Assignment 3-2D Element Formulation Challenge

TO PERFORM 2D ELEMENT FORMULATION FOR RAIL BAR

CASE : 1

• Open Hypermesh>set user profiles to RADIOSS>OK

• Click on the Import solver desk > Import model > select file FIRST_RUN_0000.rad > import

• The Import File of 0000.rad part looks like the below fig (_) in wireframe elements skin only

• Convert the rail part to shaded elements and meshed lines

• Next Step to perform radioss check to Analysis > Radioss

• Set | export options: all | run options : analysis | run number :1 | options : -nt 4 | > save as > select the folder in local disk >Radioss................the file gets run and ready for analysis after that check into the folder and open FIRST_RUN_0001.out file and go through energy error .

• How is the Energy Error in the output file (Runname_0001.out) computed?

  (1)

  %Error=100(Ek+Ekr+EiEk,1+Ek,1r+Ei,1+Ewk−Ewk,1−1)">%Error=100(Ek+Erk+EiEk,1+Erk,1+Ei,1+Ewk−Ewk,1−1)%Error=100(Ek+Ekr+EiEk,1+Ek,1r+Ei,1+Ewk−Ewk,1−1)

  Where,

  Ek">EkEk

  Translational kinetic energy at current time

  Ekr">ErkEkr

  Rotational kinetic energy at current time

  Ei">EiEi

  Internal energy

  Ewk">EwkEwk

  Work of external forces (energy brought to the system)

  E,1">E,1E,1

  Energy at beginning of the RUN (not at time t=0)

  The Hourglass energy is not counted in this energy balance, so that a negative energy error generally occurs (except if using I_shell=24 (QEPH) or I_shell=12 (BATOZ) shells, and fully integrated solids, for which there is no Hourglass).

  %Error MathType@MTEF@5@5@+=feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaiyjaiaadweacaWGYbGaamOCaiaad+gacaWGYbaaaa@3B43@">%Error is bounded to ± 99%.

  The energy error is reset after each RESTART.

  It is possible to stop a job and rerun it by using a control file containing /CHKPT. In this case, error and energy values will restart from their last value.

THE FIRST_RUN_0001.out file look like below fig(_)

• Now, Its time to analysis the data for Rail_Crash check into > results from hypermesh solver view

• After checking into Results from as shown in above figure then the hymesh window is observed as show below

• As mentioned in the question change the Run time to 55 ms & animation data to 25 to do so click on the model > cards change ENG_RUN to 55 & ENG_ANIM_DT to 25 .

• Play the Video We find the crash Happens for rail start we find that

• PLOT the internal engery , 4 RIGID WALL, hourglass energy , total resultant force go to hypermesh icon > Hypergraph 2D

• Click on HyperGraph 2D > select file T01

• Plot the above as shown in the figure .

CASE : 2

• Click on the Import solver desk > Import model > select file RAIL_CRASH_0000.rad > import

Change the Properties of Hat-Section & Close-Out Panel as Mentioned above

• Changing the property parameters for Hat-section & Close-out panel

• After Changing the properties

• Plot Hourglass energy, Internal Energy, 4 RIGID WALL , contact energy

Hourglass Deformation :

When the elements in a model deform but the strain energy is not computed for that deformation then it results in the Hourglass deformation. Usually, this can be clearly seen in the post-processing stage where the elements will have a zig-zag formation.

Now, whenever you are defining the property to a model or a component there is a parameter called Element Formulation ( in Radioss as ISHELL and in LS-Dyna as ELFORM) this name changes for different solvers.

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In Changing the parameters after testing the case 1 we can find the difference in case 2 with respect to changing the parameters ISHELL = 24 (QEPH 4 nodes shells are best combination of cost and accuracy).

We find constant linear plot in hourglass energy .

• CONCLUSION :

1. Observed, Change in Hourglass energy with respect to time .
2. Changing the property parameters gave a major change in the plotting the energy's.
3. Saving the file and knowing the error in 0001.out file.