Engineering Assessment of the OceanGate Titan Failure
BY Herschel Smith
1 year, 4 months ago
The title of this article is rather broad and audacious, so let’s do what all good engineers would do and set the boundary conditions for the analysis.
All calculations will be approximate given the time invested in this analysis and the purpose thereto. Some assumptions and engineering judgments will be made due to the lack of independently verified information and data. This analysis is meant to be brief and the intended audience is both engineers and non-engineers (for educational purposes). Why am I writing this – out of some sort of ghoulish focus on death? Well, engineers study the ghoulish consequences of the failures of other engineers as part of our profession. Consider the fact that most engineers can explain the cause of the Hyatt Regency walkway collapse (if you can’t, you shouldn’t be an engineer), the Tacoma Narrows bridge failure, the Union Carbide Bhopal disaster, and the space shuttle Challenger disaster (where Morton Thiokol was told to take off their engineer hats and put on their manager hats when considering O-ring temperature certification). This is part of what we do to become better.
Moreover, the public needs to be more aware of things like this. Every time an individual walks into a building or drives on a bridge, they are entrusting their very lives to engineers. Let’s say all you do downtown on a given day is walk into a building to use the restroom. How do you know that the HVAC system won’t kill you? At the Bellevue-Stratford hotel, the engineers designed the intake air to be in the proximity of the condensation pooling, thus concentrating what is otherwise a fairly innocuous bacteria called Legionella to a finally fatal concentration to the occupants.
We’ll go in a sort of flow of consciousness fashion under headings for purposes of clarity, and rather than clutter the analysis with links, a series of source URLs will be posted at the end. I will use information from those sources. Understand that this puts us at the disadvantage of trusting what may be later learned to be erroneous information.
Final Pressure
Computation of the final pressure upon destruction of the vessel is fairly easy, but then fairly complicated, depending upon how precise you want to make it. Under normal conditions, many mechanical engineers use a simple rule for conversion, i.e., 0.433 psi/ft. This comes from the STP (standard temperature and pressure) value of 62.4 lbm/ft³ / 144 in²/ft² = 0.433 psi/ft. So assuming that the vessel imploded at 4000 meters, this converts to 3.28084 ft/m ⋅ 4000 m = 13,123 ft, but we’ll use 13,000 feet. The pressure at that depth is 13,000 ft ⋅ 0.433 psi/ft = 5629 psi. This will be seen to be important later.
True enough, this is a simplification. The assumption of 62.4 lbm/ft³ is at STP, and water becomes more dense down to 39.2 ºF (also, there is a compressibility factor for water to be incorporated). So as the temperature of the water decreases and the pressure increases, the water will become more dense. If asked to solve this more precisely, I would use the ASME steam table data and enter it into TableCurve-2D, then use the fit and coefficients it gave me to enter into MathCAD or JupyterLab for integration. Another option might be just to solve the equations of state. But the resultant value wouldn’t be much different than the one above.
Hull Fabrication
OceanGate apparently used a mixed composite of carbon and Titanium fibers wound with adhesive to construct the hull. Whether this is a good design notwithstanding, the vessel had been to approximately this depth before. Apparently, the assumption was that if it was safely done once, it can be safely done again. But that doesn’t account for deformation where the crystalline structures slip, discontinuities form along grain boundaries, and you go beyond mere elastic deformation to loss of material strength. The operations manager wanted NDE (non-destructive examination) to be performed on the hull and viewport (we’ll get to the viewport shortly). The CEO responded that there was no NDE that could possibly be successful on this design, an assertion I flatly deny. The chief of operations was fired because of his concerns.
Viewport
From all available sources, it is apparent that the viewport was designed and certified down to a depth of 1300 meters, not 4000 meters. I have found no information to contradict this. This was perhaps the largest concern that the operations manager had. The viewport material is essentially Plexiglas. He wanted the viewport to be redesigned by the same company to be worthy and certified down to the same depth as the hull, of course, assuming the hull hadn’t sustained plastic deformation. As the analyst says in the video I embed at the end, this is the most egregious failure of all. I agree. I would assess that it’s mostly likely that the catastrophic failure the Titan sustained was caused by the viewport. It was previously stated by the CEO that each time he descended to that depth, the viewport deformed several inches inward. Whether that was plastic deformation or not is unknown, but that’s what NDE might have determined.
