Finite Element Method in Structural Mechanics - Practical Considerations

Practical Considerations

From the application point of view, it is important to model the system such that:

• Symmetry or anti-symmetry conditions are exploited in order to reduce the size of the domain.
• Displacement compatibility, including any required discontinuity, is ensured at the nodes, and preferably, along the element edges as well, particularly when adjacent elements are of different types, material or thickness. Compatibility of displacements of many nodes can usually be imposed via constraint relations—When such a feature is not available in the software package, a physical model that imposes the constraints may be used instead.
• Elements' behaviours capture the dominant actions of the actual system, both locally and globally.
• The element mesh is sufficiently fine in order to have acceptable accuracy. To assess accuracy, the mesh is refined until the important results shows little change. For higher accuracy, the aspect ratio of the elements should be as close to unity as possible, and smaller elements are used over the parts of higher stress gradient.
• Proper support constraints are imposed with special attention paid to nodes on symmetry axes.

Large scale commercial software packages often provide facilities for generating the mesh, graphical display of input and output, which greatly facilitate the verification of both input data and interpretation of the results.