American universities develop 4D printed materials that can change shape and hardness according to temperature

On April 16, 2019, the US Design News website reported that 4D printed materials developed by researchers at Rutgers University in the United States can change shape and hardness according to temperature in many applications. The research team, led by assistant professor and head of the Department of Mechanical and Aerospace Engineering, Howon Lee, created this flexible, lightweight material using 4D printing technology. The researchers say the material can be used in the design of aircraft or drone wings, soft robots and implantable biomedical devices.

Once the traditional metamaterials are manufactured with mechanical properties and geometry fixed, 4D printed metamaterials add adjustability, reconfigurability and deployability. 4D printing is based on additive manufacturing (3D printing) technology, which converts digital models into physical entities, but 4D printing goes a step further, using special materials and designs to print objects that change shape as environmental conditions change.

The effect of temperature deformation on 4D printed materials developed by Rutgers University team (Photo of Rutgers University, USA)

The Rutgers team combined their 3D printing, shape memory polymers and existing mechanical metamaterials, octal trusses and Kelvin foam in their research. The current state of 4D printing focuses on geometric transformations; the Rogers team's 4D printed mechanical metamaterials are more focused on mechanical properties.

Researchers say the Rutgers team can use temperature to adjust their materials to keep them rigid when impacted, or to become as soft as a sponge to absorb vibration. At temperatures between room temperature and 90 ° C, the stiffness can be adjusted more than 100 times and can significantly absorb shock.

In addition, these materials can be reshaped as needed, for example temporarily deformed into any shape, and then restored to their original shape as needed during heating. Adjustable materials increase material flexibility and are suitable for use in work environments or situations where mechanical properties or geometries are different, without the need to redesign and manufacture. It also adds features such as deployability to save on transportation costs or through narrow spaces. The adaptability of these materials makes them ideal for a range of applications, such as aircraft or drone wings, which can change shape to improve performance; structures that can be stretched in space, such as solar panels; can change shape or shape depending on the environment and task Soft robot of stiffness.

The next step is to find such applications for metamaterials, as well as to find excitations other than temperature to stimulate shape changes and to develop materials with new properties.