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  1. GregLocock

    Bending Force calculation on Reinforced bar bundles

    The required bending moment for fully plastic deformation will be somewhere between 15 times the moment of plasticity ((d^3/6)*yield_stress) of a single bar, and that of the entire cross section, which would be about 3 times bigger. But the bundle will be permanently bent once the outer fibres...
  2. GregLocock

    critical speed/natural frequency confusion

    Yes the first critical speed of the shaft is the first bending mode of the non rotating shaft. Am I right in thinking that gyroscopic and centrifugal forces seem to influence the lateral natural frequencies of the shaft in the rotating reference, as they essentially provide a "stiffening"...
  3. GregLocock

    Geodesic propulsion

    "Nothing is accelerating in that case. " Well that's me out of the conversation.
  4. GregLocock

    Thailand/Myanmar Earthquake: VIDEO Dramatic collapse of a high rise in Bankok

    "May also want to rethink the pool on the roof thing in earthquake prone areas" Could go either way. Correctly designed they could act as a Tuned Mass Damper. I haven't done the numbers.
  5. GregLocock

    Geodesic propulsion

    "free-falling objects experience no acceleration due to the body force" in their own non inertial frame of reference. Using a non inertial reference frame will tend to end in tears. Consider a 3 body universe. The earth. The hapless observer near the earth, who is the frame of reference. And a...
  6. GregLocock

    Excavator bucket pin material

    Easier to replace a pin than a bushing.
  7. GregLocock

    Net zero could make flying “something for the privileged”, the boss of Qantas has warned.

    Net zero could make flying “something for the privileged”, the boss of Qantas has warned. Vanessa Hudson, the chief executive of the Australian flag carrier, said the higher costs associated with clean fuel were likely to push up air fares and could put them out of reach of the masses. Her...
  8. GregLocock

    Wiring diagram for a petrol generator required

    "if it does spark at the top of the exhaust stroke, perhaps it doesn't matter. (I hope not.) " It doesn't, it's called wasted spark and is benign. https://en.wikipedia.org/wiki/Wasted_spark_system
  9. GregLocock

    Root cause of harmonic oscillation in telescopic column

    I have seen successful estimates of stick slip problems, you need to know the axial and radial compliance of the blocks and of course the coefficients of friction, as well as all the other obvious properties of the system
  10. GregLocock

    Excavator bucket pin material

    I sort of doubt that UTS is the most important property of the pin material. I'd take a guess that most excavators use something designed to be hit with sledgehammers and covered in wet gravel. Somewhere between mild steel and axle steel.
  11. GregLocock

    Tightest realistic tolerance of a 200mm ID cylinder

    If you put a kevlar wrap over it you could get zero expansion with temperature since kevlar has a negative COTE
  12. GregLocock

    Root cause of harmonic oscillation in telescopic column

    Shrugs. Without details of the payload, geometry of the tubes etc then it's all going to be handwavium but at a guess you have a non linear kitchen drawer sticking type problem if you only have one set of acetal blocks. 92 Hz is irrelevant.
  13. GregLocock

    Omniscient Elon Musk seez....

    When you are in a hole stop digging. Diesel was backed by big names in German industry, including Krupp.
  14. GregLocock

    Nuclear Now

    Never heard of it. Here's wiki https://en.wikipedia.org/wiki/Nuclear_Now Nuclear is expensive. About $10B/GW. Wind and solar and batteries comes in at only $30B/GW of 24/7 power, although to be fair there is another 1.5 GW of 'free' power when the sun shines or the wind blows more than average...
  15. GregLocock

    Follow Up

    Although this topic is not technically oriented Oh, I thought that the detail of what color you selected was pretty technical. Compared with the rest.
  16. GregLocock

    Omniscient Elon Musk seez....

    When Cummins invented the Diesel engine Earful, utter scorn, incoming. Oh, then why isn't it called the Cummins engine? Hint : Rudolf Diesel.
  17. GregLocock

    The wheels are falling off the Net Zero Bandwagon 2025 edition

    Ripple looks like it had a history of financial monkey business, and also had late connections for their windfarms. https://au.trustpilot.com/review/www.rippleenergy.com?page=3
  18. GregLocock

    Understanding when a ductile part breaks

    Just to add to the complexity the plastic moment method for steel frames actually assumes yield throughout the cross sections that form the hinges. So the structure is still intact, if bent. Similarly the crumple zones on car are designed for post yield integrity.
  19. GregLocock

    Economics of green hydrogen

    One issue I've seen in that sensible approach is that the market for green steel seems to be rather limited.

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