Week - 5 - Modelling Spotwelds

AIM:

                Create Spotwelds between the given two parts with the beam element as case 1 and use Hexa element in case2, now comparet the results of both the case and conclude the same

Steps Followed: 

Create section and material for parts:-

• Import the model to the LS pre post
• Check for the available keywords from keyword manager
• Initially we have to create the required keywords/cards
• Create a section card, go to keyword manager>Section>Shell
  
  
  
• From the above image we can see the section card for part, give the thickness as 1.5mm for the shell
• Create a material card for the same, go to keyword manager>MAT>piecewise linear plasticity material
  
• Now assign the section and material card to the respective parts

Create Rigidwall:-

• Now create a rigidwall, go to create entity>Rigidwall>create>Planar
  
  
  
• Make sure the normal of the rigidwall is faced towards the parts

Create initial velocity card:-

• Create a initial velocity card, go to keyword manager>Initial>velocity node
  
• From the above image we can see the velocity used same as in week 4 challenge

Create Beam(Case 1):-

• Now we have to ceate a spotweld using beam
• Go to Element and mesh>Element generation> Beam slect beam by option to two node set
• Select the two nodes to be connected by beam
• Below image shows the beam created 
  
• I have created total of 9 beams symmetricaly

Create section and material for Beam:-

• When the beams are created the respective sections will be created, delete all the section and create new one
• Go to keyword manager>section>beam
  
• Use ELFORM=9 for spotweld representation, used thickness as 3mm as shown in the above image
• Create material card for spotweld, go to>keyword manager>mat>MAT 100
  
• From the above image we can see the material card for spotweld, mat100 material is used s=for spotweld, The failure criteria is given to the material and time based failure is also specified as 5ms
• Now assign the material and section card for the beam

Create Hexa element(case 2):-

• Create spot welds as hexa elements
• go to>Element tools>element editing>create>elem type>HEXA
• Create the hexa in the same points where the beams are created
  

Create Section and material card for HEXA(Case 2):-

• Use the same material used in case 1
• Section card is created newly for hexa elements
• go to keyword manager>section>solid
  
• Assign the section and material card to hexa part

Create contact cards:-

• Create an automatic_single_surface to avoid the initia l penetration between the parts(go to keyword manager>contacr>Automatic_Single_surface)
• Select the both the parts and create as single part set, in this contact select only the master node
  
• Create the contact between the welds and parts by keeping the parts as master and welds as slave
• Go to keyword manager>contact>TIED_SHELL_EDGE_TO_SURFACE
  

Create control and output cards:-

• Create termination card go to keyword manager>control>termination, end time=10ms
  
• Create Database cards like ASCII, BINARYD3PLOT
• In ascii option use ELOUT ,GLSTAT, MATSUM,NODOUT, RWFORC , SLEOUT, SWFORC cards with DT=0.01ms
• Binary card is shown  in below image
  

RESULTS:

Case 1:

• Von-mises=4.12E+02Mpa
  

Case 2:

• Von-mises=6.06E+02Mpa
  
• Kinetic energy of beam and hexa element are noted down in the same loacation, the results are shown in the below image
  
• In the above image the left side graph shows the plot for beam element and right one is for Hexa element
• Part Kinetic energy for case 1= 11
• Part Kinetic energy for case 1= 73.9

CONCLUSION:

• From the above results we can see the von misess stress is more for solid(Hexa) element compared to Beam element 
• It is known now the hexa element hold good for spotweld instead of beam element
• The part kinetic energy is also high in hexa element