Construction & Vessel Closure
Videos I have seen showed no concern for FME (foreign material exclusion) during either fabrication of the vessel or closure of the aft end (done externally, I’m assuming, with torquing passes on the bolts). Foreign material in any of these design materials or in the closure head would of course completely negate any engineering analysis done on the vessel.
NDE
I am not an NDE engineer, but I know a bit about it. There are many kinds of NDE: visual examination, eddy current testing, acoustic testing, dye penetrant testing, radiograph, ultrasonic testing. Of these, I would surmise that UST would be effective, and I know for certain that radiograph would be a successful test of the hull, and I assume the viewport (I am less certain on the viewport, but the viewport may be an easier test by other means anyway). Cobalt-60 is a commonly used radionuclide for radiography. Grabbing David Kocher, ORNL/NUREG/TM-102, Co-60 emits two photons at 100% yield, 1.173 Mev and 1.332 MeV. For simplification (so I don’t have to interpolate), we’ll use 1 MeV for our calculations.
Using ANSI/ANS-6.4.3, the mass attenuation coefficient for carbon at 1 MeV is 6.352E-2 cm²/g. After doing research in which I found that most carbon fibers are being sold at around 1.5 g/cm³ density, I decided to conservatively use 2 g/cm³ to prove my point. (6.352E-2 cm²/g) ⋅ (2 g/cm³) = μ = Linear Attenuation Coefficient = 0.127 cm(-1). The hull is approximately 5″ thick ≈ 12.7 cm. EXP(-0.127 ⋅ 12.7) = 0.1993. Thus, 20% of the emitted photons would have completely penetrated the hull, and this doesn’t include buildup (in other words, these simple attenuation calculations assume death of the particle at first collision, but there are always follow-on particles). Yes, there is a better way to do this calculation, i.e., with Monte Carlo transport analysis. But doing so wouldn’t change the basic point.
Radiography would most certainly have been a successful means of NDE for the vessel. After all, we perform radiography of pressure vessel nozzle welds in nuclear power plants. I assess the claim made by OceanGate to be completely false, perhaps due to ignorance, perhaps because they didn’t have any safety culture to speak of.
Thoughts on What Engineering Is and Is Not
It is the solemn duty and responsibility of engineers to protect the safety and health of the public. There are dishonest and corrupt actors in every profession, of course, but they are to be called out, shunned, and their license revoked.
Designing a vessel that can go to a shipwreck and view the remains may be fun, challenging, and motivating. Doing it, whether successfully or not, is not engineering. It’s clear from the words of the CEO himself that he held a low view of both safety and highly experienced analysts. But it’s precisely those people he needed to hold him and the project accountable to proper engineering principles.
It’s also not engineering if you solve an ODE (ordinary differential equation). Second year calculus students do this all day, every day, all across the globe. That’s called mathematics. Engineers use math a lot, but doing math doesn’t make you an engineer, and certainly not a good one.
If you want to understand the life of an engineer, consider that ODE in a different context. A client asks you to solve an ODE for him to model a chemical or nuclear system. To begin with, all equations need input. Solving symbolically does him no good. That input might be correct, or it might not be, and might be based on instrumentation that doesn’t have the range it needs, or left in the field in harsh conditions or not inspected and calibrated on regular intervals. A simple field walkdown of the instrumentation the client is trusting indicates that workers are using impulse lines as ladders to get to valves above the instrument. The impulse lines are bent or broken. Thus, the engineer cannot trust that instrument.
The engineer must correct this with the client. He must ensure that there is a calibration done on regular intervals, and he must also understand whether the inputs he has been given are normal operating conditions or transient conditions, and what happens when the system is not operating as intended. The system is out of specification. How does that effect his calculations? What are the consequences of those out-of-normal operating conditions?
You see, he is responsible for every possible use of the system he’s modeling. He must make that clear to the client, must document each and every assumption and engineering judgment in his file, and then write a document that, in today’s expectations, looks more like a book with footnotes, references, reference page numbers, and possible use of alternative methods to arrive at his results (if he used forward differencing in EXCEL, what does JupyterLab tell him and how well does it benchmark?). Did he find errors in his work? Did he find any computational instability due to numerical stiffness of the equations? How did he document and display his results? Can the client use it without confusion, or worse, mistakes and errors that may lead to personnel or equipment safety problems?
