Learning Forum

[Jingyi Liu]

Hello everyone,

I am doing a temperature field simulation on SLM. The powder involves the transformation from solid to liquid and then to solid. When the temperature is lower than the melting point of the powder, the properties of the powder are used. When the temperature exceeds the melting point, it needs to transform to the properties of a solid. In Mechanical WB, I can only assign one material to a geometry, how to achieve this in workbench?

I have defined the thermal physical properties of solids and powders in the Engineering Data. Can this be achieved by inserting the apdl command in the geometry? How should I write the command? Does anyone have any ideas?

thanks 

Best regards

[Erik Kostson]

Hi

 

You just need to define temperature dependent material properties.

/forum/forums/topic/temperature-dependent-properties-in-ansys-workbench/

(say thermal conductivity, etc)

All the best

 

Erik

[Jingyi Liu]

 

 

Thank you, Erik, but I have already addressed this in the Engineering Data. What I mean is that when the temperature exceeds the melting point, ANSYS should switch to calculating with the properties of solid material.In the pictures you could see that there’s a significant difference in values between powder and solid when the temperature is below the melting point.

For instance, the material I’m using is copper, which has a melting point of 1365K. Below 1365K, ANSYS should use the properties of copper powder for calculations, while above 1365K, it should switch to the properties of solid copper. This switch is crucial because, after melting, copper transforms from a liquid to a solid, not back to a powder, and the cooling process should be calculated using the data for the solid. The theory might be complex to explain and understand. However, I need to insert an APDL command to achieve this. 

My question is, how do I define this in APDL? I believe it might involve an if-else statement or something similar. My knowledge of APDL commands is quite basic, so I am struggling to figure out how to implement this in APDL.

Best regards

 

 

[Erik Kostson]

Hi

This course describes what you want do:

/courses/index.php/courses/thermal-capacitance-in-heat-transfer/lessons/lesson-4-phase-change-and-enthalpy/

Go through it in detail

All the best

Erik

[Jingyi Liu]

Thank you Erik.

I have already gone through this course, and I have defined enthalpy. I just need some assistance with changing materials in simulation using APDL because in Powder Bed Fusion (PBF), the powder bed and the molded solid are equivalent to two materials. In this course, it only involves the melting and solidification of the solid, not the powder melting and solidifying into a solid. However, in the simulation of PBF, I need to change the material from powder to solid. Because if the material is not changed, the powder data will still be used during the solidification stage when the temperature drops, which will cause calculation errors and seriously distort the results. Have you any experience with this or ideas?

[Jingyi Liu]

Hi Erik,

If the powder is material 1, the solid is material 2. Is it possible to assign material 1 to the geometry when the element temperature is below the melting point and material 2 to the part when it exceeds the melting point by defining two material properties?