How can the yield strength be scaled in the radioss input file?

Aslan_20571

Hi all,

When inputting the element volume of a solid element (/INIBRI/FILL) in the radioss input file, the material stiffness and internal forces are equally scaled.

How can I achieve the same for the hardening modulus and (a different scaling for) the yield strength?

Hope someone can help me.

best regards,
Aslan

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Radioss

v2022.3

Accepted answers

PaulAltair

I don't think there is a way to change the material properties in an INI statement , but I'm not sure you need to? Doesn't the reduced material content of the element reduce automatically the yield (of the element)?

All comments

PaulAltair

Aslan_20571

I don't think there is a way to change the material properties in an INI statement , but I'm not sure you need to? Doesn't the reduced material content of the element reduce automatically the yield (of the element)?

Hi Paul, thank you for your reply!
The intent is to compute the distribution of the strain energy. And I am following the standard approach for crash topology optimization (see DOI: 10.1080/13588265.2010.544892 for example, and sec 3 for the material model). I am looking for a similar functionality.

If the option is non-existent, is there an option to define a user material that depends on a new user input in the rad file?

PaulAltair

Hi Paul, thank you for your reply!
The intent is to compute the distribution of the strain energy. And I am following the standard approach for crash topology optimization (see DOI: 10.1080/13588265.2010.544892 for example, and sec 3 for the material model). I am looking for a similar functionality.

If the option is non-existent, is there an option to define a user material that depends on a new user input in the rad file?

A colleague let me know that in fact there is maybe a way to do it:

/INIBRI/SCALE_YLD, I have not used it but maybe it can help?

SCALE_YLD in help

Aslan_20571

A colleague let me know that in fact there is maybe a way to do it:

/INIBRI/SCALE_YLD, I have not used it but maybe it can help?

SCALE_YLD in help

Hi thank you for the tip. I have tried it out but unfortunately, it does not work with the documentation link. The solver ignores the lines of the scale_yld factors, as the element# is not specified. When I include it as:

/INIBRI/SCALE_YLD # brick_ID      nptr      npts      nptt                4         1         1         1       #          scale_yld                4      0.20

The problem is fixed, but no scaling occurs (since the output gives stresses above the new 0.2sig_Y, without plasticity).

I am using 1 integration point elements (the solver also only recognizes the 1 1 1 above as correct) with material law 2. the yield stress given as 'a' in this law was 180, so the scaled stress should be 36 MPa.

Would you or your colleague be able to find what information is missing? Or how the example in the link you provided works differently for my element?

thank you for the help so far!

Best,
Aslan

Aslan_20571

I don't think there is a way to change the material properties in an INI statement , but I'm not sure you need to? Doesn't the reduced material content of the element reduce automatically the yield (of the element)?

"Doesn't the reduced material content of the element reduce automatically the yield (of the element)?"

Yes, you are right.

It is not specified in the documentation (see below), but I tested a simple model of 2 elements by manually reducing the material properties versus using the inibri function. It appears the inibri function scales the youngs modulus, hardening modulus, density and yield strength.

("2. The filling percentage is used for scaling the mass of the element, as well as its stiffness and internal forces." https://2022.help.altair.com/2022.2/hwsolvers/rad/topics/solvers/rad/inibri_fill_starter_r.htm)