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?
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add pinned support at the lift point, remove usual supports. add self weight multiplied by a dynamic allowance for lifting.
thats it!
tony
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....
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?
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...
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..
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 ?
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.
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
Perfect! (well, most likely you will need a lateral support at at least 2 corners)
or spring supports..................
Rafael Medeiros
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Should all of the "fixed directions" be checked? Like on the pic?
Rafael Medeiros
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okei, but dose it look like i have done that according to the piecture i attached?
Rafael Medeiros
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Forces on the inclined cables will produce horizontal forces on your structure.
Perhaps this is true, but your method seems like a lot of hard work for not much gain. But each to their own
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