Dynamic Simulation: Use Spring Joint or Force?

[LT.Rusty]

I'm designing a hinged cover for something right now that will use a pair of gas extension springs  for assisted opening.    I'm currently working to figure out how much force it will take to open the cover using different values of spring - it's available in 50, 100, 150, 200, etc., lb versions. 

I've tried running simulations using a force applied to the moving end of the gas spring, and I've trued running simulations using a spring joint applied between the fixed and and the moving end of the gas spring, and I'm getting dramatically different results between the two.  For instance, using a 200 lb force shows me that I need about 25 extra lbs of force applied to the handle of the cover to open it, where when I use that same 200 lbs on a spring joint, I need 50-75 lbs to keep the cover closed, because it will open on its own.

Which is the correct direction to go here?

[JDMather]

I will take their lab reports and write up a condensed report when I get a chance and attach here.

It is interesting enough that I will add this one to my book (if I ever get around to writing it).

[LT.Rusty]

heh

I want a review copy of your book, then.  😄

[LT.Rusty]

JD -

Have you had a chance to review the student solutions any further?  I'm still interested in hearing about what you found so interesting on this one ... 

[destinare]

Hello
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