Assignment 3

Assignment 3

Objective

Comparison of results with base simulation and improved shell element properties

Drive Link - https://drive.google.com/file/d/1Mb2j1Lu6YIKEilD1xPd-t11mcGRbUuFV/view?usp=sharing

Case 1 setup and Procedure – Base Simulation

• Import the engine file into the radioss block 120
• Now Run time is changed from 60ms to 55ms

• Changing the animation steps to 50 so T freq value is changed to 1.1ms
• Correctly select the input file location for the running the radioss

• Wait for the the creation of the animation files and job done status
• In this case energy error is within the limit of 15%, hence it can be proceeded for evaluation of results. (no element properties were changed during this simulation)

• Output files of the simulation are T01, animation, h3d and 0001.out files
• Animations and contour plots of results can be obtained by loading the h3d files into hyperview
• For Plotting graph for justification of the results hypergraph 2D can be used . T01 files can be used for getting those plots

Case 2 setup and Procedure – Improved shell element properties

• Correctly select the input file location for the running the radioss
• In this case the property parameters are used to more realistic and accurate results by preventing hourglass error occurring in these shell elements.

• I shell 24 is used because it prevents by adding artificial stiffness to material even before hourglass occurs.
• Hour glass occurs when the elements are reduced integration, this can be see more in case 1, where no improvement parameters were not used.
• Here by using these parameter to tackle change in thickness, plastic deformation more accurate results can be obtained.

• In this case energy error is almost 0% , it shows that this case which improved shell parameters are more accurate.

Comparison of the Plots

Case 1

Case 2

We can observe that Hour glass energy between the two systems , in case 2 its almost zero and the TE almost remains linear.

Case 1 and Case 2 (L - R)

From the contact energy of case 1 almost 4 times that of the case 2 (with improved properties). Case 2 is much close to actual results than case 1. (realsitic energy)

Intial reaction forces are almost similiar on both the case but the final peak is not sensed by case 1 due the hourglass energy(Solver is not able to measure the changes in deformation when though the elements deform) as it increased during the final ms.

Internal and KE plots of case 1 and 2. It can be observed that Interal energy are almost similiar with both cases.

Results and conclusion

Hourglass pheneomenon ( elements deform excessively unnatural into hour glass kind of shapes)

• It happens when reduced integration points are used for analysis
• Increasing integration points will solve hour glass issue or using improved
• Solver is not able to measure the changes in deformation (strains) when though the elements deform, so increasing the integration points will solve the issue.
• Manual inspection of hourglass by using hypergraph 2d plot is required. Hourglass energy error should be close to 5% of internal energy or close to zero.

- Case 2 is better accurate analysis than case 1.