Week 5 Bending of iPhone
OBJECTIVE:
To simulate the bending of iPhone using ANSYS Workbench. The following objectives have to be satisfied.
Case 1: To simulate the material using the default aluminum alloy material available in the library.
Case 2: To move the bottom fingers to the given position X= 22.5mm & Z= 10mm and to obtain the life of aluminum alloy for the material given below.
| Stress, MPa | Number of Cycles, N |
| 225 | 10000 |
| 175 | 100000 |
| 143 | 1000000 |
| 110 | 10000000 |
| 80 | 100000000 |
PROCEDURE FOR CASE SETUP:
1. Open ANSYS>>Drag and drop static structural model in the project schematic window.
2. Go to the engineering data. The following materials have to be defined for the simulation. For the second case, the given tabular values have to be inputted in the stress life parameters of aluminum alloy NL.
For the casing, the aluminum alloy material has to be assigned. For the display and the interior parts, glass and polyethylene materials have to be assigned. The fingers have to be assigned a default material of structural steel.
3. Go to the model tab for meshing and doing the case setup. Rename the parts as per convenience. Select all the fingers and assign the stiffness behavior as rigid except for the pushing fingers.
For case 2, before going to this step move the fingers to the desired coordinates as given in the problem. This is shown below.
4. In the contact definition, define a bonded contact between the display and the interior parts as shown below. Now define a frictionless contact between the fingers and the display and the fingers and frame. This is explained in the figure below.
5. Go to connections>>Define the joints as shown in the figure below. This is shown in the figure below.
6. A mesh size of 24 mm is chosen for the entire model. A mesh size less than this does not lead to the convergence of the solution. The final meshed model is shown in the figure below.
7. The following analysis settings are defined for the simulation. The total number of steps defined for the simulation is 8.
8. The following joint definitions are defined for the simulation.
9. The following displacement definition is assigned to the pushing finger.
10. From the solution option the results for directional stress, equivalent elastic strain, and force reaction are requested.
11. From the analysis settings, hit on solve to start the simulation.
RESULTS AND DISCUSSION:
1. The directional deformation obtained for the two cases are shown in the figure below.
2. The equivalent stress obtained for the two cases are shown in the figure below.
3. The life obtained for the aluminum alloy casing is shown in the figure below.
4. The safety factor obtained for the aluminum alloy NL is shown in the figure below.
ANIMATION FILES:
1. The directional deformation obtained for both cases is shown below.
2. The equivalent stress obtained for both cases is shown below.
3. The safety factor obtained for case 2 is shown below.
4. The life obtained for case 2 is shown below.
CONCLUSION:
From the simulation, it can be seen that for both cases the solution converged without any errors.
The output parameters are tabulated below.
| Test Case | Directional Deformation (in mm) | Equivalent Stress (in MPa) | Life | Factor |
| Aluminum Alloy without stress life parameters | 11.446 | 742.78 | Nil | Nil |
| Aluminum Alloy with stress life parameters | 9.5535 | 408.92 | 1e8 | 2.2126 |
From the above table, it can be seen that the directional deformation is higher for aluminum alloy without stress life parameters with a value of 11.446 mm. The value obtained for case 2 is 9.5535 mm. This is because the force applied in case 2 is in the middle of the phone when compared to case 1 which is at the edge.
The equivalent stress obtained for case 2 is the least with a value of 408.92 MPa. The value obtained for case 1 is 742.78 MPa. The maximum life obtained for case 2 is 1e8. The safety factor obtained is 2.2126.
Therefore, it can be concluded that the maximum directional deformation is obtained in case 1. The equivalent elastic strain is higher for case 1 in comparison with case 2. It can be concluded that the material performed well with aluminum alloy NL with defined stress life parameters. Hence, all the objectives are satisfied.