5.1. 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.

Files Required :

 

5.1.1. Open the ZIP File

Open 5_5_1_App_ALE_1.zip (unit : g-cm-s).

Figure 5.1: Sample file

Sample file

 

5.1.2. Open the ALE Interface

Open ALE interface.

 

5.1.3. Add Groups and Parts

  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.

    • Add part 10 to Group "Water".

    • Add part 11 to Group "HE".

    • Add part 12 to Group "Air".

    Figure 5.2: After adding group and part

    After adding group and part

 

5.1.4. Define ALE Group and Mat Parameters

  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.

    • Name : "MAT_NULL"

    • ID : 10

    • Other : RO=1.0

  4. Define eos for Group "Water": Click "." to select 'EOS' 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 'hourglass' 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.

    Figure 5.3: After define mat for groups

    After define mat for groups

 

5.1.5. Define Simulation Control Parameters

  1. Switch Simulation Control Tab.

  2. Select Donor Cell.

  3. Time=300.

  4. Num of Output=30.

  5. Reference pressure=0.

    Figure 5.4: Define control parameters

    Define control parameters

 

5.1.6. Define Advanced Control Parameters

  1. Click Advance.

  2. Check DATABASE_TRHIST.

  3. Check DATABASE_ELOUT.

  4. Check DATABASE_NODOUT.

  5. Click OK.

    Figure 5.5: Advance control paramters

    Advance control paramters

 

5.1.7. Define Detonation Time

  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.

    Figure 5.6: IC->Detonation Tab

    IC->Detonation Tab

 

5.1.8. Define Boundary Conditions

  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.

    Figure 5.7: Node Picking

    Node Picking

  6. Right-click to finish picking.

  7. Check Z.

  8. Click Save.

    Figure 5.8: BC->SPC-Z

    BC->SPC-Z

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

    Figure 5.9: y-constraint

    y-constraint

  10. Right-click to finish picking.

  11. Uncheck Z, Check Y.

  12. Click Save.

    Figure 5.10: BC->SPC-Y

    BC->SPC-Y

 

5.1.9. Output ALE File

  1. Click Output.

    Figure 5.11: Output

    Output

  2. Click Output Dyna.

  3. Run LS-DYNA with ls_ale.k.