Week 11 Car Crash simulation

Aim-

For this project, we will have to perform a parametric study using 3 different values of thickness for the car body by expicit dynamics.

Procedure-

• Here no non-linear material has been not specified to us, so we will use the materials as follow for Car body,

Stainless Steel NL-

2. Structural Steel for wall.

• Now we have to import the model for that right click on the geometry tab and hit import>>then select the file from saved location and hit ok.

Symmetry-

• Now we have to give symmerty to wall and car body since both models are halfly captured.
• To do so right click on model>>symmetry>>symmetry region>>select wall side face along x-axis as normal.

• For car side face for symmetry region.

Connections-

• Here we dont define ady contact as it is not required so we will delete the existing contacts and keep body interactions.

Mesh-

• For wall we have to insert a patch method as tetrahedrons.

• For car body we have to select method as triangles since it has lesser thickness than 6mm, so we will consider it as 2d element.

• Now we have to insert the sizing for side of car body.

• For rest keep default mesh size and hit mesh.

Analysis Setting-

• Here we will give time step as 1e-3 and max. and rest of settings as default.

• As we are going to move wall so, we will fix car as rigid body.

• We will give displacement load to wall back side with ramped 500mm.

Solution Setting-

• Here we have to define total deformation, to do so right click solution>>insert>>deformation>>Total.
• Now for stress right click on the solution>>insert>>stresses>>equivalent (von-Mises).

Parametric setting-

• As per given condition we have to evaluate the result for 3 different thickness by parametric form.
• We need to give parametric value to total deformation and equivalent stress also.

• Now parametric window will appear in the projects tab.

• Now input rest as 0.4mm and 0.5mm thickness to it in parametric settings.

Results-

Total Deformation-

Case-1-0.3mm

Case-2-0.4mm

Case-3-0.5mm

Equivalent Stress-

Case-1-0.3mm

Case-2-0.4mm

Case-3-0.5mm

Result Comparision-

Cases	Total Deformation (mm)		Equivalent Stress (MPa)
	Min.	Max.	Min.	Max.
Case-1	0	1047.22	0	12293.23
Case-2	0	1045.12	0	12237
Case-3	0	1042.87	0	12179.16

• From above table we can observe that with increase in thickness total deformation and equivalent stress decrease.

Animated Results-

Case-1-0.3mm thickness 

Total Deformation

Equivalent Stress

Case-2-0.4mm thickness 

Total Deformation

Equivalent Stress

Case-3-0.5mm thickness 

Total Deformation

Equivalent Stress

Conclusion-

• From above simulation we have to select max. thickness for safe condition what we can conclude now.
• But in actual its not about metal thickness, its about how the energy of impact is absorbed.
• We will have to understand that the sheet metal doesn't contribute totally during crash, its the internal structure which decides fate of the car during crash.