Why does form-finding warp membrane surfaces into each other?

Answer

The form-finding warps the surfaces into each other because the defined prestress on the boundary line between two membranes does not coincide at the same angle, and thus the affected FE nodes are not in equilibrium with the boundary conditions. In this case, the FE nodes of the membrane surfaces move in the direction of the remaining resultants until the form-finding process finds a solution within the tolerance limit. Since it is usually possible to only achieve this solution with large displacement of FE nodes in space, the surfaces assigned to the FE nodes seem to "swim" into each other.

This behavior results in an unfavorable FE mesh arrangement in conjunction with a singular membrane force distribution. In this case, it is necessary to adjust the prestress in order to reach the equilibrium, or to set an element at the limit situation in order to transfer the forces due to the disequilibrium.


Keywords

Membrane Warp Prestress Equilibrium Singularity

Downloads

Contact us

Did you find your question?
If not, contact us via our free e-mail, chat, or forum support, or send us your question via the online form.

(267) 702-2815

info-us@dlubal.com

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