Hanging Chain Tool

Hanging Model of Colonia Güell, Gaudi, source: http://www.rolfdieternill.de/pictures/tragwerkslehre082_Page_3.jpg

 This “Simulation Design Tool” is inspired by Gaudi’s work. It turns neshes into so called Particle Spring Systems that act similar to physical hanging chain models.
The resulting “funicular shapes” represent structures performing well as tension systems – or, when inverted – as pressure structures.

The most simple system is a single haning chain as shown in the following video. The segmented line sinks and approximates a catenary shape.

To start a simulation, a B-net is drawn. Using the subdivision tools in the context menu the shape is subdivided to create panels.

Attaching a PhysicsSpringSystem to this B-net, turns it into a Particle Spring System. The vertices of the Net become particles and the edges connecting them turn into elastic springs. When starting the simulation, the system relaxes and starts moving. Changing the gravity moves the particles up or down.

Using the sliders on the right, additional constraints can be applied to the system. They act as additional forces on each panel, trying to planarize it or qualizing its edges’ or diagonals’ length. The system autommatically balances all applied forces.

When re-editing the underlying B-net, the simulation adopts. Changes in edges’ length are translated into changes of spring restlengths. Fixpoints will move along automatically.

Attaching a PhysicsMeshExtrusion to the simulation B-net creates a thickened shell. The thickness of the shell is informed by the spring forces in the system. The higher the imbedded forces, the thicker the shell. This is a relative assignment and the minimum and maximum thickness are controled by sliders.

The shape can be modified locally by using one of the specialist tools. They allow control over local spring forces (relaxing or tightening) and over local vertex weight.