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.
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?
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.)
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).
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.
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?
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.)
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).