. The vehicles, track and structure are modeled using finite elements to take into account all the significant deformations. The numerical example presented clearly demonstrates the accuracy and computational efficiency of the proposed method.

With rapid advances in sensor and condition monitoring technologies, railways infrastructure managers are turning their attention towards the promises that digital information and big data will help them understand and manage their assets more efficiently. In addition to existing track geometry records, it is evident that track stiffness is a key physical quantity to help assess track quality and its long-term deterioration. The present paper analyses the role of the track stiffness and its spatial variability through a set of computational experiments, varying other vehicle and track physical quantities such as vehicle unsprung mass, speed and track vertical irregularities. The support stiffness conditions are obtained using a sample procedure from an Autoregressive Integrated Moving Average (ARIMA) model to generate representative larger set of data from previously on-site measured data. A set of computational experiments is carefully designed, varying different physical variables, and a vehicle-track interaction model is used to estimate track geometry deterioration rates. A series of log-linear regression models are then used to analyse the impact of the tested physical variables on the track deterioration. The main findings suggest that the spatial variability of track stiffness contributes significantly to the track deterioration rates, and thus it should be used in the future to better target design and maintenance of railway track. Finally, a comparative study of some settlement models available in literature shows that they are very dependent on the test conditions under which they have been derived.