Simulation of a Crash Tube hitting the rigid wall in LS Dyna

OBJECTIVE:

The main objective of this challenge is to perform the simulation on a crash tube hitting the wall with two varying thickness and to plot the acceleration and stress curves for both the varying thickness shell elements.

CASE SETUP AND EXECUTION:

1. Import the keyword file in LS Dyna. The unit system followed is gm-mm-ms

2. Create the section shell with the element formulation of 2 and with the thickness of 1.2mm with the integration points as 2

3. Create the Material card. MAT 24 is used for the simulation with the basic input parameter values of density, young\'s mdulus and poisson Ratio

4. Assign both the material and the section cards to the Part ID

5. Create a Rigid wall 10mm opposite to one end of the crash tube

6. Initial velocity of 13888.9 mm/ms is applied in the negative X- direction

7. Create the Automatic single surface contact so the slave and master node will be the same (Crash tube)

8. Create a database cross section set to find the energy acting on the nodes in the middle length of the crash tube

9. Control the termination upto 0.01 ms

10. The binary plot has been kept upto the time step of 5e-4

11. Other output requests like glstat, sleout, reforce, rwforce, nodout, secforce with the dt of 5e-4.

IMAGES AND GRAPHS:

FOR THICKNESS VALUE OF 1.2mm

Cross Sectional Force generated in the middle of Crash bar is plotted with the peak value at the points.

ACCELERATION PLOT OF A NODE numbered 1891 has been plotted with the acceleration along all the axis (X,Y,Z) direction.

MAXIMUM STRESS AND MAXIMUM STRAIN

STRESS along x-axis - Maximum stress is obtained at the value of 4.644e3 MPa and the minimum value around -2.427e3 MPa

STRESS ALONG Y- Axis - Maximum stress along y- axis is obtained at the maximum value of 4.224e3 MPa and the minimum value of -2.262e3 MPa

STRAIN ALONG X - axis -- Maximum strain is found in the change in length of 1.976 mm and the minimum of 0.

STRAIN along Y - Axis Maximum strain is obtained in the increase in length of 2.165mm and the minimum of 0.

PLOTTING THE ENERGIES

FOR THE THICKNESS OF 1.5mm

CROSS SECTIONAL FORCES is plotted along the multi-directional axis to the curve

ACCELERATION PLOT OF A NODE is plotted for the node numbered 1891. The plot has the accelerations acting on all the co-ordinates.

MAXIMUM AND MINIMUM STRESS AND STRAIN

Maximum STRESS along the X- axis is maximum at the deformation of 3.571E3 MPa and the minimum of -2.694e3 MPa

STRESS along Y- axis is maximum at the displacement of 4.710e3 MPa and minimum around the value of -3.174e3 MPa

STRAIN along X- axis is obtained at the maximum deformation of 2.148 mm and the minimum of zero

STRAIN along Y- axis is maximum with the deformation of 2.178mm and minimum of zero.

ENERGIES

RESULTS AND CONCLUSION:

- From the given two conditions, the simulation here buckles and folds in the axial direction so as to come in self-contact.

- Acceleration is felt higher with the element thickness of 1.2mm than 1.5mm

- Stress- Strain plots in X-Y direction is felt higher in shell thickness of 1.2mm as the stress-strain plots has nothing to do with the thickness change.

- The Input, Output and animation files are submitted.

The link for validation

https://drive.google.com/open?id=16gZPoyQTEbtGiOgPL6gj2eoWUtL7Xj2B