Exposing OceanGate Submarines Many Fatal Designs

The recent coverage of the Titan submersible has spoken a lot about the possible ways the vessel could have failed, but how did it actually work?

This video explores many of the systems onboard, from the controls and communications systems, to the propulsion and safety. Will deep sea exploration continue to be a tourist location? Or will this change the direction of the sector? Either way, I hope you learn something from this video!

Due to it being very late in the UK as I upload, I will sort the references more neatly tomorrow!

Sources:

#OceanGate #Titan #Explained

[ZirothTech]

Thanks for watching and sharing so many insightful comments! I will try and summarise points I see here for those interested (please reply to this comment with more details you have!) :

- The carbon fibre was laid in one direction for the Titan, not a four axis weave pattern, which is much stronger
- Carbon fibre hulls are better understood for single use applications
- Other carbon pressure vessels (e.g. hydrogen tanks) have high pressure inside, instead of outside. This plays to the tensile strengths of carbon fibre, instead of relying on the compressive strength.
- Although game controllers are used in the military, this is never for complete control of a manned vehicle (though they are often used for life-critical missions, such as bomb disposal). The game controller being wireless was also an added failure mode, however there may have been control available through other methods, such as the touch screens, if needed.
- There was an inertial navigation system on the Titan, but this did not guide them toward the Titanic wreckage or give details on their surroundings. They were still reliant on the mothership for directions!

[phil]

The sub was CRACKLING every time it went down. Like carbon fiber popcorn. That is the sound of carbon fiber delaminating. When a passenger asked Stockton Rush about it, he said, "Don't worry about it, the carbon fiber is five inches thick."
Some engineers have said that this was a 'one and done' sub. That the five-inch-thick carbon fiber was too thick to reliably see every delamination in it so the tube should have been replaced after every dive.
Something only James Cameron has noted, is the bizarre way the carbon fiber was laid on the tube mold to create the tube center of the sub. The carbon fiber was laid in one direction, overlapped to the piece next to it. That is a one axis contact area. The dominant carbon fiber laying process in all of the carbon fiber industry is a FOUR axis WEAVE pattern. Stockton Rush made himself a carbon fiber coffin and bolted himself and four Innocent people in it.

[angrymeowngi]

There is a reason why submarines are overengineered and therefore costs billions to make.

[JeffRL]

The two most terrifying words in aviation are "homebuilt helicopter" and the two scariest words in marine engineering are "uncertified submersible".

[juusolatva]

the CEO literally said that safety is needlessly prioritized over innovation and then he proceeded to innovate himself and others to death

[mrhoneycutter]

As my grandfather told me when teaching me how to do basic maintenance on my car, “Whenever you’re dependent on something to keep you alive, take good care of it and don’t be a cheap ass”.
Thanks for the wise words Pops RIP

[xdaniedx]

Nothing tragic about a CEO who didn't listen to his own maintenance people and fired them when they brought up huge concerns. One was the hull was supposed to be 7 inches but came from the manufacturer at only 5 inches, second was the suggestion to use an outside company to do NDT to check for cracks and fatigue, third was the window wasn't rated to endure pressure at that depth. It could endure 1300 meters depth not 4, 000+ that the titanic was at.

The only one I feel bad for is the 19 year old who was scared and didn't want to go but because it was father's day and his dad poking fun at him he went.

The Titanic is a tomb for 1500 people who lost their lives. Not a tourist attraction for rich bored billionaires and CEO's who give the middle finger to safety just to make money.

[Cheeky-fingers]

I am an ex laminator who worked with carbon fibre for motor sport, aviation and oil industries. The process of the bonding of the hull to the Titanium caps looks extremely questionable. In the videos I have seen the were hand mixing adhesive in buckets, applying with plastic scrapers in an environment that was not dust or dirt free. Frankly I am shocked it went as deep as it did. Maybe methods have changed but it is not an assembly environment I am familiar with.

