Crash analysis of tube under different contact interfaces using Altair HyperWorks.
Objective:
Comparision of the results of analysis of different contact interfaces of crash tube Using HyperMesh and HyperCrash.
Case 1: Running the crash tube model as it is.
No. of cycles: 83600
Energy error: -3.8%
Mass error: 0.00
Von mises:
Max value 7.4281E-01 , Min value 0.000E+00.
Contact forces:
Max value 93.454 KN , Min value 0.00 KN
Below are the different plots of graph which is needed for analysis:
Conclusion:
According to the results of case 1, we can observe that internal energy increases gradually with time till 20 ms. After that it increases rapidly till about 27 ms where we think our crash tube gets crushed or is impacted against rigid wall and thus after 27 ms, internal energy values remains constant 0.4201E+05 J.
For kinetic energy, it starts at around 45000J and its value decreases gradually till 20 ms . After that rapid decrease is observed until 27 ms when tube is impacted against wall. After impact slight increase in Kinetic energy is observed.
Hourglass energy remains zero.
Contact energy remains at constant rate till 20 ms after that it gradually increases till 27 ms on which its value is maximum. After impact it comes down and remains constant around 1700J.
Case 2: Change Inactive=6 and run Crush_tube.rad file.
No. of cycles: 83600
Energy error: -3.8%
Mass error: 0.00
Von mises:
Max value 7.428E-01 , Min value 0.000E+00
Contact forces:
Max value 93.45 KN , Min value 0.00 KN
Below are the different plots of graph which is needed for analysis:
Conclusion:
According to the results of case 2, we can observe that internal energy increases gradually with time till 20 ms. After that it increases rapidly till about 27 ms where we think our crash tube gets crushed or is impacted against rigid wall and thus after 27 ms, internal energy values remains constant 0.4201E+05 J.
For Kinetic energy, it starts at around 45000J and its value decreases gradually till 20 ms . After that rapid decrease is observe at 27 ms when tube is impacted against wall. After impact slight increase in Kinetic energy is observed.
Hourglass energy remains zero.
Contact energy remains at constant rate till 20 ms after that it gradually increases till 27 ms on which its value is maximum 2125J . After impact it comes down and remains constant around 1700J.
Case 3: Create TYPE11 contact interface and run it.
No. of cycles: 102700
Energy error: -7.6%
Mass error: 0.00
Von mises:
Max value 7.909E-01, Min value 0.000E+00
Contact forces:
Max value is 570.0 KN , Min value 0.00 KN
Below are the different plots of graph which is needed for analysis:
Conclusion:
From case 3, it is observed that internal energy increases gradually with time till 20 ms. After that it is observe that internal enrgy value increase rapidly at fast rate till about 26 ms where we think our carsh tube gets crushed or is impacted against rigid wall and thus after 26 ms Internal energy values remains constant 0.4035E+05 J.
For Kinetic energy, it starts at around 45000J and its value decreases gradually till 20 ms . After that rapid decrease is observe at 26 ms when tube is impacted against wall. After impact slight increase in Kinetic energy is observed.
Hourglass energy remains zero.
Contact energy remains at constant rate till 20 ms after that it gradually increases till 26 ms on which its value is maximum 3700J . After impact it comes down and remains constant around 3400J.
Case 4: Remove both notches and remove boundary conditions on rigid body node then run the model.
No. of cycles: 118800
Energy error: -8.7%
Mass error: 0.00
Von mises:
Max value 7.625E-01, Min value 0.000E+00
Contact forces:
Max value is 629.7 KN , Min value 0.00 KN
Below are the different plots of graph which is needed for analysis:
Conclusion:
According to case 4, it can observed that internal energy increases gradually with time till 20 ms. After that it is observe that internal enrgy value increase rapidly at fast rate till about 27 ms where we think our carsh tube gets crushed or is impacted against rigid wall and thus after 27 ms Internal energy values remains constant 0.3988E+05 J.
For Kinetic energy, it starts at around 45000J and its value decreases gradually till 20 ms . After that rapid decrease is observe at 27 ms when tube is impacted against wall. After impact slight increase in Kinetic energy is observed.
Hourglass energy remains zero.
