Tipping analysis for mulitple stack items....
Tipping analysis for mulitple stack items....
(OP)
What is the best approach to calculating the tipping force for a stack of multiple items? We have been asked to design some Layup Mandrels that can be stacked on top of each other for the Autoclave. The mandrels are supported by outriggers with extension legs to hold them off the surface below them. It hasn't been determined how they will move them yet – they just want us to analyze the outriggers for tipping with a stack of 8 (truthfully, it's the seismic analysis that worries us the most.....).
I have no issue doing an analysis with a single rigid body, but what factors should I include for multiple items stacked on each other? There will be a spud to provide some lateral control, but no means to bind the stack together other than gravity. Any advice is appreciated.
Thanks.
I have no issue doing an analysis with a single rigid body, but what factors should I include for multiple items stacked on each other? There will be a spud to provide some lateral control, but no means to bind the stack together other than gravity. Any advice is appreciated.
Thanks.





RE: Tipping analysis for mulitple stack items....
RE: Tipping analysis for mulitple stack items....
You could use software like ADAMS or Working Model to create test cases and see what works. These can model mechanical assemblies to any degree of complexity, and are specifically coded to deal with friction and contact.
As an example of the latter, here's a recreation of a Mythbusters experiment - htt
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Tipping analysis for mulitple stack items....
http://www
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Tipping analysis for mulitple stack items....
Tobalcane
"If you avoid failure, you also avoid success."
RE: Tipping analysis for mulitple stack items....
The only reason that I don't just do a free body diagram is that I am concerned about the interaction of the 8 different bodies on top of each other. If the stack only weighed a few kips I would worry so much, but the total weight could get to 80 k and that's a lot of hurt if it falls down.
Greg
RE: Tipping analysis for mulitple stack items....
What does your seismic event look like? Just a lateral half sine pulse to the base of the stack?
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Tipping analysis for mulitple stack items....
It's the old pulling the tablecloth out from under the wineglass trick.
That is not a general result, but it does indicate that the complexities are there.
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Tipping analysis for mulitple stack items....
You are correct that the linear analysis will not fully capture the instability from the pulse at the base of the stack, but it will tell us if the reactions on the opposite side begin to approach zero. If does get close to an uplift, then I will re-create the model in a different software and run an MES on it.
Actually, after considering your check on the disks, I think I will still run the MES analysis just to prove out the customers desire to stack that tall.
Thanks again..
Greg D