Optimization of Lightweight, Fold Based StructuresCopyright: Chair of Structures and Structural Design
Stress Oriented Foldings as an Optimized Lightweight System
Folded load bearing structures, such as geodesic domes or tunnel vaults have been built out of rhomboidal shaped elements of sheet metal or plastic paneling, since the early 1950's. Based on an elementary and symmetrical geometric form (such as a sphere or cylinder), such folded structures lead to a uniform tessellation and can be broken down into identical or group wise identical base elements. Since the arrival of CAD programs, it has become possible to tessellate non-symmetrical, free form surfaces, and transform them into single or multilayer folded structures consisting of a various of unique base elements. In view of the simplicity of their production and assembly, the members of a folded structure that are planar, are in advantage over those of a shell that are continuously curved.
The edges and elements of a folded load bearing structure can be aligned in a uniform mesh-like arrangement or, load bearing adapted and optimized, in the directions of the stress trajectories under an assumed main load. Folding is an appropriate form structuring principle for light weight, load bearing systems, where planar or curved load bearing structures are broken down into individual planar elements.The formulation of folded load bearing structures on the basis of free forms as well as in respect to the load bearing optimization, leads to irregular tessellation and many unique folds. This brings the question how to develop methods and algorithms where the geometric diversity of the building components in a folded load bearing system based on a free form, optimized for load bearing, or both, is reduced. In such a case, deviations between the desired final form and the optimized fold geometry must be tolerated.
The goal is to develop algorithms, which translate given, for example by FEM determined, field vectors into trajectories and tessellations, and transform them under constructive considerations (such as effective depth and folding frequency) into folded bearing structures. Furthermore, algorithms are to be developed, which, with respect towards the modification of the initial form and folding pattern, produce folded bearing structures with a reduced number of geometrically unique folding elements.
Within the framework of parametrical studies, the affect of the folding optimization process is to be evaluated for selected planar and curved surface geometries by comparing the required building structure mass for a dictated load bearing configuration. The results should shed light on the effectiveness of a light weight building system, based on the load bearing optimized folding principle and reduced single element diversification. Such a system is, because of its simple structure and elements equally predestined for application in Architecture, Civil and Mechanical Engineering.
The project is funded by the "Deutsche Forschungsgemeinschaft DFG".