G-forces
G-forces
(OP)
A fluid bearing supplier wants us to specify impact loads in terms of g-forces. Does anyone have any idea on how to convert expected impact loads into g-forces?
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RE: G-forces
If those could be accuratley predicted - the car and plane manufacturers would have little to test...
RE: G-forces
what the...
force is force, acceleration is acceleration.
1g=1 gravitational unit of acceleration
Fe
RE: G-forces
OF course!
I am supposed to an impact load of (say) 5,000 N into an equivalent g-force. How do I go about doing that?
Mike,
I suspect you are right. I think we may be in for a tug of war on the issue of determining "stopping time".
RE: G-forces
Force = Mass * Acceleration
Newton worked that out quite some time back and most of us would have learnt it early in highschool I'd hope. I'd also hope you can rearange it to.
Force/Mass = Acceleration
You then need to divide your acceleration by g to get your equivalent g force. Again, pretty basic stuff.
If on the other hand you have impact velocity or drop height etc then as Mike says, it's a bit more tricky.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: G-forces
How would you convert a force of 5,000 N into an equivalent g-force?
RE: G-forces
David
RE: G-forces
Tobalcane
"If you avoid failure, you also avoid success."
RE: G-forces
What everyone is trying to explain to you is that acceleration and force are not equivalent. You will understand all this better if you purge the term "G-force" from your vocabulary.
A lot of components are said to be able to withstand an acceleration of some number of G's. This reflects some known accident condition that you may subject the component to. Perhaps you will drop your component onto the floor. Perhaps a vehicle accident will generate a known maximum deceleration. Your fluid bearing wants to know this.
Another possibility is that this is not a good description of your accident. Perhaps you will drop a screwdriver on your component, or back a forklift into it. Now, you have an external component, which will have kinetic energy which will have to be dissipated by your fluid bearing. Working out the forces is semi-complicated engineering.
RE: G-forces
RE: G-forces
That is were a SRS comes into play.
May be if you can tell us how the shock is created (drop, hammer hit,...etc)
Tobalcane
"If you avoid failure, you also avoid success."
RE: G-forces
I realize now that a statement like "impact load is 2x the operating load" is meaningless without any mention of the "interaction time".
But, some suppliers are satisfied with such a specification while others require this number in terms of "g-force".
I suppose, now the mass required to compute the g-force will be a combination of the mass of fluid being pumped and the rotor. However, simply adding the 2 masses will lead to a very high load (over-conservative). Also, without a prototype I cannot obtain a realistic measure of the impact force expected at the bearings.
Anyone know a way out of this dilemma?
RE: G-forces
Does that help?
Please stop saying g-force it is driving me mad.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: G-forces
It has more meaning to us
Fe
RE: G-forces
(5lb/32.14ft/s^2)(16ft/s/.05s) = 49.75 lbs
RE: G-forces
That seems awfully generic. What about dropping a 5lb rubber block onto carpet?
Here is a link to another thread on impact... not exactly related to OP, but interesting nonetheless.
http://www.eng-tips.com/viewthread.cfm?qid=218312
-Dustin
Professional Engineer
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