Loads

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Anonymous Poster	Loads 08/04/2009 3:03 PM
	Can anyone please explain the difference between gradually applied loads, impact/shock loads and suddenly applied loads?
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jack of all trades Guru Join Date: Sep 2006 Location: Auckland, New Zealand Posts: 8777 Good Answers: 376	#1 Re: Very Urgent 08/04/2009 3:12 PM
	How about some general examples to simply illustrate loads. A gradually applied load is the equivalent of me leaning on you. A suddenly applied load is the equivalent of me pushing you. An impact/shock load is the equivalent of me slapping you. That's about as simple and clear as I can explain it to someone who doesn't know what the basic definitions of the words 'gradually', 'impact', 'suddenly' and possibly 'load' are. __________________ jack of all trades
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sb Guru Join Date: Mar 2007 Posts: 2550 Good Answers: 103	#2 In reply to #1 Re: Very Urgent 08/04/2009 10:04 PM
	ASAICG BTW: Why not punch? __________________ Fantastic ideas for a Fantastic World, I make the illogical logical.They put me in cars,they put me in yer tv.They put me in stereos and those little radios you stick in your ears.They even put me in watches, they have teeny gremlins for your watches
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jack of all trades Guru Join Date: Sep 2006 Location: Auckland, New Zealand Posts: 8777 Good Answers: 376	#3 In reply to #2 Re: Very Urgent 08/04/2009 10:55 PM
	I actually considered punch but that is more applicable to a 'hammer' load than 'impact/shock' load. As this was outside of the scope of the original question I didn't bother putting it in. Keep it simple after all. __________________ jack of all trades
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Mikerho Guru Join Date: Jan 2007 Location: Moses Lake, WA, USA, Thulcandra - The Silent Planet (C.S. Lewis) Posts: 4216 Good Answers: 194	#5 In reply to #1 Re: Very Urgent 08/07/2009 2:15 PM
	GA! _{I felt like slapping him myself!} __________________ "Reason is not automatic. Those who deny it cannot be conquered by it. Do not count on them. Leave them alone." - Ayn Rand
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aeon Active Contributor Join Date: May 2009 Posts: 10	#4 Re: Loads 08/04/2009 11:56 PM
	Guest (post 0): As load is applied, the applied load increases from zero to its maximum value in a finite time t_r. If t_r > 3/f, where f = first-mode natural frequency of structure, then your applied load is considered to be gradually applied (static), meaning dynamic effects can generally be ignored. Let's take an example. Let's say your applied load is applied from zero to its full value, in the shape of a quarter sine wave, in an elapsed time of t_r = 70 ms. And let's say your structure fundamental natural frequency is f = 45.6 Hz. Therefore, because 0.070 s > 3/(45.6 Hz), your loading is static. Conversely, I think sudden loading will be when t_r is significantly less than 3/f.
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aeon (1); jack of all trades (2); Mikerho (1); sb (1)

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