Creating your own programs using textual programming requires in-depth knowledge and a great capacity for abstraction. Understandably, only very few engineering offices face up to this hurdle. For this reason, there are additional software solutions that provide the user with a visual development environment.
In this environment, selected elements of the programming language are available in the form of graphic building blocks. The user must place them in a logical sequence so that their self-created tool can solve the task. The Rhinoceros software in connection with the implemented visual programming environment Grasshopper offers exactly this functionality. Some possibilities as well as the interaction with RFEM will be presented in more detail below.
Rhino and Grasshopper
Grasshopper is mainly used for the creation of generative algorithms. This allows especially complex geometries to be created much more easily than in the traditional way (manual modeling). The current stand of the algorithm is displayed via the Rhino graphic window. Any errors are thus directly visible.
By integrating parameters, the model can be modified arbitrarily, so that several variants for later analysis can be created in just a few steps.
However, Rhino does not only serve as a viewer. Through the multitude of import formats, existing geometries can be imported and referenced in Grasshopper. Adjustments in the geometry are thus directly taken into account.
Interaction between Grasshopper and Dlubal
Grasshopper can be extended with a multitude of plug-ins. These add-on modules range from support in modeling to the analysis of the structure to the export of data to third-party software. These can thus interactively integrate into the Grasshopper world. There are also plug-ins available for controlling Dlubal programs. These can either be downloaded here or are automatically activated during the installation of RFEM and RSTAB:
The latter refers to the Dlubal proprietary plug-in. Using this, structural-specific information can be attached to lines and surfaces in Grasshopper and exported to RFEM and RSTAB. The plug-in in the current development stand is suitable for users who want to gain initial experience in the interaction with Grasshopper – especially since, despite using COM technology, it can be used without the corresponding license.
Another Grasshopper add-on was developed by Diego Apellániz in collaboration with Bollinger+Grohmann. The "Parametric FEM Toolbox" enables bidirectional data exchange between RFEM and Grasshopper. This allows complete models including loads to be exported to RFEM and calculated. The results can subsequently be imported into Grasshopper.
Similarly, RFEM models can be partially or completely imported into Grasshopper. In the following graphic, a member structure from RFEM is imported into Grasshopper and subsequently rendered in Rhino.
The import can also be used for the parameterization of RFEM structures. For this purpose, the components have a modify function. Via a downstream export component, an existing RFEM model can be modified by changing the Grasshopper parameters. If these possibilities are additionally combined with a genetic solver (Galapagos), complex optimizations can be automated. The following image shows a cut-out from an algorithm that automatically modifies the height and the cross-sections of the truss girder with the objective of weight optimization – while simultaneously complying with the required designs.
For more information about this plug-in, it is recommended to take a look at the associated example files or at the webinar recording published on YouTube:
Conclusion
With Grasshopper, you can create your own algorithms tailored specifically to the task at hand by placing and combining building blocks (components). Programming knowledge, although certainly advantageous, is not necessary. The strengths lie in model generation, but extend to structural optimization in connection with the design. A multitude of additional plug-ins facilitates and expands the possibilities. Dlubal Software has therefore set itself the objective of extending and optimizing its own plug-in. For the current program versions, users have at their disposal in particular the "Parametric FEM Toolbox", a powerful add-on.