A DCAMM seminar will be presented by
Professor José L. Escalona
Dept. of Mechanical and Manufacturing Engineering
University of Seville, Spain
Abstract:
Considering track flexibility in railroad vehicle simulations can lead to improved results. In modeling a railroad vehicle as a multibody system, track flexibility can be incorporated by using the floating frame of reference formulation (FFRF), which describes rail deformations in terms of shape functions defined in the track body frame of reference. However, the FFRF method is subject to two serious shortcomings, namely: it uses unreal track boundary conditions to calculate shape functions and requires a large number of functions to describe deformation. These shortcomings can be circumvented by defining shape functions in the track coordinate system (TCS). The procedure presented makes use of a fully Arbitrary Lagrangian-Eulerian (ALE) description of a long solid whose mechanical properties are captured using a dynamics preserving selection of modes. In this study, the mesh moves through the solid at a prescribed velocity. The ALE frame of reference used to describe the flexible body dynamics can also be used as a trajectory frame of reference for a set of bodies that interact with the long flexible body.
This talk show a method combining a trajectory frame of reference, an ALE description of a long solid, and structure deformation based on assumed modes is optimum for the study of moving multibody systems over linear complex structures. The selection of the track modes of deformation is carried out from a finite element model by using Krylov subspaces as the model-order reduction technique. The modes of deformation move along the track fixed to the TCS using the moving modes method (MMM), avoiding the issue concerning the spatial convergence of the load (wheels) on the track and preserving their frequency contents whose accuracy can be chosen beforehand. Numerical results show the influence of track flexibility on the steady motion, stability and the ride on geometrically irregular tracks of railroad vehicles.
Danish pastry, coffee and tea will be served 15 minutes before the seminar starts.
All interested persons are invited