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Better designs through evolution.

Every so often, something comes along that makes you look twice. WithinLab, a London-based engineering firm, recently designed an engine block segment that that could be built with an EOS laser metal sintering system. But rather than mimic conventional engine components, WithinLab's "liquid lattice" looks more like an alien life form. That is appropriate, because the company didn't calculate the features of the liquid lattice-they evolved.

Within uses artificial intelligence to create biologically inspired designs. These consist of variable density surface skins supported by internal lattices with varying wail thicknesses and strengths. This makes it possible to control the flexibility, displacement, weight, and strength of different segments of the same part.


Instead of calculating these factors, Within's software evolved them. Just as evolution selects the fittest from a random assortment of genetic variations in nature, Within's Enhance software rapidly generates and tests multiple designs to find the one that best meets design goals, said Siavash Mahdavi, the company's managing director.

The stainless steel liquid lattice shows how this works. It is a demonstration load-bearing engine block containing two pipes that merge into a larger pipe that exits at a right angle. Ordinarily, manufacturers would make it by drilling two holes from the top to meet a larger hole drilled from the side. Unfortunately, this produces a right angle that resists flow and reduces efficiency.

Designing for additive manufacturing, Within made a smoothly curving junction that reduced flow resistance where the pipes merged. It added columns to support the pipes and the loads placed on the top and bottom plates. "The software analyzed the stress, and made the columns that were not needed thinner and the ones that were needed thicker." Mahdavi said.

Even more impressive is a new type of heat exchanger developed by Within and 3T RPT. The device consists of a series of teardrop-shaped tubes. They are so thin and narrow, they do not need internal supports. Each tube holds a series of small airfoils ca[led turbulators. They boost surface area and disrupt airflow, forcing the hottest air from the middle to the edges of the tube to maximize heat transfer. The device also includes integrated cooling fins.

Within has developed a number of other designs that highlight its software's ability to optimize strength, stiffness, deformation, and weight. These include finger implants, acetabular cups for hip replacements, spinal fusion implants, and bone rasps. Within plans to commercialize the software.

This section was edited by Associate Editor Alan S. Brown

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Title Annotation:TECH FOCUS: Materials and Assembly
Comment:Better designs through evolution.(TECH FOCUS: Materials and Assembly)
Author:Brown, Alan S.
Publication:Mechanical Engineering-CIME
Geographic Code:1USA
Date:Sep 1, 2011
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