Week - 5 - Modelling Spotwelds

OBJECTIVE: create spotwelds with beam and solid elements between the two shells and give prescribed motion set as load and analyse the forces on spotweld elements.

PROCEDURE:

Import the keyword file into LS Dyna and create the rigid wall for collision, midplane section for database, and CNRB for load application.

as shown below.

now create the spotwelds with beam elements using element generation option and solid elements using element editing option in the toolbar as shown below.

now create the material cards for shells and and spotwelds as shown below.

as the simulation requires failure at the halfway of termination time I have given TFAIL at 3 ms.

and section card goes as shown below.

now create sets for shells and spotwelds to specify the contact and set shell part set as master and spotwelds as slave.

after giving the same imposed velocity load the simulation occured as below.

now the energy plots are shown as below.

global energies of the system. Red line- kinetic energy, Green line - internal energy, Blue line - total energy.

sliding energy plot.

internal energy plot of the spotwelds. you can see at failure 3ms the spotweld elements are deleted so energy is zero.

kinetic energy plot of the spotwelds. here as well the energies become zero due to element deletion due to failure.

the acceleration plots are given below.

rigid body acceleration of a spotweld beam element.

rigid body acceleration of spotweld solid element.

axial forces on spotwelds.

shear forces on spotwelds.

resultant forces on spotwelds.

resultant moments on spotwelds.

you can observe that at 3ms the forces disappear instantly due to element deletion for failure.

section force at midplane along the direction of length.

max directional stress along the length 1247 `g*mm^-1*ms^-2`.

max X strain contour.

max Y strain contour.

CONCLUSION:

In this challenge I have modelled the spotweld using two different elements one is beam and second one is solid and given the condition to fail the spotwelds at time 3ms. and observed the results and interpreted the forces on beam elements in the report.