Week 3 Sheet metal Bending challenge
Objective:
To perform sheet bending simulation in ANSYS for different materials and to analyse results of simulation performed
Procedure to set up simulation:
- Given die, punch and sheet geometry is loaded in Space claim GUI
- Required materials are loaded from Engineering materials section
- In case 1, simulation is carried out for different materials of sheet such as Aluminium alloy 1199, Copper alloy NL and Magnesium alloy NL. Die and punch are given structural steel material.
- Frictional contacts are setup between mating faces of punch-sheet and between mating faces of sheet-die with a friction co efficient of 0.1
- Augmented Lagrange formulation is chosen and normal stiffness is set to manual with normal stiffness factor of 0.1. Auto Asymmetric behaviour is chosen.
- Mating faces of die and punch are meshed using 1 mm size. Sheet is given a mesh size of 1 mm with tetrahedron patch method
- Analysis is set up for 10 steps. Direct solver is used. Large deflection is switched on.
- In Non linear controls, stabilization is set to constant. Energy dissipation factor is set to 0.1
- Sheet is fixed in z axes and is free to deform in x and y axes
- Die and punch are given displacements in step wise manner so as to simulate bending of sheet
- Solution could be run and results could be generated.
- In case 2, friction co efficient of contacts are set to 0.19 and results are generated.
Results discussion:
Case 1:
a) Sheet Material- Aluminium alloy 1199
Equivalent stress of sheet:
Maximum value- 66.084 MPa
Total deformation in Y direction:
Maximum value- 12.456 mm
Equivalent elastic strain:
Maximum value- 1.5624
b) Sheet Material - Copper Alloy NL
Equivalent Stress of Sheet:
Maximum value- 128.05 MPa
Total deformation in Y direction:
Maximum value- 11.673 mm
Equivalent elastic strain:
Maximum value- 1.4834
c) Sheet Material - Magnesium Alloy NL
Equivalent Stress of Sheet:
Maximum value- 126.95 MPa
Total deformation in Y direction:
Maximum value- 11.099 mm
Equivalent elastic strain:
Maximum value- 0.0018041
Case 2: Aluminium Alloy 1199 sheet with firctional coefficient of 0.19
Equivalent stress of sheet:
Maximum value- 66.986 MPa
Total deformation in Y direction:
Maximum value -10.138 mm
Equivalent elastic strain:
Maximum value- 0.0016104
Case 3: Comparison of results for different mesh sizes:
Mesh size of sheet was refined to 0.8 mm and simulation results were obtained as follows.
Equivalent Stress of Sheet:
Maximum value- 75.736 MPa
Comparing with maximum stress obtained from case with 0.1 friction coefficient, maximum stress has increased in this case.
Total deformation in Y direction:
Maximum value- 12.673 mm
Comparing with total deformation in Y direction obtained from case with 0.1 friction coefficient, total deformation in Y direction has increased in this case.
Equivalent Elastic Strain:
Maximum value- 1.362
Comparing with equivalent elastic strain obtained from case with 0.1 friction coefficient, equivalent elastic strain has decreased in this case.
Conclusion:
Comparing case 1 with Aluminium alloy 1199 sheet and case 2, it can be understood that increasing friction coefficient has increased maximum stress, but total deformation and maximum elastic strain values are decreased considerably.
Comparing three different sheet materials in case 1, aluminium alloy 1199 is subjected to minimum stress. But, total deformation and elastic strain in maximum for aluminium alloy 1199.
Learnings:
While performing simulation of sheet bending, in some cases solution was unconverged due to high distortion. In such cases, method of increasing the number of steps to gradually apply loads was followed and fruitful results were obtained.