Material definition in Radioss

hiranwale_bharat
hiranwale_bharat Altair Community Member
edited October 2020 in Community Q&A

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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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited October 2015

    Hi Bharat,

     

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

  • hiranwale_bharat
    hiranwale_bharat Altair Community Member
    edited October 2015

    Thank you Prakash for the help.

     

    Regards,

    Bharat

  • jsk459
    jsk459 Altair Community Member
    edited March 2018

    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
    Altair Forum User
    Altair Employee
    edited March 2018

    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
    jsk459 Altair Community Member
    edited March 2018

    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

     

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  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited March 2018

    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
    jsk459 Altair Community Member
    edited March 2018

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

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited March 2018

    Hi,

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

  • jsk459
    jsk459 Altair Community Member
    edited March 2018

    Thanks george.

     

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

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited March 2018

    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.

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