How is it possible to avoid singularities on membrane surfaces due to form-finding?

Answer

Singular reactions are induced by inappropriate form-finding data on the membrane edges and an unfavorable FE mesh.

  1. If there is a cable with unfavorable form-finding settings (too great sag or insufficient force) resting on a membrane edge, the membrane surface is unusual in the form-finding process, and thus results in a non-optimally arranged FE mesh with the corresponding singular force reactions.

    Figure 01 - Unfavorable Setting of Form-Finding

    In this case, it is necessary to adjust the form-finding settings of the membrane and the boundary element to each other.

  2. The form-finding process starts with the initial FE mesh arrangement. If this arrangement is already unfavorable and does not correspond to the required shape parameters, the force corresponding to the shape found is also negatively affected.

    Figure 02 - Poor Mesh Arrangement

    In this case, it is necessary to adjust the basic geometry so that the initial mesh corresponds to all shape parameters.
The graphical display of the mesh quality before and after the form-finding can be activated in Display Navigator.

Mesh Quality

Keywords

Singularity Form-finding Mesh quality

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RFEM Main Program
RFEM 5.xx

Main Program

Structural engineering software for finite element analysis (FEA) of planar and spatial structural systems consisting of plates, walls, shells, members (beams), solids and contact elements

Price of First License
3,540.00 USD
RFEM Tensile Membrane Structures
RF-FORM-FINDING 5.xx

Add-on Module

Form-finding of tensile membrane and cable structures

Price of First License
1,750.00 USD