Next, on to the PowerPoint presentation of results to the client, along with recommendations for corrective actions, field notes and observations, and statements of liability. After all, the Hyatt Regency walkway collapse occurred due to deviations the construction company made from the drawings and specifications. But our engineer knows that the engineering firm was held responsible for not knowing that, and their errors and omissions insurance had to come to the rescue.
Unless there is complete and total traceability of inputs, references, communications, instrument calibrations, SSC (structure, system and component) qualifications and environmental conditions throughout the entire SSC train, no engineering has been done. I repeat. Unless these things obtain, engineering has not been done. Someone is pretending to be an engineer, but he’s not doing engineering.
These are lessons every engineering student learns in their classes all the way through school. But incorporation of these principles takes time and experience, and rarely if ever have I seen a student fresh out of any school, regardless of pedigree or extent of education, display these attributes. This approach has to be trained into people. That’s the value of age and experience.
The CEO had a low view of that, apparently leading to confirmation bias. Because I’ve done it before, I can do it again. Chain of SSC qualifications (is the viewport qualified to the same depth as the hull), testing to detect plastic deformation, understanding material fatigue, spending a bit more money to ensure that proper engineering principles have been followed, obtaining fully independent review of his design – these are all things that were apparently not motivating or exciting or inspiring to him. The fact that this craft had a fairly new design schema doesn’t negate the need for review by experienced engineers – it increases it. The principles of physics, mathematics and engineering are timeless.
I am not saying that doing any or all of this would have prevented the implosion. I am saying that this vessel was not “engineered.” It was fabricated and set to voyage, but it was not engineered. The company also apparently marketed this vessel as having industry and academic involvement that it didn’t have.
I assess this failure to likely have been preventable, and the company negligent. Unfortunately, this will probably take its place as a case study alongside other engineering disasters like the Hyatt Regency walkway collapse, Union Carbide Bhopal disaster, the Texas A&M bonfire disaster, and the Tacoma Narrows bridge failure.
UPDATE: Source.
New evidence continues to strongly suggest that OceanGate’s submersible, which catastrophically imploded and killed all five passengers on its way to the wreck of the Titanic last week, unfit for the journey.
Arnie Weissman, editor-in-chief of Travel Weekly, initially agreed to join the June expedition, the Washington Post reports, but backed out at the last minute due to a scheduling conflict. A May dive he was supposed to go on also was canceled due to bad weather.
A conversation he had with OceanGate CEO Stockton Rush the night before the expedition, however, still haunts him to this day.
According to Weissman, Rush had bought the carbon fiber used to make the Titan “at a big discount from Boeing,” because “it was past its shelf life for use in airplanes.”
In other words, Rush knew that the carbon fiber — which is a very poor choice of material for a deepsea vessel, as many experts have pointed out — already potentially had flaws that could’ve played a role in the Titan’s tragic demise.
It’s yet another indication that Rush and OceanGate cut alarming corners in the development of the sub. In fact, experts had been warning them for years that building such a vessel while dismissing any efforts to have it qualified and tested by experts and regulators is a very bad idea.
Even after his death — Rush himself was on board during last week’s implosion — the CEO’s poor decision-making and rejections of prioritizing safety are starting to come to light.
“I responded right away, saying, ‘Don’t you have any concerns about that?'” Weissman told the WaPo, recalling his conversation about Rush’s decision to use expired carbon fiber for the hull of the Titan. “He was very dismissive and said: ‘No, it’s perfectly fine. Having all these certifications for airplanes is one thing, but the carbon fiber was perfectly sound.'”
Meaning what, exactly? Certifications for aircraft are fine, but not necessary for sea craft? Anyway, I don’t know how Boeing (or the manufacturer of the carbon fibers) ascertains a shelf life. But this exchange goes to show a cavalier and dismissive attitude towards SSC certification and traceability. I continue to believe the most likely failure point was the viewport, certified as we discussed above down to 1300 meters, or < 2000 psi. If I was the manufacturer of the viewport, at this point in the warranty I would get very, very precise with my calculations of depth, temperature/density assumptions, and pressure, as well as fold in margin of safety.
UPDATE #2: U.S. Coast Guard Launches Investigation into Titan Submersible Implosion.
The U.S. Coast Guard has announced the launch of an investigation into the implosion of the Titan submersible that killed the five people on board.
The Deseret News reported that the Titan lost communications with the Canadian research ship Polar Prince about an hour and 45 minutes after the dive initially began and that the U.S. Navy heard a potential implosion of the submersible on June 18.
