Poly-Pocket is a sticky spiral staircase of tensioned spring-capsules. The Individual components are held together using only tension members and friction enhanced by the “stickyness” of soft pvc plastic. The sticky pvc is laid over stiff polypropylene, which uses tension forces to hold the surfaces in active bending.

The video above shows the assembly process of the final model from our weekend workshop. The video below shows the process of computer-aided structural analysis, via the gh add-on Karamba. The Galapagos Solver of gh was used to find the lowest structural utilization among the possible combinations of geometric variables. The variables are applied to a single component, which associatively updates the global geometry.

[formula used for testing: (utilization percent range)*(square of utilization percent maximum)]

As stated above, the stair’s design follows principals from studies in the translation of soft materials to structural materials. These studies produced components which can oppose compressive forces, and implied a set of rules related to geometry, scale, and material properties. In the first case (pictured below), we see the technique of active bending used to enhance the 3-dimensional rigidity of an other wise flexible 2-d PVC sheet.

The second component (below) exhibits a different type of material manipulation based on the properties of sheet rubber, and seeking geometries which will compliment these properties. By understanding the relationship between tension-enhanced ‘vaulted’ geometries and the resultant spring-back effect observed in plastics, we can draw conclusions about the aggregation of both components.

The use of tension in connecting these components vertically takes advantage of both the spring-back effect and the surface ‘stickiness’ of plastic materials to create frictional resistance to shear forces without the use of direct connections between the surfaces of adjacent plastics.

The two prototypes comes out of the fascination of bending materials.  Looking at the properties of for example plywood, it is possible to fold and bend a flat plane  into a 3-dimensional structure.  We have made several experiment with different bending patterns in paper, cardboard and plastic to try to understand the different opportunities and limits within the bending.

Protype 01

Protype 02

PROTOTYPE 01: FROM A PLANE TO A STRUCTURE
The construction comes out of one flat plane. When the plane is cut and corners of each cut is joined, the plane converts into an arch.

PROTOTYPE 01: BUILDING THE STRUCTURE
By having a bending in two different directions, gives a stiffness to structure. The bending in two directions is achieved by cutting crosses in the material and folding the edges in two different directions (see drawing below).

PROTOTYPE 01: FORCES IN THE STRUCTURE
The construction is made out of minor folding arches in two directions. In combination they create one big arch.  The whole structure works as one arch. The whole arch, as a concept, works with tension in the outer core and compression in the inside core of the arch. The arch is made out of several arches, which is working in two directions. By bending the material, the forces are transferred throughout the construction – from one arch to the other.

USING INFLATION TO CHANGE THE STRUCTURAL BEHAVIOR

The next evoultion of the structure is how the shape of the construction could change by inflation air into the structure. We made different experiment with different materials and constructions, which all included folding elements. The final test proved that we were able with a ballon to convert a flat structure into a vertical structure by inflating a ballon inside the bottom of the construction.

VIDEO OF FABRICATION AND EXPERIMENTS