WLF Shift Function

Question - When to use WLF Shift function?

Answer - The WLF shift function is used for modeling the thermo-viscoelastic behavior of materials below their glass transition temperature. First confirm that the principle of thermorheologically simple (TRS) behavior applies to your material . That is to say,"the material response to a load at high temperature over short duration is the same as the response at a lower temperature over a longer duration". WLF shift function has been found to be most helpful with polymers undergoing temperature dependent relaxation. While it is recommended to model the response below the glass transition temperature, there is no numerical limitation in the formulation. Therefore, it may still be used beyond the glass transition temperature but the user must verify the results from the analysis.