Screwed Up: Can Technology Be A Substitute For Regular Maintenance

The bane of life for anyone who possesses a well-used pile of spanners is the humble nut and bolt. Durable and easy to fasten, over our lifetimes we must screw and unscrew them by the million. When they do their job they’re great, but too often they seize up solid, or more alarmingly, gradually undo themselves over time due to vibration or thermal stress. There are a host of products such as locking nuts or thread sealant to deal with this problem, but the Fraunhofer Institute have an idea which might just remove the worry surrounding important fastenings. Their work has resulted in a solar-powered bolt with an embedded sensor that phones home when the connection loosens, allowing an engineer to be dispatched with a spanner to tighten it up.

The sensor itself is a washer which reports the force placed upon it, when this reduces an alert is sent. Communication is via Fraunhofer’s own MIoTy low-power wide-area network (LPWAN) protocol, but we’d imagine that one of the many competitor technologies could also serve.

This is an interesting idea that could no doubt result in targeted maintenance catching faulty fastenings early and averting disaster in the infrastructure projects such as bridges and wind turbines that they mention. We worry slightly though, because these types of structures have lives not in the few years of most tech products but in centuries. Will an IoT bolt head sensor still be phoning home in a few decades time, or will the system rely on old bolts being replaced at regular intervals of a decade? It’s not unknown for disasters to be the result of failures in fastenings a century old, so we sincerely hope that authorities in charge of whatever bridge relies on these won’t be tempted to skimp on their replacements. Perhaps a guy with a spanner every few years might be a more dependable option.

47 thoughts on “Screwed Up: Can Technology Be A Substitute For Regular Maintenance

  1. What a stupid idea. A) solar? really so what all my equipment needs to be outside for this to work? B) If you have that kind of issue where Loctite or a locking nut don’t work, you have larger issues. Then get a lock wire bolt and use locking wire to keep it there. Jeez talk about over inventing something.

    1. What about the application where the Materials Move underneath the Bolt/Nut.. Just because the Nut did not turn does not mean it’s still tight.

      Granted this is not the First Nut Bolt Washer Combo I’d be using, but for Long Term I think it has applications..

      The Hanger that was built to handle the First Blimps in the US, are MASSIVE arched Beam with Nut and Bolt Fasteners. They pay people to scurry around the structure, to re-tighten them on a regular basis.. If simple Cotter Key/Wire would be the simple fix, I think it would have been done by now..

      Cap

          1. Those Nord-lock washers are truly great. I’ve used them in race car turbo/manifold/exhaust flanges, where everything else fails because of high temperature changes, different materias and heavy vibrations.

    2. I can not believe how much you guys miss that point of these things. Just think of it a nut with a DRM and a monthly subscription. Think about selling this to any of the auto makers if only for lug nuts it would be a near limitless supply money streaming in with the monthly subscription to make sure your lug nuts are tight. Then on top of that if you replace them with a non-drm’ed lug nut, Warranty Void! Shut Automobile Down Now! Do not allow for flat tire to be replaced except at a authorized service center…..well maybe john deere has already looked into this i dunno……

  2. I really can’t see the point – if you need such sensors you build space for them into the frame and wire all the pressure sensors up – effectively turn your construction into one giant and strange shaped trackpad. Its wired, so actually reliable, should work out vastly cheaper as all you need at each sensor is whichever component does the method of sensing used and perhaps a few passives so the central brain can identify which one has gone out of spec…

    Or if you are really that worried about working loose over time use other fastening systems that don’t (or at least wont in this situation) have that issue – weld, rivet, make bigger single pieces, the pinned nut, pinned construction etc…

      1. That is very true of any system that has electronics inbuilt though, which leads to the question of if you really need such a thing over external calibrated tools and weekly/monthly/yearly type inspections

    1. Tbh I’m fairly sure the wire runs for the sensors in your solution would cost more then low power micro and solar panels, together the actual parts are probably in the 50¢ range, and even if they sell it for 20-30$ a bolt, you would likely spend more in copper over the length of a bridge

  3. The six 8mm Nyloc nuts holding the hinges to the clerestory framing for my ventilation louvre won’t ever be vulnerable to a distributed denial of maintenance alert (DDoMA) attack

    1. A few Blackhalks have come down because the (joystick) yoke pin has come out. Commercially it’s worth probably a dollar, militarily it’s worth maybe $100 and the cost a Blackhalk and the lost lives.

