Mesh parameters #
A line mesh can be generated by selecting the corresponding elements, after going to the ‘Mesh’ tab. The following criteria can be set:
- Maximum deviation from arc: Chord height cannot exceed the value specified.
- Maximum element size: Length of the mesh lines cannot exceed the value specified.
- Division into N segments: Line elements are divided into N parts.
- By angle: Central angle of arced mesh segments cannot exceed the value specified.
The finite element of a beam contains 2 nodes, one at the beginning and one at the end. During the analysis, the displacement and stress results are first calculated for these two nodes. These elements are divided into at least 10 further individual sections with the aid of intermediate points. However, these points are not finite element nodes, but merely serve to record the result values on them. These values are calculated from the results at the end nodes and from the forces acting on the finite element. In this way, it is possible to create detailed stress and displacement diagrams that are defined at many points with relatively low computational effort.
For small displacements, it is therefore generally not necessary to mesh the beam elements, the result is quite detailed even without it. For large displacements, for buckling or vibration tests, it is necessary to mesh as the calculation methods are different from the one described above.
Below is a summary for the different cases:
- Meshing is not necessary:
- Linear analysis
- Decision should be based on the scale of the displacement:
- Material nonlinearity
- Geometric nonlinearity
- Meshing is always necessary:
- Buckling analysis
- Vibration analysis
Ribs are different from general beams as their shear deformation cannot be neglected. Therefore, the program uses a different type of finite element that can take this effect into account. This finite element consists of a total of three nodes, but has the disadvantage that it is not possible to write intermediate results on it as on a beam. The results are therefore only calculated at three points. In order to be able to calculate accurate results, these elements must be divided manually into several parts.
If a rib is placed within a domain or is connected to a domain with a line/line interface element, a line mesh will be automatically created for the rib when the domain is meshed. If a rib is defined without connection to a domain, the line mesh has to be manually generated.
Domain edges #
In addition, a line mesh can also be defined for lines within domains (including the domain’s edges) to affect the mesh size in the generation of the surface mesh.