Load cells and destruction testing
It’s not often you get to test something to complete destruction, especially when it’s part of a very expensive America’s Cup racing yacht! Yet this is exactly what the team at Persico Marine got to do with one of the foil arms for the new AC75 racing class.
The America’s Cup team decided to destruction test one of the carbon foil arms, after one failed earlier than expected during testing in September 2018. These foils are crucial to the speed a stability of the this new breed of racing yachts, as this AC concept video shows.
Not foiling the opposition!
Any part of an AC75 yacht must comply with strict rules as laid down by the America’s Cup:
“The AC75 Class Rule defines the parameters within which teams can design a yacht eligible to compete in the 36th America’s Cup. It regulates all aspects of the boat to ensure fair and exciting racing, whilst leaving plenty of freedom for innovation to flourish.”
The rule also specifies “Supplied foil arms and cant system to save design time and construction costs.” So, if the AC75 foils were to be supplied to all teams, the engineers needed to know they were up to the rigours of open ocean racing.
Foil arm testing with load cells
In the first test, the foil arm only reached 88% of maximum test load before cracking noises were detected. In preparing for the second test, Alessandro Franceschetti, Head of Structures for Luna Rossa (designers of the foil arm) was quoted in Sail World:
“This last test is one way, there is no way back. Breaking this arm is going beyond the usual engineering screening that we normally do on components.”
Fortunately, in the second test, the foil arm took 180% of working load, with the load cell registering a load of over 27.3 tonnes before the arm exploded. You can see this dramatic moment in the video – we love a good destruction test video!
For a diagram of the various tests, see the end of this article from Sailing Scuttlebutt.
The first America’s Cup featuring the AC75 takes place in New Zealand in March 2021.
Why load cells need testing too
Fabio Quartararo was in second place in the MotoGP Spanish Grand Prix when his Yamaha M1 bike got stuck in third gear. As a report on Yahoo! Sport explained, this was due to:
“A failure of the gearshift load cell, which is made up of two rods linked by a sensor and serves to detect when the rider is pushing the lever to change gears.”
As a result, Yamaha will be lowering the mileage a load cell on this type of bike completes before it is replaced. After all, as a very disappointed Quartararo said, the failure was “Something really small that cost a lot”.
