car crash simulations

Objective: To perform a frontal car crash simulation using explicit dynamics and perform parametric study of 3 different values of thickness of car body. We need to analyse the total deformations and equivalent stress acting on the model.

Use explicit dynamics system and select the material from the engineering data library. The material we are using is stainless steel NL and its properties are shown below.

Import the cad geometry into explicit dynamics system. Assign the materials and thickness to the car body in the mechanical model cell and apply symmetry region to car body as shown below.

A thickness of 0.3, 0.6 and 0.9 mm was taken for car body.

Delete all the contact set by default.

Meshing: The car rear body was first meshed using face sizing of element size 300 mm and later the whole car body was meshed using triangle element method. The wall was meshed using tetrahedron method. An element size of 300mm was used for meshing the car body.

Face sizing Triangular method

Tetrahedron method (wall)

Anlaysis setting: End time for this simulations was 0.001 sec with 0.1 maximum energy. error.

Boundary conditons: A fixed support was given to the rear face of the car body to take the impact and displacement of 500mm given to the wall in z direction.

Results:

Total deformations:

• Case 1: 0.3mm

• Case 2: 0.6mm

• Case 3: 0.9mm

Equivalent stress:

• Case 1: 0.3mm

• Case 2: 0.6mm

• Case 3: 0.9mm

Graphs comparison:

Deformations vs time:-

Avg stress vs time

Conclusion:

from the table above it can be seen that on increasing the thickness the deformations value goes on decreasing and due to this, stress also decreases along with increasing thickness.