The axon diagram showed the major element of the whole structure system. Which the membrane applied on the top and the bottom layer which doesn‘t consider as a structure element (even it could hold the tension load). The frame hold the whole system by tension. 8 compression members arraied by circle, an elastic member in the center which creat the deformation of the openning. The section structure diagram showed the force applied in the system, which only tension and compression in the system, no bending moment exist. Then compression member‘s height is .6m which is close to the golden ratio 0.618 to the radius.
For the actuator, we decide use manual control the whole system, we will set up a hand knob to twist the frame. To maxiam the deformation of the structure, we try to figure out a way to slove the problem caused by the two tension cable when they met together. We propose to layer them in different level, so that they won‘t conflic each other.
The structure consists of two wheel-shaped frames. The outer frame has a C-shaped section detail and the inner wheel is located within the hole of that „C“. There is a lateral opening in the outer wheel that allows a small handle to come out from the inner frame. This handle acts like the actuator of all the system, since it makes the inner wheel rotate independently from the outer wheel. In the center of the whole set there is a rubber band. In between the double wheel frame and the rubber band, there is a group of poles and strings. The vertical poles are under compression stress, while the strings are under tension stress. All the poles are linked to the inner wheel, the outer wheel and the rubber band by a series of strings. This principle makes that, when the inner wheel rotates and the outer wheel stays still, all the poles relocate themselves and they make the rubber band expand, making the hole in the middle grow. Over the whole system, membranes can be placed to cover the space below the structure.