Week - 8 Mass Scaling
Objective- To use the mass scaling technique to reduce the run time of the model.
1- The hard limit on mass scaling is 8% and stability should be completely intact
2- Both the DT and TSSFAC parameters should be optimized.
3- A histogram should be plotted to compare the runtime with mass scaling trials.
Explanation-
Mass scaling use for the increase and decrease in the run time of the simulation, in Ls- Dyna its handle by control_timestep keywords. We can optimize tssfac and dt2ms to increase or decrease the run time of the simulation as per the requirment.
Case-1- No Change in .k file.
In this case, we did not change anything in the control_timestep card, hence we can see that run time is too high and the added mass is zero.
Case-2- Control_Timestep card comment out in .k file.
In this case, we commented out the control_timestep card, hence we can see that run time is near to 42hrs and the added mass is zero.
Case-3- dt2ms chnage to -4.5e-5 in .k file.
In this case, we changed the dt2ms to -4.5e-5 in the control_timestep card, hence we can see that the run time is reduced to 26hrs and the added mass is zero.
Case-4- dt2ms chnage to -5.5e-5 in .k file.
In this case, we changed the dt2ms to -5.5e-5 in the control_timestep card, hence we can see that the run time is near 38hrs and the added mass is 2.855e+3
Case-5- dt2ms chnage to -6.5e-5 in .k file.
In this case, we changed the dt2ms to -6.5e-5 in the control_timestep card, hence we can see that the run time is near 28hrs and the added mass is 1.655e+4.
Case-6- dt2ms chnage to -7.5e-5 in .k file.
In this case, we changed the dt2ms to -7.5e-5 in the control_timestep card, hence we can see that the run time is near 28hrs and the added mass is 1.065e+5.
Case-7- dt2ms chnage to -8.5e-5 in .k file.
In this case, we changed the dt2ms to -8.5e-5 in the control_timestep card, hence we can see that the run time is near 18hrs and the added mass is 4.55e+5.
Case-8- dt2ms chnage to -9.5e-5 in .k file.
In this case, we changed the dt2ms to -9.5e-5 in the control_timestep card, hence we can see that the run time is near 22hrs and the added mass is 1.225e+6.
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Case-9- dt2ms chnage to -1.02e-4 in .k file.
In this case, we changed the dt2ms to -1.02e-4 in the control_timestep card, hence we can see that the run time is near 16hrs and the added mass is 2.125e+6.
Results and Graphs-
| TSSFAC | DT2MS | RUN TIME | %MASS INCREASE |
| 0.9 | -3.5E-5 | 194hrs | 0 |
| 0.9 | w/o card | 43hrs | 0 |
| 0.9 | -4.5E-5 | 27hrs | 0 |
| 0.9 | -5.5E-5 | 38hrs | 1.00 |
| 0.9 | -6.5E-5 | 28hrs | 5.80 |
| 0.9 | -7.5E-5 | 28hrs | 3.80 |
| 0.9 | -8.5E-5 | 18hrs | 1.60 |
| 0.9 | -9.5E-5 | 22hrs | 4.40 |
| 0.9 | -1.02E-4 | 16hrs | 7.47 |
Implicit Analysis with changes required---
In this case, we can see the run time is too little as compared to explicit analysis because the software did not calculate the values at every time step its come with the results at only that happens to last. Here total time near to 2minuts.
Conclusion-
1-Mass scaling is done until the 8% added mass reached with a decrease in run time.
2- The trial and error method has been done to vary the value of st2ms.
3- Implicite analysis also has been done.
4- Results and plot has been plotted.