Radioss is stuck in 'Restart Files' loop (Static simulations for Human-Seat interactions)

Goutham Sridhar_21896
Goutham Sridhar_21896 New Altair Community Member
edited November 2021 in Community Q&A

Hello,

I'm a new PhD student trying to run Biomechanical models of Seating simulations left by a previous student. I would like to perform a biomechanical Static simulation of Occupant-Aircraft seat interactions in Hypermesh Radioss. The termination time is 450ms. When I run the starter and engine files (using the '-both' option) in Radioss, 48 animation files get created and after that the analysis is stuck at 238ms (see picture below) and Radioss is stuck in a 'Restart Files' loop.

Can someone please guide me on why I'm facing this problem and how to resolve the issue?

Also, can you please tell me if this is run using explicit or implicit method? I don't know how to identify if this is a static simulation or not? Can you please explain how to define the engine parameters for running a static simulation, please?

Here's the Engine parameters already defined by the previous student in this model:

Run time- 450ms

TFILE - Time_Frequency = 0.0 (Type 4: Binary IEEE 32-bit (Default value))

DT/CRICK/CST - Tscale = 1.0 and Tmin = 0.0

DYREL - T_Period = 30.0 and Beta_Relx_Factor = 1.0

OUTP/DT - Tfreq = 5.0

RFILE - N_cycle = 40000

ANIM/DT - Tfreq = 5.

ANIM/BRICK/TENS/STRAIN and ANIM/BRICK/TENS/STRESS are defined with 'IJK' selected.

 

I'm new to Hypermesh and Radioss , and any useful suggestions and assistance would be really appreciated!

 

image

 

image

 

 

Looking forward to hearing your suggestions!

Thank you very much!

Best regards,

Goutham.

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Answers

  • Rogerio Nakano_21179
    Rogerio Nakano_21179 New Altair Community Member
    edited November 2021

    Hi

    Your model is not stuck, it just happens that the time step is too small (0.13e-13)

    It can mean you need to better better your time step control parameters.

     

    As start in, I would suggest you go thru the tutorials of the Radioss. you can find them in the help documentation.

    And register for an introduction training.

    Please check on the Altair's page for the next training

    https://learn.altair.com/totara/reportbuilder/report.php?id=70&sid=19

     

    I hope this is helpful

    Regards

     

     

  • Goutham Sridhar_21896
    Goutham Sridhar_21896 New Altair Community Member
    edited November 2021

    Hi Rogerio,

    Thanks for your suggestions, I actually saw a video on defining time step control in Radioss (Video link:

    https://altair-2.wistia.com/medias/o0bfml9ah5?wvideo=o0bfml9ah5).
    I tried to define time steps similarly for my model, but in my engine keywords, there is no DT/NODE/CST, instead, there are:

    DT/BRICK/CST(Tscale: 1 and Tmin:0)

    PRINT (N_print: 2000)

     

    Since my model has elemental time step defined, could you tell me what parameters I should change and how to chage so that I can run my simulations correctly and make it faster?

    (PS: In the video, the instructor says that in Radioss, we only have Nodal time step and not Elemental time step. But in my model, DT/BRICK/CST is defined which is elemental time step, could you please explain this?)

     

    Thanks, looking forward to your inputs!

     

    Best regards,

    Goutham.

     

  • Rogerio Nakano_21179
    Rogerio Nakano_21179 New Altair Community Member
    edited November 2021
    Goutham Sridhar_21896 said:

    Hi Rogerio,

    Thanks for your suggestions, I actually saw a video on defining time step control in Radioss (Video link:

    https://altair-2.wistia.com/medias/o0bfml9ah5?wvideo=o0bfml9ah5).
    I tried to define time steps similarly for my model, but in my engine keywords, there is no DT/NODE/CST, instead, there are:

    DT/BRICK/CST(Tscale: 1 and Tmin:0)

    PRINT (N_print: 2000)

     

    Since my model has elemental time step defined, could you tell me what parameters I should change and how to chage so that I can run my simulations correctly and make it faster?

    (PS: In the video, the instructor says that in Radioss, we only have Nodal time step and not Elemental time step. But in my model, DT/BRICK/CST is defined which is elemental time step, could you please explain this?)

     

    Thanks, looking forward to your inputs!

     

    Best regards,

    Goutham.

     

    Hi

    With /DT/BRICK/CST/0

    you need to define the tmin. Without it , the elemental time step control is not taking place.

    Wth this option, as the time step drops to the value of tmin you set, the element strain formulation is switched 

    Refer to the documentation of elemental time step control

     

    https://2021.help.altair.com/2021.2/hwsolvers/rad/topics/solvers/rad/dt_eltyp_keyword3_iflag_engine_r.htm

     

    Also, there is nodal time step control

    it is reached by /DT/NODA/keyword3/flag

    Please also refer to the documentation

    https://2021.help.altair.com/2021.2/hwsolvers/rad/topics/solvers/rad/dt_noda_keyword3_engine_r.htm

     

    Regards

     

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