Autodesk Robot Structural Analysis

[#1]

How can i simulate that the construction is getting lifted in robot. The construction i have build is going to be lifted onto an oil rig. how do i simulate this in robot?

[#2]

add pinned support at the lift point, remove usual supports.  add self weight multiplied by a dynamic allowance for lifting.  

thats it!

tony

[#3]

Kudos for you Tony :-)

[#4]

I have done that now, and I have connected the cable from the four corners to the pinned support. but when i calculate I get several warnings about instability in nodes and other warnings. How can I solve this problem? After the calculation the ratio is extremly high....

[#5]

no sorry, I didnt mean add cables and then a single pinned support.  I mean add 4 (or how many you need) pinned supports at the place WHERE THE CABLE IS GOING TO CONNECT.  you don't really need to model the cable, no?  

[#6]

My construction is going to be lifted at 1 point, so i added a pinned support over center of gravity of the contruction and connected cables from it to the 4 corners... but that didnt work very well... so what you are saying is that i should add 4 supports over center of gravity and then i dont need to pull cables to the corners? 
I dont need to calculate the wire no... 

[#7]

I would not add the support OVER the CG, rather add a support(s) to the BEAM itself at the point(s) where the cable will attach.  Looking at the reactions at each support will tell you if the structure will be stable when it's lifted.

Adding a single support for a structure with no rotational restraint can't ever be modelled..

 

[#8]

I have attached a pic of what I have done, is this what you mean I should do (supports.png)? I have also attached a pic of how the lift will look like in my mind (supports2.png). Will it calculate the same thing ?

[#9 · Accepted solution]

Of course, the structure modelled in "supports2" can never work.

It can spin around the support with out ever stopping!

So no, it won't calculate the same thing.  
 

[#10]

okei, but if i had added a support that only takes forces from x and y directions in each corner at the bottom of the construction, and made sure that the reactions in the support is very low, so that the construction would not spin, would that be a possible solution? and make the support in top only takes forces in z-direction