Learning Forum

[cajluni]

Hello all,

I am working with a material who's reference temperature (zero-stress temperature) is above room temperature (~500). I want to import the geometry of that component at room temperature then observe the thermal expansion up to a operating temp (~1000). I set my reference temperature for the material (using MP,REFT,500 apdl command), however now the geometry imports to that reference temperature and shrinks when brought down to room temperature. This means that my thermal expansion from room temp to operating temp is incorrect.

I could oversize the cad model and account for the shrinkage, but I was hoping there was a better way to properly simulate the zero stress temperature while still retaining the proper geometry at room temp in Ansys.

TLDR: Room Temp = 0; Ref Temp = 500; Operating Temp = 1000, geometry is importing at ref temp instead of room temp. I want to simulate expansion from room temp to operating temp.

 

[Dennis Chen]

Hello, you may be overthinking it.   Thermal strain is simply a function of your delta T (operating temp - reference temp).   So if you have a table of CTE vs temperature that covers room, reference and operating, then simply start at room temp, ramp it to 500 and then ramp it to operating temp of 1000.    divide it into 2 steps, this way at the start of step 2, you have your "reference temp" at 500 and then thermal strain is further calculated at delta T between 500 to 1000. 

Hope this makes sense and helps

[cajluni]

Thanks for the advice, unfortunately I'm interested in the stresses that build up from uneven thermal expansion (it's an anisotropic material), ideally the room temp state should be prestressed, as it increases the reference temperature the stress should decrease, then as it goes to the operating temp the stress should increase again. The net result is that the stress should be lower with the same amount of strain compared to if I'd have set the reference temperature to the same as room temperature.