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    • Rahul Ponginan

      Please click here for a short but important announcement   03/26/17

      Dear Users Our Commercial and Academic users around the world can use these same forums here as before i.e. the Altair Support Forum , Commercial users from India with solver queries can go to the Solver Forum for India Commercial Users , Academic Users from India and AOC India Participants are requested to go to the Forum for India Academic Users and AOC India Participants , We will be tending to all queries in all the forums promptly as before, thank you for your understanding. 


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  1. Material Law Characterization with RADIOSS

    Hello, I am trying to "fit" a curve (from a simulation) to a compressive test of a rubber. Using the LAW42 (Ogden formulation with "mu and "alpha"). I don't really understand how the "request" and "component" options work when I want to create a vector. As you can see in the attached screenshot. And I don't have the "tensile_test..." file as mentionned in the tutorial (in the picture) to check it. Thus, I can't figure it out how it works... I just know that I need the Force and the displacement from the simulation, but with which type of file (.txt? .rad? etc...) Can you help me please? Thanks, Regards. Corentin
  2. Hello, I am trying to use Hyperstudy to perform an inverse analysis to characterize a rubber. But in the tutorial (p367 attached pdf) I used, there is an .xy file required (Stress-Strain data points). How can I switch my type file .txt to .xy please? Thx Regards, Corentin HyperStudy_11.0_Tutorials.pdf
  3. Material Laws

    Hi George, Ok thx. I will also search computed paramters if they "exist"... I performed a compression test on my rubber, but there is a ERROR (attached) about negative stress-strain curve... It seems it is impossible to use compression test then... Or there is an alternative? Thanks, Best, Corentin
  4. Material Laws

    And I forgot. With the LAW69: Is it possible to know the paramters that the software computed (mu and alpha)? Or is it only a definition of the material through the stress-strain curve (without the "output" Ogden parameters, mu and alpha) ? Thanks again, Corentin
  5. Material Laws

    Hi George, Ok thank you for this pdf! I am actually performing only uniaxial compresion test on my rubbers... Do you think it's enough for the LAW69? It seems ok to me. I am using version 12.0 unfortunately (with a school license). And I can not update it by my own... Thanks, Best, Corentin
  6. Material Laws

    Hi george, I did not find what is the function (Ogden formulation) used for the LAW69. I found this reference "RADIOSS 10.0 Reference Guide2.pdf " for now, but this one is not there. Can you help me please? Thanks
  7. Negative Volume - Hourglass

    Hi George, Thanks for your help. There are .rad files (with Isolid=12 (full integration, no hourglass)), wich is my best result. I do not know what means "update the drivers and update the status". But I will try to figure it out. Best regards, Thanks again, Corentin TEST-Sili-H17-v2.7_0000.rad TEST-Sili-H17-v2.7_0001.rad
  8. Negative Volume - Hourglass

    Hi George, Thank you. It is actually faster with Isolid=24 (HEPH formulation). I have to check material parameters now because there is still hourglass effect (as you can see on the attached screenshot). The computation with Isolid=12 (full integration, no hourglass) give a better result, but is really longer (4*longer). By the way, it seems that material parameters are fine, I guess. And even if I tried to change preferences option, I cant "apply" because the same error messages come up... Then I can't actually select this option. Best regards, Thanks, Corentin
  9. Negative Volume - Hourglass

    Hello, I am studying the compression of a soft material (hyperelastic) with RADIOSS. But it seems like a hourglass effect happens during the compression (as you can see on the attached screenshots). - I used [Ismstr] =2 and [Isolid] =1 - with /DT/BRICK/CST 0.67 0.0001 - material=LAW42 (Ogden) nu=0.495 (incompressible) I can send you the .RAD files if possible. I am trying full integration [Isolid] =12, but the computation time is really (really) increased even if the result seems better (for the begining of the compression). I also got a poblem as the script in the other screenshot. I do not really know where it comes from... If you can help me please? Thanks, Corentin
  10. Material Laws

    Hi George, Thank you, but I unfortunately did not find what is the D parameter for the Ogden formulation through the web. However, I am particularly interested about the LAW69, I think I will use it. But I have misunderstanding about the diference between: [FCT_ID] Bulk function identifier, and [FCT_ID1] Curve identifier for user input data curve and, what is the aim of the '[N_PAIR] Number of data pairs' parameter? If I want to use severals datas? Thanks Best Corentin
  11. Hello, I have a problem when I want to watch my results on Hyperview. Indeed, the numeric value (of the displacement for example) displayed/computed is correct, but during the animation, we can see the displacement does not reach the value (really small displacement animation compare to the value)... I guess it is a problem about the display only. I checked the Scale factor and changed it ('deformed' button), but when I chose beyond around 20, the display diverge/'explode'. Besides, it is not high enough to clearly see the 'real' displacement (value displayed). Can you help me please? Thank you, Corentin
  12. Hello, I am a beginer with Altair softwares (v12.0). I am working on modelling the compression of a soft silicon (similar to the skin). I want to introduce viscosity in my model, so I chose a LAW42+prony serie (and I will try LAW82 too). But when I create a property for the silicon, there are lambda_v and mu_v (navier stokes viscosity). And the only thing I know for now is that its viscosity is 20,000-30,000cps. But I do not know what to set (even the unit recquired for those parameters... I am actualy [N mm g ms] system). Can you help me with this please? Furthermore, I do not know what to set for the minimum time step (dt_min). Thanks, Best. Corentin
  13. Material Laws

    Hello, I am using Hypercrash 12.0 110 (RADIOSSV12X), and I want to use the Ogden model with viscosity (LAW82, "visco-elastic"), but 3 parameters are recquired (alpha, mu and D). But I do not know what is the parameter "D". I check on the "RADIOSS 10.0 Reference Guide2.pdf" (which is LAW62), but that is not mentionned. Can you help me to understand how the LAW82 works in Hypercrash 12.0 please? One more question: Ogden model can be used in different ways (custom formulations... ex: lambda[1]^(alpha[1]-1)...), is it possible to create its "own" custom formulation with Hypercrash 12.0? Thank you, Corentin Rabot