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.
Let me also point out that carbon fiber composite doesn’t yield, it just fails catastrophically
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.
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.)
I have done destructive strength testing on carbon fiber. It would not shatter like porcelain. Carbon fiber is made of thin, very strong but very flexible stands of carbon embedded in more brittle resin (plastic). The resin by itself probably would shatter. Carbon fiber will snap suddenly as the resin fails, but the fibers keep it from flying apart.
With steel, it would depend very much on the alloy. Some are very ductile (will bend very far without breaking) whereas some are more brittle and actually will shatter with enough force.
This video gives a good idea of how steel would compare to carbon fiber. Carbon fiber starts at 3:57 and high speed steel (a very brittle steel) at 6:19. There is no ductile steel, but 6061aluminum at 2:48 fails pretty much the same way just with a lower force.
Appreciate the knowledge on the various materials. I probably misinterpreted the carbon fiber thing from the video.
And looking at the inside of the sub after I posted that comment, I also noticed how much material surrounds that carbon fiber (I don’t know if that’s the composite or some kind of insulation).
Semi-related, they also had the monitors screwed into that on the inside, which I’m guessing would be very bad if it reached the carbon fiber interior?
Scott Manley did a 2 hour rant on this. He’s not a materials scientist, but I’m sure he covered much of the important detail (I haven’t managed all of it yet).
Typically it is ultrasound, or X-ray CT. It does become difficult to do with large pieces and/or thick sections, but I don’t know if this hull was too large. However, if the manufacturing process were qualified using smaller pieces that were testable with NDE/DE or a full size piece that was DE, that would generally be acceptable for the large component.
100% with you on the value of codes and standards. I used to work in a field that was very safe except for the rare occasions on which it was very unsafe, and we all learned not only what the regulations were, but why those regulations were in place. Having the reason explained usually killed any desire I might have had to break that regulation, which of course is why the explanations were part of the training process. “Don’t do this thing that is likely to lead to extremely painful injuries” or “make sure to do this thing in order to keep the very expensive machine from breaking” are rules I am delighted to follow.
I read somewhere that Rush had wanted to be an astronaut, but hadn’t made the grade for some reason. I wonder if it was because he would have endangered everyone around him if he had been involved in a mission.
I believe the reason that Rush publicised was that his vision wasn’t 20/20, but I suspect your point would have disqualified him later in the process anyway.
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.)
I have done destructive strength testing on carbon fiber. It would not shatter like porcelain. Carbon fiber is made of thin, very strong but very flexible stands of carbon embedded in more brittle resin (plastic). The resin by itself probably would shatter. Carbon fiber will snap suddenly as the resin fails, but the fibers keep it from flying apart.
With steel, it would depend very much on the alloy. Some are very ductile (will bend very far without breaking) whereas some are more brittle and actually will shatter with enough force.
This video gives a good idea of how steel would compare to carbon fiber. Carbon fiber starts at 3:57 and high speed steel (a very brittle steel) at 6:19. There is no ductile steel, but 6061aluminum at 2:48 fails pretty much the same way just with a lower force.
https://youtu.be/ifOzrOgpI4g
Thanks for that! I’ll check it out.
Appreciate the knowledge on the various materials. I probably misinterpreted the carbon fiber thing from the video.
And looking at the inside of the sub after I posted that comment, I also noticed how much material surrounds that carbon fiber (I don’t know if that’s the composite or some kind of insulation).
Semi-related, they also had the monitors screwed into that on the inside, which I’m guessing would be very bad if it reached the carbon fiber interior?
Scott Manley did a 2 hour rant on this. He’s not a materials scientist, but I’m sure he covered much of the important detail (I haven’t managed all of it yet).
Do you know what would have been involved here? Some kind of imaging, I assume?
Thanks for the write up!
Typically it is ultrasound, or X-ray CT. It does become difficult to do with large pieces and/or thick sections, but I don’t know if this hull was too large. However, if the manufacturing process were qualified using smaller pieces that were testable with NDE/DE or a full size piece that was DE, that would generally be acceptable for the large component.
100% with you on the value of codes and standards. I used to work in a field that was very safe except for the rare occasions on which it was very unsafe, and we all learned not only what the regulations were, but why those regulations were in place. Having the reason explained usually killed any desire I might have had to break that regulation, which of course is why the explanations were part of the training process. “Don’t do this thing that is likely to lead to extremely painful injuries” or “make sure to do this thing in order to keep the very expensive machine from breaking” are rules I am delighted to follow.
I read somewhere that Rush had wanted to be an astronaut, but hadn’t made the grade for some reason. I wonder if it was because he would have endangered everyone around him if he had been involved in a mission.
I believe the reason that Rush publicised was that his vision wasn’t 20/20, but I suspect your point would have disqualified him later in the process anyway.
Repeatedly.