Change of display of Negative Jacobian Errors

[dougblake]

Does version 2.9.1 no longer display the element number with the negative Jacobian error? I used the information for diagnosing problems with my model when it was run, but noticed when I ran 2.9.1 for the first time, there was a single generic error instead of one for each element. Is there a way to still get the element number information for negative Jacobians?

THanks,
Doug Blake

[sschwaner]

I was wondering the same thing. am having trouble finding the problem areas in my model.

[maas]

Hi,

The option to spit out detailed information on where negative jacobians occurred can be set in the FEBio configuration file (febio.xml, in the same folder as the executable) by adding the tag:

<output_negative_jacobians>1</output_negative_jacobians>

This used to be on by default, but I decided to turn it off because I rarely found this information useful and for large models it can take quite some time and space to print out all the information. Instead, when I debug a model I usually rerun it in debug mode by adding the -g command line option and then inspecting what happens to the model in PostView. Visual inspection of a model can often tell you more quickly what is wrong (e.g. rigid body modes, inverted surfaces normals, buckling etc.) than a long list of element numbers, so this is the approach I would recommend. Still, the option to print out all the elements is still available, if you prefer.

Cheers,

Steve

[sschwaner]

Ahhh, thank you for the advice. I have never used debug mode, but I probably should be using it.

Thanks!
Stephen

[dougblake]

Steve,

Thanks for the clarification. I have used both the -g and the element numbers at different times, and appreciate knowing how to turn it back on when needed.

Doug

[lyra]

Hi all,

Would you please be more specific about where should this line be added to? I mean under which tag of the febio file? I have tried both inside and outside of the "Output" tag, but it didn't work. Would you please help me with it?

Also would you please write an example command which shows how to call the febio in the debug mode?

Thanks

Best

[maas]

Hi,

The flag mentioned above should be added to the FEBio configuration file, not the FEBio input file. The configuration file is usually called febio.xml and located in the same folder as your FEBio executable.

To run FEBio in debug mode, assuming your input file name is called file.feb, you would enter the following command:

febio2 -i file.feb -g

Let us know if you have any further questions about this.

Cheers,

Steve

[avb2132]

Hi Steve,

Hope you're doing well. I'm trying to output the negative jacobians for the FEBio package that came when I downloaded FEBio Studio 2.1.1 for Mac. I'm trying to look for the febio.xml file but I don't see in the folder where the febio3 executable is (sdk -> debug -> bin -> febio3). I think I remember seeing the febio.xml file in older downloads of FEBio Studio though. Any insight is appreciated.

Thanks,
Andrew

[mherron]

Andrew,

The febio.xml file that you're looking for is inside the .app bundle. In your applications folder, you'll see a folder called FEBioStudio. In there, there's an application bundle by the same name. Right click (or control click) on that application bundle and go to Show Package Contents, from there you'll find it in Contents -> MacOS -> febio.xml.

Let me know if you run into any issues.

Michael Herron