Finite Element Analysis of an Infinite Beam on a Viscoelastic Foundation Subjected to a Moving Vehicle

The objective of this paper is to develop a finite element modeling procedure that is accurate for tackling vehicle–track interaction problems. This procedure enables us to compute the transient response of the vehicle when it accelerates over the track from rest and to investigate the applicability of using the vehicle response for identifying the foundation stiffness variation of railway tracks. To this end, a left half-infinite element, a general element subjected to a moving vehicle, other general elements under no vehicle, and a right half-infinite element were assembled to simulate an infinite beam on a viscoelastic foundation subjected to a moving vehicle. The system governing equations were solved by the Newmark average acceleration method to obtain the responses of rail and vehicle. First, a proper model discretization was investigated by comparing finite element results with available analytical solutions to constantly moving load, mass, or vehicle problems. Next, the dynamic response of the vehicle was explored when the vehicle accelerated from rest along the track. It was found that the initial response of the vehicle was influenced by boundary conditions in the model where the vehicle started to accelerate. Finally, the dynamic responses of the vehicle passing a healthy track and damaged tracks where foundation stiffness loss occurs were simulated. The results showed that the changes in the acceleration response of the unsprung mass of the vehicle due to the foundation stiffness loss can be used as an effective indicator for detecting the damage location, level and extent.