Week 3 Sheet metal Bending challenge
Understanding the effect of static structural analysis on a Sheet Metal
Objective: To study and perform structural analysis on a Sheet Metal with different material and frictional coefficient .Grid dependency test was also performed to optimize the element size for better accuracy
Case 1: 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
Case 3: with Aluminium alloy as material, changing the mesh size
Simulation Process:
Input Geometry
The cad model is imported and viewed in spaceclaim and checked for any errors.
The Model has a punch and die arrangement with sheet metal as workpiece
Material:
An analysis was conducted for three different materials of the sheet metal namely Aluminium Alloy 1199, copper Alloy NL, Magnesium Alloy NL. Non-linear materials are considered to account for the regions of plastic deformation
Mesh
- The sheet metal and faces of punch and die which come in contact with sheet are alone meshed with an element Size of 1mm.other part are meshed with an element size of 4mm
- For case (3) - the sheet metal and the face of punch and die which come in contact with sheet are alone meshed with an element size of 1.5mm. the sheet metal element are of tetrahedrons type
Contacts:
Two contacts between punch and sheet metal as well as the contact between sheet metal and die are defined as frictional contact with frictional coefficient of 0.1
For case (2) the frictional contact is increased to 0.19
Analysis setting:
The analysis is setup for 10 steps. This does not control the time step, but is only an indication of points where boundary changes. The time step is auto control
Boundary conditions
Displacement of punch- the top and side faces of punch are selected and given a downward displacement in y- axis in a tabular from
Displacement of sheet and die- the sheet metal is given Zero displacement in Z-axis and X-axis directional. It is done to avoid any lateral movement the die is fixed and doesn’t have any degree of freedom
Solutions:
All the necessary output variable are selected such as von Mesis stress, stress intensity, equivalent strain etc.
Note- for all three cases the set are same as above we discuss
Result –
Case_1
In this analysis the punch and die displacement is given as boundary conditions, therefore it can be expected that the displacement and strain would be the same for all three materials in the linear region
It should be expected that stress will vary depending on the material stiffness and yield strength. The harder material will exhibit higher stress
| Aluminium Alloy 1199 | Copper Alloy NL | Magnesium Alloy NL |
| Equivalent Stress | ||
| Equivalent Strain | ||
| Deformations | ||
Case 2: With the material as Aluminium Alloy, change the friction coefficient to 0.19
The frictional coefficient will have an impact on the punch force needed and therefore it is useful to keep it as low as possible. The contact tool is used to obtain the frictional stress between the two aforementioned contacts
As the frictional coefficient increases, Equivalent stress and Equivalent strain decreases and Directional deformation increases as we can see it in the above table
Case 3: with Aluminium alloy as material, changing the mesh size
Equivalent strain
Equivalent Stress
Deformation
As the mesh gets finer, the results will become more accurate. From the above table, we can see that as the mesh gets finer the results are increased meaning that the results gets more accurate
Case- 1 Among the three materials used Aluminums alloy 1199 has the least amount of stress developed
Case- 2 – with Aluminium alloy 1199 as material, changing the frictional coefficient from 0.1 to 0.19 doesn’t affect the results.
Case- 3 – with Aluminium alloy 1199 as material, increasing the mesh size from 1mm to 1.5mm doesn’t affect the results.