Titan submersible

[Billo]

Its a really small group of Sub manufacturer so who else wouldhave knowledge to give ??

The facts are the Aussie made Sub used by James Cameron was rated for 16,500 PSI and was tested in the Mariana trench at depth in excess of 10,000m

Larry the coke can resting next to the titanic wasn't rated for even a fraction of that.

[wanneroo]

The people really caning the construction of the sub are the competitors. Thats pretty bad form in my book doing the I told you so.

Everyone is caning everything about this and rightfully so. Only fools don't learn from stuff foolish people do.

We've gotten to a point in society where many do not want faults or mistakes pointed out or have "their feelings hurt". But ultimately ignoring such things leads to other disasters. In my business as I point out to folks, when we make a mistake or goof lets put ego aside, look at what happened and take corrective action so it doesn't happen again. Because if people really screw up they get seriously hurt or die.

This whole debacle is an example worth studying and folks should pick it apart and learn from it.

[Lazarus]

The people really caning the construction of the sub are the competitors. Thats pretty bad form in my book doing the I told you so.

That's a commendable sentiment Larry, and if Stockton Rush had been alone in his untested, unrated and uncertified "home build", like mad Mike Hughs when he smeared himself in his home made rocket, then perhaps.

As he advertised for customers and assured them his radically experimental hull construction was safe, then pureed them as a direct result of ignoring multiple warnings, it's not bad form it's common sense that will hopefully make some other rich glory hunters think twice.

https://www.bbc.com/news/world-us-canada-65998914

[womble]

Yes but Lazarus he could have tested it with poor people first. Instead he got greedy for fast big money .
This article explains https://www.theonion.com/critics-say-submersible-should-ve-been-tested-with-poor-1850566314

[Lazarus]

Yes but Lazarus he could have tested it with poor people first. Instead he got greedy for fast big money .
This article explains https://www.theonion.com/critics-say-submersible-should-ve-been-tested-with-poor-1850566314

Very true Womble, what's a few povvos here or there?
The world today is creating povvos faster than rabbits.

[northdude]

So I guess the people that pointed out this submersibles faults and desigh were the usual tin foil hat wearers that everyone poo poos these days????

[JohnV]

But what I want to know is , if the submersible imploded and it was only 500 meters away from the bow of the Titanic and near the ascent / decent sled then it must have been very close to the mother ship , why the hell did the crew on the mother ship not see a huge boil of air bubbles coming up and there would be some buoyant debris rising with that ?
Why is there no images of the alleged debris field and the alleged 5 pieces of wreckage recovered ?
Why do most of the seasoned coast guard officers look like they are in a state of shock ?
Something is not kosher .

[Die Judicii]

I've heard,,,,,,,,,, that the Titan Company are now veering away from deep diving in high pressure environments,,,,,, and are now starting
to build units that are designed for the opposite.

Stand in line people,,,, to buy your tickets for a flight to the moon.

[Larry]

Billo do you see the irony in what you said. The testing was carried out under real life diving conditions. If that is what is deemed acceptable then Titan would be considered tested as well. It had made prior dives to the Titanic. The company was not a fly by night home garage setup as you guys are suggesting. They have been diving since 2009 and have had multiple subs making over 200 dives.

I was originally on the other side but trying to look at both sides and you guys have sort of taken offense to what I have said making me defend my original side thoughts.

[JohnV]

Billo do you see the irony in what you said. The testing was carried out under real life diving conditions. If that is what is deemed acceptable then Titan would be considered tested as well. It had made prior dives to the Titanic. The company was not a fly by night home garage setup as you guys are suggesting. They have been diving since 2009 and have had multiple subs making over 200 dives.

I was originally on the other side but trying to look at both sides and you guys have sort of taken offense to what I have said making me defend my original side thoughts.

The viewing port on the sub was only certified to 1300 meters ! That came out in the law suite that the company took out against an employee who they sacked for pointing out safety problems in the design . Just because a sub has done multiple dives to a certain depth does not mean it will always be safe as the design may be too prone to flexing and stress cracking to give a reasonable working life . Many aircraft have failed and crashed for this very reason .

[Oldbloke]

Billo do you see the irony in what you said. The testing was carried out under real life diving conditions. If that is what is deemed acceptable then Titan would be considered tested as well. It had made prior dives to the Titanic. The company was not a fly by night home garage setup as you guys are suggesting. They have been diving since 2009 and have had multiple subs making over 200 dives.

I was originally on the other side but trying to look at both sides and you guys have sort of taken offense to what I have said making me defend my original side thoughts.

