Carbon fiber, one of the Titan submersible's experimental materials, comes under scrutiny

AOL ^ | June 23, 2023 | TOM COSTELLO AND MELISSA CHAN AND MARLENE LENTHANG

[xxqqzz]

The one-of-a-kind Titan submersible that imploded on its descent to the site of the Titanic this week, killing all five passengers, was made with experimental materials, including carbon fiber, which experts say has not been pressure-tested over time in such extreme depths.

Since the fatal dive, the innovation behind the Titan and OceanGate Expeditions — the company that owned and operated the vessel for paid tours to the Titanic — has come under increased and intense scrutiny.

Days after the Titan was reported missing, sparking a frantic search, the U.S. Coast Guard said Thursday that the 22-foot craft imploded, though officials do not yet know when or why.

[xxqqzz]

The US, France, and Russia have military deep sea submursibles. The first was built in 1960,and none has ever been lost. Carbon fiber has never been used for submarines. There is also an issue with gluing titanium to the carbon fiber, as the materials expand and contract at different rates. Apparently, Rush bought the carbon fiber at a big discount, as it was too old to use on airplanes. He hired young engineers, who were cheaper, and who would not tell him their was something wrong with the design. The voyages almost always had mechanical and electronic problems. They might have found problems with the carbon fiber using ultrasound.

[Jonty30]

Carbon Fibre also is known to tear suddenly and expectedly.

[Alberta's Child]

It seems like some basic fundamentals about tensile and compressive strength of materials may have been ignored here.

There are several important reasons why steel displaced iron as the preferred material for structural framing in buildings and bridges long ago. One big one is that steel deforms as it fails, while iron tends to fracture suddenly with little or no warning.

[blackdog]

But carbon fiber is inspiring to 20 something engineers.

[NorthMountain]

Rush bought the carbon fiber at a big discount, as it was too old to use on airplanes.

Those "uninspiring" 50 year old White men would have told him "No. In fact HELL NO!!!"

[Chad C. Mulligan]

Dittos. I was just a dirty-fingernail mechanical penguineer, working mostly in machine tools and then automotive process control, but even at that I was incredulous that anybody would use CF for a submarine hull. Still trying to imagine how they laid it up. No aerospace tape-layer I ever saw would do it.

[FarCenter]

Any leak turns into a water jet cutter.

[Sicon]

Link is no bueno.

[rdcbn1]

Carbon fiber composites are totally unsuitable for the hulls of deep sea submersibles, even in an optimum implementation. If the records of the fabrication of the vessel are correct and the vessel was completely hoop wound (which seems to be the case) then the design is criminally negligent.

Carbon fiber composites have huge positives and and some really bad negatives. Hulls for deep seas submersibles cannot take advantage of the positives of composite construction and are uniquely impacted by the negatives.

Furthermore, it looks like the composite section of the vessel used a technique known as wet winding which is totally inappropriate for this application due to lack of control of the process and susceptibility to defects that lead to critical safety problems.

And nobody in their right mind uses a cylindrical vessel for deep sea work, everyone uses spherical vessels .

[Sicon]

Oh, never mind, I am “unauthorized” to read crap on AOL.com.

[PGR88]

Also carbon fiber

[VTenigma]

Carbon fiber is not the issue, it’s the application in use.

[Abathar]

Carbon fiber is wonderful stuff, I machine it all the time. What I’m understanding about it from the engineers I work with is that it’s great stuff for elongation pressures, but the epoxy would want to start failing in a compressive state. The fibers are meant to hold up under expansion just fine, they are tough as hell and won’t stretch at all, it’s why they are so good for high pressure tanks from the inside. These forces are exactly opposite of that, the pressure wants to push the fibers shorter and then the epoxy comes in to hold the shell rigid. I would love to see the FEA analysis of the sub, especially around the Plexiglas portal area. Wouldn’t it be interesting if Ansys or Nastran showed it failing at only 8% or so safety factor instead of something much higher like what OSHA would demand.

[cgbg]

“He hired young engineers, who were cheaper, and who would not tell him their was something wrong with the design.”

He fired the old engineer who detailed the many reasons why the submersible was unsafe.

The young engineers got the message—shut up and keep getting your paycheck.

[desertsolitaire]

Are younger engineers who may have kept quiet to keep receiving a paycheck, then liable in some litigable way for the results?

[sloanrb]

Video showing the sub construction.

Hoop wound carbon fiber and glued to the titanium endcap.

https://www.couriermail.com.au/news/world/titan-sub-built-by-macgyvering-offtheshelf-parts-journalist/video/de529dc9b8647cb00cc17bb87b768dc3

[griffin]

Yup.

People use a material irresponsibly....then it’s the materials’ fault.

Just like firearms.

Idiocracy proven right, AGAIN.

[griffin]

if used incorrectly or manufactured incorrectly.

[griffin]

its all inherent in the material. Iron is brittle. Steel alloys - and there are hundreds - are all tailored for the use they are asked to perform.

[Iceclimber58]

Been a Yeti mountain bike rider for many years. They switched from all aluminum frames to aluminum frames and carbon fiber swing arms. Then the whole bike was carbon fiber.
I have broken swing arms and frames since the move to carbon.
I never managed to crack an aluminum bike.