Assignment 3-2D Element Formulation Challenge
Assignment No.3
Comparison of results with base simulation and improved shell element 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.
Solution
1) Using the file of the previous run, change the run time from 60ms to 55ms.
Step1-
Import the file in Hypermesh as below,
Step 2-
Select cards and change the value Tstop to 55 as below
2) Change the number of animation steps during simulation to a minimum of 25 and a maximum of 60.
Here, we can take no of steps in between 25 and 60. Let us take 50
Therefore, Frequency = 55/50 =1.1
Select card ENG_ANIM_DT from cards and set the value of Tfreq as 1.1
3) Run the base simulation without any modification to element properties.
Click on Analysis Tab in Hypermesh
Save the model in local directory first, and then click the Radioss button to Run base the analysis.
4) At the end of the simulation, do the energy error and mass error checks and determine whether results would be acceptable.
Here we can check the energy and mass error, if they are in acceptable limits or not.
For checking the energy and mass error, we have to open the file Element_Formulation-Shell-3_assignment_0001.outas the energy error is -10.3% and is less than 15% so it is acceptable.
also, the mass error is 0.1659E-0.3.
5) If acceptable, Plot rigid wall forces, internal energy, hourglass energy, contact energy, the total energy of the simulations.
As energy error is in acceptable, we will plot graphs for Rigid wall forces, internal energy, hourglass energy, contact energy and total energy
Switch the environment to Hyperview from Application menu from the top bar
Open the file Element_Formulation-Shell-3_assignment.h3d file and click apply
The model gets opened
To view all energy graphs with respect to time, we have to open a new window with Hypergraph 2D
6) Change all the shell elements properties to recommended properties, save this as separate, rad files and run the simulation.
We will change the Shell properties to recommended properties as below,
Recommended properties:
Parameters Comment
I =24 QEPH 4 nodes shells are the best combination of cost and accuracy.
I =2 Full geometric nonlinearities (default)with possible small strain formulation activation in RADIOSS Engine.
I =2 Standard 3 noded shell (C0)with modification for large rotation(default)
N=5 The number of integration points set to 5 for accuracy bending.
I =1 Thickness change is taken into account for accuracy.
I =1
Iterative plasticity for good accuracy
Run the model as per step 3 and save as another name or location
7) Follow steps 4 and 5
Here we can check the energy and mass error, if they are in acceptable limits or not.
For checking the energy and mass error, we have to open the file Element_Formulation-Shell-3_assignment_0001.out
as the energy error is -0.1% and is less than 15% so it is acceptable.
also, the mass error is 0.1659E-0.3.
As energy error is in acceptable, we will plot graphs for Rigid wall forces, internal energy, hourglass energy, contact energy and total energy
Switch the environment to Hyperview from Application menu from the top bar
Open the file Element_Formulation-Shell-3_assignment.h3d file and click apply
The model gets opened
To view all energy graphs with respect to time, we have to open a new window with Hypergraph 2D
Then open file Element_Formulation-Shell-3_assignment
8) Create a brief report comparing all the results from steps 4 and 5 for both simulations.
9)Comment whether there is any change in the results and why there is any change in the result.
Learnings
1) Property modifications
2) Graph plotting for forces
3) Shell property changes and effects on results
Conclusion
1) QEPH shell formulation reduced energy error
2) Best results obtained at optimum cost