The Coast Guard’s Marine Board of Investigation is looking into the case and is set to include officials “from Canada, France and the United Kingdom as they look into what caused the deadly implosion,” according to CBS News.
[ … ]
The Guardian reported that some questions being asked following the incident included questions about “the craft’s experimental design, safety standards and lack of certification” for the submersible.
“My primary goal is to prevent a similar occurrence by making the necessary recommendations to advance the safety of the maritime domain worldwide,” chief investigator Capt. Jason Neubauer said, according to ABC News.
[ … ]
Axios reported that Neubauer said that officials investigating the incident “are taking all proper precautions on site if we are to encounter any human remains.”
No human remains will be found. Without trying to be ghoulish, the bodies have been incinerated and torn apart. This is what happens when engineers don’t do their job. However, this development does expand the potential scope of legal liability for the company, as well as cause pause to consider potential charges depending upon the outcome.
UPDATE #3:
A comment points to this photo.
NEW: photo reveals the monitor in the doomed Titanic sub was *screwed into* the carbon fiber hull… 😳 pic.twitter.com/0mrxf8gTCb
— LeGate🇺🇦 (@williamlegate) June 23, 2023
I would have to know more about how the interior inner lining was attached to the hull before I commented on it. If there is a compressible barrier (such as cork) and the hull doesn’t sustain a lot of deformation, it’s possible this modification to the lining makes no difference. However, if the lining becomes essentially an integral part of the hull and is compressed with it, then the screw holes become a “stress concentration point.” Every mechanical engineer knows about stress concentrations at keys on shafts, teeth on gears, etc., that cause localized stress to degrade the whole structure. It probably would have been better if the device was never mounted on anything attached to the hull.
I highly recommend these videos.
Many more, too numerous to link.
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On June 25, 2023 at 10:25 pm, george 1 said:
Well Herschel I ain’t no engineer but I took one look at that thing and concluded I would not get in it to dive 50 feet. No way Jose.
Now you look at a subs like the Trieste or the Alvin. Those are proper deep dive subs. Not this Titan abomination.
On June 26, 2023 at 12:00 am, Phil Ossiferz Stone said:
I’ll just leave this here.
https://www.youtube.com/watch?v=xCxQhA1nYIo
On June 26, 2023 at 8:55 am, DrBob said:
Having worked in both engineering and science for decades, I will add the following point about engineers: The “50-year old engineer” has seen designs fail which were thought to be good, and has learned an appreciation for the unanticipated. The engineer fresh out of college not only has not had those experiences, but worse, trusts simulations. Too much reverence for computing power, and too little for experience. I am consulting for a group of engineers in graduate school now and it’s the same lesson over and over. I asked them about a fundamental and critical aspect of an imaging system. Instead of measuring it, they want to model it. I started yelling.
On June 26, 2023 at 9:32 am, Fudge Cracker said:
But hey it looked cool
On June 26, 2023 at 10:06 am, Herschel Smith said:
Models and measurements both have their role. For instance, models simulate behavior in the absence of data, e.g., when transient and off-normal conditions cannot be tested because of things like safety. Data confirms the models and lends confidence to the simulations. I’ve seen incorrect models before, but I’ve also seen erroneous measurements.
On June 26, 2023 at 10:58 am, Stealth Spaniel said:
Yikes! That thing was scary looking just being ABOVE the water! But DIE-VER-SITY! Yeppers, that will get you killed. Personally, I don’t want a 22 yro FluffBunny designing my boat, jet, or house. I like my stuff engineered with an old fashioned education and pioneered by a 55+ guy who doesn’t twerk, wear PRIDE T-shirts, or can’t write cursive.
On June 26, 2023 at 12:04 pm, JC said:
Excellent write-up. Thanks for this.
Serious question though: you mention testing for non-plastic deformation. I was under simplistic understanding that elastic/recoverable deformation good, plastic/permanent deformation bad. I admittedly don’t have experience in composites… Can you please offer high-level explanation of the concept/concern, or point me in direction to learn more? Several minutes on Google just keeps circling back to undergrad elastic vs. plastic explanations.
Thanks.
On June 26, 2023 at 12:21 pm, Herschel Smith said:
Great question! I reviewed my writeup and had one word that needed to be changed.
