Simulation of Sheet metal Bending using ANSYS Workbench

OBJECTIVE:

Sheet metal bending has to be performed for 3 different materials using ANSYS Workbench. For the following cases, case setup and comparison of results should be done.

Case 1: To simulate using three different materials for sheet namely Aluminum alloy 1199, Copper Alloy NL, and Magnesium Alloy NL, and to compare results of equivalent stress, equivalent elastic strain, and directional deformation along Y-axis.

Case 2: With aluminum alloy as the material the frictional coefficient has to be changed to 0.19 and the results are to be compared with case 1.

Case 3: Mesh refining must be done in the plate with aluminum alloy as material and the results are to be compared with case 1.

PROCEDURE FOR CASE SETUP:

1. Open ANSYS >> Drag and drop static structural in the project schematic window.

2. Go to engineering data for defining the materials given in the problem. Choose aluminum alloy NL, copper alloy NL, and Magnesium alloy NL from the material library. Now, duplicate the aluminum alloy NL and rename it as aluminum alloy 1199 and change the properties. This is shown in the figure below.

For case 1, the material chosen is aluminum alloy 1199.

3. Select the model tab to establish the meshing, contact definitions, and analysis settings definition. Rename the parts according to convenience.

4. Go to contact and define the contacts shown in the figure below. The first contact establishes the contact between punch and sheet. The second contact establishes the contact between sheet and die. The frictional coefficient is 0.1.

5. For meshing, tetrahedrons are used for the plate by using the patch conforming method. The body sizing option is used to set the element size of the die as 4mm. The same option is used to set the element size of the plate as 1mm. The face sizing option is used to set an element size of 1mm for the die and punch faces that are in contact with the plate. For the third case, the mesh is refined to a size of 0.75 mm. The final meshed model is shown in the figure below.

6. Go to analysis settings. The number of steps defined for this analysis is 10. Select all the steps and make the settings as shown in the figure below.

7. For the boundary conditions, the displacement is defined along the negative Y-axis. The tabulated values are shown in the figure below.

8. The plate is fixed along the z-axis to prevent the motion along the z-axis when the punch hits the plate. This is shown in the figure below.

9. The degrees of freedom along the X-axis and Z-axis are arrested for the die to avoid lateral movement of the die. This is shown in the figure below.

10. The output requests for equivalent stress, directional deformation (along Y-axis), and equivalent elastic strain are placed. It is to be noted that the output requests remain the same for all three cases.

11. From the analysis settings, hit on solve to start the simulation.

12. The simulation for the first case has to be done by changing the materials. For the second case, the frictional coefficient has to be changed to 0.19 and simulation has to be done. For the third case, the mesh size on the plate is reduced and the simulation has to be done.

RESULTS AND DISCUSSION:

Case 1:

1. The equivalent stress observed for all the materials is shown below.

2. The equivalent elastic strain for all the materials is shown below.

3. The directional deformation are shown in the figure below.

Case 2:

1. The equivalent stress for a frictional coefficient of 0.19 is shown in the figure below.

2. The equivalent elastic strain for a frictional coefficient of 0.19 is shown in the figure below.

3. The directional deformation is shown in the figure below.

Case 3:

1. The equivalent stress is shown in the figure below.

2. The equivalent elastic strain is shown in the figure below.

3. The directional deformation is shown in the figure below.

ANIMATION FILES:

Case 1:

1. The equivalent stress is shown in the figures below.

2. The equivalent elastic strain is shown in the figures below.

3. The directional deformation is shown in the figures below.

Case 2: (For a frictional coefficient of 0.19)

1. The equivalent stress is shown below.

2. The equivalent elastic strain is shown below.

3. The directional deformation is shown below.

Case 3: (Mesh size of 0.75 mm with a frictional coefficient of 0.1)

1. The equivalent stress is shown below.

2. The equivalent elastic strain is shown below.

3. The directional deformation is shown below.

CONCLUSION:

From the simulation, it can be seen that for all the cases the solution converged without any errors. 

Case 1:

The output parameters are tabulated below.

From the above table, it can be seen that the directional deformation (along Y-axis) is highest for magnesium alloy NL with a value of 3.7454 mm. The minimum value of directional deformation is obtained for aluminum alloy 1199 with a value of 2.285 mm. The value obtained for the copper alloy NL is 3.6941 mm.

The equivalent stress observed for aluminum alloy is highest for aluminum alloy 1199 with a value of 2.55e5 MPa. The value obtained for copper alloy NL and magnesium alloy NL is 2.138e5 and 1.747e5 MPa respectively.

The equivalent elastic strain obtained is highest for aluminum alloy 1199 with a value of 1.2472. The value obtained for copper alloy NL and magnesium alloy NL is 1.0701 and 0.86959 respectively.

Case 2:

The output parameters are tabulated below.

From the above table, it can be seen that the directional deformation (along Y-axis) is higher for a frictional coefficient of 0.19 with a value of 3.6774 mm. The value obtained for the default frictional coefficient of 0.1 is 2.285 mm.

The equivalent stress observed is higher for a frictional coefficient of 0.1 with a value of 2.55e5 MPa. The value obtained for the frictional coefficient of 0.19 is 1.8602e5.

The equivalent elastic strain observed is higher for a frictional coefficient of 0.1 with a value of 1.2472. The value obtained for the frictional coefficient of 0.19 is 0.93207.

Case 3:

The output parameters are tabulated below.

It can be observed from the results that after mesh refinement there is a considerable change in the directional deformation with a value of 3.6507 mm. The equivalent stress variation is less with a refinement value of 2.6647e5 MPa. The elastic strain obtained is 1.333.

Therefore, it can be concluded that due to mesh refinement the accuracy of the result can be improved. The value of gets converged to the actual value as observed in case 3. But this comes as a trade-off between cost and accuracy. The mesh refinement increases the computational cost. In the overall scheme, it can be observed that the total deformation for aluminum alloy 1199 is the least which shows that more force is required to get the required deformation. Hence, all the case objectives are satisfied.