Assignment 4-RADIOSS Material Laws Challenge
Aim: The given model is run for crash analysis by applying the different materials laws as instructed using Radioss and post process the results obtained compare the solution.
Objective: To carry out the simulation of the given model and compare the results. There shall be 7 cases with different parameter as instructed compared the plots and graphs.
Procedure:
Case 1:
The file of Failure_johnson_0000.rad file is downloaded and open in the hypermesh software. Later, the file is renamed as “Law2_epsmax_failure”, without any change the file is Run using “Radioss” solver.
Figure 1: Total Number of cycles
Figure 2: Energy Error
Figure 3: Energy Graph
Figure 4: Plastic strain contour
Figure 5: Stress contour
The elements are being deleted when they reach the 15.1% plastic strain area, the yield stress is 290Mpa, the maximum stress is 275.2Mpa.
Case 2:
The “Law2_epsmax_failure” is imported to hypermesh software and made changes to it by enabling the failure plastic strain and fail johnson card. Later renamed as “Law2_epsmax_crack”.
Changes made:
Ifail_sh=1
Dadv=1
Ixfem=1
The file is run using the radioss solver.
Figure 6: Total Number of cycles
Figure 7: Energy Error
Figure 8: Energy Graph
Figure 9: Plastic strain contour
Figure 10: Stress contour
The elements have crack and later the elements at end stage gets deleted, when they reach the 15.1% plastic strain area, the yield stress is 290Mpa, the maximum stress is 295.1Mpa.
Case 3:
The “Law2_epsmax_crack” is imported to hypermesh software and made changes to it by removing fail johnson card. Later renamed as “Law2_epsmax_nofail”. The file is run using the radioss solver.
Figure 11: Total Number of cycles
Figure 12: Energy Error
Figure 13: Energy Graph
Figure 14: Plastic strain contour
Figure 15: Stress contour
The elements get deleted, when they reach the 15.1% plastic strain area, the yield stress is 290Mpa, the maximum stress is 270.7Mpa.
Case 4:
The “Law2_epsmax_nofail” is imported to hypermesh software and made changes to it by removing both failure plastic strain and fail johnson card. The file is run using the radioss solver.
Figure 16: Total Number of cycles
Figure 17: Energy Error
Figure 18: Energy Graph
Figure 19: Plastic strain contour
Figure 20: Stress contour
The elements did not get deleted nor crack, the yield stress is 290Mpa, the maximum stress is 10894Mpa.
Case 5:
The file of case 4, “Law2_epsmax_nofail” is imported to hypermesh software and made changes to material card by changing it to Law 1. The file is run using the radioss solver.
Figure 21: Total Number of cycles
Figure 22: Energy Error
Figure 23: Energy Graph
Figure 24: Plastic strain contour
Figure 25: Stress contour
The elements did not get deleted nor crack, the yield stress is 290Mpa, the maximum stress is 10894Mpa.
Case 6:
The file of case 1, “Law2_epsmax_failure” is imported to hypermesh software and made changes to material card by changing it to Law 36. The file is run using the radioss solver.
Changes made to card
Figure A:changes in Card
Figure 21: Total Number of cycles
Figure 22: Energy Error
Figure 23: Energy Graph
Figure 24: Plastic strain contour
Figure 25: Stress contour
The elements did get crack at first and later got deleted, the yield stress is 290Mpa, the maximum stress is 548.5Mpa.
Case 7:
The file of “Law7_0000.rad” is imported to hypermesh software. The file is run using the radioss solver.
Figure 21: Total Number of cycles
Figure 22: Energy Error
Figure 23: Energy Graph
Figure 24: Plastic strain contour
Figure 25: Stress contour
The elements did get crack at first and later got deleted, the yield stress is 290Mpa, the maximum stress is 278.5Mpa.
| Case | Material Law | Simulation name | Energy error% | Simulation time(s) | Number of cycles | Maximum stress value | Element behaviour |
| 1 | Law-2(John-cook model) | EPS_max_failure | 0.2 | 73.61 | 49480 | 287.6 | Deleted |
| 2 | Law-2(John-cook model) | EPS_max_Crack | 4 | 75.86 | 49397 | 294.7 | cracks first and then gets deleted |
| 3 | Law-2(John-cook model) | EPS_max_nofail | 0.8 | 82.56 | 49405 | 270.5 | Deleted |
| 4 | Law-2(John-cook model) | Law 2 | 3 | 73.42 | 48737 | 424.7 | No Crack No Deletion |
| 5 | Law 1(linear elastic material) | Law 1 | 0.3 | 70.33 | 47969 | 10860 | No Crack No Deletion |
| 6 | Law 27(brittle failure model) | Law 27 | 1 | 78.31 | 49364 | 277.3 | Deleted |
| 7 | Law 36(elastic plastic material) | Law 36 | 0.8 | 76.07 | 52237 | 1286 | Deleted |
Conclusion:
The comparison with different cases of material and failure cards is simulated. the element behaviour and the stress development is discussed with case 2 to be best for simulation.