Here is a fairly brief primer. Elastic deformation is okay. Plastic deformation involves irreversible loss of strength.
https://pediaa.com/difference-between-elastic-and-plastic-deformation/
The reviewer also covers this in the first video.
On June 26, 2023 at 12:34 pm, ExpatNJ said:
Carbon fiber is ok for bicycles, marginal for planes, deadly for deep-submersibles.
OceanGate/Titan CEO Stockton Rush did not want to hire, “50-year-old White [he did say White] Engineers”. Well, Rush has just inspired a new catch-phrase:
“Go woke, Go boom!”
[PS. I have never plagiarized. I stole this from:
https://mundabor.wordpress.com/2023/06/24/get-woke-go-boom/%5D
On June 26, 2023 at 12:57 pm, scott s. said:
But there is the saying “there comes a time in the life of any project where you have to shoot the engineers and ship the product”.
On June 26, 2023 at 1:17 pm, Herschel Smith said:
Never heard that expression, but if real, it’s dumb. Anyway, it doesn’t apply to the folks left at OceanGate. They never did any engineering. They might wish they had.
https://www.foxnews.com/world/oceangate-titanic-sub-royal-canadian-mounted-police-not-ruling-out-possible-criminal-investigation
On June 26, 2023 at 1:23 pm, Georgiaboy61 said:
@ H. Smith
Thanks for the write-up. I am not an engineer – wish I was! – but did my best to follow along anyway. Just saw over at WRSA blog a photo of the control monitor or instrument cluster screen – depicting the fact that it was simply screwed into the outer hull of the sub! Even a dumb redneck like me knows that’s a no-no…
@ Scott S.
Re: “But there is the saying ‘there comes a time in the life of any project where you have to shoot the engineers and ship the product.'”
Yeah – usually spoken by people (marketing, sales, management, etc.) who have never been gotten dirt under their fingernails in the course of their jobs, been in a lab, worked a slide-rule, held a hammer, etc. Ask me how I know! Been down that road a lot of times when I was working as a biochemist back in the old days. The guy who ran the division (and later the entire Fortune 500 company) was a finance guy with an MBA or something, whose “real” specialty was taking credit for the work of other smarter people and getting promoted and paid for it.
This particular guy when running diagnostics division, pushed out the door a product which was not yet ready for market – and his engineers, scientists, and the QC dept. had told him so on numerous occasions – and it blew back on the company to the tune of a $200 million dollar “consent decree” which is legalese for a giant punitive fine from the FDA.
Not only did our super-hero division head not apologize, he blamed others for the mishap. And to put a cherry on that particular sundae, he got himself promoted to CEO of the entire company, and a giant raise to boot. The company in question shall remain nameless, but it was headquartered in Abbott Park, IL.
The standard joke by the technical staff – you know, the guys who actually worked for a living, the scientists, engineers, technicians and so forth – was that the higher-ups kept us in the basement because we were poor relations, and they didn’t want visiting dignitaries to see any of us! Even though the tech staff were the people upon whose work the entire success of the company rested.
The story gets better. The company’s star seller in diagnostics at the time was a billionaire-dollar product, a sophisticated automated robotic clinical laboratory diagnostic analyzer. After the initial launch of the product, the firm laid off a bunch of the key computer scientists who written the code by which the machine functioned.
The company’s new business model, thought up by some MBA from Warton or Northwestern University, no doubt – was to make all but a few top key tech people “contingent,” which is corporate-speak for contractors. The core business group, who were permanent and enjoyed much nicer pay and compensation, were mostly finance, marketing, sales, etc. – folks who didn’t get their hands dirty.
Well, by and by, there are problems with the kits (each kit tested for one specific type of compound or substance, i.e. FSH in blood plasma or urine, etc.), but the company finds that the institutional memory and knowledge isn’t adequate to fix the issue, since those guys had been let go. So the company had to hire them back at double or triple their prior rates, to assist in solving the problem. Am I the only one who finds such an approach to be stupid and short-sighted, or is it just me?
The real kicker is that the FDA inspectors who assessed the fine wouldn’t tell the company the source of the citations; i.e., the specific quality control problems. So the company had to hire an outside consulting firm for big bucks to comb through the division’s manufacturing, R&D, product support, and other operations to find and fix possible culprits. Which was done and eventually the company was recertified as go-to-go. After fed.gov got paid, that is. But I digress…
The problem isn’t that sales and marketing want to get products out the door and into the hands of would-be customers; it is that they promise what they can’t deliver in terms of time-lines, and then b*tch and moan about it until some top dog cracks the whip and forces the STEM people to release it, even if it isn’t actually ready.
