Assignment 3-2D Element Formulation Challenge

AIM

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Simulation for beam file by using different element formulation and then compares results.

OBJECTIVE

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• Get familiar with different kinds of shell elements formulation.
• Knowledge of Guasian Quadrate, Integrated points.
• Get aquatinted with Reduced and fully integrated method.

Import the starter file

This is the base model in which analysis is done first.

Import solver deck < import

1. Using the crash beam file from the previous assignment, change the run time to 55 ms.

Soln: Solver <Engine Keywords < Run < Run < T _stop

2. Change the number of animation steps during animation to minimum of 25 and maximum of 60.

Soln: Since the animation time step is between 25-60, 35 is taken average value.

Treq = Run time/Animation step

= 55/35

= 1.57

Solver < Engine Keywords < Anim < Anim/DT

3. Run the base simulation without modification.

Panel < Analysis < Radioss

4. At the end of simulation, do the energy error and mass error checks and determine whether the results would be acceptable or not.

Soln: The energy error is 10.3% and mass error is 0.1659E-03.

5. If acceptable plot rigidwall force, contact energy, hourglass energy,total energy and internal energy.

Since energy error is more than 5% hence it is not acceptable.

6. Change shell elements properties and save a separate file.

Model < Properties

I_shell = Element formulation of 2D elements having 4 nodes.

I_smstr = Shell small strain formulation flag

I_sh3n = Element formulation of 2D elements having 3 nodes.

N = Number of integratopn points through thickness.

I_thick = Shell resultant stresses calculation flag

I_plas = Shell plane stress Plasticity flag

7. Again run the simulation.

7. Again check for energy error,if acceptable then plot rigidwall force, contact energy, hourglass energy, internal energy and total energy

This time the energy error is -3.8% however the mass error remains same.

Model/Errors	Energy error %	Mass error %
Unedited beam model	-10.3%	0.1659E-03
Edited beam model	-3.8%	0.1659E-03

Comparing the both results

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Rigid wall force graph

Unedited	Edited

Energy graph

Unedited	Edited

Conclusion

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As per the graph the rigid wall force is decreasing first and again increasing in unedited model however in the edited model the force decreased and keep on decreasing.

As the element formulation changed hence the hourglass energy is changed .