Moving Finite Element Mesh Modelling for Induced Vibration Estimation of Moving Vehicles on Infinite Elastic Media

Resumo

This paper describes the development of one-dimensional beam elements and 3D finite elements with moving meshes for applications on induced vibration due to moving loads (or moving vehicles in contact with the rail or road) in a semi-infinite elastic homogeneous media, such as trains on railroad track or vehicles on roads. A conventional finite-element strategy requires very large meshes to allow the estimation of induced vibration of a moving vehicle, because a large portion of the mesh is required to model the distance travelled by the vehicle during simulation, in addition to a domain required at both sides of the model to separate the boundaries so that no undesired boundary effects are presented. An alternative approach is the use of moving elements to ensure that the loads do not approach the boundaries of the model, determining a significant reduction of the mesh. The moving mesh moves at the speed of the vehicle, maintaining the contact points location in the moving reference frame. This determines that a time-invariant model can be obtained for constant velocity analysis in the case of homogeneous media. One important aspect of the formulation is the asymmetric nature of stiffness and damping matrices of the finite element model due to the effects of velocity of the moving mesh. Random process modelling of roughness of the rails or road allows the assessment of its effect on induced vibration of moving vehicles on infinite media. Different vehicle models can be connected the moving mesh model, including different number of wheel axes by defining nodes of the mesh bellow each wheel, making the formulation very practical. Some application examples of the modelling technique are presented and limitations of the technique are mentioned.