Exactly my thought. But, then I’m a 50+ year old white guy, so unqualified to speak.
In my personal experience w/ carbon fiber overwound tanks for compressed natural gas — my very first thought when I first heard they used a carbon fiber “pressure vessel” was:
“Wow, ballsy; carbon fiber composite is great in tension, worthless in compression”.
Funny, the downvotes from people who (like the CEO, apparently) … don’t have a clue.
When you hear a “pop” or a “crunch” from a carbon-fiber wound composite tank: it means some part of the fiber/resin matrix has delaminated, or allowed intrusion of gas/fluid into its matrix.
This means that this layer of the vessel now allows relative motion under torsion or compression.
If the intruding material is higher pressure than the average within the matrix — it will push the matrix apart, causing more delaminating, at ever deeper levels (now exposed to the intrusion).
At the massive pressure differentials in this situation (800 bar), failure of this vessel once compromised would predictably happen in milliseconds. As it turns out…
There was a time people came to HN because of the interesting comments by subject-matter experts.
The downvotes might be from people that don't realize that "But, then I’m a 50+ year old white guy, so unqualified to speak." is a reference to something else the OceanGate CEO said
Composites are used all the time in applications in which they undergo cyclic compression. So your first thought is one you should have dismissed. You know what else is good in tension but not in compression? Bicycle spokes. And yet...
There are plenty of other potential design flaws. The assertion that fibers are not good in compression is facile.
Any compression pressure gradient that causes the N-layer composite to yield beyond its natural elasticity, and causes any breakdown of level 1 in the N-layer matrix allowing intrusion of fluid beyond that level, has now caused a permanent failure.
You now have a vessel of effective thickness N-1 (the outer layer will be sheared away and lost).
However, your new N-1 layer vessel now has an average pressure gradient across N-1 instead of N layers, increasing the deflection of the remaining layers, resulting in accelerated cracking, failure and loss of the next layer.
This all occurs over < ~1 millisecond at an 800bar pressure differential.
This failure mode is radically different than the failure modes of carbon fiber composites under tension. The capacity of such vessels for compression vs. tension is so comparatively low that it would be deemed effectively zero in most cases.
In my personal experience w/ carbon fiber overwound tanks for compressed natural gas — my very first thought when I first heard they used a carbon fiber “pressure vessel” was:
“Wow, ballsy; carbon fiber composite is great in tension, worthless in compression”.