Issue 33

R. Sepe et alii, Frattura ed Integrità Strutturale, 33 (2015) 451-462; DOI: 10.3221/IGF-ESIS.33.50 456 FEM model To obtain the best balanced accuracy and efficiency in numerical simulations, standard convergence tests are applied. By using different mesh refinement levels, stresses in the critical regions are computed and an acceptable mesh refinement level is determined. The final container FE model is composed of 428,622 SHELL63 and 6,928 SOLID45 (ANSYS code), for a total of 435,550 elements and 449,556 nodes. Plates, sheets, pipes and the cross members which support them, are discretized with SHELL63 elements (four-node with six degrees of freedom at each node). The joint plates are discretized uniformly with hexahedral elements SOLID45 (eight-node with three translational degrees of freedom at each node). In addition, 160,188 rigid connection elements are used to represent fasteners in freight car FE model. Fig. 6 and 7 show the roof module mesh made of the aforesaid shell and solid elements. Figure 6 : Roof module mesh. Figure 7 : Roof module mesh (detailed view). Loading and boundary conditions To obtain static structural behaviour of the roof structure, EN 12663, UIC CODE OR 577 and ERRI B12/RP17 standards are used. Railway vehicles are subjected to different loading scenarios in these standards such as symmetrical compression force and tensile force. According to these standards, loading and boundary conditions are adapted to FE simulations. In Tab. 4 and 5 are shown static and fatigue loading cases used in FE simulation.