  4. And when the communications tech changes? How are the bolts going to call home? Big Solar Flare – they are all fried and can’t tell anyone they don’t work anymore.

    Just recently we were told about a car that had equipment that only continued to work if the subscription fee were paid – wireless cell tech. One manufacturer, before cell carriers shut down a particular protocol messaged all of their cars to keep working if communication were lost.

    I think regular inspections and PM programs are far more suitable.

  5. IMO needs to be more like an RFID tag with maybe a go/no-go pressure switch in it. Cheaper, less to go wrong. We are trying to make less things go wrong right?

  6. They plan on sending an _engineer_ to tighten a bolt?
    I think they are just trying to justify their expensive, useless washer by hugely inflating the cost of bolt tightening.

    That or they are basket weaving majors confused on tech vs engineer. Completely understandable, from dumbasses who have been continuously told they are the smart ones.

    Protip: In cases were nuts and bolts are routinely twisted, the whole thing is also being inspected. These washers do nothing for that point. They don’t understand the basic problem.

  7. I can’t help but wonder about the long term drift of the strain gauge itself. Especially if exposed to a varying environment, let along the stability of rest of the electronics. And failures of said electronics.

    To be fair, other solutions should likely be looked at than trying to solve everything with “technology”.

    Now, a locking washer or thread locking compound might not be suitable, and honestly a more rigid connection can at times be worse than a more springy one, it all depends on the application.

    And at times, perhaps a bolt/screw isn’t even the right tool for the job, perhaps a rivit or weld is the better choice. It though depends on the application.

    1. Strain gauges are typically setup in Wheetstone bridges. With the amplifier physically right on top of the reading gauge and 3 identical gauges in the circuit also right there and the whole thing wrapped in grounded shielding.

      Fundamentally, your right. This washer will have a higher failure rate than a sanely secured bolt.

  8. “Any sufficiently advanced technology is indistinguishable from magic”

    And real magic never fails, so there will be a time that maintenance will become obsolete.

    In the current mad world however, we try to make “stuff” that is so cheap that it is not “economically viable” to repair it and glue cases shut and devise other methods to make repair difficult or impossible.

    Apparently there is a race going on to make sure we run out of raw materials before our society is advanced enough.

  9. Seriously, none of you have any clue of what your talking.

    In the world of NDT (non-destructive testing), technicians are routinely sent around checking and verifying the “tightness” of large fasteners in critical applications – structural flanges, pipeline flanges and fittings, large tanks, etc… This often involves using something like an ultrasonic extensometer, which measures the length of the fastener to less than 0.0001 inches resolution. By using before/after readings, one can get a quite accurate measurement of the load, stress, or strain that a given fastener is under. You measure the length of the fastener at rest, then again when under load. Knowing the elastic modulus of the fastener material and the clamped length, the testing gear calculates load, stress, or strain. Much more accurate than a torque wrench.

    How does this work ? First, all fasteners stretch when put under load. As long as you don’t exceed the yield strength, the faster will relax to original length when unloaded, just like a spring. Exceed the yield strength, and you’ve permanently stretched (and probably weakened) your fastener.

    Second, ultrasonic extensometers measure the length of the fastened by sending a high-frequency (Mhz) acoustic wave down the length of the fastener, and timing the arrival of the reflected echo. Obviously you have to know the acoustic velocity for the given material to determine the length, and then with a few other material constants you can compute the load, stress, or strain.

