Learning Forum

[CraigSneddon]

Does Mechanical AM process take into account/model with phase change?n

[John Doyle]

The short answer is that WB-Additive does not account for phase change between solid and liquid phases.nThere is no enthalpy vs temperature property used in the transient thermal. In the static structural run , we set a new layer, which is already solid, then allow it cool between layers. If a user wants to set the new layer temperature to a higher value, the liquid-solid phase change can be captured, but the user would need to update the material properties to capture that. Our sample properties generally do not go into that range.  nHaving said that, we do offer a relaxation temperature (TRELAX) field as part of the AMMAT command at which the past history is lost (plastic strains reset to zero): nAMMAT, MATPART, TMELT,TRELAXnThis might give you something close enough, but you would have to validate it.

[John Doyle]

Some additional information about phase change from my colleagues:nIf you would like to do phase transitions of any kind-there are two places which need to capture the phase transitionn 1) Enthalpy:- Nonlinear Controls for Transient Thermal Analyses (ansys.com)nand n2) Coefficient of Thermal Expansion changes due to phase transition: Temperature dependent CALPHAD data, published data or special material models (modulus is important as well)n Doing one and not doing the other in Mechanical will not be helpful with phase transition. nThe ideal workflow to accomplish this in Mechanical, would be to set the top layer at liquidus temperature (not solidus) and solve using Newton Raphson to get temperatures followed by applying the BF, Temp with appropriate TRef and CTEs in xx,yy and zz. For solid state phase transition, they also have xy components etc. due to the rotation of solid phase of crystals accompanied by phase transitions and may require special techniques (state variables and UPFs) to handle those aspects.n