Additive manufacturing in metal fabrication - TUM researchers use 3D printing technology to construct tensegrity tower

Projects, Study, Research |

Researchers at the Technical University of Munich (TUM) have built a tower made of tubes and cables that appears to float in space. Commissioned by the Deutsches Museum of Science and Technology in Munich, the five-meter “tensegrity tower” can be seen in the museum’s new "Bridge and Water Engineering” exhibition that will open in July 2022. With the project, the scientists demonstrated that 3D printing technology can also be used in metal fabrication.

Tensegrity tower rendering Image: Michael Obermeier
A group of researchers in front of the tensegrity tower Image: Michael Obermeier

Bridges, office towers and warehouses: buildings with a basic aluminum or steel structure need connecting elements to hold together the various profiles, cables and sheet metal components. “In the past, these connecting nodes were always produced using grinding, welding or casting methods. Considerable material savings could be achieved with additive manufacturing techniques. But 3D printing is not yet established in the world of metal fabrication,” says Florian Oberhaidinger of the Chair of Metal Structures at TUM.

In the tensegrity tower project, the engineer and his team showed that 3D printing technology can also be used to make highly stressed components with optimized shapes – and can bring about considerable materials savings.  

Nodes must withstand enormous forces

The term tensegrity combines the words “tensional integrity”. The researchers were commissioned by the Deutsches Museum to design and build a five-meter tall tower out of tubes and cables that appears to float in the air. It is stabilized entirely through the tension between the tensile and compressive members. In this type of structure, the connecting elements – the nodes – to which the cables and tubes are attached, must withstand enormous forces.

“It was therefore a special challenge to design these connecting nodes and manufacture them with our 3D printer,” explains the project leader. With the aid of computer models and form-finding methods, the team initially determined the geometry of the tower. The team then had to use this geometry to design every node, including measurements and form optimization.  Through the form optimization, in which the TUM Chair of Structural Analysis was also involved, the engineers achieved material savings of up to 28 percent.

Further applications of additive manufacturing in metal fabrication

To make the nodes, the team used the 3D printer at the TUM Chair of Metal Structures. In the laser powder bed fusion (LPBF) process, a thin layer of aluminum powder is heated and fused by a laser at the points where solid material is needed. Then the next layer is applied. The quality of the workpiece is controlled by varying the laser power, the thickness of the powder layer, the scan speed and the track spacing, explains Johannes Diller, the team’s additive manufacturing specialist: “Our goal was to produce a light but strong and dense component using minimal resources.”

Measurements conducted at the TUM Chair of Metal Structures confirmed that the printed aluminum nodes can withstand the tensile forces and dynamic stresses to which the tensegrity tower is exposed. With the design, printing and final testing of the components, the TUM researchers created the basis for further developments.  The potential applications for additive manufacturing in metal fabrication are wide-ranging. Connecting elements are needed in every application where bridges or buildings are constructed with pillars, beams and cables.

 

Contact:
Florian Oberhaidinger
Technical University of Munich (TUM)
Chair of Metal Structures
Tel: + 49.89.289.22526
f.oberhaidinger@tum.de
Profile: https://www.cee.ed.tum.de/en/metallbau/team/research-associates/florian-oberhaidinger/​​​​​​​