    All of this requires techs in the field with training and expensive equipment, as well as a non-trivial amount of data management (which machine are you checking ? which joint ? Which bolt ?) From this standpoint alone, a company might find it compelling to use the featured “smart bolt”.

    It does seem a bit overly complicated though.

    1. Additionally – one isn’t always looking for fasteners that have *loosened*. A fastener that is under *more* load than expected often points to other (developing) problems within the joint.

  10. Solar powered? Have the people who designed this not heard of paint? It’s costly enough to keep the paint in good condition on a steel bridge. To have to mask or shield the solar panels on thousands of fasteners would make it take far longer to paint a bridge, and drive up the cost of the work.

    Some large bridges are constantly being repainted, crews start at one end and by the time they get to the other, the paint where they started has weathered to where it has to be painted again. Having to not paint thousands of little spots would increase the time or the crew size would have to be increased.

    Then there’s the problem of every one of those solar panels making a hole through the paint film where moisture can creep in under it.

    Another problem is they’d have to work with very minimal amounts of light due to the majority of bolts in a bridge not facing toward the Sun. They’d have to work with light reflected off not too reflective surfaces. Then there’s the ones tucked away in completely shaded areas that get no light at all or perhaps a few seconds of dim light now and then. Dramatically altering a bridge design just so all the fasteners can get enough sunlight to power their sensors is a silly thing to contemplate.

    Solar Bolts is as dumb as Solar Roadways.

    A technology already exists for washers that indicate the bolt has been properly tightened. They have an internal void filled with plastic, and several radial holes out to the edge. When the bolt is tightened the void is crushed, forcing the plastic out through the radial holes. That provides a visual indicator of proper torque, one not bothered by being painted over.

    How about a HaD article on those?

  11. You do miss the point, the strength of a screw connection is it’s pretension.

    Also there are applications where your additional loads on the that connection are for example vibration and the layer that are kept within a screw connection can also be subject to micro creep of for example softer surface treatment (sprayed zink coating for example will creep).

    Put the nylon ring version under vibratory loads and that additional friction that the nylon gives will be overcome – as well as the much bigger friction from the loaded thread.

    Normally people don’t think much about a screw connection, but you normally tighten it by turning the screw insinde a thread and this constitutes a torque to force multiplier based on the slope of the thread.

    The magic happens within the word pretension, by that force you elongate the screw and that screw acts as a spring is the friction within the thread contact as well as the friction underneath the bolt head.

    But what keeps the screw from pulling itself loose by the slope is the friction underneath the bolt head and the friction within the thread and that friction is a function of the friction coefficient and the “pretension”, meaning reduced prentension (by creeping for example) and you also get a degradation of the self locking of the thread.

    (thought experiment: make that slope slippery – active MoS2 or Graphite – and you will see a self loosening connection when put under certain loads.

    Where MoS2 / Molykote is used and works is because during the tightening the MoS2 layers acting to reduce the friction however the friction will degrade the layer structure of the MoS2 and it will sheared thin and destroyed and thus be inactivated, and in turn the self locking will come into action.

    Never contaminate a thread that is perhaps at first tightend by turning, but in the future will be subjected to hydraulic pulling chances are that the MoS2 will still be active enough to give you “a supprise”.

    And there are different types of screw connections even ones where the nut is just used to keep the pretension and not to tension the bolt – the bolt is hydraulically pulled and the nut is turned down to lock that pretension in place however the surface connections are subject to creeping a gradually flattening of surface roughness this leads to a loss of pretension.

    The reason for using that hydraulic pulling is given when you have long bolts where the friction within the thread gets so high due to the pretension that the twist the screw is subjected will limit the amount of pretension you can accomplish by such a turn-tightening.

    Just to say that much, thread-lock, lock washers(Nordlock), Nylon rings, metal ring, lock-wire, and so on all have a reason to exist, and where applied they mostly work.

