reasons for Singular stiffness matrix issue

Hi Every one,

Recently, I try to analysis frame structure with certain "O" shape crossection beam. If I change the crossection dimension, the solver will report the the singular stiffness matrix report.

However, if I use the default dimension of crossection, the solver can generate calculation results.

So, is there anyone know what's the reason for this.

Best Regards,

Yunlong

Attachments:

Demonstation.3dm, 2 MB
DemonstrationOfProblem.gh, 213 KB

Replies to This Discussion

Permalink Reply by Rafael Pastrana on May 8, 2015 at 8:03am

Hi Yunlong,

Is your grasshopper and rhino files the right ones? Tried to open them but it apparently looks like there are no properly referenced curves....See screenshot below.

Best,

Rafael

Attachments:

error.JPG, 133 KB

Permalink Reply by Yunlong Tang on May 8, 2015 at 8:12am

Hi Rafael,

Thanks a lot for your help. Sorry for the problem. I just update the upload. Can you download it again to see errors. If it cannot match again. You can directly select all the curves in the Rhino model. These are the frame I want to analysis.

Thanks again for your help.

BEST REGARDS,

yUNLONG

Permalink Reply by Rafael Pastrana on May 8, 2015 at 9:14am

Hi YunLong,

Apparently, 2 of your lines are not connected to the others, and I think this is why Karamba shows an error.

You could always use the "Connected Lines" component to see if all the lines are properly connected. In these case, it shows that 2 lines are not.

Attached comes a modified version of your script that demonstrates the point and makes a sphere in the middle of those "disconnected" lines for easier identification.

A screenshot also comes so you can see what I mean :) See if by reimporting your lines and skiping these two your model works.

Furtheremore, it is always good practice to set your Rhino file units to meters. Otherwise, Karamba will yield strange results!

Hope this helps :)

Rafael

Attachments: