Heat Helps 4D Printed Materials Remember Their Shapes

Researchers have developed a new method that could save up to 90 percent of the time and materials used in 4D printing process.

AsianScientist (Apr. 25, 2017) – An international team of researchers has used heat to make 4D printing up to 90 percent faster and cheaper than existing methods. Their findings have been published in Science Advances.

4D printing is an emerging technology that allows a 3D-printed component to transform its structure by exposing it to heat, light, humidity, or other environmental stimuli. However, 4D printing generally involves complex and time-consuming post-processing steps to mechanically program the component. Furthermore, the materials are often restricted to soft polymers, limiting their applicability in structural scenarios.

A group of researchers from the Singapore University of Technology and Design (SUTD), Georgia Institute of Technology, Xi’an Jiaotong University and Zhejiang University has developed an approach that significantly simplifies and increases the potential of 4D printing.

By incorporating the mechanical programming post-processing step directly into the 3D printing process,
they can directly transform the 3D-printed components into new permanent configurations using heat. This approach can help save printing time and materials used by up to 90 percent, while completely eliminating the time-consuming mechanical programming process from the design and manufacturing workflow.

“Our approach involves printing composite materials where at room temperature one material is soft but can be programmed to contain internal stress, and the other material is stiff,” said Dr. Zhen Ding of SUTD.

“We use computational simulations to design composite components where the stiff material has a shape and size that prevents the release of the programmed internal stress from the soft material after 3D printing. Upon heating, the stiff material softens and allows the soft material to release its stress. This results in a change—often dramatic—in the product shape.”

A 4D-printed structure can be transformed from its permanent shape into many different shapes that are structurally stiff at room temperature and then returned to its permanent shape by applying heat. Credit: Ding et al.

Using this new method, the researchers demonstrated many interesting shape-changing parts, including a lattice that can expand by almost eight times when heated. The composite material does not return to its original 3D-printed shape upon further heating or cooling, making the new shape permanent.

“This is because of the shape memory effect,” said Professor H. Jerry Qi of Georgia Tech. “In the two-material composite design, the stiff material exhibits shape memory, which helps lock the transformed shape into a permanent one. Additionally, the printed structure also exhibits the shape memory effect, i.e. it can then be programmed into further arbitrary shapes that can always be recovered to its new permanent shape, but not its 3D-printed shape.”

“The key advance of this work is a 4D printing method that is dramatically simplified and allows the creation of high-resolution complex 3D reprogrammable products; it promises to enable myriad applications across biomedical devices, 3D electronics, and consumer products. It even opens the door to a new paradigm in product design, where components are designed from the onset to inhabit multiple configurations during service,” said SUTD’s Professor Martin Dunn.

The article can be found at: Ding et al. (2017) Direct 4D Printing via Active Composite Materials.


Source: Singapore University of Technology and Design.
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