Week - 4 - crash box simulation

AIM:

To perform crash test simulation for the crash box provided.

Parameters given:

Material- steel

System units- gm/mm/ms

Procedure:

First the material and section is defined. The material card used is MAT-24 PIECEWISE_LINEAR-PLASTICITY. the properties of steel are defined using the prescribed units. Then the section is defined using SECTION_SHELL card. After the defination of these attributes, they are defined in the part card.

The next step is used to create the rigidwall. the rigidwall is created by

CreateEntity>>RigidWall>>RigidWall

here planer option is selected and the required values are given by selecting the normal.

Now Initial velocity is defined for the crash box. The initial velocity of 13.88 mm/ms is defined in x direction.

After the defination of velocity, Contact is defined. For this problem AUTOMATIC_SINGLE_SURFACE is used.

Control termination is set to 10 .

now since we have two thickness we divide into two cases,

Case 1:

Material Thickness= 1.2 mm

The above graph gives a view of the cross section force on the crash box.this force is found out at the middle of the crash box. For this DATABASE_CROSS_SECTION_SET was created.

The above graph results in the acceleration of the crash box along the center of the box at node 9387. As seen in graph the x acceleration is almost similar to the resultant acceleration. and the maximum accleration is found to be around 1.85 `(mm)/(ms^2) at 1 second.

Maximum directional stress across the centre of crashbox:

`sigma_x=2.186*10^2MPa`

`sigma_y=1.989*10^2 MPa`

`sigma_z=1.64*10^2 MPa`

Maximum directional strain across the centre of crashbox :

`epsilon_x=6.7e^-6`

`epsilon_y=5.62e^-6`

`epsilon_z=5.015e^-6`

Energies

The above plot gives the information of kinetic energy,Internal energy, Total energy and sliding energy from GLSTAT data.

The above graph gives information of Hourglass energy etc from Matsum Data.

Case 2:

Material Thickness= 1.5 mm

The above graph gives a view of the cross section force on the crash box with shell thickness 1.5 mm

The above graph results in the acceleration of the crash box along the center of the box . The maximum accleration is found to be around 2.1 `(mm)/(ms^2)` at 1 second.

Maximum directional stress across the centre of crashbox:

`sigma_x=2.50*10^2 MPa`

`sigma_y=1.97*10^2 MPa`

`sigma_z=1.588*10^2 MPa`

Maximum directional strain across the centre of crashbox:

`epsilon_x=8.82e^-6`

`epsilon_y=6.06e^-6`

`epsilon_z=4.96 e^-6`

Energies:

The above plot gives the information of kinetic energy,Internal energy, Total energy and sliding energy from GLSTAT data.

The above graph gives information of Hourglass energy etc. from Matsum Data.

Comparision

from the above graph we can infer that the sectional resultant force of 1.2 mm is more than 1.5 mm.

thickness	X-stress	Y-stress	z-stress
1.2 mm	`2.16*10^2`	`1.98*10^2`	`1.64*10^2`
1.5 mm	`2.50*10^2`	`1.97*10^2`	`1.58*10^2`

from the above the above comparision , we can note that the stress are higher in thiner shell element i.e. box of 1.2 mm.

thickness	X-strain	Y-strain	z-strain
1.2 mm	`6.71e^-6`	`5.60 e^-6`	`5.01e^-6`
1.5 mm	`8.82 e^-6`	`6.06 e^-6`	`4.96 e^-6`

the maximum accleration is found to be around 1.85 `(mm)/(ms^2) at 1 second for 1.2 mm thickness.

The maximum accleration is found to be around 2.1 `(mm)/(ms^2)` at 1 second` for 1.5 mm thickness.

Conclusion

The crash box simulation was conducted and the results were verified to find the comparision between 1.2 mm thickness shell part and 1.5 mm thickness part shell.