The following is an excerpt.

Representatives from SFI CASA and partner Multiconsult recently paid a visit to MX3D, a small Dutch company specializing in the 3D printing of large steel structures.

A robot-printed steel bridge can lead deeper into 3D-printing. From left: SFI CASA researcher Miguel Costas, lead engineer at MX3D Filippo Gilardi, Nicolas Neumann at Multiconsult. (Photo: Magnus Langseth).

The major attraction was a 12- metre long stainless-steel footbridge, designed by humans and printed by robots. Since last summer there have been some preliminary activities in the field of 3-D printing running at SFI CASA. Researcher Miguel Costas has been looking into the behaviour of additively manufactured parts under crushing and ballistic penetration. «The goal is to see if our well-established modelling strategies can predict the behaviour of a 3D-printed aluminium alloy. So far, the results are satisfactory», Costas states.

 In January, Nicolas Neumann, head of the section of steel structures at CASA partner Multiconsult, invited Costas and Professor Magnus Langseth to visit MX3D.

The Dutch company has become renowned because of the 3D-printed bridge that is to be installed in the Red-Light district in Amsterdam. Prior to completion the award-winning design is stretching out on the floor in one of the old buildings by the NSDM wharf. The former industrial shipyard in Amsterdam Noord has been transformed into a cultural hotspot and a hub for creativity. With Arup as the lead structural engineering firm, MX3D have created software that transforms welding machines into 3-D robotic printers.

Three parties Collaboration Discussed

The steel bridge is 12 metres long and weighs 4500 kilos. During their visit, Langseth, Costas and Neumann made a thorough inspection of the impressive structure. The company’s CEO Gijs van der Velden and lead engineer Filippo Gilardi guided them through their workshop explaining how their technology worked.

According to SFI CASA´s Miguel Costas there is no doubt that the technology of additive manufacturing is becoming very attractive for some applications in engineering, like the production of parts with complicated geometries.

«Structural performance needs to be assessed»

«Since no design codes exist so far for additively manufactured parts, their structural performance needs to be assessed by experimental tests or computational methods. This is a field where SFI CASA has sound experience».

On the other hand, the mechanical properties of 3D-printed metals stem from their production process.  In other words, the same alloy can have radically different properties if it is printed by different printers or configurations.

«This is a challenge when it comes research: if we want to investigate how these materials behave, we will need feedback from those who control the process. Therefore, collaboration with companies like MX3D will be essential for us if we want to establish new knowledge», Costas says.

Also, potential collaboration between NTNU, MX3D and Multiconsult was discussed in the framework of SFI CASA. Whether this will become a research activity at the Centre is too early to say.

Monitoring the Bridge

3D printing, also known as additive manufacturing, is a new method for manufacturing parts directly from a digital model by building layer after layer of a material.

According to Arup, the printing and assembly of the large bridge parts began in March 2017.  The printing work was completed in October 2018. The bridge will be equipped with a sensor network, allowing the partners of MX3D to gather data which will be used to build a digital twin for monitoring the health of the bridge. This digital twin will be used to track performance under different environmental conditions and under changing dynamic loads, enabling a data-centric design language to be developed.