Discussion Forum

Hi folks,

I am currently working on a solid mechanics simulation for a laser welding process. The actual problem is the modeling of the stresses and strains after melting temperature. So during welding, one calculates stresses and strains until the melting temperature. But because fluids can not transmit normal forces (and melted metal is considered as a fluid), it is required somehow to remove the material history/ to set element's strain to zero at that point. There are other programs such as Ansys, which offer the feature of birth and death of elements (see: www.ansys.stuba.sk/html/guide_55/g-adv/GADV6.htm) so that the element's strain is set to zero as soon as that element is killed and an activation temperature as a stress-free temperature can be specified.

So the question is, is there a workaround for this in COMSOL? How can one remove the element's strain after a certain time or above a certain temperature?

P.S.: I tried to remove the effective plastic strain with a pointwise constraint if(T>Tmelt, solid.epe,0) so that Comsol will set solid.epe to zero when the temperature rise above Tmelt. Unfortunately, this doesn't work, because only reaction forces acting on the displacement and not direct on the effective plastic strain can be defined internally.

Many thanks for any help!

Best regards,
Antoni Artinov