We provide hints and tips to help you get started with the RFEM program.
Dlubal RFEM 5 - Add-on Modules: RF-FORM-FINDING & RF-CUTTING-PATTERN
First Steps with RFEM
Add-on modules for form-finding of membrane and cable structures. The shape is determined by the equilibrium between the surface tension (prestress) and the natural or geometric boundary reactions.
- Simulation of isotropic and orthotropic membranes
- Considering the flexibility of the substructure
- NURBS transformation
- Generate additional NURBS points for load input
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Models to Download
Knowledge Base Articles
The RF‑FORM‑FINDING add‑on module can be activated in the ‘Edit Model - General Data’ window, ‘Options’ tab. By activating the module, a new RF‑FORM‑FINDING load case is created and an additional menu appears in the main program, allowing for the definition of prestress conditions for membrane and cable elements.
Product Features Articles
The form-finding function can be activated in the General Data dialog box, Options tab. Prestresses (or geometrical requirements for members) can be defined in the parameters for surfaces and members. The form‑finding process is performed by calculation of an RF‑FORM‑FINDING case.Steps of the working sequence:
- Creation of a model in RFEM (surfaces, beams, cables, supports, material definition, etc.)
- Setting of required prestress for membranes and force or length/sag for members (e.g. cable)
- Optional consideration of other loads for the form-finding process in special form‑finding load cases (self‑weight, pressure, steel node weight, etc.)
- Setting of loads and load combinations for further structural analyses
Frequently Asked Questions (FAQ)
- How is it possible to create the cutting pattern geometry for a decorative sticker on a biaxially curved membrane roof?
- How are the properties of the elasticity and shear modulus of a membrane fabric with the usual force/length syntax transformed into the general force/surface syntax to be entered in RFEM?
- I have already divided my membrane roof into individual surfaces. Can I quickly create a cutting pattern from these surfaces?
- How is an inflatable object simulated in RFEM?
- How can I define a material allowance at the edge of a cutting pattern?
- I have modeled a structure made of outer and inner cables as well as membranes, and get a message about instability or the error message "Jacobi matrix is not positive definite" in the RF‑FORM‑FINDING add-on module. What should I do?
- Why does the FE mesh of my conical membrane look like angular after the form-finding?
- How to model a cable net structure in using the RF-FORM-FINDING add-on module?
- Which Dlubal Software programs are required to calculate membrane and tensile structures?
- I would like to analyze cable and tensile structures. Is it possible to use RFEM or RSTAB for this?