Cable Instabilities

[tomdilley]

I have a relatively simple cable model which has a horizontal cable supporting a series of vertical cables.  I have split the horizontal cable into a chain of smaller elements so there are nodes at the connections between the horizontal and vertical cables.  The assembly case works fine, with just the dead load of the elements themselves.

I wish to apply horizontal (lateral) loads to the vertical cables which will react onto the horizontal cable.  Whenever I do this, I get an instability of type 1 in the global Y direction which I don't really understand how I can overcome.  I could understand a rotional instability but not a directional one.

Any ideas?

Can't attach File as .rtd extension is not allowed?!

Tom.

[Discussion_Admin]

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@tomdilley wrote:

Can't attach File as .rtd extension is not allowed?!

Tom.

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Try now. I just add the .rtd extension to the discussions.

Thanks
Discussion_Admin

[Artur.Kosakowski]

If a rtd file is too large try to zip it first. Otherwise check http://forums.autodesk.com/t5/Autodesk-Robot-Structural/Sending-bigger-files/td-p/3795062

[tomdilley]

Here is the file.

Thanks
Tom.

[Artur.Kosakowski]

As far as I can see the instability is reported for case 2 in which there is no load defined. You have two options:

1. Delete case 2 

2. Set  P-Delta analysis for case 2 (as done for case 1). In such case the case 2 will be just case 1 which is the assembly one.

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