I’ve created a experimental method of generating composite materials with unique properties for 3D printing. This first example is called Macro Foam and you can download the data on thingiverse here: http://www.thingiverse.com/thing:27495
The idea of this material is that it will be very compressible because of the soft interconnections between the cells (shown in green). When the material deforms enough, the solid parts (shown in white) will collide and begin to resist further compression. By varying the density of the cells and the width of the connections, the material properties can be continuously controlled.
It’s no secret that 3D printing holds a lot of promise for improvements in materials and manufacturing. The most often stated advantages are that complexity is free, and unique shapes can be produced with no added cost. When applied to manufacturing, so far this has meant that a part can be made lighter-weight with less material, due to the 3D printing’s ability to easily form truss-like structures and hollows. Complex mechanisms can also be produced such as hinges and wheels, but so far the materials and precision are just not comparable to what we are used to in mass production.
What has not yet been addressed is composite materials. A few processes are capable of forming parts with multiple materials in very fine arrangements, but there are no examples of using the properties of the separate materials in a way that takes advantage of their spatial arrangement. Objet describes their material mixtures as composites, but these materials are homogenous (evenly distributed). In the current generation of printer, two resins and a support material can be applied in a single part. The machine uses dithering, just like a regular home inkjet printer. Objet is claiming that each possible proportional variation of the dithering pattern (4×4 voxels) is a unique material. Multiply that by the number of possible materials, and you get a very large number, so that your marketing materials can state you have 107 materials (and counting). The reality is that these materials behave in a homogenous way. That is, they behave no differently than if you had mixed the resins in the various proportions before putting them in the cartridge. The possibility that is being ignored is that of creating a true composite based on the neighboring relationship of the material elements.
To demonstrate this potential I’ve created an example of a composite material, generated using procedural 3d texture maps from an animation program. This example has not been tested, and would probably take some development to become useful, but the concept is fairly clear. Their are open spaces in the material, and the contacts between the touching materials are constrained and predictable. There is random variation in the finer structure, but overall the material will exhibit a regular behavior that can vary smoothly based on the density of the seed particles that generate the pattern. Simulations will eventually be used to drive the patterning of parts (and even architectural structures) made with 3D printing. This is an example of how the structures will be generated from the simulation results like strain, temperature, etc.