Week - 8 Mass Scaling
Objective:- The objective of this assignment is to use mass scaling to reduce the runtime of a model and ensure the stability of mass scaling with mas scaling hard limit of 8% .
Procedure:-
Case1 :- W/O mass scaling the dt value is observed to be 4.40e-05 and the corresponding total clock time is 64 hrs 19 mins.
CASE 2:- WITH MASS SCALING
The computational time for the simulation was 64 hrs, to reduce this time the initial time step should be increased. The time step generally gets affected due to the min length elements which takes for time to process. So, timestep
Can generally be increased by giving physical mass to the min length elements. So, Timestep keyword is used where TSSFAC and DT2MS values are provided and the time is compare. DT2MS is the initial timestep provided and TSSFAC is the factor by which this DT2MS time for the min length elements will get boosted increasing the masses by some amount.
TSSFAC- 0.90, DT2MS- 5.40e-05, dt-4.86e-05,CT: 27hrs 7 mins,0.00822%
CT=20hrs,TSSFAC- 0.95, DT2MS- 5.40e-05, dt=4.86e-05 mass add ratio=0.00822%
CT=18hrs, TSSFAC- 0.9, DT2MS- 8.40e-05, dt=7.56e-05 mass percentage 1.40%
CT=13hrs, TSSFAC- 0.9, DT2MS -8.50e-05, dt=7.65e-05 mass percentage 1.58%
CT=9hrs, TSSFAC- 0.9, DT2MS -9.000e-05, dt=8.10e-05, mass percentage=2.74%
CT=9:29 hrs, TSSFAC- 0.9, DT2MS -1.100e-04, dt=9.90e-05, mass percentage=20.393%
CT=11:43 hrs, TSSFAC- 0.9, DT2MS -1.020e-04, dt=9.18e-05, mass percentage=7.47%
CT=08:59 hrs, TSSFAC- 0.9, DT2MS -1.030e-04, dt=9.27e-05, mass percentage=8.06%
CT=9:00 hrs, TSSFAC- 0.9, DT2MS -1.027e-04, dt=9.24e-05, mass percentage=7.88%
CT=11:00 hrs, TSSFAC- 0.9, DT2MS -1.029e-04, dt=9.26e-05, mass percentage=8.00%
CT=8hrs, TSSFAC- 0.9, DT2MS- 12.40, dt=1.12e-04 mass percentage 49%
TSSFAC=0.8,DT2MS=5.40e-05, 28.24hrs, 0.00822%
DT2MS=8.40e-05, 15.33hrs, 1.40%, TSSFAC=0.8
DT2MS=8.50e-05, 11.48hrs, 1.58%, TSSFAC=0.8
DT2MS=9.0-05, CT=14.2, 1.58%, TSSFAC=0.8
DT2MS=1.10-04, CT=13.36, 8.06%, TSSFAC=0.8
DT2MS=1.02-04, CT=10.23, 7.47%, TSSFAC=0.8
DT2MS=1.027-04, CT=11.59, 7.87%, TSSFAC=0.8
DT2MS=1.029-04, CT=12.41, 8.00%, TSSFAC=0.8
DT2MS=1.030-04, CT=20.35, 8.06%, TSSFAC=0.8
TABULAR DATA FROM THE ABOVE OUTPUTS:-
| DT2MS | RUN TIME | TSSFAC | %increase | TSSFAC | RUN TIME(hrs) | %increase |
| 5.40E-05 | 27 | 0.9 | 0.01% | 0.8 | 28.24 | 0.00822 |
| 5.40E-05 | 20 | 0.9 | 0.01% | 0.8 | 28.24 | 0.00822 |
| 8.40E-05 | 18 | 0.9 | 1.40% | 0.8 | 15.33 | 1.4 |
| 8.50E-05 | 13 | 0.9 | 1.58% | 0.8 | 11.48 | 1.58 |
| 9.00E-05 | 9.57 | 0.9 | 2.74% | 0.8 | 14.2 | 1.58 |
| 1.10E-04 | 9.3 | 0.9 | 20.39% | 0.8 | 13.36 | 8.06 |
| 1.02E-04 | 11.43 | 0.9 | 7.47% | 0.8 | 15.2 | 7.47 |
| 1.03E-04 | 8.59 | 0.9 | 8.06% | 0.8 | 20.35 | 8.06 |
| 1.027E-04 | 9 | 0.9 | 7.88% | 0.8 | 11.59 | 7.88 |
| 1.029E-04 | 11.27 | 0.9 | 8.00% | 0.8 | 12.41 | 8 |
HISTOGRAM RUNTIME VS MASS SCALING TRIALS:- 
IMPLICIT ANALYSIS-
The same simulation is performed with the implicit analysis. The IMPLICIT_AUTO, IMPLICIT_GENERAL, IMPLICIT_SOLVER, IMPLICIT_SOLUTION, these cards were defined. Initial time step was given as 0.01. THE IMFLAG was kept 1 as implicit analysis to be defined.
RESULT-
The computational time using implicit method is observed to be 28515 nano sec i.e. 2 minutes 3 secs which is way smaller than the explicit analysis result. This is because we have taken bigger time step in case of implicit method. Bigger the timestep will ultimately reduce the computational time and here same case is observed.
Conclusion:-
From this assignment we can conclude that mas scaling is the method that can be used to control the computational time of the simulation. Also we can conclude that the tssfac and DT2MS values need to be optimised in such a way that te model is stable.