Creating a Designer Chair With Intelligent Internal Structure
Accelerating product development and
optimizing production processes, laser sintering was used to finish a
designer chair because it is one of the very few methods to produce
such complex structures and large dimensions.
Stress analysis and structure manipulation software developed by Dr. Siavash Mahdavi at University College London has enabled world-renowned designer Assa Ashuash to create Osteon, a chair that combines his artistic flair with precise mechanical characteristics. They include lightness, extra strength in areas that are under the greatest stress and minimum material usage. In the past, this design would have been impossible to build because the chair has undercuts and complex internal structures which are not possible to produce with conventional methods; but modern rapid manufacturing technology came to the rescue. Osteon was made a reality by taking horizontal slices through a 3D computer-aided design (CAD) model. The resulting data was then used to drive a laser-sintering machine, which created the product by fusing successive layers of plastic powder.
From Virtual Design to 3D Object
Designed
for consumers, the chair, which has been shown at several trade and
design shows and can be bought in the near future on www.assaashuach.com,
was ordered by Ashuash, and first realized by EOS (Novi, MI) using
their EOSINT P 730 plastic laser sintering system. The original
intention was to show the chair at the London design show and sell it
to consumers afterwards.
According to Ashuash, the Osteon Chair is the first to be designed using a combination of 3D production tools and artificial intelligence. The software knows where to create sufficient support, like the evolution of the biological structure and mechanism of bone. The chair is grown in free space with a ‘DNA’ code containing all the information required to ensure that the object will transform perfectly from a virtual design into a 3D object that achieves optimum strength while maintaining the desired visual aesthetic.
Dr. Mahdavi, managing director of Complex Matters—a software solutions service which adds the biological structures to existing designs and a spinoff from his research at University College London—states, “Our software works rather like finite element analysis in reverse. We formulate an ideal set of end results as the starting point and work backwards to create the optimal structure required to achieve that goal. On our Web site, www. complexmatters.com, there is a Projects section which shows the main projects that we have done. The software is used for other applications as well, e.g. football boot soles or implants.
“However, in this project, our software imported the CAD model of the chair and all of the relevant parameters, including the average person’s weight and the maximum permissible amount of flex at various points around the chair’s structure,” explains Dr. Mahdavi. “Artificial intelligence in the software then worked on the data, identifying stress points in the chair, morphing the original design slightly to satisfy the physical requirements and generating a custom lattice that minimized the amount of plastic used, yet incorporating the necessary strength and mechanical characteristics. An external skin was incorporated over a majority of the structure for aesthetics and user comfort.”
Laser Sintering
The Osteon took
physical form with laser sintering technology. The virtual chair design
was split into sections so that each could be grown
within the 27.5 x 15 x 23 inch build envelope of an EOSINT P 700
laser-sintering machine.
EOS manufactures laser-sintering systems. Laser sintering is the key technology for e-Manufacturing, the fast, flexible and cost-effective production of products, patterns or tools. The technology manufactures parts for every phase of the product life cycle, directly from electronic data. Laser sintering accelerates product development and optimizes production processes. Ashuash decided to use laser sintering instead of another technology to finish the chair because it is one of the very few methods to produce such complex structures and large dimensions. “The build envelope of the EOSINT P 700/ EOSINT P 730 series was most suitable for this kind of geometry. Machines with a lower build envelope would have meant that the chair would have been built either in smaller dimensions or it would have been necessary to glue lots of parts afterwards.” Features required on the laser sintering machine for the project included the ability to handle large and complex geometries—rectangular building field geometry.
“It took 53 hours to ‘grow’the chair on an EOSINT P 700 plastic lasersintering— which also ran at night—thus, two to two and a half working days was the building time,” says Ashuash. “Due to the best fit into the EOS machine, there was definitely time and cost saving, specifically with the gluing process and avoiding gluing lines which disturb the design.”
Stuart Jackson, EOS’ regional manager for the U.K. and Ireland, comments, “It has been fascinating to work with Assa and Siavash on the Osteon Chair project and to see the realization of a beautiful, yet practical, piece of furniture. It is noteworthy that our rapid manufacturing technology lends itself to the creation of customized products. So, if a person is heavier than average or wants greater stiffness in the lumbar region, for example, the chair could be modified to suit.”
“ With Dr. Mahdavi’s new software, the possibilities of laser sintering in the arts and industry are endless, and applications are already being found in engineering, construction and medicine,” Jackson concludes.
For more information, contact Jim Fendrick of EOS of North America, Inc. (Novi, MI)
