TU Delft ready to unleash the beast
When you buy a car, you hope the mechanics won’t find anything during the annual service. When you buy a ship, they always find something. In short, maintenance costs are a nightmare for every ship owner, according to Mirek Kaminski, professor of ship and offshore structures in the Department of Maritime and Transport Technology at TU Delft (ME). In his perfect future, ships are more sustainable, more effective and more affordable.
TU Delft - Hexapod
Kaminski wants to improve the design method used for ships. Until now it’s not been necessary to take material fatigue explicitly into account while designing. If people do take this into account they always use the results of tests that have been done since the twentieth century to discover when a structure fails based on forces that act in one direction. This uniaxial force is insufficient to describe all of the forces that ships are subject to. After all, waves come from all directions. ‘As soon as we have a more realistic model of how things really are, which takes all forces into account, then we can improve our designs,’ the professor says.
Too strong
Does that mean that all ships navigating our seas right now are actually unsafe? The professor won’t go quite that far. Although material fatigue is an important reason why we lose ships – and we do lose a few a day – Kaminski says that generally ships meet all of the safety requirements. ‘If a ship doesn’t break down, that usually means it was built too strong. It’s common for too much unnecessary material to be used, which makes ships needlessly expensive.’ But that’s not the main point. ‘It’s not only a question of using fewer materials, but also adding materials in places where the ship is most likely to suffer damage as a result of fatigue. Essentially you want to only use materials where they’re needed in the future. We can do that by designing more efficiently.’ So the level of safety remains the same. ‘It’s generally said that ships are becoming safer, but actually that’s not true. We want to make them more sustainable, more effective and more affordable.’
‘We don’t know what the outcome is going to be, because nothing like this has ever been tested in the world before. But if I were to make an estimate, I would expect the lifetime of multi-axially loaded ship structural elements to shorten by at least a factor of ten relative to those loaded uniaxially. Instead of twenty years, they will last two, or even less’
The beast
The world’s most unique test facility at TU Delft is where it’s all going to happen: the hexapod. Weighing about 60 tonnes (60,000 kilos), it’s also referred to as the beast. Kaminski is planning to put pieces of ships between it, or to be more precise, structural details no larger than 1 m3 with welded parts. ‘Fatigue in ships always concerns welded materials, because welding causes micro-cracks, which weakens the joints between two welded structural elements ,’ he says. He subsequently exerts the actual forces that a ship will be subject to onto one of these test specimens, as he calls them. Ultimately Kaminski wants to test all characteristic welded structural joints of a ship for a month, during which he can simulate a lifespan of twenty years. The latter is feasible because he can exert the forces with a higher frequency than in reality, 30 Hz to be precise. ‘We don’t know what the outcome is going to be, because nothing like this has ever been tested in the world before. But if I were to make an estimate, I would expect the lifespan of a multi-axially loaded ship structural elements to shorten by at least a factor of ten relative to those loaded uniaxially. Instead of twenty years, they will last two.’ Whether that’s really going to be the case is something I would like to find out as quickly as possible. It’s incredibly exciting!’
Six directions
But how exactly will the orange beast do its thing? ‘The hexapod can generate forces of 100 tonnes in all directions. That’s important because a ship in the waves at sea also has to deal with loads from all directions,’ Kaminski says. He often uses the word multi-axial, which means that the machine can move in six directions in space: surge, sway, heave, roll, pitch and yaw. A mechanical bull and a flight simulator can move like this as well, but the hexapod is the first machine that can exert six forces on a structure simultaneously. The combination of great power, high speed and accuracy makes the Hexapod unique.
A mechanical bull and a flight simulator can move like this as well, but the hexapod is the first machine that can exert six forces and high speed on a structure accurately and simultaneously.
All constructions
Imagine that in a few years’ time researchers at Delft manage to test all of the welded structural details in a ship and develop a new design method for ships. Would that make the hexapod redundant? ‘No, there’s still a series of questions that will need to be answered,’ Kaminski says. ‘The hexapod is a universal machine that we can essentially use at other TU Delft faculties to design more effective structures that are also subject to multiaxial forces. Cars that drive on roads, for example, aeroplanes that experience turbulence, bridges that trucks drive on, buildings that have to endure earthquakes, windmills that have to deal with wind and so on and so on!’
The Eureka moment
Four years ago, he organised a brainstorm session with people from industry and science to come up with a method that will take into account all of the different forces in order to determine the lifespan of a structure. ‘At a certain point I knew what we had to do. I said: “Bingo!”’ says Kaminski, snapping his fingers. During that Eureka moment, he envisioned a machine with six hydraulic arms, which would enable it to subject material to tremendous forces from six different directions. “With my sketch of this machine, I then wrote to eleven companies and asked them if they could make something like that. Ten companies immediately threw in the towel. They said: Dream on, Mirek. The only company that wanted to build my idea right away was the German company FGB.’
The colour orange
In the meantime, four years have passed and the first and only hexapod in the world is housed at TU Delft. The university invested half of the money itself in the innovative machine, a quarter came from the government and another quarter came from 23 companies – essentially the entire offshore industry participated. Kaminski calls the hexapod his orange beast. ‘It’s exactly like the Dutch version of orange. I looked up the colour code myself and passed it on to the manufacturer,’ says the proud professor, who likes to wear an orange tie to boot.
Warm feeling
He remembers well the first time he touched his new, 6 by 5 by 3 metre pet. ‘It felt warm, like a dog. That’s because of the oil that was already in it. That was really amazing. My heart started racing immediately,’ the professor says, putting his hand on the machine. ‘Standing next to it now makes me feel emotional again. My voice starts to tremble and I get tears in my eyes, because for four years it took an enormous effort to design, specify, build and install the hexapod.’ Yet the real work is only just starting for the ship expert, because thanks to the hexapod all kinds of structures can be tested so that new models, formulas and designs can be made that describe reality better than the present one.
Mirek Kaminski
His parents wanted him to become a surgeon and bought a piano, so that Mirek Kaminski (Szczecin, 1956) would develop long, thin fingers. When their son disassembled the piano, it was clear that he, just like his father, would become an engineer. He was already working at the Szczecin University of Technology when the government was taken over by the military in 1981. He didn’t want to cooperate with the dictatorship and decided to flee with his wife. They were trying to reach Paris by sailing boat but it broke down in Amsterdam. Kaminski applied for asylum there. He discovered that maritime research was only being conducted at TU Delft and called them. Luckily professor Hans Nibbering had met his Polish professor at a conference and he was able to immediately work on his PhD there. His three-year-old son, who had remained in Poland with his grandfather and grandmother, joined him in the Netherlands six months later. Kaminski dedicated his inaugural speech to him. After taking his PhD, before becoming a professor at TU Delft, he worked for years in the maritime industry. He co-designed submarines and air defence and commando frigates for the maritime engineering firm Nevesbu. He subsequently worked at Marin, a maritime research institute in Wageningen, where he successfully set up joint industry projects. As a professor, he also builds bridges with industry and combines fundamental and applied research.
Text: Desiree Hoving