Two Zurich architects are producing 'blow-up' metal objects up to six meters across, thanks to a new welding robot.
The technique involves joining two sheets of metal and simply inflating the space between. It produces objects of great stability, since the material can find the optimum shape by itself.
One initial product is the Plopp chair, which can withstand a weight of 2.5 tons.
But the new robot and workshop allows for bigger objects. The metal sheets are cut using a conventional laser, welded together by the robot, and the structure is inflated with an ordinary commercial compressor. This enables components to be prefabricated, taken to the building site stacked on pallets to save space, and then not inflated to attain their final volume until they are in situ.
The structures appear so lightweight that even experts greatly underestimate their load-bearing ability. For example, a bridge six meters long was constructed and subjected to a loading test.
"We invited structural engineers and asked them what weight the bridge was likely to bear," says Philipp Dohmen of ETH Zurich. " None of them believed it would take more than 200 kilos, maximum 300." The bridge, which weighed 170 kilos, broke only at 1,800 kilograms.
Now, Dohmen and partner Oskar Zieta want to build rotors for wind turbine generators one size larger than the 1.5 metre diameter prototype that already exists. Designs for crash barriers and passenger compartments are also lined up.