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Active Member
ServusJeff
Posts: 9
Registered: ‎04-26-2013
Accepted Solution

Structural Frame - beam analysis won't start

311 Views, 5 Replies
10-03-2013 11:05 AM

I'm trying to run a stress analysis of a frame made from beam elements. The frame will eventually support a diesel generator. When I run the analysis, I receive the following error:

 

 **** Error detected in the BCSLIB-EXT solver.
 **** Code:  -503
            Exactly zero pivot encountered during numeric factorization.
            Possible reason: The model may not be tied down enough
            or you may have a change in stiffness somewhere in the
            model which is too abrupt.
            Suggestion: check model and boundary conditions.

 

I've tried to check the model and boundary conditions, but can't seem to figure out what is going wrong here. Any help would be greatly appreciated.

 

I've attached the model in question.

 

Thanks

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Active Member
ServusJeff
Posts: 9
Registered: ‎04-26-2013

Re: Structural Frame - beam analysis won't start

10-03-2013 11:06 AM in reply to: ServusJeff
Sorry had to zip the archive to get it to upload for some reason.
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Distinguished Contributor
ilyas
Posts: 139
Registered: ‎06-13-2012

Re: Structural Frame - beam analysis won't start

10-04-2013 02:50 AM in reply to: ServusJeff

Hi,

 

It seems that some of the lines are not connected properly (node-to-node). In FEA, it is important that the elements are connected to each other by their nodes. Simply having a line intersect another line does not actually connect the lines. To connect them, there has to be a node at the intersection. To do this, you can use the Draw > Modify > Global Intersect tool and Draw > Modify > Intersect to split the lines and create nodes at their intersection. If it doesn't work, simply delete the lines and create new ones using Draw > Draw > Line. Though these tools may help, I do believe that the best way is to create the model with the idea that they must be connected at the ends.

 

Regards

Ilyas

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Active Member
ServusJeff
Posts: 9
Registered: ‎04-26-2013

Re: Structural Frame - beam analysis won't start

10-04-2013 06:18 AM in reply to: ilyas
Thanks for the help. The simulation is now running, but the resultant stresses are incredibly large compared to previous frames we have built. I've run the frame analysis in Inventor to compare the results. In Inventor, I have a max normal stress of 21.8 ksi in the vertical beams and a maximum displacement of 0.253 in. In Simulation, I have a max stress of 55.4 ksi at the junction between the little horizontal beam and a displacement of 2.636e12 in. Obviously wrong. Any ideas?
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Distinguished Contributor
ilyas
Posts: 139
Registered: ‎06-13-2012

Re: Structural Frame - beam analysis won't start

10-04-2013 07:04 AM in reply to: ServusJeff

I think some of your lines are still not fully split. Use the Select > Select > Lines tool and hover over the lines to highlight it, make sure all of them are split correctly as I noticed that the global intersect tool did not do its job well on my side. I had to use the intersect tool manually to split the lines. I got 22 ksi worst stress and 0.16in deflection.

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Active Member
ServusJeff
Posts: 9
Registered: ‎04-26-2013

Re: Structural Frame - beam analysis won't start

10-17-2013 12:19 PM in reply to: ilyas
Redrew it from scratch. That fixed it. Thank you very much for your help.
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