Jun 14, 2017 | By Benedict

Researchers from the Georgia Institute of Technology have used 3D printing to create objects capable of expanding to much larger sizes. These 3D printed objects could someday be used in applications ranging from space missions to biomedical devices.

3D printed tensegrity structures could be used to build structures in space

(Image: Rob Felt)

Tensegrity, a term you’re as likely to hear in physics as in architecture, is a structural principle based on using isolated components in compression inside a net of continuous tension. The term was coined by American architect Buckminster Fuller, who wanted a word to indicate when the integrity of a structure was derived from the balance of tension members, not the compression struts.

Using the principle of tensegrity, a team of researchers from the Georgia Institute of Technology has developed a 3D printing technique for creating objects that are capable of expanding dramatically by controlling certain temperature conditions. They say the technique could be used for space missions, creating biomedical devices, and other applications. You might even call the technique an example of 4D printing.

“Tensegrity structures are extremely lightweight while also being very strong,” said Glaucio Paulino, a professor in Georgia Tech’s School of Civil and Environmental Engineering. “That’s the reason there’s a heavy amount of interest right now in researching the use of tensegrity structures for outer space exploration. The goal is to find a way to deploy a large object that initially takes up little space.”

Glaucio Paulino and Jerry Qi show off their 3D printed creations

(Image: Rob Felt)

The researchers, whose work has been published in Scientific Reports, used 3D printers to create struts that make up one of the primary components of the tensegrity structure. The researchers designed these struts to be hollow with a narrow opening that runs the length of the tube, so that they are able to be temporarily folded flat. Each strut has an attachment point on each end that allows it to be connected to a network of (also 3D printed) elastic cables.

When these 3D printed struts are heated to 65 degrees Celsius, the researchers can partially flatten and fold them into a “W” shape. When cooled, the structures then retain the temporary shape. Afterwards, with 3D printed cable attached, the objects can be reheated to turn them into tensegrity structures.

The 3D printed assembly becomes a tensegrity structure after being reheated

(Image: Rob Felt)

The technique, which allows potentially large 3D structures to be packed flat, holds promise for outer-space construction, as well as other fields.

“We believe that you could build something like an antenna that initially is compressed and takes up little space, but once it’s heated, say just from the heat of the sun, would fully expand,” said Jerry Qi, a professor in the George W. Woodruff School of Mechanical Engineering at Georgia Tech.

There were, however, big challenges to overcome in developing this 3D printing method. For one, the researchers had to precisely control the rate and sequence of the structures’ expansion. Fortunately, the team can do this using shape memory polymers, which can be fine-tuned in terms of how quickly each strut expands. Struts can therefore be “programmed” to expand sequentially.

“For bigger and more complicated structures, if you don’t control the sequence that these struts expand, it tangles and you have a mess,” Paulino said. “By controlling the temperature at which each strut expands, we can have a phased deployment and avoid this entanglement.”

The Georgia Dome in Atlanta is a famous example of a tensegrity structure

(Image: Ross Catrow)

The researchers think their 3D printed tensegrity structures could be used to build the kind of lightweight structures needed for space exploration—or even shape-changing soft robots.

“These active tensegrity objects are very elegant in design and open up a range of possibilities for deployable 3D structures,” Paulino said.

Notable examples of tensegrity structures include the Georgia Dome in Atlanta, Georgia, and the Olympic Gymnastics Arena in Seoul, South Korea.

 

 

Posted in 3D Printing Application

 

 

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