Explosion Under Water

Purpose:

Consider a Lagrange shell structure floating on a water surface. Above there is air and at some distance below, an explosive submerged in the water igniting. the explosion creates a pressure wave that travels through water and finally reaches the structure. The pressure wave hits the structure and causes it to be deform.

This sample is going to show a simple ALE model setup.

Step 1:

Open ALE_Explosion_Under_Water.K (unit : g-cm-s)

Sample file

Step 2:

Open ALE interface.

Step 3:

1. Add group: "Water", "HE", "Air". Both Add Group and Right Mouse Menu on blank area can do this.

2. Add part: Right Mouse Menu on group to Add Part or Pick Part

After adding group and part

Step 4:

1. Switch to Mat tab.

2. Select Group "Water" from the list.

3. Define mat for Group "Water": Click "." to select mat from list, or "+" to define a new one.

4. Define eos for Group "Water": Click "." to select mat from list, or "+" to define a new one.

Name : "EOS_GRUNEISEN"

ID : 10

Other : C=0.148, S1=1.75, GAMAO=0.28, V0=1.0

5. Define hourglass for Group "Water": Click "." to select mat from list, or "+" to define a new one.

ID : 10

Other : QM=1.0E-6, IBQ=0, Q1=0, Q2=0, QB/VDC=0, QW=0.

6. Click Save.

7. Select Group "HE" from the list.

8. Define mat for Group "HE"

Name : "MAT_HIGH_EXPLOSIVE_BURN"

ID : 11

Other : RO=1.63, D=0.784, PCJ=0.26

9. Define eos for Group "HE"

Name : "EOS_JWL"

ID : 11

Other : A=3.71, B=0.0323, R1=4.15, R2=0.95, OMEG=0.3, E0=0.043, VO=1.0

10. Define hourglass for Group "HE": Select hourglass 10.

11 Click Save.

12 Select Group "Air" from the list.

13. Define mat for Group "Air"

Name : "MAT_NULL"

ID : 12

Other : RO=0.00128

14. Define eos for Group "Air"

Name : "EOS_LINEAR_POLYNOMIAL"

ID : 12

Other : C4=0.4, C5=0.4

15. Define hourglass for "Air": Select hourglass 10.

16. Click Save.

After define mat for groups

Step 5:

1. Swithc Simulation Control Tab

2. Select Donor Cell

3. Time=300,

4. Num of Output=30,

5. Reference pressure=0..

Define control parameters

Step 6:

1. click Advance

2. Check DATABASE_TRHIST

3. Check DATABASE_ELOUT

4. Check DATABASE_NODOUT

5. Click OK

Advance control paramters

Step 7:

1. Switch IC/BC Tab

2. Switch Detonation Tab

3. Right Mouse Menu on list to add part 11.

4. Set X=0.0, Y=0.0, Z=0.0, Lighting TIME=0.0.

IC->Detonation Tab

Step 8:

1. Switch Boundary Conditions Tab.

2. Switch SPC Tab.

3. Right Mouse Menu on "", Click Pick and Add

4. Click Area on General Selection Dialog.

5. Pick nodes as follow picture

 

6. Right click to finish picking.

7. Check Z

8. Click Save

BC->SPC-Z

9. Add y-constraints on -y face due to half symmetry as follow picture.

y-constraint

10. Right click to finish picking.

11. Uncheck Z, Check Y.

12. Click Save

BC->SPC-Y

Step 9:

1. Click Output.

Output

2. Click Output Dyna

3. Run LS-DYNA with ls_ale.k