    However there are screwed connetions that are in really shitty/dangerous/expensive conditions, hard to reach and so on, and this is where the idea of that washer becomes important.

    Some time ago I tried out a similar system and the result back then were not that good, the failing rate when subjected to force was too high .. was a bench test however.

    And to give an idea the pretension was in the range of 400-700 kN (which is more or less 40 – 70 metric tons of pretension for one screw) we talk about a wrench size of ~2 inches and when not being pulled applied torques in the range of 2500-4000 Nm.

      1. The phone manufacturers claimed “nobody wants a real keyboard” and ensured sales of phone with real keyboards would be low by only offering keyboards on phones with slower CPUs, with fewer cores, with less RAM, less built in storage, lower display resolutions etc. The top of the line phones were only offered in versions without real keyboards.

        1. The best you could get attached to a phone is tiny, crappy chicklet.

          Any phone will work with a blue tooth ‘real keyboard’. Crackberry keyboards weren’t much better than on screen.

          Think about all the time wasted. Getting fast at texting on a keypad, learning to write in ‘palm’ script.

          Makes me feel better about the parts of my youth wasted reinstalling MS and Novell crapware. (Eye starts to twitch as I recall Netmare 2, genning sys from 360k floppys).

          1. IMO the little blackberry keyboards are massively massively better than on screen, as you can actually feel even with big hands like mine that you hit the one you wanted to, and only the one you wanted to. Onscreen its so garbage that you are just having to trust the automatic spelling guesser has picked out the right word, and are basically entirely useless for typing a very deliberate phrase – perhaps to message your co-developer the name of the variable that does x they are asking about it in the code, as while its technically just about possible its entirely hell to be that precise with them…

            And those sliding keyboard phones of the early days of smart phone where you get a keyboard just about as large as the entire phone are simply joyous to use compared to onscreen, heck better IMO than many of the not full size ‘real’ keyboards – as those are usually too big to just use a thumb/finger on without moving your whole hand to get at some keys but can be far too small to actually type on properly (at least when you don’t have tiny hands)…

  12. @Michael / motion detection

    Yes there are systems in use that use either laser speckels or spray-on speckels and a high speed camera in _test rig scenarios_ where the environment is controlable.

    In reallity it is not used (idea: phone camera looks at things) even with those cameras getting being cheap,
    optical systems are prone to error in environmental challenging conditions, you also need to take of that system when doing maintainance on the connections, this is why this “disc” idea is so interesting – it is still in its very early days however – because you can work on the connection without having to dismantle things.

  13. no offense… but i think a lineman or someone who specializes in maintenance of items like this is more reliable than any electronic device…. having said that, a better application would be to use sonic imaging to determine if there is a chance for the bolts to shear, microfractures, etc. there have been ana alarming amount of massive cranes that collapse because a proper enginerd was not deployed for proper maintenance.

    https://m.youtube.com/watch?v=eFwpfkDL-Gk

    1. Could apply a variant of the old school mechanics crack finding trick, whitewash it and bang it with a hammer… now since engine parts are well oiled they will have presoaked the oil for this bit, but when it’s “pinged” hairline cracks will pump oil out and make a dark line on the whitewash. So there’d have to be an extra step of soaking it in oil and washing it off again.

      1. i am unsure of the process of inspection on mega machines and mega structures. however, i do realize the need for someone with proper diligence and qualification to do such things.
        when i worked for a car manufacturer i wont name, they used a dead simple and cheap sound device to identify cracks in welds for quality control. it is ironic because the engines in these cars almost never last to 200k miles. lol

        i will keep your whitewash trick in mind if i ever find myself with the need for such an application.

  14. An engineer definitely came up with this idea. 1) Most bolts are hidden by a cover, so the bolts that would send back data are only there for looks 2) Unless the bolts are for critical components (like a nuclear power plant or an airplane) you would be pinged so often you’d have maintenance guys quitting every week.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.