I have a model that is top heavy which will be sitting on the floor when installed. Is there a way for SW2010 to calculate the force it would take to tip over this object?
I have uploaded a pdf that contains a sample tip over hand calculation. It is a conservative (worst case) approach. It takes friction out of the problem by assuming the foot is against some sort of edge. If there is a chance that the device will slide, then the tip force would be less.
This is semi trivial as a hand calculation. It is basically summing moments about the foot that the system will tip about. Finding the push force when the other foot's reaction force is zero. That will identify the push force that will begin the tip. Continued application of that force will continue the tip. Once the moment due to the weight changes direction (helps to tip vs. resists tip) the system will fall.
At the very least, you could run a series of simulations varying the applied force and looking at the reaction on the foot that will eventually lift off. Once that reaction is zero... or turns to tension... the foot will lift off.
There is probably a more elegant solution... but that was the first that came to mind.
Expanding on Dustin's input...
Tipping happens when the center of gravity goes outside of an objects stance, e.g. a line between where two table legs meet the floor.
As Dustin mentioned, it's a matter of moment. That means the required force will vary depending on where the force is applied. It will also change as the object tips.
As far as using Simulation, I would apply movement to the object by pushing it with another object (like a piston or actuator). I would move the actuator using a slow constant speed linear motion (linear motor) and then get the applied force from the motor.
Man would I love to see a well written tutorial/example of how to do this. This is a perfect example of a question the software is not specifically designed to answer that should still be reasonable to work out.
I believe there is something like this out there but I agree, it would make for a great tutorial.
I've seen several approaches to this over the years, and it depends on the application. I also agree a hand calc can be done pretty quickly to verify this (it just doesn't look as cool if you don't see your equipment rolling over and wonder about the repair bill).
I've seen the use of tilt tables for vehicles to determine rollover angle. So you have your device on a ramp that gradually rotates up from horizontal.
Contact is a more accurate way of modeling liftoff, but not always necessary (and sometimes slow). You can use mates at the extreme lateral contact points (Use a hinge mate for the pivot side and a point-plane coincident mate for the side lifting up) and just monitor the reaction force at the far side for when it reverses direction.
The idea of using an actuator to push on an object isn't bad either, but I think lends itself more to determining the tipping position than the force.
I can put together an example if you want. I'd be interested in know what's more important in most cases; tipping angle or force needed to tip? Is it important to see if the object will tip during transport (ie truck going around a corner)?.
I don't think I would even bother with trying to solve that with simulation. You could just as easily get the answer through hand calculations and probably faster as well. Solidworks can give you CG data but you would still need to supply your own assumptions about the surface it is sitting on. If it is in a low friction situation it will require a much greater force to tip than a high friction situation.
What would be the hand calculation for this? This is not my area of design....something I'm doing on the side.
I of course have the:
mass & center of gravity
I don't know the calculation of the friction I have with the floor (need to figure that out)
I've been looking for a formula for this problem but I don't think I've been looking in the right place.
Would this same equation work in this instance?
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