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Error named "ISTOP=-2"

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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Rahul Rajan_21763

Hi,

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

Regards

Rahul R

Unable to find an attachment - read this blog

hiranwale_bharat

Thank you very much Rahul.

Regards,

Bharat

hiranwale_bharat

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

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

Hello Prakash,

Yes I have used Mathe card and it ran smoothly.

Thanks and Regards

Bharat