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Posts posted by Shrinaath

  1. thanks ivan 


    i tried with time step DT/NODA/CST 0.144E-02 i am having mass error and energy error as follow 



    RESTART FILES: 2D_SHELL_0001_[0001-0001].rst WRITTEN
     NC=  605000 T= 8.7604E+02 DT= 1.4481E-03 ERR=-60.0% DM/M= 3.2230E-02
     ELAPSED TIME=       1579.40 s  REMAINING TIME=     304910.89 s
     NC=  605500 T= 8.7676E+02 DT= 1.4481E-03 ERR=-60.0% DM/M= 3.2230E-02
     ELAPSED TIME=       1580.85 s  REMAINING TIME=     304938.64 s
     NC=  606000 T= 8.7749E+02 DT= 1.4481E-03 ERR=-60.2% DM/M= 3.2230E-02
     ELAPSED TIME=       1582.20 s  REMAINING TIME=     304945.54 s
     NC=  606500 T= 8.7821E+02 DT= 1.4481E-03 ERR=-60.3% DM/M= 3.2230E-02
     ELAPSED TIME=       1583.49 s  REMAINING TIME=     304941.06 s
     NC=  607000 T= 8.7894E+02 DT= 1.4481E-03 ERR=-60.4% DM/M= 3.2230E-02
     ELAPSED TIME=       1584.80 s  REMAINING TIME=     304941.00 s
     NC=  607500 T= 8.7966E+02 DT= 1.4481E-03 ERR=-60.5% DM/M= 3.2230E-02
     ELAPSED TIME=       1586.16 s  REMAINING TIME=     304950.37 s
     NC=  608000 T= 8.8038E+02 DT= 1.4481E-03 ERR=-60.6% DM/M= 3.2230E-02
     ELAPSED TIME=       1587.61 s  REMAINING TIME=     304976.63 s
     NC=  608500 T= 8.8111E+02 DT= 1.4481E-03 ERR=-60.7% DM/M= 3.2230E-02
     ELAPSED TIME=       1588.93 s  REMAINING TIME=     304978.07 s
     NC=  609000 T= 8.8183E+02 DT= 1.4481E-03 ERR=-60.8% DM/M= 3.2230E-02
     ELAPSED TIME=       1590.30 s  REMAINING TIME=     304988.53 s

  2. hi 


    i having problem in time step.

    i checked the minimum time step in the model that comes around 1.934e-03. 

    when i run the model in radioss with out mass scaling it takes the DT= 0.1448E-02.

    but usually the minimum time step * 0.9 will be taken in radioss as initial time step, when we calculate that 0.001934 * 0.9 = 0.0017406

    what is reason behind this

  3. hi @Ivan


    i will do some iteration on this Rayleigh damping coefficient and lets u know if i had any difficulties.....


    i having doubt in the spring back i used the implicit spring back option as mentioned in the example 25 but my results are not that much correlating .

    In implicit spring back what kind of solver should we use in tutorial it mentioned /IMPL/SOLVER/2 but in the file which is mentioned in the tutorial DBEND_44 they mentioned /IMPL/SOLVER/1 


    i have attached the tutorial and file from tutorial for reference.





  4. hi @ivan 


    thanks for your reply.

    In Rayleigh damping (/DAMP) how to find the values of alpha & beta. 



    And if i apply the values for alpha and beta means the time step which i imposed through Advance Mass Scaling (/AMS) is not taken into consideration.The simulation runs on with the actual time step... What is the reason behind this issue.


  5. Hi @Ivan


    thank you, its clear......


    energy error% it is goes on increasing 


    2447500  2985.      0.1239E-02 NODE          27 -89.9%   230.2       9.932       5.925       2448.       0.000    
    2448000  2986.      0.1239E-02 NODE          27 -90.0%   229.3       10.88       5.927       2449.       0.000    
    2448500  2987.      0.1239E-02 NODE          27 -90.0%   228.4       11.67       5.930       2450.       0.000    
    2449000  2987.      0.1239E-02 NODE          27 -90.0%   227.7       12.38       5.935       2450.       0.000    
    2449500  2988.      0.1239E-02 NODE          27 -90.0%   227.0       12.98       5.919       2451.       0.000    


    i didn't specify any mass scaling /DT/NODA/CST or /DT/AMS

  6. hi @Ivan


    i am simulating the manufacturing process 3 roll bending process in radioss, early i used 3D model now i am trying with a  2D model, since plate thickness 3 mm