The viewing port on the sub was only certified to 1300 meters ! That came out in the law suite that the company took out against an employee who they sacked for pointing out safety problems in the design . Just because a sub has done multiple dives to a certain depth does not mean it will always be safe as the design may be too prone to flexing and stress cracking to give a reasonable working life . Many aircraft have failed and crashed for this very reason .

Thet makes zero sense. Must be a typo!

[JohnV]

I read this bombshell post by a carbon fiber materials Engineer I can't credit his name because it was not supplied . So as it was posted public domain I see this as fair use . The people who built the sub should be up on criminal negligence resulting in death .
Quote " The fundamental design flaw for this vessel is that the designers forgot that "You can't push a rope." All fiber composites have their greatest strength in pure tension. Such materials are ideal for pressure tanks, which have a hoop stress of pure tension. The Titan, however, was not a pressure tank, it was a type of vacuum chamber, where the hoop stress is pure compression, and depended on the integrity of the resin matrix for its strength. Repeated cyclic compression along the fiber axis will cause microscopic separations to accumulate between the fibers and the matrix, eventually leading to microscopic fiber buckling. Fiber composites are highly anisotropic materials, and the designers did not take this property adequately into account. Failure in tension is radically different from failure in compression for these materials. Metals are almost completely isotropic in their mechanical properties and do not have this problem. Metals also have some ductility and will get stronger by work hardening before they ultimately fail. Fiber composites behave more like brittle materials and their fatigue life is not well characterized, especially under cyclic axial compression conditions. They fail suddenly and without warning, even when their application loads them mostly in tension. When the Titan hull suddenly failed, it was crushed by an immensely powerful water hammer powered by enormous momentum which probably turned most of the fiber composite mass into fine dust which will never be found. The underwater implosion of the Titan could conceptually be compared to the implosion of a plutonium nuclear bomb pit like the Trinity 'gadget' (without a subsequent nuclear fission reaction). "

[JohnV]

Billo do you see the irony in what you said. The testing was carried out under real life diving conditions. If that is what is deemed acceptable then Titan would be considered tested as well. It had made prior dives to the Titanic. The company was not a fly by night home garage setup as you guys are suggesting. They have been diving since 2009 and have had multiple subs making over 200 dives.

I was originally on the other side but trying to look at both sides and you guys have sort of taken offense to what I have said making me defend my original side thoughts.

The viewing port on the sub was only certified to 1300 meters ! That came out in the law suite that the company took out against an employee who they sacked for pointing out safety problems in the design . Just because a sub has done multiple dives to a certain depth does not mean it will always be safe as the design may be too prone to flexing and stress cracking to give a reasonable working life . Many aircraft have failed and crashed for this very reason .

Thet makes zero sense. Must be a typo!

The viewing porthole in the front of the sub was only certified by the porthole manufacturer for 1300 meters depth . That came out in the court case .
What don't you understand about that ?

[Oldbloke]

IF that's TRUE. Only a lunatic would take it to 3,800mtrs. ( 3 x it's its rating) And the submersible would have sunk on one of its previous dives.


Hence I question that number.
There must be more to it!

[JohnV]

IF that's TRUE. Only a lunatic would take it to 3,800mtrs. ( 3 x it's its rating) And the submersible would have sunk on one of its previous dives.


Hence I question that number.
There must be more to it!

It was from the court transcripts and evidence supplied by the manufacturers . That's correct the guy was a lunatic , read my other post to see the full depth of the lunacy . It's quite wrong to think that any structure will fail immediately under more stress than it was designed for . It takes time to develop the weakness and fatigue but will fail very prematurely than one would normally expect . Read the other long post it explains exactly why it failed .

[Billo]

[Baronvonrort]

I read this bombshell post by a carbon fiber materials Engineer I can't credit his name because it was not supplied . So as it was posted public domain I see this as fair use . The people who built the sub should be up on criminal negligence resulting in death .
Quote " The fundamental design flaw for this vessel is that the designers forgot that "You can't push a rope." All fiber composites have their greatest strength in pure tension. Such materials are ideal for pressure tanks, which have a hoop stress of pure tension. The Titan, however, was not a pressure tank, it was a type of vacuum chamber, where the hoop stress is pure compression "

The CEO had a degree in Aerospace engineering so he would be very familiar with CF.

Steel is stonger in tension compared to compression. You can hang good weight from coat hangar wire don't expect it to hold anything up if loaded in compression. Beams and posts loaded in compression have to be carefully considered for buckling failure. Concrete is really good in compression sucks in tension so they put steel in for tensile loads.

A good article on the build of this sub it wasn't the first carbon fibre one they have a link to that.