[SomeCanine]

I'm not surprised it imploded. I'm surprised it lasted as long as it did for as many dives as it had without imploding up until the point where it did. It clearly was not built to withstand that pressure and stress.

[RC]

My gradfather used to tell me "Lo barato sale caro" which translated means, "cheap things are expensive." A very accurate (and tragic) oxymoron when applied to this situation.

[jshooper]

Everything about this vessel seemed like a death trap. It's crazy that the owner bragged about cutting corners and avoiding regulations and certification.

[jmo]

Worked as an aerospace materials and composites engineer for some time. From what I've heard it was filament wound and then unidirectional layup on top done by hand...which is an odd design choice. The other issue I don't hear about is the fact that composites under compression don't have nearly the benefit they do in tension or even shear. In compression you're highly dependent on your matrix (resins) not the reinforcement (carbon fiber). In some design choices this is acceptable and accounted for. For a tube under this kind of pressure...it's a MAJOR design challenge.

For example, say you take a strip of dried super glue (matrix) and try pulling it. By itself it isn't very strong and likely brittle. Now take that super glue (matrix) and soak a strip of fabric (reinforcement) and the two work together. By itself the fabric is very limp, but now glued it has the stiffness and acts as a reinforcement to the super glue and will be relatively strong if you try to pull it (tension). Now take that same glued fabric and squish it lengthwise (compression), the fabric contributes very little to the strength of this composite and you are now almost entirely dependent on the strength of the glue at this point (aka, your matrix). This is the general principal behind most carbon fiber reinforced polymers.

Intralaminar failure is the separation of the matrix (superglue) and reinforcement (fabric) and can occur for a number of reasons. Generally, it occurs when the stresses exceed the matrix's strength or there is poor bonding between the two. Contamination, voids, expired resin, improperly cured resins, improper cure environments are some of the examples that can lead to poor bonding. Lastly I heard this wasn't bagged or cured in an autoclave. Don't know if this is true but depending on the composite used, manufacturers specify if it requires just bagging, oven cured or needs to be cured in an autoclave.

Generally speaking, out of autoclave curing is less superior to autoclaved cured. The autoclave is essentially an oven that pulls vacuum. As it pulls vacuum it forces air out of the resin and the resin is much more evenly distributed within the fabric. In other words, better bond...better strength. Given the size of the Oceangate cylinder I have my doubts it was cured in an autoclave given there aren't many autoclaves in the world that size open to just anyone and running one that size is not cheap. That’s not to say it’s wrong, design would just need to account for that in their margins. Also I'd like to know how rigorous their build process was. How clean was their environment? How accurately were things laid down? Temperature? Humidity? These all contribute to proper curing and bonding.

Filament winding is used in modern aircraft and tanks where the reinforcement is under TENSION. For aircraft, atmospheric pressure decreases as you increase altitude which means the cabin is applying a pressure from the inside. This means that the carbon fiber (reinforcement) is actually under tension. Carbon fiber (reinforcement) has the benefit of supporting the matrix in this case. Similarly, filament wound air tanks can hold thousands of PSI easily and commonly used in scuba/firefighter air tanks. In the case of a sub, the pressure is applied from the outside of the tank and the reinforcement is in COMPRESSION. Think of a net shaped like a balloon wrapped around the balloon. As the balloon expands, that net supports it and the fabric of the net is under tension. Opposite to this, if the balloon were placed in a vacuum, the balloon would shrink as their is now pressure on the outside of this. The net does nothing to support it.

With thick composite layups like this submersible, it can be very difficult to find these intralaminar cracks with non-destructive inspection. The appropriate testing method would require some type of fatigue testing that structural engineering determines the structure will face in its environment and is representative of the expected lifespan. After this testing, destructive inspection will then be done of the structure. I'd want to chop up sections of the cylinder, resin mount/polish them and inspect under a microscope at various locations to inspect the layup, especially higher stress locations determined in analysis. Voids in a matrix are generally accounted for in a design’s safety margin, but they are not and should not be designed with the expectation that intralaminar failure occurs.

