Week - 5 - Modelling Spotwelds

Aim:- In this challenge, we create two types of spot weld one from the beam element and the other from the solid element, and compare them to the given component.

procedure:-

1. Spot weld with beam element:-

• First open Ls-prepost and import the file here.

• To create beam element go to mesh>elegen and create the element as shown in below image.

• After creating all beam elements define section ID two different types one shell and the other beam.

• In beam section element formulation of beam element as 9 which signifies the behavior of spot weld as beam element.

• Then create material properties both for weld and shell parts.
• Material property of the weld parts.

• Material property of the shell parts.

• Now assign all the respective material properties to the part ID and beam.

• Then we have to define contact cards for the shell for auto single surface contacts and one for the spot weld element which is a tied shell edge-to-edge contact card.

• in auto single surface contact we need only to define slave which is set as a part for the shell.
• in tied shell edge-to-edge contact card the slave card is given as a node set of spot weld beam elements and a master card is given as a part set of shell parts set for shell part.

• Now we define boundary conditions like prescribed motion set for displacement and spc set (single point constrained) for fixed.

• After that we define the curve for displacement.

• Then define the database like ASCII, binary d3plot, and history node.

• now define termination with 10ms.

Post-processing(result):-

• plot for all energies (total, internal, kinetic, sliding)

• Maximum directional stress along the length crash box.
• X -stress to the beam element.

• we can see the displacement of the beam element through the graph. in this graph, some elements show the gradual displacement and some show the shudden displacement.

• we can see through the graph shear force for the beam element is high at 12.5 n/mm at 3ms and after 6ms it gradually decreases at 7ms it becomes 0.

• Axial force generated in the weld of the crass box along the weld length. The highest value of force shown on the F weld (orange line ) is 8n at the time 5ms and after that it rapdly decrease at 7ms all weld brakes.

Spot weld with solid element

• First create solid elements between two shells using the element edit option. To create the solid elements select four nodes of both opposite shells that the solid element formed.

• Next we create a section card for the Hexa element. Here we select ELFORM 1 which is the default for solid elements.

• then we select the material ID for the solid element.

• Now assign the material ID and section ID in the part card.

• Now create node-set and part set for all the parts using the entity option.

• Now we create a control card that includes an automatic single-surface and select shell part as a slave part.

• After that we create a spotweld card and select a hexa element as a slave part and shell as a master part.

• Then define the ASCII data like binary d3plot, historynode.
• Then define control termination with termination 10ms.

• boundary condition similar to the above case.

Post-processing for hexa weld element:-

• plot all energies for all parts kinetic, internal, total, sliding.

• we can see the displacement of the beam element through the graph. in this graph, some elements show the grasuall displacement and some show the shudden displacement.

• Axial force generated in the welds along the length. The highest value of axial lode is 25n and after 6ms it's become 0.

• we can see through the graph shear force valuen for every elements here highest value of shear force is 10.5n/mm and after 6ms it's become 0.

• we see the material energies like internal, and kinetic.

• Acceleration plot for the weld, we can able to plot every node graph.

• Here, we can see maximum stress develop at 4ms is 2n/mm greenline and maximum compression at 1ms is -3.5n/mm at 7ms these brack .

Comparison:-

Beam element	solid element

Conclusion:-

• In this challenge I learned the process to be followed to smooth the analysis procedure while working on a model.