Error named "ISTOP=-2"

hiranwale_bharat
hiranwale_bharat Altair Community Member
edited October 2020 in Community Q&A

Hello,

 

I am performing static analysis of an object with using MATS1 card for defining stress strain curve and type as elastic. But during the analysis I always get an error named 'ISTOP=-2, Radioss implicit stopped due to time step limit'.

 

I have already tried increasing number of increments, changing the slover type from NEWT to BFGS in '

NLPARAM' but no use.

 

Is there any remedy to avoid this problem ?

 

Regards,

Bharat

 

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Answers

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited October 2015

    Hi,

     

    Please find attached troubleshooting method for Istop=-2 error.

     

    Regards

    Rahul R

    Unable to find an attachment - read this blog

  • hiranwale_bharat
    hiranwale_bharat Altair Community Member
    edited October 2015

    Thank you very much Rahul.

     

    Regards,

    Bharat

  • hiranwale_bharat
    hiranwale_bharat Altair Community Member
    edited October 2015

    Hello Rahul,

     

    1. I have read the PDF and tried to simulate accordingly. But I am still getting the error Istop=-2. I have defined material using MATS1 and Tables1 for stress strain curve.Can this error rise because of the stress strain curve (I guess I should make it more fine that is I should define more points in it). But using the same curve in MATHE did not gave me any error.

     

    2. Also if I have a case which has compressive load and another case which has tensile load. So in such case how should I define stress curve. (i.e. for compressive load case ,curve should be third quadrant and for tensile case curve should be in first quadrant?  I am asking this because in another example, for compressive load, I defined curve in first quadrant and still recieved correct results using Mats1. Material was Rubber i.e. Hyperelastic)

     

    Can you add any comments on this matter?

     

    Regards,

    Bharat

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited October 2015

    Hi Bharat,

     

     

    Since you have a hypereleastic material, MATHE should be the perfect choice. But be careful when referencing the curve because the X axis should be the stretch ratio and not the engineering/true strain.

  • hiranwale_bharat
    hiranwale_bharat Altair Community Member
    edited October 2015

    Hello Prakash,

     

    Yes I have used Mathe card and it ran smoothly.

     

    Thanks and Regards

     

    Bharat

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