Static versus Dynamic (impact) load 1

[nestorphi]

Hello Everybody,

I am trying to analyse a composite tube impacted by a certain mass (50 kg) drop at a height of 3 m (velocity = 7.7 m/s). What would be the relationship between the static load (m x g) to the dynamic load (drop at a height of 3 m)?. Obviously, dynamic load should be higher than the static load. I appreciate your help.

Regards to all and thanks lot.

Nestor

 

[Archie264]

Set energy equal to work, that is, set E = .5mv^2 equal to W = fd and solve for f (the force).

But, the problem with this approach is that you have to assume a d to begin with so that requires an iterative process.

Therefore assume a deflected distance that you think is reasonable and use it to generate the resultant force. Apply that force to the system and check the deflection. If it's close to what you assumed then refine the calculations to the degree of accuracy you want. If it's not close to what you assumed, do the same thing, but with larger modifications to your assumptions.

And, of course, watch your units.

 

[rb1957]

1) another impact question ... same answer, "how long does the impact event last ?" that'll determine the impact force due to the impact energy.

2) please don't multi-post, RF one or the other.

 

[MiketheEngineer]

This type of questions has been asked probably hundreds of times. DO a search...

 

[GregLocock]

If you measure the staic linear stiffness of the part, k, then
v0=7.7 x0=0
v1=0 x1=unknown
1/2*m^v0^2=1/2*k*(x1-x0)^2

then peak acceleration=k*x1/m

How does that compare with your answer?





Cheers

Greg Locock


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