Car crash simulation - Ansys
OBJECTIVE :
To simulate the car crash with the rigidwall with three different thickness for a car body. The given car body is only the surface of the BIW.
PROCEDURE :
Basic setup :
In the given model, there are two geometries, one is car surface and other is rigidwall. Car body is made up of Stainless steel NL and the rigidwall is a material of Structural steel. In connections region, since it is explicit dynamics simulation body interactions are defined. Both the geometries are cut down into half so that the symmetry option for both rigidwall and car body is defined in the symmetry axis. To mirror the car body, edges of the surface are selected and applied.
Patch conforming method for rigidwall is applied with tetrahedral elements.
Face sizing for the car surfaces are defined in order to increase the length of the elements because it doesn't need finer mesh at all. The crash is going to happen at front so the mesh is finer at there.
All triangles method is used to deploy only tetrahedral elements for the car surface. If not the quads are placed automatically.
In this case, body of the car is fixed and the rigidwall is applied with displacement. The rigidwall is displaced for 500mm towards car body. A represents displacement and B represents the fixed support in the above image.
Case 1 : 0.2mm thickness
The thickness for the car body is defined as 0.2mm.
Case 2 : 0.3mm thickness
In this case, thickness of the car body is 0.3mm.
Case 3 : 0.4mm thickness
In this case, the thickness of the body is 0.4mm.
RESULTS :
Case 1 : 0.2mm thickness
Total deformation :
Equivalent stress :
Equivalent strain :
Case 2 : 0.3mm thickness
Total deformation :
Equivalent stress :
Equivalent strain :
Case 3 : 0.4mm thickness
Total deformation :
Equivalent stress :
Equivalent strain :
CONCLUSION :
| Total deformation(mm) | Equivalent stress(MPa) | Equivalent strain(mm/mm) | |
| 0.2mm thickness | 875.6 | 12071 | 0.061645 |
| 0.3mm thickness | 875.26 | 12067 | 0.061624 |
| 0.4mm thickness | 874.23 | 12064 | 0.061607 |
The above table shows that the values in all the criteria are almost same. Three cases are behaving like the same. As the rigidwall hits the car body, the body immediately deformed and strectched into it. Since the car body is a sheet metal the stress will not much in it. The maximum sttress developed is in the rigidwall. Sheet metal absorbs energy and strectched immediately.
All the values are varies infinitesimely.
Thus the simulations are done and the results are tabulated and compared for the better thickness. It shows that the need of material change required since the results are more like to each other.