    For that i extracted the midsurface of the plate and assign the thickness of the plate as 3mm. i used P1_shell ishell=24 N=5 thick=3 Istrain=1. 

    i assigned the material property to roll and plate, boundary condition, contact every thing as same. 

    shell is bending only in the region inside the rolls, region outside the roll is not bending i have marked in the image .

     does i have used any shell parameters wrongly.


    i having problem in imposed velocity also that the rotation of roller. the roller is not rotating in both the direction i have assigned negative sign(-) to change the direction of roller in curve editor. 


    i have attached my file pls check 









  7. hi


    i am getting an error what is the problem behind this my simulation goes on like this 



     ELAPSED TIME=        451.37 s  REMAINING TIME=     238056.46 s

     NC=    9500 T= 5.9868E-02 DT= 5.8914E-06 ERR= -0.5% DM/M= 0.0000E+00

     ELAPSED TIME=        476.10 s  REMAINING TIME=     238100.41 s

         RESTART FILES: bend_0001_[0001-0001].rst WRITTEN

     NC=   10000 T= 6.2957E-02 DT= 6.4528E-06 ERR= -0.6% DM/M= 0.0000E+00

     ELAPSED TIME=        500.97 s  REMAINING TIME=     238219.10 s

     NC=   10500 T= 6.6150E-02 DT= 5.8914E-06 ERR= -0.6% DM/M= 0.0000E+00

     ELAPSED TIME=        529.13 s  REMAINING TIME=     239438.85 s

     NC=   11000 T= 6.9340E-02 DT= 6.4528E-06 ERR= -0.6% DM/M= 0.0000E+00

     ELAPSED TIME=        557.75 s  REMAINING TIME=     240755.26 s

     NC=   11500 T= 7.2549E-02 DT= 6.4528E-06 ERR= -0.6% DM/M= 0.0000E+00

     ELAPSED TIME=        584.23 s  REMAINING TIME=     241002.99 s

     NC=   12000 T= 7.5685E-02 DT= 6.1558E-06 ERR= -0.6% DM/M= 0.0000E+00

     ELAPSED TIME=        612.67 s  REMAINING TIME=     242236.66 s

  8. hi pranav hari 


    thanks for ur reply.  i have one more doubt during first pass material undergoes plastic deformation so that material properties of plate will change during first pass, does the change of properties will be taken into account if we do like this?????



  9. hi pranav hari 


    if i do like this means does i need to assign the boundary condition, material laws etc to this model 


    then the material behavior will change know 


    i need the results like stress and strain in first pass should carried to  second pass




  10. hi ivan 


    is type 21 is for shell element in type21 unable to select the slave as brick element


    for arresting the dof's i try one method 

    i created an second engine file to arrest DOF's of the component at a specific time by adding these commands 


    node numbers 


    simulation get terminated because of mass error 


    releasing the dof's is fine works well is there any similar way for arresting the dof's 







  11. hi ivan 

    can u explain me briefly about Tstart/Tstop parameter 


    i need to fully constrain the plate at the specific time i have created constrain for this as in the image is that an appropriate way. when i am running this i am getting the warning as a incompatible kinematic condition and it simulated is get stopped. 







  12. hi pranav hari 


    thanks for your reply


    my work is simulation of 3 point roll bending in that top roller is moved in vertical direction and bend the plate then the peripheral velocity is given to the roller to bend the plate all over its length. i am trying to do more detailed way by apply small displacement and rolling the plate then again apply the displacement and roll the plate. 


    i have done simulation for the first displacement and first pass it working properly i am having problem in the second displacement. 

    i need to apply the second displacement at the same point of the plate where the first displacement is applied on the plate, since it is time dependent i cant able to position the same point because of friction and slip between plate and the roll. 


    is there any other way to do this second displacement by taking the first pass results and positioning the plate then run the simulation. 

    please check the files.





  13. Hi 

    i am doing 3 point roll bending simulation in that i need to gradually increase the top roller displacement (i.e) at first stage top roller displacement is given as 2 units then the plate is rolled.

    After this i need to apply the top roller displacement at the same point on the plate and again rolling need to be done. since it is having friction and slip i cant able to find position at the exact point. is there any way to do by creating a separate engine file or any other way like .sta file




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