IaaC Blog

In this experiment we tried to build a physical model of a free form surface, using the technique of the geodesic curves of the surface.

The general definition of the geodesic curves is: “the shortes path between points on a surface” but an other definition, describes them on a more efficient way : “being γ(s) a geodesic on a surface X, and A a point on γ(s), the curvature of γ(s) in A is the minimum possible curvature among all curves passing through A and having the same tangent line of γ(s) in A”(Hilbert/Cohn-Vossen).

With few words, this means that in every point of the geodesic curve, the normal vector of the surface on that point is perpendicular also with the curve. Fact that simplifies a lot the joints, wich result all the same and very simple.

We started from choosing the type of surface to use and we decided to try a complex surface wich would include multiple curvatures.

This would permit us to verify the potential of this technique on surfaces that present positive and negative curvature.

With the help of Grasshopper plugin for Rhino we created a definition that made possible testing different situations and see the result of the geodesic curves generated immediatelly.

Trimmed Surface

Parallel points geodesic curves 1

Parallel points geodesic curves 2

Diagonal points geodesic curves 1

Diagonal points geodesic curves 2

Connecting Hole1 with Points

Connecting Hole2 with Points

Connecting Hole1 & Hole2

Intersecting Geodesic Curves

Extracting Geodesic Curves

Naming and organizing the different Geodesics

Rendering

Laser cut File

Assembly phase

Finished model

Carrying on from our previous experiments on Rigid Origami,  2 groups of us have decided to combine forces in making a real scale furniture prototype in order to further experiment on the same technique. Thru this exercise we aimed to be particular in the strategies in the appropiate uses of folding angles in the terms of the object’s functions, the materiality as well as the fabrication techinique.

The image above shows our final cutting files of a recliner chair that we have fabricated. Lines are to be laser engraved at both sides of the polycarbonate sheet (Blue and Red). We have also introduced, through our working process, that by punching holes at the intersections of folding lines would faciliate easier folding.

In the second phase of our experiment on the gridshell rectangular structures, we experimented on construction a flat 2d gridshell which we later on applied on a 3d physical model surface. In order to do that, we milled the below shown surface [in yellow]. We printed the 2d grid on a plan projection of the 3d surface by extracting the UV curves of the 3d surface [shown in grey].

In order to see the digital result of the gridshell, we projected the 2d gridshell on the 3d surface, same way we did with the physical model. 

Above are shown the two results that came out after giving thickness to the projected gridshell particles.

In the first case, the gridshell is created out of continuous stripes, while on the second case, the gridshell is made out of equal fragmented particles. The result in the second case is closer to the physical model result.

Physical Model Construction 

For the construction of the physical model, we needed a material which would be elastic, bendable and able to remain in the bended positions that we give it. Therefore we used teflon tubes and flat screws with screwnuts for the joints.

We created the flat gridshell on the printed UV plan of the 3d surface by loosly joining the teflon tubes with the screws. After having finished the 2d gridshell, we positioned it on the milled surface and fixed the screws to tighten the joints. 

Although the gridshell followed correctly the form of the 3d surface, the elasticity of the material was uncontrollable, so the gridshell could not stand alone after fixing the joints if we took out the surface.

As shown below, the sphere we created has different types of surfaces that fold, so that each color represents the group of surfaces that fold the same way.

We did three different physical model attempts. The first one, due to its materiality, broke before it was finished. The second attempt showed us that, although the vertical slices are actually one piece, the horizontal ones should be small connected pieces in stead of a bigger piece that folds. Finally, this third model (image below) is successful because it actually folds, but the necessity of a rail that will help the sphere be stiff is obvious.

Starting from a  dynamic origami structure that resembles a spring,

we developed several models in different sizes and number of sides and hight

until we got into the perfect shape that led us have a self standing structure that bounces up and down in order to make a craddle that can hold a baby

then become a stroller to help the baby give the very first steps safely and also be transformed into a stool once the baby grows.