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Radioss Block 11.0 Timestep + Stress

Hey guys,

how it is possible to limit the timestep?
In the beginning of generating the model I want to get the results in 1 hour, not even 2 days.
I tried with
/DT/NODA/0
0.000e+000 1.000e-001
but it doesn´t work. I also tried to change the second value, but nothing happened.

In addition to that I have to check the tensile stress and compression stress. For VonMises I use
/ANIM/BRICK/TENS/STRESS. What is the command for the tensile/compression stress?

Thank you,
Manuel

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Altair Forum User

Manuel

Can you send me your engine file? or tell us the /RUN /ANIM inputs? you can control the time of the event and the result file frequency respectively using these cards, the latter has to be lower than the former.

Also what is the type of analysis you are running/what are you trying to simulate?

The command for the stress looks right you should be able to identify the compressive stress from this output.

Altair Forum User

I try to simulate a hit of an impactor to the top of a cutter. The impactor is acceleratet and the cutter is fixed. The impactor hits the cutter eccentrically, so there are tensile and compression stresses. I need them separated, because the material is anisotropic.

Here is the engine file:

# RADIOSS ENGINE INPUT DECK
# Altair Engineering, Inc. © 2013
# Radioss Engine Deck Generated by HyperMesh v11.0-130
#---OUTPUT DEFINITION
##-----------------------------------------------------------------------------
/VERS/110
/RUN/v4b/1/
1.20000e-03
/ANIM/DT
0.000000 0.000200
/ANIM/BRICK/TENS/STRESS
/DT/NODA/0
0.000e+000 1.000e-001

In HyperView - Result Type, I can't find tensile- or compressive stress.

Altair Forum User

Manuel,

All the inputs look fine,

I would say that the solver calculating the timestep from the model itself, and this is very low (hence overriding your /DT input) and hence the long time taken for the analysis,

Check your engine out file , this will list the timesteps for each iteration, please identify the lowest timestep and the entity that may be causing this, you may have to rethink/redo your model (as far as the identified entity is concerned at least) in such a way that the timestep is convenient for you.

Please note that you can use check elems panel of HyperMesh to get a good idea of the timestep of certain entities before you solve.

Altair Forum User

Ok, the timestep can be limited by mass scaling.
The command is /DT/NODA/CST. The minimum time step and a scale factor is needed.
In my case a scale factor of 6.000e-01 and a minimum time step of 5.000e-07 works great.

Altair Forum User

anuel,

Thank you very much for updating the solution,

for future users with similar problems read A Method to Increase Computing Speed and Maintain Accuracy in

User's Guide > What is Altair RADIOSS? > Block Format Input > Advanced Mass Scaling (AMS) Guidelines

Altair Forum User

Manuel,

The compressive stress must be discerned from the tensor result, for example a negative value in xx when the loading is such, would show the compressive stress.

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