Week - 5 - Modelling Spotwelds

Objective:

• To create a crash simulation by connecting the 2 brackets using beam & solid (hexa) elements which are represented as spotwelds.
• Compare the results in both cases.

Procedure :

Case 1:

Step 1:- Import:

• Import the keyword file using LS - Prepost.

Step 2:- Create Material and Section Card:

• There are two components present in this model. Create a material card and section card and later assign these properties to the 2 parts in PART keyword.
• I have used steel properties and Element form 16 which are fully integrated shell elements for high accuracy.

Step 3:- Creating Spot Welds:

• Here spot welds are represented as BEAM elements. I have created 10 spotwelds using Mesh >> Element Generation>>Beam option as shown below.
• Pick two nodes and accept.

Step 4:- Material and Section cards for beam elements

• MAT_SPOTWELD - is material card for the spot weld beam elements.
• SECTION_BEAM - is section card for the spot weld beam elements.
• I have created same material id (MID) for spot welds as 100.
• We wanted the weld elements to fail during the simulation, we will set the TFAIL value as 10ms which is half the TERMINATION time (10ms) of simulation.

Step 5:- Contacts:

• Now we need to define appropriate contacts between the beam elements and the two parts which are connected to beam elements,
• TIED_SHELL_EDGE_TO_SURFACE - this contact is given keeping beam elements as the slave and the two brackets shell elements as master as shown below using part set ID.
• AUTOMATIC_SURFACE_TO_SURFACE is created using part ID where one part acts as a slave and other part as a master. This contact defines avoids penetration between the 2 parts when they come in contact during the simulation.

PART_SET:-

Step 6:- Creat Rigid_wall to Distanc of 20 From Shell Body.

Step 7:- Creat Node Set For Velocity and Assign Velocity to NSet.

Step 8:- Control_Terminetion of 10mS:-

CASE 2:

Step 9:- Create Solid Hexa spot welds

• We can apply some changes to the file in case 1 and remaining properties will remain same
• In this 2nd case, we are going to model the spot welds as solid Hexa elements.
• First delete all the 8 beam elements and replace them using 8 solids Hexa elements.
• The Hexa elements are created using the element creation option under the EleTool button.
• use the options as shown below.

• Hexa elements are created successfully, now we can use the existing material cards and assign them to these solid hexa elements. Also, delete the section which is created for beam and replace it with a new solid section with ELEFORM 1 and assign it to the solid hexa elements,
• We should changes the contacts in this case 2. Use CONTACT_SPOTWELD card which defines spotweld connection for solid elements. All the remaining settings are same as in case 1.

Take outputs:-

• D3_plot, swforc, and some more.

Check:-

Model RUN And RESULT:-

FOR ONE BEAM ELEMENT

https://youtu.be/uMzEgiFkG2E

Conclusion:

Crashbox simulation is done successfully with 1.2mm and 1.5mm thicknesses respectively. All the objectives are fulfilled. From comparing the plots and animations we can say that simulation results will change as the thickness of the model changes.