On June 26, 2023 at 1:27 pm, ExpatNJ said:
On June 26, 2023 at 12:57 pm, scott s. said:
” … ship the product”.
This directive comes from Marketing and/or Management, despite objections from technical people about product safety not fully vetted. Being a Scientist from the Pharmaceutical/HAPPI fields, I can attest to having observed these circumstances.
While the hope is that no blood is ever shed in such a ‘shipping’ decision, from the OceanGate/Titan debacle, it would seem Management got its way, and blood was shed.
On June 26, 2023 at 2:13 pm, Scott C. said:
I spent 40 years as an ITE Engineer and yes at some point you need to stop testing and let the product move on, but if it has not met or exceeded the design requirements at that point then anything left on the table becomes an accepted risk.
The folks running OceanGate were apparently willing to accept 100% risk of failure – never a good idea when human life is on the line.
On June 26, 2023 at 2:18 pm, Herschel Smith said:
As long as you’re honest with your clients. You’d never get a PE to sign off on something like that (I wouldn’t put my own seal on it), so you’d have to ensure that your clients understood that no engineering was involved in the design, and that they’d surely perish if they rode the vessel.
On June 26, 2023 at 2:30 pm, Scott C. said:
Agreed – in most of the testing I have done it was 100% meet or exceed the requirements, if not then back to the drawing board.
The few exceptions I have seen were cases where the original requirement was too tight and the customer bought off on it with the understanding that the requirement was going to be updated.
On June 26, 2023 at 3:17 pm, Watson Elementary School said:
Did they even inspect every inch of the vessel after each trip down there?
WRSA has a photo of a monitor screwed into place!
Darr, derp, drool.
Use some Velcro or some tape anything but screws.
Remember the German fish tank that ruptured?
Is that the same material?
Search reveals that it was.
Maybe the carbon fiber has a problem with water exposure over time and or repeated use at depth?
I’m not an engineer but I do know one and it is an honor and privilege.
On June 26, 2023 at 3:38 pm, FAR_25.1309 said:
“I am saying that this vessel was not “engineered.” It was fabricated and set to voyage, but it was not engineered.”
I think that quite accurately summarizes the situation. When I first read that they used a game controller as part of the design, I first laughed, then figuratively slapped myself in the forehead at the idiocy.
I’m a former electronics hardware designer (and later, aircraft avionics certification engineer/regulator for aircraft modifications). When I worked in black-box design, our products underwent an extensive environmental qualification test program that was mandated and expected by the customer (and ultimately, the regulator). Testing of each box included such things as
– temperature extremes;
– humidity;
– altitude;
– over-pressure;
– salt spray;
– sand incursion;
– fungus growth;
– shock & vibration;
– conducted & radiated emissions and susceptibility (i.e. electromagnetic compatibility);
One item that left an impression on me (since I wasn’t/aren’t a mechanical or materials engineer) was that of dissimilar metals/materials behaviours under extreme temperature and vibration/pressure conditions. Example: how do different materials react alongside one another when they have different temperature expansion/contraction rates? We had an incident where an aluminum heat sink broke off from a circuit board integrated circuit during temperature and vibration cycling. Turned out the aluminum, ceramic DIP IC and epoxy adhesive expanded/contracted at different rates (duh?). This has me wondering if the Oceangate sub had other deficiencies in its structural construction. There’s a video floating around Youtube showing them gluing a metal ring to the carbon fiber hull/fuselage. I’m wondering if the adhesive glue was the only thing holding the metal rings (to which the titanium end-caps were bolted) to the carbon structure, or whether the end-cap bolts penetrated through the rings into the carbon structure (which would introduce its own set of problems/failure modes). Besides the possibly under-rated viewing window, is it possible the metal ring/carbon composite hull/fuselage interface was a weak spot that grew weaker in the colder water depths and/or during the changes in temperature between the ocean surface and ocean depth?
The use of a consumer game controller is just plain asinine. I doubt it has any formal qualification for any of the environmental conditions that I mentioned above. Of concern to me (wireless aspects aside) would be its push-button and toggle switch/lever reliability and ability to withstand temperature extremes, humidity & salt spray (it is on board an sea-going vessel), fungus growth (from being exposed to humidity & salt spray), sand/dust incursion and shock and vibration (in case the unit was ever dropped on a hard surface and compromised internally).
