Week 3 Sheet metal Bending challenge

Objective

To perform a sheet metal bending simulation as per the cases given below and compared the output results for equivalent stress, equivalent elastic strain, and directional deformation.

Case 1

Modeling the sheet with Aluminium Alloy 1199, Copper Alloy NL, and Magnesium Alloy NL.

Case 2

With the material as Aluminium Alloy, change the friction coefficient to 0.19 and run the analysis as mentioned in Case 1. Compare the results with that in case 1.

Case 3

Refine the mesh on the plate such that it doesn't cross the academic limit. With Aluminium alloy as material, run the analysis as in Case 1 and compare the results.

Procedure

• Open Ansys workbench and drop down the static structure onto the project window from the analysis systems.
• The material used for this project are Aluminium Alloy 1199, Copper Alloy NL, and Magnesium Alloy NL (General Non-linear materials) and its has been added from the engineering data. If any change is done to a material cad, check whether our unit systems are consistent.
• Import the geometry and open it in the pace claim. The model was checked if any abnormality was present and the correction was made if needed. Click on the update and proceed to the next step.

     

• Right-click module and click edit to open up the mechanical module. The geometry tab is expanded and renamed accordingly.
• Expand the connection and from contact delete all the default contacts that have been generated. After that right-click contacts>insert>manual contact region. There will be contact between the punch and the sheet and selection were made as shown below.

     

• Similarly, another manual contact region was created and the selection for the die and the sheet surfaces are made as shown below.

     

• Select both the contact at once using control keys and change the type to frictional and assign a frictional coefficient of 0.1 with the behavior of Auto Asymmetric type. Other changes were made as shown below.

     

• From the mesh, a mesh sizing was done for the die and the punch part using 4mm element size and an element size of 1mm for the sheet part. For the faces in contact, the mesh was refined by sizing to 1mm by selecting the corresponding faces as shown below.

     

• Before generating the mesh, right-click>insert>method, select the sheet and choose tetrahedron as the element type.

     

• Now from the analysis set up, the total step was assigned as ten, and select all the time steps using the shift key and changes were done as per the image shown below.

     

• Now the loads can be defined. During the bending process, the punch will advance downward and hits the sheet and after that, it will impact the die, it needs to be removed and the punch should move backward after the bending process is complete.
• Static structural>insert>displacement, and select the three faces shown below. Also change the x,y,z components to tabular data.

     

• Also, the displacement for the punch is defined as shown below.

     

• From the plot, it can be observed that the plot is moving forward up to a maximum displacement of 13.5mm, and then it's withdrawn back.
• Now displacement for the sheet is defined. The motion in z-direction was fixed and after motion along x and y direction since sheet metal deform while bending. To fix the sheet in z-direction , right-click static structural>insert>displacement. Select the two faces shown below.

     

• From definition>z-component>tabular data. With this, the movement will be constrained along the z direction.

     

• For the die, select the five faces as shown below>right-click static structural>insert>displacement.

    

• Here the all x,y, and z components are inserted from the tabular data. Since it needs to stay at this place until the punch advances and once the punch is withdrawn this die should be also withdrawn. So we change the last step as shown below.

     

• The data has been inserted along the y-direction and made sure that the die stays in place and after the punch is withdrawn, the die is also withdrawn with a 3mm displacement.
• Finally, the output parameters such as the Equivalent stress, Equivalent elastic strain, and Total Deformation in the Y direction have been requested and run the simulation.

Results and Conclusion

The simulation for sheet metal bending has been performed using three different materials and compared the results. The results got from the simulation are discussed below.

The below plots shows some of the results obtained for the case which was modeled using Aluminium Aloy 1199 as the material.

Equivalent stress

 

Equivalent elastic strain

     

Directional deformation along Y-axis   

     

Similarly, the results for all the cases were found out and tabulated the results for comparison. 

Case 1

Case 1 includes modeling with Aluminium Alloy1199, Copper Alloy NL, and Magnesium Alloy NL with the same mesh sizes and the frictional coefficient.

• From the table, it's been observed that the sheet modeled with Copper Alloy NL gave the highest value for the equivalent stress and the Aluminum Alloy 1199 gave the minimum stress value. Therefore the sheet with Aluminum Alloy 1199 will be having maximum strength to withstand the failure compared to others in the list.
• The equivalent strain was found to be more for Magnesium Alloy NL and least for Aluminium Alloy 1199. 
• The directional deformation along Y-direction is highest for Copper Alloy NL and least for Aluminium Alloy 1199 and the sheet with Copper Alloy NL will bend more.

Case 2

For case 2 the Coefficient of friction was compared for the values for 0.1 and 0.19 using the  Aluminum Alloy 1199 sheet material.

• The maximum equivalent stress with a coefficient of 0.19 is more compared to 0.1. So when the frictional coefficient is increased the equivalent stress value also increases.
• The equivalent elastic strain is more for co-efficient with 0.1.
• The directional deformation with 0.19 is found to be the highest.

Case 3

For case 3 simulation was performed by decreasing the mesh size for the sheet modeled with Aluminium Alloy 1199 sheet material with a frictional coefficient of 0.1.

 

• From the table, it's inferred that when the mesh size changes the value for the stress and strain changes. Here we can find that equivalent stress and equivalent elastic strain is more for 0.75mm mesh size and directional deformation is more for the 1mm mesh size.
• Meshing is one of the key components to obtaining accurate results from an FEA model. Typically, the smaller the mesh size, the more accurate the solution as the designs are better sampled across the physical domains. The trade-off is that the higher the accuracy, the larger the simulations become, and thus solve times are extended. There is no point in spending extra hours running a simulation with a dense mesh If a coarser mesh will give you the results you need. Engineers often perform convergence studies to obtain the optimal balance between accuracy and solve time.

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File: https://drive.google.com/drive/folders/1gp1IUXEyABo0igAYQasy4vAWc-qgSjGn?usp=sharing