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AMS IS LIKELY DIVERGING

Hi,
I have started applying AMS in RADIOSS v14.0 .Initially the simulation is running and after some time. Later an error is sprouting .Pl see the below error message.

** ERROR : AMS IS LIKELY DIVERGING:
TOTAL C.G. ITERATION NUMBER = 1000 AT CYCLE NUMBER 1239

Can you suggest a possible soultion to curb this? The values recorded in .OUT file are normal. in the sense there is no abnormalities in %energy error or mass error%.

I do not know where the problem is, please help me look at it?

Thanks for your support in advance.

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gopal_rathore

Hi,

as the file shows data only for t=0 , it is not clear where the issue is due to.

You can check the animation file and the T01 file and identify if any abnormal behaviour is observed in the model.

What is the scale factor and time step used for AMS. Generally scale factor is 0.67 and time step is 10 times the natural time step i.e time step with no AMS )

Also if possible share .rad file in 13 format.

Solver runs iterations to perform AMS calculation per cycle if this crosses 1000, this error comes which you are getting.

I have an attached an image for reference.

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Hi,

Normally AMS job may either fail or diverge, most likely with an error message. Once an AMS run goes through, several aspects remain to be carefully checked in.

These aspects are:

•Time step value evolution and comparison with the targeted time step:

-The time step should follow the targeted time step without time step drop (occasionally)

-If the time step is at any time smaller than the targeted one, the target time step should be reduced

•Entity controlling the time step at cycle (SOLID, SHELL, SPRING, BEAM, NODE, INTER, and so on.)

•Energy Error evolution (should decrease slowly negatively - not increase)

Monitor and correct these parameters during the run, so that it is possible to converge the run.

Altair Forum User

Hi,
I have started applying AMS in RADIOSS v14.0 .Initially the simulation is running and after some time. Later an error is sprouting .Pl see the below error message.

** ERROR : AMS IS LIKELY DIVERGING:
TOTAL C.G. ITERATION NUMBER = 1000 AT CYCLE NUMBER 1239

Can you suggest a possible soultion to curb this? The values recorded in .OUT file are normal. in the sense there is no abnormalities in %energy error or mass error%.

I do not know where the problem is, please help me look at it?

Thanks for your support in advance.

Unable to find an attachment - read this blog

Altair Forum User

Hi,

Normally AMS job may either fail or diverge, most likely with an error message. Once an AMS run goes through, several aspects remain to be carefully checked in.

These aspects are:

•Time step value evolution and comparison with the targeted time step:

-The time step should follow the targeted time step without time step drop (occasionally)

-If the time step is at any time smaller than the targeted one, the target time step should be reduced

•Entity controlling the time step at cycle (SOLID, SHELL, SPRING, BEAM, NODE, INTER, and so on.)

•Energy Error evolution (should decrease slowly negatively - not increase)

Monitor and correct these parameters during the run, so that it is possible to converge the run.

Hi,can you check my files and see where the problem is?

I am not good at this.Thankyou very much.

Unable to find an attachment - read this blog

Altair Forum User

Hi,

Please go through the files attached and let us know whether you are trying to simulate a similar kind one.

HyperForm tutorials are also attached for your referemce.

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