Comparing base simulation results with improved shell elements properties

Objectives:

Comparing base simulation results with improved shell elements properties

1. Using the crash beam file from the previous assignment, change the run time to 55 ms.
2. Change the number of animation steps during simulation to a minimum of 25 and maximum of 60.
3. Run the base simulation without any modification to element properties.
4. At the end of the simulation, do the energy error and mass error checks and determine whether results would be acceptable.
5. If acceptable, Plot rigid wall forces, internal energy, hourglass energy, contact energy, total energy of the simulations.
6. Change all the shell elements properties to recommended properties, save this as separate, rad files and run the simulation.
7. Follow steps 5 and 6.
8. Create a brief report comparing all the results from steps 5 and 6 for both simulations.
9. Comment whether there is any change in the results and why there is any change in the result.

Procedure:

Case 1:

• Import the crash beam file from the previous assignment as a solver deck in radioss
• After importing change the engine run time to 55 ms

• Change the engine animation step to minimum of 25 and max of 60

• After this run the simulation by going to > analysis > radioss >
• Change the input file name as FIRST_RUN_0000.rad
• Tik mark include connectors and in the options type (-nt 4) click Radioss

• After running the base simulation output screen will pop up as FIRST_RUN_0001.rad

• Open FIRST_RUN_0001.rad file with text editor

• From the above results its cleared that energy error is -10.3% and mass error is 0.1659E-03. the acceptable value of energy error is must be in the range of 5% to -15% positive for further simulation

Simulation results:

Counter Plot Results

Case 2:

Simulation with improved shell element properties

Parameters		Comment
Ishell =24		QEPH 4 nodes shells are the best combination of cost and accuracy.
Ismstr=2		Full geometric nonlinearities (default)with possible small strain formulation activation in RADIOSS Engine.
Ish3n=2		Standard 3 noded shell (C0) with modification for large rotation(default)
N=5		Number of integration points set to 5 for accuracy bending.
Ithick=1		Thickness change is taken into account for accuracy.
Iplas=1		Iterative plasticity for good accuracy.

• Change the property parameter’s as mentioned above

• Repeat the steps from 1-5 as made in case 1
• Run the simulation save the radioss file in case 2 folder
• Open FIRST_RUN_0001.out file in the text editor

• In the above case, Maximum energy error is 0.1% which is close to zero which is in the range of 5% to -15% which is acceptable
• Mass error is 0.1659E-03

Simulation results:

Counter plot results:

Conclusion:

• By comparing both case 1 and case 2 energy error changes from -10.3% to 0.1%
• and hourglass energy remains zero by applying improved shell element property