Finding vertical CG of a large box structure 1

[mackconsult]

We have mfg a large box structure that we need to find the vertical center of gravity. We just shipped it out and have access to it on the other side of town. What I am looking for would be a way to to estimate the vertical center of gravity location on it. The base of it is structural so we can lift it or weigh it with scales no problem, but the walls and roof are not structural enough to tip it or anything like that.

Any help greatly appreciated.

 

[chbrow10]

This might be too late, but it sounds like you want to perform an inclining experiment, like we do when we build ships. We have to experimentally determine the VCG for stability purposes. For something like this, there is a precedure for inclining the object in the air. You will need to know what the object weighs, and good methods for that have been discussed above.

The process works by moving a known weight over a known distance, and measuring the resulting inclination. you have to pick the item up and sling it with a beam make sure that it can only rotate about the longitudinal direction. Then you have to make an apparatus mounted to the top (or bottom) where you can move the known weight a known distance. you might need a small leveling weight to ensure you start from a level position.

You measure the resulting angle with a pendulum or a digital inclinometer.

Then you use an equation that says GM= (known weight x known distance)/(tangent of the resultant angle x the weight of the entire object) . For an incline in air, the GM is the distance from the hinge point to the VCG.

See ASTM F1321 for the process to perform the inclining in water. Same principles apply for in air.

 

[mackconsult]

OR there is this ....

http://www.longacreracing.com/articles/art.asp?ARTID=22