Appendix A.9 - Temperature (TREF)

If the value of the TREF field is set to -1.0, the temperature dependence feature will be activated. If the value of the TREF field is greater than or equal to 0.0, the value is the temperature of the desired environment in the material data (mdata) file.

Temperature Dependence

For this feature to influence results, the material must be characterized at multiple environments. When temperature dependence is active, composite and constituent properties are interpolated linearly for any given temperature that lies within the bounds of the lowest and highest temperature points stored in the material file. For temperatures below the lowest stored temperature datum, material properties stored at the lowest temperature datum are used (Helius PFA will not extrapolate properties beyond the bounding stored temperature data points). The same is true for temperatures above the highest stored temperature datum. This linear interpolation of material properties is illustrated below.

Temperature Selection

For materials that contain multiple sets of material properties (thus they contain multiple environments), the value of the TREF field must equal the temperature of the desired environment. For materials characterized at a single environment, this value may be left blank since there is only one set of material properties in the material file.