Challenge

Simulating Rolling Operation on a workpiece made of copper

Objective

Increase the length of the workpiece by 60mm and decrease its size on both sides by 8mm. Run the simulation for 14 steps. Ensure that the edge of the workpiece is displaced by 90mm.

Find out the

1. Equivalent stress for the whole setup
2. Equivalent Plastic strain for the workpiece
3. Directional Deformation in the Z-axis for the workpiece
4. Prove that the workpiece has displaced by Once 90mm.

Step 1: Selecting the Material required for Analysis

Once “Static Structural” is loaded on Ansys Workbench, we Edit “Engineering Data” to select the materials required for analysis.

For simulating the rolling operation on a workpiece, we need two materials- one for the rolls and one for the workpiece.

In our case, we assign “Structural Steel” for the rolls and “Copper Alloy NL” for the workpiece. For now, the materials are just selected. “Assignment” is done in Ansys Mechanical APDL.

Stainless Steel Properties

Density	7850 kg/m^3
Young’s Modulus	2E+11 Pa
Poisson’s Ratio	0.3
Bulk Modulus	1.6667E+11 Pa
Isotropic secant co-eff of thermal expansion	1.2E-5 C^-1
Compressive Strength	2.5E+08 Pa
Tensile Ultimate Strength	4.6E+08 Pa
Tensile Yield Strength	2.5E+08 Pa

Copper Alloy NL Properties

Density	8300 kg/m^3
Young’s Modulus	1.1E+11 Pa
Poisson’s Ratio	0.34
Bulk Modulus	1.1458E+11 Pa
Shear Modulus	4.1045E+10 Pa
Compressive Strength	2.5E+08 Pa
Yield Strength	2.8E+08 Pa
Tangent Modulus	1.15E+09 Pa

Step 2: Edit Geometry in SpaceClaim

The file containing the geometry is loaded on Ansys SpaceClaim for editing. This is how the initial geometry looks like:

To meet the intended dimensions for Analysis, the length of the workpiece is extruded by 60mm using the “Pull” option. The same is done for the sides of the workpiece, i.e, they are extruded in the negative direction to reduce the thickness by 8mm on both sides. The final geometry looks as follows:

This geometry is updated and loaded on Ansys Mechanical for Analysis.

Step 3: Defining the Contacts

As discussed in step 1, the respective materials are assigned to the rolls and the workpiece.

Next, we need to define the nature of contact between the rolls and the workpiece for rolling.

Since two contacts are already predefined in the system, we need to change them as per our requirement. First, the upper roll and workpiece contact is defined.

Next, the lower roll and workpiece contact is defined.

It is clear that the rolls and workpiece share frictional contact (Rolling). The same is defined as per the following values:

Type of Contact	Frictional
Friction Coefficient	0.2
Formulation	Augmented Lagrange
Normal Stiffness Factor	0.1
Interface Treatment	Add Offset, Ramped Effects

Inserting the Joints

In rolling operation, the rolls rotate along a fixed axis while the workpiece is pulled between them. Therefore, we need to define the joints for upper and lower rolls. A “Cylindrical” Body-Ground joint is defined for both and coordinate axes are adjusted based on our preference.

Step 4: Meshing

The default mesh suggested by Ansys looks coarse. Since the analysis of the workpiece is our main concern, we refine its mesh elements with a face sizing of 4mm. There is scope for further refinement of mesh. Since grid dependency is not our concern here and to reduce the overall computational time, I am proceeding with the analysis with the element sizing of 4mm for the workpiece.

Step 5: Analysis Settings

For the analysis, we need to define the time steps/ sub-steps and other control values. The following values are selected:

No. of Steps	14
Large Deflection	On
Stabilization	Constant
Energy Dissipation Ratio	0.1

Since the workpiece has to move along Y-axis, we need to insert displacement values for it. The values for each step are tabulated gradually as follows:

Similarly, we need to insert rotation to both rolls and adjust the direction of rotation carefully. The following values are tabulated for the rolls:

Step 6: Running the Simulation

Now that all the boundary conditions are properly defined, we select the required output and generate the solution.

The results obtained are as follows:

Deformation of the workpiece along Z-axis: 5.91 mm (Max)

Equivalent Stress (All-Bodies): 3207.4 MPa (Max)

Equivalent Plastic Strain- workpiece: 1.3565 (Max)

Distance moved by the workpiece:Proof of 90mm displacement. This is done by tracking the displacement for the edge of the workpiece.

Animations:

Directional deformation of the workpiece (Y-axis): https://youtu.be/NhxsDNoYQ-s

Equivalent Stress: https://youtu.be/VfNZEk-ccmA

Equivalent Strain: https://youtu.be/VmsjxRzVF84

Proof of 90mm displacement: https://youtu.be/XLrOftxo5Vw