Contact energy remains at constant rate till 20 ms after that it gradually increases till 27 ms on which its value is maximum. After impact it comes down and remains constant.
Normal force increases rapidly after 20 ms and it reaches its maximum value 1198KN at 27 ms.
Maximum Contact force obtained is of value 629.7 KN.
Case 5: Create a new notch in the middle ,select the whole section and run the model.
No. of cycles: 104900
Energy error: -7.8%
Mass error: 0.00
Von mises:
Max value 7.637E-01, Min value 0.000E+00
Contact forces:
Max value is 570.2 KN , Min value 0.00 KN
Below are the different plots of graph which is needed for analysis:
Conclusion:
According to case 5, it can observed that internal energy increases gradually with time till 20 ms. After that it is observe that internal enrgy value increase rapidly at fast rate till about 27 ms where we think our carsh tube gets crushed or is impacted against rigid wall and thus after 27 ms Internal energy values remains constant 0.4012E+05 J.
For Kinetic energy, it starts at around 45000J and its value decreases gradually till 20 ms . After that rapid decrease is observe at 27 ms when tube is impacted against wall. After impact slight increase in Kinetic energy is observed.
Hourglass energy remains zero.
Contact energy remains at constant rate till 20 ms after that it gradually increases till 27 ms on which its value is maximum. After impact it comes down and remains constant.
Normal force increases rapidly after 20 ms and it reaches its maximum value 1505KN at 26 ms.
Maximum Contact force obtained is of value 570.2 KN.
Case 6: Create a new notch with nodes only from opposing 2 faces and run the model.
No. of cycles: 110800
Energy error: -8.1%
Mass error: 0.00
Von mises:
Max value 7.795E-01, Min value 0.000E+00
Contact forces:
Max value is 549.3 KN , Min value 0.00 KN
Below are the different plots of graph which is needed for analysis:
Conclusion:
According to case 6, it can observed that internal energy increases gradually with time till 20 ms. After that it is observe that internal enrgy value increase rapidly at fast rate till about 27 ms where we think our carsh tube gets crushed or is impacted against rigid wall and thus after 27 ms Internal energy values remains constant 0.3996E+05 J.
For Kinetic energy, it starts at around 45000J and its value decreases gradually till 20 ms . After that rapid decrease is observe at 27 ms when tube is impacted against wall. After impact slight increase in Kinetic energy is observed.
Hourglass energy remains zero.
Contact energy remains at constant rate till 20 ms after that it gradually increases till 27 ms on which its value is maximum. After impact it comes down and remains constant.
Normal force increases rapidly after 20 ms and it reaches its maximum value 1500KN at 26 ms.
Maximum Contact force obtained is of value 549.3 KN.
Results:
| Cases | Energy error (%) | Rigid wall forces (kN) | Contact forces (kN) | Internal energy (E+05 J) |
| 1 | -3.8 | 1350 | 93.45 | 0.4201 |
| 2 | -3.8 | 1350 | 93.45 | 0.4201 |
| 3 | -7.6 | 1555 | 570 | 0.4035 |
| 4 | -8.7 | 1198 | 629.7 | 0.3988 |
| 5 | -7.8 | 1505 | 570.2 | 0.4021 |
| 6 | -8.1 | 1500 | 549.3 | 0.3996 |
Through a close observation it can be said that adding inacti=6 in the second case did not make any difference as all the parameters tabulated conveys this, when case 1 and case2 are compared. There may be some difference in the two cases when a complex crash application is considered.
Looking into case3, adding the the edge to edge contact TYPE 11 has shown some difference as the Rwall forces,Contact Forces and the contact energy have shown rise in their values.
Since, there is no notch and boundary condition, the deformations at some parameters are normal as that of the case1 and case2 but, due to the TYPE11 contact there is a spike in the Contact forces, contact energy. The sliding contact is in a Non-Linear fashion.
In the Fifth case by adding the notch again, the contact forces and Rwall forces have increased.
Due to only two notches on the nodes in Case6 the Rwall forces are more than those in the Case4 but the less than Case5.
Finally the error is less in the first two cases due to the notches as most of the energy is absorbed by the Crush Tube and the next four cases the error is a little more may be due to the addition of the TYPE 11 contact between the slave and the master nodes.