Time step

Altair Forum User

Hi,

I am confused about time step.

I checked minimum time step for the model from Tool-check elems which is 9.636E-04.

Then run the analysis without imposing time step(DT/NODA/CST) and check output file.

In output file got the time step 0.5028E-03.

Both time steps are different.

So which time step I have to consider?

Also suggest the this time step is correct or not  

/DT/NODA/CST
0.900000000000000    1.00000000000000E-02   (if considered time step 0.5028E-03)

Find the attachments and suggest the correct solution.

gopal_rathore

Hi,

The time step for computation is reduced by scale factor of 0.9 by default and can be more based on the loads and boundary conditions and thus the values are not same. You can consider the computation time step.

In DT/NODA/CST 0.9 is the scale factor and 0.01 is the target time step and the computation time step is 5e-04 . This seems to be quite a large gap. In this case if the time step goes less than 0.01 , addition of mass in the system will take place and needs to be verified in the output. 

You can go for using AMS also for the same and make it as 0.67 scale factor and target time step of 5e-03.

Altair Forum User

The time step will be multiplied by 0.9 which is the scale factor and it is used for computation. Check in the starter out (.0000 out) for the time step. The time step you are trying to impose seems to be more. Check  the mass addition in the mass error and impose a good time step.

 

Please refer the video below for timestep in Radioss Explicit.

https://altair-2.wistia.com/medias/o0bfml9ah5

Altair Forum User

Thanks all of you.