this post was submitted on 26 Jun 2023
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I am a materials scientist working in another highly, highly regulated field, and part of my job is working on how to accelerate materials discovery and qualification for next-gen technology. Part of that means working with codes and standards bodies and regulatory agencies to get their acceptance in the new tech. It's going to take some time, but it's worth it.
Thus, the Titan story touches a particular nerve for me.
This entire tragedy could have been avoided if codes and standards were followed. The 2018 whistleblower was concerned about flaws in the carbon fiber composite that could grow and cause implosion failure after repeated pressure cycling. It looks like this is exactly what happened.
Let me point out that the pressure at 4000m is about 100 MPa: that's above or near the yield strength of many common alloys. It's a lot. Let me also point out that carbon fiber composite doesn't yield, it just fails catastrophically, and also let me point out the idea of Weibull statistics, which look at the variation of things like yield and ultimate strength for brittle materials - there is generally a large range of measured strength based on the internal flaw structure of a component. Whistleblower asked for non destructive examination of the material to understand its flaw structure: an extremely usual request and generally something that everyone is on board with doing. Why not here?
Multiple people raised concerns about the safety of this sub. Rush ignored them all, or refuted them all with BS arguments. He said they didn't need to qualify the sub because commercial subs were so safe over the last 35 years that it's just human error these days, ignoring that the reason subs are safe is BECAUSE they are qualified, leaving ONLY human error as a problem source! It's like saying "I don't need to vaccinate against measles because no one catches measles anymore"... Because everyone is vaccinated against measles! But look what happens when vax rates drop: we get measles case clusters.
Regulations are written in blood, and this was ignored by Rush. The first thing drilled in to you in engineering school is that you must protect the safety of the people you are engineering for. Rush abandoned this principle out of greed and hubris. And now a teenage boy is dead who didn't even want to go on this trip. It sickens me.
I actually have a question about this because I saw someone on YouTube speaking about this two days before the debris was discovered (the channel is Sub Brief, and they were going through all the things wrong with the vessel and how it likely imploded).
With metal/steel/other alloys (forgive me, I'm not familiar with the engineering, hence my question), when they implode, it's straight up crushed, right? Like force on a tin can.
In the video I mentioned, the guy was saying that carbon fiber doesn't crack; it's like porcelain (I think he said, or another fragile material) and it just shatters completely.
So I've been curious about something. The implosion that this submersible suffered, what would it have looked like?
If the hull just shattered under pressure, would the implosion be more like hundreds of thousands of shattered pieces ripping apart everyone rather than "crush" them in the "traditional" sense (and they'd be immediately crushed anyway by the water pressure regardless)?
Or would the implosion still present itself more or less the same as it would with a steel(?) hull?
It feels almost worse if they were, for lack of a better term, shredded. I know that it would still be instantaneous, but it feels like... I don't know, much more visceral.
From what I understand, the sub was basically two heavy titanium ends separated by a tube of carbon fiber. When the hull failed, there would have been a really brief moment where there were 5 people in a small void under tons of pressure pushing in from all sides. I'm wondering more specifically if they were crushed by the titanium ends coming together before they could have been crushed by the pressure itself.
Just as an fyi on the pressure ...
"The remains of the Titanic are 12,500 feet deep. Experts say the pressure at that depth is between 370-380 bars." https://www.bbc.com/news/world-us-canada-65934887
1 bar is equal to 14.7 psi (the pressure of the air around us on our bodies at sea level).
370-380 bars is equal to 5366-5511 psi ... with the added bonus of an auto-ignited explosion of hydrocarbons (that have concentrated in the sub) after the initial implosion ... all completed within 1-3 milliseconds.
The explosion burns everything to ash and dust, which is why only the titanium rear cover and landing gear have been found so far. (The front titanium cover housed the woefully-inadequate "window" and, if it was the failure point, it could be buried in the silt, shattered into pieces or even shot through the Titanic wreck itself ... anybody's guess at this point.)