Engineering Issues

2/ really clear what was better or innovative about this design, other than it’s propensity to implode. The one part of this that is redeeming is that he wasn’t cutting corners with other peoples lives. He clearly believed in the tech enough to put his own life on the line.

— Josh Marshall (@joshtpm) June 25, 2023

It’s the lawyer in me, but I don’t see convincing four people to take the risk because you’ll be the fifth, to be very redeeming. That’s more a solid argument for why this never should have happened.

I haven’t read the op-ed, but the first question is: why not test this thing without people, first? Lower it, if possible, to depth and raise it up. Surely that kind of test is essential before loading it with people and heading for the bottom? I don’t know anything about structural engineering but it seems clear to me you don’t test the untested design with paying guests. But is that what happened?

This is, so far, the most cogent analysis I’ve read.

What was the ‘catastrophic implosion’ of the Titan submersible? An expert explainshttps://t.co/onoRVka79M

— Raw Story (@RawStory) June 25, 2023

Most, if not all, submersibles and submarines operating at depth have a pressure vessel made of a single metallic material with high yield strength. This is typically steel for relatively shallow depths (roughly less than 300m), or titanium for deeper depths. 

A titanium or thick steel pressure vessel is usually a spherical shape that can withstand the crushing pressures you might expect at 3,800m – the depth at which the Titanic wreck lies. 

The Titan, however, was different. It’s pressure vessel was made of a combination of titanium and composite carbon fibre. This is somewhat unusual from a structural engineering perspective since, in a deep diving context, titanium and carbon fibre are materials with vastly different properties. 

Titanium is elastic and can adapt to an extended range of stresses without any measurable permanent strain remaining after the return to atmospheric pressure. It shrinks to adjust to pressure forces, and re-expands as these forces are alleviated. A carbon-fibre composite, on the other hand, is much stiffer and does not have the same kind of elasticity. We can only speculate about what happened with the combination of these two technologies, which do not dynamically behave the same way under pressure. 

But what we can say almost certainly is that there would have been some kind of loss of integrity due to the differences between these materials. A composite material could potential suffer from “delamination”, which leads to a separation of the layers of reinforcement.

If that much can be known theoretically, shouldn’t such a new design be throughly tested before being put into use? Or is that too much interference with innovation?