Tech Tuesday 3/27/18 – Materials Edition

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Oscar Gordon

A Navy Turbine Tech who learned to spin wrenches on old cars, Oscar has since been trained as an Engineer & Software Developer & now writes tools for other engineers. When not in his shop or at work, he can be found spending time with his family, gardening, hiking, kayaking, gaming, or whatever strikes his fancy & fits in the budget.

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27 Responses

  1. Avatar bookdragon says:

    A real treasure trove this week!

    I always enjoy Tech Tuesday and wanted to let you how much I appreciate all the links.

    Smart materials are fascinating, though I’ve seen a lot of them come and go. Shape memory alloy for airplane wings looks cool, but I’d want back up. Most of those alloys fatigue out of full range use well before standard actuator components would. Self-healing materials are a Holy Grail of sorts and I’ve seen a lot discussed with high hopes. I do love the idea of using fungi in concrete though. Even if it doesn’t actually ‘heal’ the material, blunting crack growth would significantly enhance useful life.

    And the bubble chain to reduce the impact of hurricanes is just cool science. 😀Report

    • Avatar Oscar Gordon says:

      Thank you, I enjoy putting them together and I’m happy for my loyal following of readers and commenters on these.Report

  2. Avatar dragonfrog says:

    15 had some wording in it about ‘solving America’s crumbling infrastructure problem’ – but it sounds more like it would help avoid next century’s crumbling infrastructure problem, since the fungus spores have to be mixed into the concrete in advance.

    That seems like a tricky sort of thing to predict – you’re interested in a process that you can’t test in the field without recruiting your unborn great grandchildren to collect the data…Report

    • Avatar bookdragon says:

      There are ways of testing it. Civil Engineering labs most major universities have accelerated weathering and fatigue set ups, and field testing is done on identified strips of road over several years.

      When I was in high school in central Ohio, there was a stretch of state route just north of us that had patches of a number of experimental pavements. The area was ideal since it saw major freeze/thaw, heat/humidity, occasionally flooding, and tons of heavy truck traffic. And yes, there were signs advising that the next two miles were trial pavement, so use caution and stick to the speed limit.Report

      • Avatar Michael Cain says:

        And yes, there were signs advising that the next two miles were trial pavement, so use caution and stick to the speed limit.

        I remember signs like that in Iowa and Nebraska as well.Report

      • Avatar dragonfrog says:

        Accelerated aging tests would be helpful – but does the fungal spores’ aging & decreased viability accelerate by more or less than the concrete’s crumbling? What about the rate at which it repairs the accelerated damage?

        When the material is dead and expected only to deteriorate seems like a simpler thing than a race between deterioration and recovery, mediated by living organisms.Report

        • Avatar bookdragon says:

          That’s a really good question and one I’d expect a well thought out test program to address. Even with completely dead materials, you have to account for things like viscoelastic effects in accelerated aging, so I’m sure it could be handled.

          I personally doubt the ability of the fungi to provide real recovery here. It’s more a crack stop measure. If you want to extend life or increase toughness, finding a way to blunt and/or turn crack tips in emerging fractures is the go-to method. If in addition to keeping the crack from growing, it provides ‘glue’ between the fracture surfaces, it has potential to add years to concrete. Even if it just limits spalling, it could be worth it.Report

          • Avatar Oscar Gordon says:

            Crack growth is one of those very important topics in structural mechanics that the public is largely unaware of.

            Back when I was hovercraft crew, hull cracks were always a concern, given how fast they could propagate in the AL hull (hovercraft vibrate, a lot, who knew?). We always had a drill on hand with a fully charged battery and a 1/4″ drill bit chucked up. If we spotted a crack in any part of the hull when we were underway, we’d grab the drill, locate all the crack endpoints, and drill them. If it was below the waterline, we’d fill the hole with 5 minute epoxy and get back to the ship quick as we could. The hull techs would weld the crack when we got back.Report

            • Avatar Michael Cain says:

              Crack growth is one of those very important topics in structural mechanics that the public is largely unaware of.

              Shows up in all sorts of interesting places, though. Fencing blades break due to microcrack propagation. International fencing competitions require fencers to use blades made of an approved maraging steel alloy, which is much more resistant to propagation. (More expensive as well.) There are some new dual-phase steels that are even better (and even more expensive), but top-level fencers consistently say that blades made with D-P feel weird in use.

              Doing armory work for fencing led me into reading stuff about just how complex a subject “steel” is.Report

  3. Avatar Kolohe says:

    04 – Fish farming has some externalities that we haven’t quite got our hands around yet. Using wild fish for non-food purposes would be even worse.

    edit – I suppose though, rtfa, if the scales are being thrown away under current practices, this use is a net positive development.Report

  4. Avatar Kolohe says:

    05 – the problem is that I think hurricanes are Actually Necessary to get the ‘correct’ amount of annual rainfall in places where they are currently common.Report

  5. Avatar Kolohe says:

    11 –

    “Each cotton aerogel pellet can expand to 16 times its size in 4.5 seconds – larger and more than three times faster than existing cellulose-based sponges – while retaining their structural integrity. The unique morphology of the cotton aerogels allows for a larger absorption capacity, while the compressible nature enables the material to expand faster to exert pressure on the wound,” added Assoc Prof Duong.

    This might have the same problem as the previous generation of super-clotting agents, in that it stops the bleeding, but makes such a mess inside the body that it’s nearly impossible for surgeons to do the follow on work necessary.Report

    • Avatar Oscar Gordon says:

      I think it would depend on the strength of the expansion. Just because something can expand 16x doesn’t mean it will if the volume is constricted. If it can expand enough to staunch the bleeding without adding compressive stress, it’s a win.Report

  6. Avatar Kolohe says:

    12 – It’s possible that the quantity of titanium required is small enough that it is “abundant”, in the words of the article. Titanium dioxide can be used in quantities small enough yet useful enough that it’s economical as an ingredient in massed-produced food, for instance.Report

  7. Avatar Kolohe says:

    13 – isn’t this the same sort of the thing that made ancient Roman concrete so super duper? (and that the secret wasn’t ‘lost’, it just couldn’t really be used without Italy’s specific geology?)Report

  8. Avatar Oscar Gordon says:

    Fun personal bit: Today I became the proud owner of an electric bike. I got this guy delivered (still gotta put it together, the front wheel and the handlebars aren’t mounted).Report

    • Avatar Aaron David says:

      Well, to paraphrase Jaws:

      You’re gonna need a bigger Fluke!Report

      • Avatar Oscar Gordon says:

        I miss my Fluke (it died last year and I haven’t had good cause to get another one yet…)Report

        • Avatar Aaron David says:

          Well, you have good cause now! (I saw the price of the bike, but something tells me you are gonna need good diagnostics with this. At least that is what I would tell myself. Then again, I have three Flukes, so I have probably told myself that too many times.)Report