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Design of bolts

  1. Jul 10, 2015 #1
    We are working on a machine component structure that weighs around 500 kg.This component is fixed inside the train on top roof using 6 bolts..Now the part is we need to design bolt size and no of bolts under worst condition..The acceleration of train may be taken as 0.3g,where g-accn due to gravity..

    what kind of forces act on this bolt and how to design? BOLT PLATE.PNG BOLT PLATE.PNG
  2. jcsd
  3. Jul 10, 2015 #2


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    You description says the load is 500 kg, but your diagram says the load is 1000 kg. Which is it?

    Since the train is accelerating, and presumably the c.g. of the load is located somewhere below the mounting plate attached to the roof, you'll need to expand your diagram and draw a free body diagram which includes the load and the mounting plate and then determine the static + dynamic loads when the train is accelerating.
  4. Jul 10, 2015 #3


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    You may want to find deceleration during emergency breaking, I'd guess it's more than acceleration under power.
  5. Jul 10, 2015 #4


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    You don't have any professional Mechanical Engineers working on this project who can figure this out? That's kind of scary, IMO. You don't even mention issues like vibration and shock (I presume this location qualifies for the "sprung truck" shock/vibe spec?)
  6. Jul 13, 2015 #5
    very valid point..The value of deceleration is 0.3g.i mentioned it wrongly..And load consider it as 1000 kg...
  7. Jul 13, 2015 #6
    Hi SteamKing,
    I regret that mistake...Load is 1000 kg..If possible can you elaborate the method...

  8. Jul 13, 2015 #7


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    By using the acceleration of the train and the mass of the load, you can create a "fictitious" force acting on the load, F = ma. Apply this load at the center of gravity of the object, and then use statics to figure out what tensions the bolts must hold.
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