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News | July 1, 2009 | By:


It is hard to experiment with any new building material, especially when that material is outside the standard choices. Structural fabric is one of those materials. Structural fabrics (or membranes as they are called in Europe) have been around for decades, but due to their unique qualities that demand nonstandard construction methods, they remain relatively obscure. Add to this already intimidating situation the dependence of today’s architects, designers and students on CAD systems, and the task is daunting.

Traditionally, CAD systems or formfinding software have been overwhelmingly complex and have needed technical staff of their own. The trend in software design has been user friendliness, and as a result more designers and architects that formerly shied away from complex CAD systems are embracing programs such as Google SketchUp. These user-friendly programs are taking the mystery and the fear out of these computer tools and are allowing exploration in fields normally closed to novices.


Educated as a computer scientist, an architect and a structural engineer, Robert Wehdorn decided to take on this fear factor as it relates to membrane structures. “I feel that the most beautiful fabric structures are the result of a long design process. I also know that these structures are very hard to sketch by hand. One needs physical models as well as 3-D computer models to explore the design correctly.” Given that, in 2001 Wehdorn traveled to the Technische Universität of Berlin, Department for Geodesy and Geo-information Science, to discuss his ideas with professor Lothar Gründig of Technet fame who had authored the EASY formfinding software. His interaction with Gründig was the start of his Ph.D. studies which culminated in what later came to be known as Formfinder v1.0.

Wehdorn started with a simple goal for this software. “As a tool, this software must be as easy to use as a sheet of paper and a pencil in hand.”

In 2003, after finishing his Ph.D., he set to test his program in real situations on real projects. He traveled to England and worked on a number of projects for various firms while debugging his software system. He streamlined the software for architects and designers and honed the ease of use by employing a user-friendly interface and screen graphics. Finally in 2006, after three years of field testing and development, with the support of Technet GmbH and Lenzing Plastics GmbH, Wehdorn released the first version of the software under the brand name Formfinder.

Formfinder today

Although Formfinder uses an identical algorithm for calculation and form generation as the preceding formfinding and engineering software EASY, Formfinder is not as burdened and as complex of a program. It is a lean and to-the-point program tailored for use by architects, designers and students. It is a tool with capabilities and characteristics that make it useful to handle expressions of force equilibriums without entering in the force-density-algorithms. In other words, you do not need to be a structural engineer to use the software. Architects, designers and students barely use static analysis concerning forces and loads to generate their work; therefore Formfinder employs a form-based interface and intuitive means for manipulation. To alter the shape of the original form one simply moves selected points to desired locations. This is a visible interaction with the model on the screen, in real time.

What makes Formfinder more useful and user-friendly is the inclusion of various databases through an integrated Internet browser. An extensive index of built membrane projects allows the user to browse for inspiration or precedent study. The project presentations in the software database include high-res pictures as well as construction details and all essential project information.

This project directory is constantly updated with the wealth of material from Formfinder users all over the world.

Formfinder Light is available for free download through its Web site, but if you want to upgrade to Formfinder Professional you need to pay the price. The major difference between the two versions is the file transferability. In other words, Formfinder has the ability to import and export to other CAD programs including EASY. Formfinder uses dxf file format for imports and exports. Formfinder’s files are compatible and could be open directly in EASY, which allows for a seamless interaction between designers and engineers.

Using Formfinder

After a file setup and only a few clicks, the user defines the boundaries of the basic form as a closed polygon on a viewport. The form can be modified by altering the edges, tweaking the sag, the elevation of the related nodes or the number of the intermediate points. Modification of the form is done by means of moving the points or entering numeric values in related property dialogue boxes. The program generates a 3-D mesh within the defined boundaries. This mesh is also very flexible. One can manipulate the spacing and the refinement of the mesh as well as the weave direction and the stress level. Split Curve command allows you to introduce a new anchoring point in a highlighted curve without having to start a whole new mesh. A helpful resource accessible from the screen is the list of many anticlastic advanced membrane forms that can be used directly by dragging and dropping or after manipulation.

The navigation through different tools and dialogue boxes is done with ease and the graphics are transparent. Toggling between floor plan and perspective view is intuitive.

The program is very stable so long as one is not trying to work with more than one horizontal layer on top of another or using too many meshes that are connected to each other in a complex way or are penetrating each other.

Formfinder is an appropriate tool for architects, designers and students, novice or advanced, looking to explore or gain experience in the design of membrane structures. Here one can see firsthand how modification of various parameters influences the formfinding process and the ultimate shape.

Formfinder tomorrow

Scheduled for release in mid-2009, Formfinder v2.0 will include synclastic forms like air-supported structures for exploration and manipulation. There is a new powerful and simple sun study component which would help with greatly needed solar studies of the models. A helpful improvement is that the system will recommend adequately dimensioned profiles for masts and cables. In addition to the inclusion of historic membrane projects from around the world, an international network of universities, engineers, architects, designers and students promises to make Formfinder one of the most widely used formfinding programs for the design and development of membrane structures around the world.

Ali Heshmati, AIA, principal of L.E.A.D. Inc. of Husnes, Norway and Minneapolis, Minn., U.S.A., is a contributing editor to Fabric Architecture. Lars Meeß-Olsohn is a lighting architect based in Germany.

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