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Geometry & Material Performance
Posted by Bradley Rothenberg 01-27-15
Water droplets slide off the surface when it is gently tilted - and bounce off when they are dropped onto it

Water droplets slide off the surface when it is gently tilted – and bounce off when they are dropped onto it

In a recent issue of the Journal of Applied Physics, A. Y. Vorobyev & Chunlei Guo show how material performance is a result of geometry in making a metal surface hydrophobic by etching nano-meter sized grooves into it. In addition to the surface being hydrophobic, these grooves also trap light, such that the metal now appears to be a very matte black(similar to Epner’s Laser Black coating). In their introduction, they reference a lotus leaf & butterfly wing, which both use micro-grooves to effect material properties & optical properties in the case of the butterfly wing. In this study, the Authors use a laser cutter to etch grooves into metal, a subtractive process. 

The blackened metals could be useful for making non-rusting devices, or collecting rainwater efficiently

The blackened metals could be useful for making non-rusting devices, or collecting rainwater efficiently

Complex structures are superimposed on the tiny grooves - seen here with an electron micrsocope

Complex structures are superimposed on the tiny grooves – seen here with an electron micrsocope

 

While this is a really good example of how geometry effects material performance, the authors have developed what is essentially a surface treatment. Additive methods, like 3D printing, though not yet able to make large objects on a namometer scale, allow material & structure to be completely variable. Variations in geometry can effect a material properties such as poisson ratio, compressive strength, ductility, yield strength, & others (think a strong steel X-lattice vs. steel wool, same material, different geometry). The future of manufacturing is in customization. Not just making things different, but being able to customize materiality specific to use. It is in additive methods, that can give us the ability to build up customized structures so material performance can be highly specific to use throughout a product. This is a major step beyond just changing surface properties. I think we will soon think picking out materials for a design is old fashioned.

you can find Vorobyev & Guo’s full paper here.

Recent Flexible 3D printed Prototypes in TPU

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