MODELLING BEAM AND SOLID WELDSPOT AND CRASH TEST RESULTS ARE COMPARED USING LS DYNA

OBJECTIVE

Modelling the beam and Solid spottweld for the plates and crash test  result of  axial and shear force should be compared among beam and solid elements.

CAD MODEL

The Cad Model Contains Two Parts Such As Uppar Part And Lower Part. They Are Not Connected Each Other In This Challenge We used Connect Them By BEAM Element. 

PROCEDURE FOR MODELLING BEAM ELEMENT

1.Create Beam Element Using Mesh Command.In Mesh Command Using Element Generation Command We Have To Create Beam Element, There Are Many Methods To Create Beam Element, I Taken Two_Node _Set_Method.

2.Create Part ID For Shell Parts And Beam Element.

3.Define Material For Beam Element Using Spottweld MAT_100.

   Define Material For Shell Parts Using Elastic MAT_001.

4.Define Section For Beam Element Using Section BEAM.The Element Formulation Should Be EQ.9: spotweld beam, see *MAT_SPOTWELD (Type 100).

   Define Section For Shell Parts Using Section SHELL.The Element Formulation is 16.

5.Define Boundary Condition Using SPC And SET_NODE.To run impact test we have to create rigidwall and specify velocity.

6.Define Contact Using Automatic_Single_Surface And Tied_Shell_Edge_To_Surface.

7.Define Control Termination And Database.After Defining All Keyword Save The File.

THE ABOVE FIGURE SHOWS CAD MODEL WITH BEAM ELEMENTS

ANIMATION LINK--https://drive.google.com/file/d/1Vda9-X4R0_vbibIntCnSPwigo3_zGQoL/view?usp=sharing

 PROCEDURE FOR MODELLING SOLID SPOTTWELD ELEMENT

1.Create Solid Spottweld Element Using ELEMENT TOOL Command.In ELEMENT TOOL Command Using Element Edit Command We Have To Create Solid Spottweld Element, There Are Many Methods To Create Solid Spottweld  Element, I Taken Element Type HEXA.

2.Create Part ID For Shell Parts And Solid Spottweld Element.

3.Define Material For Spottweld Element Using Spottweld MAT_100.

   Define Material For Shell Parts Using Elastic MAT_001.

4.Define Section For Spottweld Element Using Section Solid.The Element Formulation Should Be EQ.-1: fully integrated S/R solid intended for elements with poor aspect ratio, efficient formulation.

   Define Section For Shell Parts Using Section SHELL.The Element Formulation is 16.

5.Define Boundary Condition Using SPC And SET_NODE.To run impact test we have to create rigidwall and specify the velocity.

6.Define Contact Using Automatic_Single_Surface And Spottweld.

7.Define Control Termination And Database.After Defining All Keyword Save The File.

ABOVE FIGURE SHOWS THE CAD MODEL WITH SOLID SPOTTWELD 

 ANIMATION LINK--https://drive.google.com/file/d/1DjcAGdoib_ZRf-232dv7oMDYL21f-r2s/view?usp=sharing

BEAM ELEMENT GRAPH

ABOVE FIGURE SHOWS THE SHEAR AND AXIAL FORCE GRAPH FOR BEAM ELEMENT.MAXIMUM AXIAL FORCE AROUND 2550N AND SHEAR FORCE 3200N.IN MAT_100 SPOTTWELD WE SPECIFY THE AXIAL AND SHEAR FORCE 10000N, SO THE BEAM IS NOT FAILED.

The energy ratio is 1 Upto time 9 seconds, it means the energy balance of simulation is perfect. after 9 second suddnly changes.

Sliding energy is nothing but friction energy.it is force generated between two parts when come in contact, after the spottweld failure the two parts coming into contact and penetration is not occured we get positive sliding energy value.

Above figure shows the kinetic energy,internal energy, and total energy.Total energy is the sum of kinetic energy and internal energy.

Hourglass energy is zero because we are using element formulation 9 for shell element it means it fully integrated.so there is no element deformation and results are mor accurate.

The above plot shows the rigidwall force.The rigidwall force generated in x direction only while y and z are zer0.

SOLID SPOTTWELD GRAPH

 ABOVE FIGURE SHOWS AXIAL AND SHEAR FORCE GRAPH FOR SOLID SPOTTWELD.

 MAXIMUM AXIAL FORCE AROUND 4000N AND SHEAR FORCE AROUND 12000N.

Above figure shows the kinetic energy,internal energy, and total energy.Total energy is the sum of kinetic energy and internal energy.

Sliding energy is nothing but friction energy.it is force generated between two parts when come in contact, In above graph shows there is no penetration between two parts.

The above graph shows the energy ratio ,The energy ratio is 0 Upto time 9 seconds, after 9 second suddnly changes.

 The above plot shows the rigidwall force.The rigidwall force generated in x direction only while y and z are zer0.

 CONCLUSION

From the above comparison of axial and shear force of the beam and solid spottweld we conclude that.

The values we are getting for the beam element is lower than solid element.

solid spottweld represent the proper presentation of weldspot and the values proper accurate.

since axial force and shear force is very less for beam element it is better to go with beam to avoid failure