Aerospace engineer working to make aircraft greener & safer.

He/him. 🇺🇲

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Joined 1 year ago
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Cake day: June 15th, 2023

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  • The conviction was about a year after the crimes, which is a lot faster than I would expect than in my country. 5.5 years does seem light to me, too.

    The rhetoric is still somewhat apologetic to the perpetrators. Like “it’s difficult for students to resist due to a sense of closeness to their teachers” doesn’t say anything about rank, authority, and power that teachers have over students. And “checking whether a teacher is under excessive pressure” seems to redirect fault away from the perpetrator.












  • I agree with all of that. My intuition is that prior to curing, the polymers are less stable and may change in unpredictable ways depending on subtleties in the storage environment and handling. After curing, the polymers are much more stable and durable.

    Metals definitely are more forgiving, and we have better tools for testing, especially non-destructive testing. Whether the CF flaws are due to fatigue or workmanship, it’s easy to miss them in inspection.

    I’m also curious what the sub designers saw as the advantage of CF for this application. Is light weight really all that advantageous for a submersible? Generally no one chooses CF if they are prioritizing cost.


  • From my limited experience with laying up carbon fiber, I know there’s the raw carbon fiber cloth and there’s liquid resin that you spread into the cloth. It’s also very common to see carbon fiber cloth that is “pre-impregnated” - the resin is already applied to the cloth. Everyone calls this “pre-preg”.

    So I’ve seen a lot of folks online scratching their heads about “how can carbon expire?” or “my carbon fiber (bike/boat/etc.) is N-years old, is it expired?” but I think the most likely thing to expire is the resin. Once the resin is cured it is much more stable.

    Any materials folks or structures engineers who want step in and correct me, please do.