Building hierarchical structures: an alternative approach

-- MicheleLanzetta? - 09 Aug 2007

Building up of hierarchical structures can be done in the transverse direction, like in traditional Rapid Prototyping or Layered Manufacturing.

A mold (or a positive) can be created stacking layers perpendicularly to the drawing plane, with the shape of an arbitrary hierarchical structure, like the one in figure.

The black lines represent the voids that will be filled by a good filling and deformable material (soft silicone). After the stack is complete, a functional part can be directly cast.

Different positive-negative sequences are possible options to allow better material compatibility, mold reuse etc.

Considering previous results, stalks should be tapered (not displayed in figure).

There is complete freedom on the actual lamella shape, packing and size ratio between hierarchy level.

The deposited thickness ratio determines the width of stalks. Continuous lamellae (perpendicularly to the drawing plane) can be obtained. They are only limited by the maximum layer thickness (I am thinking of using a photocurable masked polymer like SU-8 to make the mold layers).

Separated lamellae (perpendicularly to the drawing plane) can obtained instead by shifting the pattern for each deposited layer, as for the red dashed pattern in figure. The branched structures, whose section is displayed in figure, will all be attached to the same base.

Possible functional problem: the stalks of all the hierarchy levels will all have the same thickness (perpendicularly to the drawing plane). Possible solution: building each section using a composite pattern mask, composed of different parts for each hierarchy level. Each pattern mask, could be shifted at each layer deposition.