Modelling simulation for 6g shock

[siddy88]

Hi all,

I am a student designing a camera fixture for my senior design project. We are halfway through our project right now and we are trying to do some validation stuff for our fixture.

One of the requirements for our fixture is for it to withstand 6 g's of shock during shipping/transportation etc. the whole fixture sits on one large base plate and most of the shock on the system can be modeled as though it is acting directly on this base plate. I have a few questions regarding this.

a) Any suggestions on what might be the most effective way to do this?

b) 6 gees is acceleration but obviously I can model it as a force as well. Any advice on what is better

c) I was thinking of using ADAMS software to model the shock but have no clue what I would input to mimic the 6 gees of shock.

Any advice on this would be helpful. Thank you

Of course we could just do it once our prototype is ready however this might not be the best idea because if it does not withstand that force then our model will just collapse and that will be bad.

 

[Filip Larsen]

Assuming that the fixture is padded for transport with material that can compress during impact with even force over the distance d and the fixture can sustain k gees, then the padded fixture can be dropped into free fall onto a hard surface from the height h = (k-1)*d. If dropped from above that height the average (and therefore also peak) acceleration during impact will be above k gees. This is of course a very simple model that only gives the "optimal" relationship between h and d, so in practice you will find peak acceleration going above k gees at drop heights below h.

The above model is a simple DC model. A somewhat better model would require that you know or analyze the "frequency response" of your fixture to see if may accept higher gees in higher frequencies. Also, if there is a "resonance" at a fairly low frequency you may want to use a padding that moves this resonance to a "safer" frequency or spread it out a bit.

(Disclaimer: above comments are made from the points of control engineering. I have no special theoretical or practical experience with constructing such transportation paddings).