Last year I had a computer mouse start giving me multiple button-bounce clicks after only about seven to eight months of use after buying it brand new. So much for consumer product reliability. Some Youtube videos show other people with the same problem with the same brand of mouse and how to replace the failing push-button mouse button switch. This type of unreliability is unacceptable in an aircraft environment and is unacceptable in any situation involving any life safety system.
The Oceangate “vessel” had no oversight by any regulatory body or subject matter experts. It appears the CEO went out of his way to keep it that way. The engineering profession has no room for anyone who is not humble enough to admit they don’t know it all or who has the attitude that “they’re right and everyone else is an idiot”. I think of the statement by Clint Eastwood in one of his Dirty Harry flicks: “A man’s got know his limitations”. In Canada, engineers are regulated by the provincial/territorial governments (and ultimately report to the respective provincial/territorial overseeing self-regulatory body). It is obligatory upon the practicing engineer to not practice beyond one’s area of competence and knowledge and to work with and consult with other engineers who have expertise that s/he doesn’t.
On June 26, 2023 at 3:45 pm, Roland Smith said:
As a mechanical engineer who has been involved with the design and manufacturing of composite materials for 29 years now, I would consider them *unsuitable* for this application.
A basic fact of fiber reinforced plastics is that their compression strength is only about 50-60% of the tensile strength. Basically, because you can pull on a string but you can’t push on it.
When a composite is exposed to compression along the fiber direction, the resin has to keep the fibers together. And that basically turns a material properties problem into a *stability/buckling* problem. And it converts things like voids and fiber kinking from minor annoyances to potential failure modes.
Compression failures in composites tend to be sudden and catastrophic. Having done bend testing to failure of sandwich constructions, the part can go from whole to completely broken in less than 1/100 of a second.
What I have seen of the pressure vessel constriction is that is was made with filament winding. Nothing wrong with that per se. It’s often used for pipes and and tanks containing inside pressure. What puzzled me was the seemingly complete absence of fibers in the longitudinal direction that I could see.
Also the titanium rings bonded on to the carbon/epoxy tube are a potential cause of failure. While I don’t have experience with titanium, it is well-known that metals like stainless steel and aluminium are very vulnerable to galvanic corrosion when in contact with carbon/epoxy structure. Especially in a salt water environment. So e.g. when bonding aluminium honeycomb to a carbon/epoxy laminate I would always add an insulating layer of fiberglass between the honeycomb and the carbon fiber laminate.
Having said all that, if it is true that the window was only designed and rated for 1300 m depth, I guess we don’t have to look much further for the most probable cause of failure.
On June 26, 2023 at 4:50 pm, Hairball said:
I am reminded of an old Mickey Rooney movie, done when he was but a child:
“HEY KIDS, LET’S PUT ON A SHOW!!”
Sounds like that is exactly the sort of unprofessional, child-like production that a-hole put together, and he killed people in the process.
On June 27, 2023 at 6:31 pm, Todd said:
Here’s the part of the video [starts at 22:07] by Spanish actor Alan Estrada, who dove in the Titan as a passenger, in which Rush explains the 7-inch think plexiglass will “squeeze in about 3/4 of an inch – it just deforms” at Titanic depths:
https://www.youtube.com/watch?v=uD5SUDFE6CA&t=1327s&ab_channel=alanxelmundo
Rush goes on to say:
“And acrylic is great because it squeezes in, and before it cracks or fails, it starts to crackle, and so you get a huge warning if it’s going to fail.”
I do hope that’s another thing he was wrong about. The crew watching and/or hearing the viewport start to “crackle” before the implosion is too horrible to think about.
On June 28, 2023 at 12:29 pm, 0007 said:
Way back when, a team I was on was tasked to do some upgrades at Groton, CT on what was laughing referred to Adm. Rickover’s private submarine. Essentially a deep diving submergible used for oceanic exploring. Anyhow while working on the boat I got to talking to some dudes and they mentioned that the viewing “portholes” were tapered holes with 8″ thick tapered inserts that sealed tighter the deeper the boat went. And it was not an “extreme depth” submergible. . . Mostly used to explore the bottom of the Mediterranean Sea and such from what I was told.