By combining the principles of tensegrity with components 3D printed from shape memory polymers, Georgia Tech engineers produced an object that can be compressed and re-expanded to its original shape. This technology could have many applications, from building structures in space to biomedical devices.
Buckminster Fuller created the portmanteau term “tensegrity” by combining “tensional” and “integrity.” Tensegrity structures consist of members in compression connected with cables that are in tension. These structures are both strong and light. Several domed stadiums, among other public structures, have roofs constructed along tensegrity principles.
The characteristic strength and light weight of tensegrity structures could make them well-suited for use in space exploration. The Georgia Tech research team tackled the problem of delivering a large structure in a way that uses less space.
Their experimental object contains five rods, or struts, connected by cables. The researchers designed hollow struts with a narrow lengthwise opening, allowing them to be folded flat, and attachment points for the cables. All components are 3D printed from shape memory polymers.
Heating the struts to 65 degrees Celsius made the struts pliable enough to partially flatten them into a letter W shape. After attaching the cables, the collapsed structure was reheated to restore its original shape.
The team discovered that controlling the rate and sequence of expansion is critical to a successful restoration of shape. Using polymers that expand at different temperatures gave the researchers the necessary control.
“These active tensegrity objects are very elegant in design and open up a range of possibilities for deployable 3D structures,” Glaucio Paulino, a Georgia Tech professor of Civil and Environmental Engineering, said.