Error 144, Element has singular strain functions

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

Hi,

 

I'm having problems with the solver:

 

Error 144: CHEXA Element 70206 has singular strain functions

Please check material data

 

this error occurs in module stsdrv

 

 

the element is a 2x2x2mm (approx.) CHEXA element representing a part of my aluminum hoenycomb core (homogenized as solids using ortotropic material).

 

the material data is correct and i could run several analysis / optimizations using this material. (only a warning 1553: MAT9 has 1 zero eigenvalues)

 

the strange thing is that sometimes it works, sometimes it doesnt. when i had the error the last time, i remeshed my mesh (again with a ~2mm size) and then i could run it without problems !?

 

 

Can someone explain what this error means and what it comes from? i couldnt find anything useful online or in the help...

 

thanks ! 

Michael

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited August 2015

    Hi,

     

    normally there is a 'material property check' for MAT1, MAT2, MAT3, MAT8 and MAT9. (see Reference Guide, Material Property Checks)

     

    A warning is produced if any individual mode of deformation has zero stiffness. It seems that is the problem with your material model.

    If you have no deformations for this mode, the solver is able to analyse it. If you have deformations, the strains of course becomes infinite.

     

    Try to check your material model.

     

    Best regards,

    Mario

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited August 2015

    Thanks for you answer,

     

     

    Using a MAT1 works. But since the same MAT9 material model works in another analysis, it must be a combination of the mesh and the material that doesn't work properly....

     

    I double checked the material data, all entries for an ortotropic material are assigned. To avoid conditioning problems, G44 is set to 1000Pa (instead of 0), but this has no influence, as it also didn't work with 1e+8 for G44 (which it was by mistake in the beginning). 

     

    regards.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited April 2016

    Hi,

     

    Is anyone has a solution for this issue?

    I also have the same problem when running topology optimization with MAT9ORT.

    I'm trying to optimize 3D printed structure which has weaker properties in Z axis.

     

     

     

    regards

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited April 2016

    Hi,

    Can you please add the below Debug card and re-run the job

     

    DEBUG,HEPPPRTC,1

     

    Please send me the .out file after running with this card

    Regards

    Rahul R

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