Composite submersibles: Under pressure in deep, deep waters

Published 5/10/2017

Manned deepsea exploration calls for a highly engineered composites solution that saves weight and preserves life — at 6,500-psi service pressure.

Metallic hulls, however, because they are not buoyant in designs for depths of more than 2,000m, present challenges when it comes to managing ballast for ascent and descent. In particular, metal-hulled craft require the use of syntactic foam attached to the outside of the craft to achieve neutral buoyancy.

OceanGate CEO Stockton Rush says the company had been evaluating the potential of using a carbon fiber composite hull since 2010, primarily because it permits creation of a pressure vessel that is naturally buoyant and, therefore, would enable OceanGate to forgo the use — and the significant expense — of syntactic foam on its exterior. So, for Cyclops 2 OceanGate decided to avoid the metallic hull altogether and began a search for a manufacturer that could help it develop a composite hull.

Spencer Composites’ president Brian Spencer signed a contract with OceanGate for the Cyclops 2 hull in early January 2017 and was presented with very basic — but challenging — performance parameters: Length, 2,540 mm; outside diameter, 1,676 mm; service pressure, 6,600 psi; pressure safety factor, 2.25. “They basically said, ‘This is the pressure we have to meet, this is the factor of safety, this is the basic envelope. Go design and build it,’” Spencer reports. And he was given six weeks in which to do it.

Thus, in the event of catastrophic failure of a submersible at any depth greater than even 250m, deepsea water pressure would instantly kill every passenger on board. And this is the primary concern of OceanGate and, by extension, Spencer Composites. Cyclops 2 faces potential failure in any one of three structures: the composite hull, the titanium end caps and the acrylic viewport.

The viewport, says Rush, because it is acrylic, fails optically long before it fails structurally — and in this case, catastrophically — thus the crew will detect a problem visually first.

Initial design work indicated that the hull, to be rated for 4,000m depth with a 2.25 safety factor, should be 114 mm thick or 4.5 inches, which OceanGate opted to round up to 5 inches (127 mm) to build in an additional safety margin.

More here worth a read- https://www.compositesworld.com/articles/composite-submersibles-under-pressure-in-deep-deep-waters

A Factor of Safety 2.25 is ballpark for aircraft which is what Aerospace engineers like the former CEO use.
With working load of 6600 PSI a FOS of 2.25 gives 14,850 PSI breaking load.

Those who have studied engineering would be saying WTF the Factor of Safety should be minimum 4-5 for something like this. With FOS of 4 = 26,400 PSI breaking load with FOS 5 = 33,000 PSI.
The problem with increasing FOS is increased weight and cost due to using more materials.

Carbon fibre is excellent for fatigue strength compared to steel/alloys provided it has a decent factor of safety to keep stress levels down.

It wasn't a backyard build as the fake news reported i don't think Spencer Composites are to blame they provided what was asked.

When engineers design something the question they ask is what are the consequences of failure then they decide on a factor of safety to make sure it stays together. Sometimes they add a bit to compensate for manufacturing flaws.

Nothing wrong with materials used in this sub the Factor of safety was far to low at 2.25.

[Baronvonrort]

They scrapped that sub and built a new one. That letter was for a previous sub.

[JohnV]

There is plenty of evidence to support the fact that carbon fiber was the wrong hull material for those depths . Including the fact it failed and 5 people died . The one built by a TV technician here in his back yard went to 12 000 meters and is still operating . Why ? because it's a proven design using proven materials . Five people are dead and some people are still trying to say the sub construction was fine .
Unbelievable .

[Baronvonrort]

Just reading that the builder admitted that the construction materials he used Carbon Fiber and Titanium combination was potentially dangerous in this situation due to galvanic corrosion.

Sound like it was a time bomb ticking away similar to rust slowly degrading then boom.

Titanium is the only metal compatible with Carbon Fibre

Carbon Fibre eats all other metals if it isn't insulated

[bladeracer]

Titanium is the only metal compatible with Carbon Fibre

Carbon Fibre eats all other metals if it isn't insulated

Wouldn't that depend on the resin used? Carbon fibre wheels have aluminium and magnesium inserts in them.

[Baronvonrort]

There is plenty of evidence to support the fact that carbon fiber was the wrong hull material for those depths . Including the fact it failed and 5 people died . The one built by a TV technician here in his back yard went to 12 000 meters and is still operating . Why ? because it's a proven design using proven materials . Five people are dead and some people are still trying to say the sub construction was fine .
Unbelievable .

What factor of safety was that metal sub designed with?

I bet is was nowhere near as low as 2.25.

Ask any engineer if they would dive down to those depths in anything with a factor of safety of 2.25 i would bet they all say no.

