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Material definition in Radioss

Hello everyone,

In radioss ,while defining material there are lot of property options are present. But what if I don,t have properties available apart from E, density, Poisson's ratio and stress strain curve. How do I define material correctly then. I am trying for rubber materials.

Regards,

Bharat

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Altair Forum User

Hi Bharat,

In your case you can use MAT/LAW 36 for the properties which you. Rest you can leave it default.

hiranwale_bharat

Thank you Prakash for the help.

Regards,

Bharat

jsk459

Hi @Prakash Pagadala

I have one query about applying material property. Suppose if a material data doesn't have yield limit and it has only ultimate tensile strength how can we define it in the curve ? It is Nylon product so i have used LAW 36

Altair Forum User

Hi,

For /MAT/LAW36, the elastic portion of the material is defined by Young modulus and Poisson’s ratio where as the plastic behavior is defined by the stress-strain curve.

And the curve should start from the yield point value, in short the curve should have post yield values.

For your case you can try with /MAT/LAW65 (ELASTOMER), where user has to provide the full stress-strain curve.

jsk459

Hi George,

Thanks for your feedback.

Please see the attached material data and i have defined it in LAW36 as shown below.

Density - 1.16e-9 ton\mm3

Poisson ratio : 0.33

youngs modulus : 13800MPa

Stress- strain Curve :

0 207

0.02 210

1 210

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

Altair Forum User

Hi,

207 is the tensile strength of the material, that is the ultimate strength a member can carry but when you define as this in /MAT/LAW36 207 becomes the yield strength and it breaks at a very close value to yield, behaving something like a brittle material.

I'm not sure whether this will give you the proper results.

jsk459

Ya i am also having the same concern. So for these kind of materials which material card i need to use ?

Altair Forum User

Hi,

As suggested above you can try with /MAT/LAW65 (ELASTOMER) for nylon but user has to provide the full stress-strain curve.

jsk459

Thanks george.

What is the difference between LAW36 and LAW65. Both are elastic-plastic behavior card right ?

Altair Forum User

Hi,

In LAW36 user has to provide the stress-strain function from post yield values, so that it defines the plastic behavior of the material.

Whereas in LAW65 for the material behavior user has to provide the full stress-strain curve, and I feel that for your purpose this material law will serve the purpose.