Using TREF and TUNIF Commands in MAPDL — Lesson 1

How does Ansys Mechanical™ software and MAPDL use TREF and TUNIF to identify the temperature used to define material properties?

If you do not have a coefficient of thermal expansion (alpha) defined, then the environment temperature (the TREF command in MAPDL) should not affect the results. That temperature is only used to calculate the thermal strains based on the difference between it and the nodal temperatures (alpha* deltaT). If alpha is zero, the calculated thermal strains are zero, regardless of the TREF setting.

Nodal temperatures are calculated from a thermal analysis or imposed by a thermal condition (the TUNIF command in MAPDL). If temperature-dependent material properties are defined, the nodal temperatures are used by the solver to identify the correct material properties. If material properties are only defined for one temperature, then the solver will use those properties regardless of the nodal temperatures.

Reference temperature is the temperature at which the model experiences zero strain. It is only used to calculate the thermal strains. It doesn't affect the material properties used by the solver.