[Baronvonrort]

Titanium is the only metal compatible with Carbon Fibre

Carbon Fibre eats all other metals if it isn't insulated

Wouldn't that depend on the resin used? Carbon fibre wheels have aluminium and magnesium inserts in them.

They would insulate it with layer of E or S Glass maybe Basalt fibres where metal bits touch CF.

Resin wouldn't make any difference they would be using pre impregnated cloth which has to be baked under pressure at 80-150 deg C.

One of the things that surprised me with this sub is they didn't bake it in a autoclave. Vacum bagging gives around 14 PSI clamping force to compact the layup which is quite considerable when you add up how many square inches involved. Autoclave gives up to around 60 PSI clamping force.

10-12 mm is considered pretty thick for Carbon fibre layup so this sub at 5 inches thick would have been one of the thickest layups done.

[on_one_wheel]

Iv been listening to the radio so that makes me pretty much an authority on the topic.
Apparently carbon fibre is great under tension but extremely bad under compression.
Great for scuba diving tanks, not so great for submarines.

[northdude]

I read about it on face book so that makes me a proffesor on the subject

[Billo]

26 min video shot only days before that pretty much shows that this contraption really did have a few issues, skip to the 11 min mark to see what happened on the 3rd mission. Scary stuff but this thing wasnt sea worthy

https://youtu.be/O-8U08yJlb8

[Oldbloke]

I read about it on face book so that makes me a proffesor on the subject

Awesome.jpg (16.75 KiB) Viewed 7173 times

[Lazarus]

There is plenty of evidence to support the fact that carbon fiber was the wrong hull material for those depths . Including the fact it failed and 5 people died . The one built by a TV technician here in his back yard went to 12 000 meters and is still operating . Why ? because it's a proven design using proven materials . Five people are dead and some people are still trying to say the sub construction was fine .
Unbelievable .

What factor of safety was that metal sub designed with?

I bet is was nowhere near as low as 2.25.

Ask any engineer if they would dive down to those depths in anything with a factor of safety of 2.25 i would bet they all say no.

I would say, Baron, that the "safety factor" you quote is moot.
The proof is in the fact that the metallic sub has been down numerous times to far greater depth and it brings its crew back alive, and is still in a certifiable condition.
Unlike the Titan, which turned the crew to chum.

Sounds like a pretty good proof of safety to me.

[Baronvonrort]

Iv been listening to the radio so that makes me pretty much an authority on the topic.
Apparently carbon fibre is great under tension but extremely bad under compression.
Great for scuba diving tanks, not so great for submarines.

I disagree with it being great for scuba tanks. Scuba divers strap lead weights on so no real benefit for weight savings. Taking 8lbs from the back of a firefighter might be good.

If it has 2.5mm wall thickness and you gouge a 1-1.5mm scratch in it which is pretty easy to do then it's stuffed.

A friends carbon fibre pushbike fell over hit knee high brick wall and smashed the top tube that was an expensive repair. It's one of the reasons why i will stick with alloy pushbike.

Fiberglass LPG tanks are great half the weight of steel you can see how full they are they don't rust.

[Baronvonrort]

There is plenty of evidence to support the fact that carbon fiber was the wrong hull material for those depths . Including the fact it failed and 5 people died . The one built by a TV technician here in his back yard went to 12 000 meters and is still operating . Why ? because it's a proven design using proven materials . Five people are dead and some people are still trying to say the sub construction was fine .
Unbelievable .

What factor of safety was that metal sub designed with?

I bet is was nowhere near as low as 2.25.

Ask any engineer if they would dive down to those depths in anything with a factor of safety of 2.25 i would bet they all say no.

I would say, Baron, that the "safety factor" you quote is moot.
The proof is in the fact that the metallic sub has been down numerous times to far greater depth and it brings its crew back alive, and is still in a certifiable condition.
Unlike the Titan, which turned the crew to chum.

Sounds like a pretty good proof of safety to me.

The first question older engineers ask when something breaks is - what was the factor of safety?

With FOS of 2 you're operating at half the breaking load which is probably why that CEO didn't want to hire old white guys they know something with FOS that low has a limited life.

FOS is calculated from breaking load there is something called Youngs Modulus to consider which is where something goes through inelastic deformation before it breaks. If you load anything up and it bends/stetches then springs back to it's original shape you haven't exceeded Youngs Modulus. If it doesn't spring back you have exceeded YM.

With steel it doesn't just break before breaking load is achieved it will have inelastic deformation before failure this can happen around 70% of breaking load.

Factor of Safety is one of the first considerations with any design along with Youngs Modulus when you consider consquences of failure.