# 3D static equilbrium

## Homework Statement

how to find FA, FB, FC, FD in 3D equiblirium static?

## Homework Equations

W1 = 500kg

[URL]http://www.flickr.com/photos/djaguank/5450648168[/URL]

distance (see at image)

http://www.flickr.com/photos/djaguank/5450648168

## The Attempt at a Solution

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PhanthomJay
Homework Helper
Gold Member
I didn't see much of an attempt. Is the load in the center of the table? If no, forget about finding the reactions without a computer program or a copy of Roarke's 'Stress and Strain". If yes, the solution is relatively simple.

I didn't see much of an attempt. Is the load in the center of the table? If no, forget about finding the reactions without a computer program or a copy of Roarke's 'Stress and Strain". If yes, the solution is relatively simple.
yes.. its in the center.. could you tell me how to solve it?? because, i confused about 3D static..

anyway.. do you have any recomendation for 3D static equil book??

thanks

PhanthomJay
Homework Helper
Gold Member
If it's in the center, is there any reason to believe that the force in one leg will be greater than any other, if the table sits on level floor and its legs are identical in lenght? The loading is symmetrical. Most books on statics touch on 3D, which is at a level of difficulty greater than 2D. In 3D, You are dealing with more equations of equilibrium, since there are 3 axes inolved. The particular plate problem is generally statically indeterminate if the load is not centered.

@phantom

thanks for your explanation, i think i start to get the idea..

http://www.flickr.com/photos/djaguank/5452658183/

could it use symetrical?? COG for body and antenna in middle.. but the leg/support not in same plane (see picture from above)

do you have email?? i want to ask you some question, please send your email to g.ghunk.np@gmail.com

thanks again

PhanthomJay
Homework Helper
Gold Member
@phantom

thanks for your explanation, i think i start to get the idea..

http://www.flickr.com/photos/djaguank/5452658183/

could it use symetrical?? COG for body and antenna in middle.. but the leg/support not in same plane (see picture from above)

do you have email?? i want to ask you some question, please send your email to g.ghunk.np@gmail.com

thanks again
It appears that the outrigger supports are symmetrical about the axes of the plane, in which case you could represent the loading as equivalent forces and couples appied at the COG, and compute reaction forces at the 4 supports by looking at the components of the loading about each respective axis, computing the reactive forces accordingly by applying the equilibrium equations in each direction (noting due to symmetry that the loading is shared equally by the near and far supports), then add them up algebraically (a corner support may take the maximum load).
Since this does not appear to be a homework problem, you should post future questions that are not homework related in the General Engineering forum (assuming this is not homework). No private emails, please! You'll get more responses in these forums from a host of others, also.