In late 2015, a group of researchers with a common interest in calibrating the output from Kangaroo2 with regard to structural behaviour was formed. This research has since then been shared with the computational design community through two workshops in 2016 under the title “Calibrated and Interactive Modelling of Form-Active Hybrid Structures”.
Form-active hybrid structures are characterised by a system, which combines elements of low stiffness into a stronger whole. This is achieved by using elements/materials for what they are best suited at thus creating very light-weight and structurally transparent structures. Since the shape directly depends of the force flow, it is necessary to include a form-finding step to generate the actual geometry. The flexibility of these structures means that they undergo large deformations when subjected to external loads, which implies that it becomes crucial to account for geometric non-linearity during the analysis. In addition to this, the form-finding and analysis has a strong correlation and therefore need to be performed within the same software to avoid losing important information between the two stages. As a result, the existing design and analysis workflow is very cumbersome.
The research presented at the workshops offers the ability to analyse form-active hybrid structures in a much more interactive environment that encourages an informed exploration in the early design stage. It is centred around the physics constraint solver “Kangaroo2” developed by Daniel Piker, which is an ideal platform due to its improved stability with regard to handling high stiffness values and its solving strategy, which inherently deals with non-linear behaviour. An extension called “K2Engineering” has been developed, which calibrates the output to accurate structural behaviour. Both K2 and K2Engineering have been combined into one modelling pipeline developed by Anders Holden Delauran, which enables a smooth workflow between the modelling of the coarse geometry, form-finding, analysis and fabrication (using an assembly graph).
The output from modelling pipeline has in addition to comparisons with analytical solutions and other finite element packages been validated through physical testing by means of a projection board, which enables a live interaction between the digital and physical. The setup was developed by Gregory Quinn and it consists of a white board with pre-drilled holes in a grid arrangement, where structural elements can be attached to whilst a projector overlays the digital simulation.
Smart Geometry (SG) and Advances in Architectural Geometry (AAG)
Both workshops were structured into a number of presentations that explained the underlying theory/software implementation and were supported by live demos. In-between these presentations, the participants were encouraged to explore the modelling pipeline. Small and large scale physical models were also built at the SG workshop, which included a 5 m tall tower made from GFRP rods and plastic strings with a total weight of approximately 5 kg.