At bare minimum if full scale testing and destructive inspection isn't possible, I'd want coupon (small representative pieces) testing with the same layup process done for fatigue testing and static testing in compression also followed by inspections.

I've heard that material was possibly purchased expired from Boeing. This is more than likely prepreg. Prepreg is essentially the reinforcement (carbon fiber) already soaked in the resin(matrix) just not yet cured from the manufacturer. They're generally stored in freezers to slow the curing process and have a shelf life the manufacturer determines as the cold temps only slow, not stop, the curing (crosslinking). After the shelf life has passed, it's possible you won't have a composite that meets the manufacturers strength specifications. Manufacturers of these materials are sometimes conservative with their dates. Shelf life extension is possible if coupons are made and destructive testing is performed to validate the material is still good even past the manufacturer’s date. Not heard anything anywhere if this was done.

There are other variables that are also not brought up. Salt water and UV can be detrimental to many composites. I have my doubts testing on this was done. The other concern I'd have is handling of the sub. Damage caused by impact can be invisible on the outside of many composites. If this was bumped in transport there's a possibility of unseen damage. Metals generally yield and have visual indications of impact.

Why they chose to use composites instead of steel or even titanium, is odd to me. It doesn't make sense...weight savings isn't all that critical for a submarine/submersible. To properly design a composite tube to take those kinds of compressive loads is extremely expensive given the time to design, test, and build a reliable process. With steel or titanium for example, material strength is readily validated with simple testing and easily designed for. There are plenty of designs out there that are also time tested. It would be significantly cheaper and easier to do structural analysis on a steel tube with certified and tested material. All said, it's hard to say the composite structure was even the culprit, it could have been the other parts of the structure that resulted in it's failure. Either way, sounds like marketing/executive decisions drove design instead of engineering.

[AIMusicMaster]

Whoever designed this submarine and thought it was safe must be under a lot of pressure after this

[davinp]

First, the CEO bought the carbon fiber from Boeing at a discount because they said it was at the end of its shelf life. Secondly, the tubular shape cannot hold up for long under that water pressure 12, 500 feet below. He also built the submersible with off-the-shelf materials cheaply and did not get it certified. The carbon fiber probably weakened after several dives and suffered fatigue. Some experts had said it was unsafe, but the CEO and pilot disregarded safety warnings

[jagheterhopp]

The sensors for the carbon-fiber is just tricking you into thinking you're safe. As James Cameron said that if you need sensors to know that the hull is breaking, there's something seriously wrong with your design

[andrewdavidson]

The failure of the dead man's switch (ballast drop) to operate within 10 hours must have made the rescuers very suspicious that a catastrophic event had happened. It's a shame this wasn't mentioned on day 2 in the media.

[rcsontag]

Military-grade "controllers" are quite different from what was used on the Titan.

[lostinpa-dadenduro]

It was a backyard project. An expensive one, but still basically a backyard job.

[add]

5:50 Most of the complaints about the use of the game controller for the submersible wasn't actually about the use of a controller as a concept; It was more about their selection of a significantly substandard controller from a 3rd party manufacturer. Most organizations that make use of controllers for these kinds of applications usually use 1st party hardware because of its high reliability, and ease of replacement. It is well documented that the specific model of Logitech Xbox controller that was showcased in the interview had known reliability problems. This raised concerns because it showcased that OceanGate were completely willing to use substandard parts for vital functions on their submersibles.

[lockedasian]

Stockton Rush couldn't afford rolls of interwoven carbon fiber material, so he skipped the interweaving process of making the material and took the raw strands of carbon fiber and wrapped it around the pressure cylinder like a spool of thread, adding epoxy. Cross- interweaving the fibers is the most important process to achieve strength, similar to cross-interweaving threads to make a piece of fabric. It's in the video of him during the manufacturing process.