Bravo Sierra

FEA is an analysis, a computer model. You verify an analysis with a real test.

Perhaps of interest:

Spencer Composites Corporation |

Jebus Blinking Xrist

Stockton Rush didn't use an autoclave so the hull wasn't cured under pressure. And he mixed prepreg materials with room temp cure wet layup.

This guy had zero idea. An autoclave is a pressurized oven where you cure a composite part with heat and pressure. The pressure compacts the plies and removes air pockets and the heat cures the resin.

https://th.bing.com/th/id/OIP.RJ1sUm...376&h=305&rs=1

Most autoclaves are run around 100 psi and most common prepreg materials are cured around 250 F.

Room temp cure carbon fiber has about the same mechanical properties as room temp cure fiberglass when in compression.

At least two US Navy NUKULAR subs are down in the North Atlantic... lives lost.

Implosions.

I suspect there are some weapons and reactor materials down there with them.

I suspect that much related knowledge has been gained, and tech developed since those two subs were lost, likely a good portion by US DOD.

Thoughts with family and friends of those lost.

Well we have a thread poster that apparently knows more about composite engineering than the folks at for example Spencer Composites.

I have some tubes in my garage that I made without an autoclave and cured at room temp. Wet lay up.

One layer 5 oz CF/kevlar cloth, one layer baltek mat and one layer of CF/kevlar on the inside. Epoxy resin.

Just tightly wrapped and cured at room temp-- did not even use my vac bag rig.

One of these tubes is less than 1/8 thick and less than two inches in diameter. A 200 pound person can stand on this tube. As expected.

I wonder why they chose to layer the CF like a paper towels on a roll like that?

I am not a composites engineer or expert, but have done enough of that work (repairing aircraft nose bowls, wing tips, and so forth) to know that if you want strength, and are layering, you don't situate the fiber layers all in the same direction. Sure seems strange to me.

It makes it faster. You lay more material for each pass of the arm. I was looking for the trough of resin that each TOW (string) must pass through to get inpregnated. It may be there but I couldn't tell. Prepreg material comes out of the box with the resin already squeegeed into the material. Its done at the vendor and placed in a vacuum sealed bag and frozen so it doesn't start curing. Normal shelf life is a year at 32 F or less.

Looks like Stockton Rush got a mom and pop shop to do the composite part of the hull.

I bet Brian Spencer PhD now wishes he never answered the phone with Rush.

It sure seems like the technique they used would have resulted in tons of air bubble pockets in the resin and between the layers. Amazing.

And quicker process means less cost, naturally. Damn, sure seems like a foolish time to pinch pennies, to me.

Pressure, yes, mostly the weight of the water above you, just like the air pressure that we all experience is due to the weight of the air above us.

Life finds a way. There's life in pretty much every inhospitable place that you can imagine, hot, cold, high pressure, poisonous gases and liquids. Not only is there a ton of pressure 2.5 miles down, but the water temp is only barely above freezing.
https://a-z-animals.com/blog/what-lives-at-the-bottom-of-the-mariana-trench/

Humans are mostly water. Water is mostly uncompressible. Anywhere in the body filled with air would compress if it didn't fill with water first. Humans would not be pulverized. When a person drowns at the surface the water fills what would normally be full of air and then the lesson is uncompressible.

Lots of folks think that a person would be squished to nothing because of the pressure. The only way we get squished like that is if or because we aren't subjected to high pressures uniformly, for instance, if a tornado drops a house on you.

it does wonders to a styrofoam cup though.

The sudden inrush of 6000 psi would certainly crush
and render a person unrecognizable as a person.
The air temperature would rise to unimaginable levels
due to compression,
but I'm not sure if there would be enough time to
incinerate flesh before being quenched by the water.

Lot of design/manufacturing info. in this video ��

I see so many basic, fundamental, good practive composite design/manufacturing omissions

Without knowing the full history of what was done, the reasons why or how it failed it's impossible for speculate how it failed

I can speculate with the best of them…

It failed because it wasn’t overbuilt sufficiently and with enough redundancy to withstand whatever happened to it between the design studio and the ocean floor.

Engineers tend to be cautious. Salesmen tend to look for quick, imperfect results.

In the video, it look like there was may be 2 inches of engagement or overlap between the CF tube and the bulkhead. It's not much to my untrained eye.

How would the 6000psi crush a person? It's not like the 6000psi would hit them and press them against the side of the sub. Wouldn't the 6000psi press against them from every side and angle? And if it was pressing from every angle, wouldn't the body be mostly (except for the hollow filled with air in the lungs/throat) incompressible?

Yes and yes. And ears. The body parts containing no air will basically 'equalize' with the surrounding water.

I'm still struggling to wrap my head around 6000 psi. That would be 864,000 lbs/SF.

The SCUBA depth record is 1,060 ft. Pressures there are immense enough. I think the last guy who tried for the record did not resurface. It is well-known that liquids are not compressible and that a human body can withstand fairly extreme pressures, but one of the main problems with surviving this is nitrogen and also oxygen saturation. Decompression times can be VERY long. The record for diving in a diving bell is 2,200 ft.

The occupants of Titan would have seen much more extreme pressure and more importantly, would have seen it in the blink of an eye. The volume of air in a full pair of lungs would have been reduced to about the size of a pea.

Now that this has gotten worldwide attention, some people who backed out of this adventure are chiming in about their concerns. Not sure at what point they backed out, but certainly by the time they read the waiver that the vehicle was not certified by any organization whatsoever.

Mind-boggling how smart/successful passengers would follow someone using basically a home made craft going into one of the most inhospitable places on our planet. And with a CEO salesman who challenged the certification process and then flat out refused to go through that process.

Still, sad how this group met their end.

Mythbusters did a gag a few years ago with a dive suit. They presurized the suit, took it down to 300 feet and then decompressed the suit to crush. Meatman liquified.

I can only imagine the mini-sub passengers became one with the force, or one with the sea as well.

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