Coefficient of Thermal Softening
The yield stress Y of a material decreases linearly with temperature. This relation can be represented by the equation:
Y=Y0*(1–CTS*(Tmodel–Tref))
where:
• Y0 is the yield stress at the reference temperature
• Tmodel is the temperature of the model
• Tref is the reference temperature
• CTS is the coefficient of thermal softening which is a constant for a material
The coefficient of thermal softening is a parameter that is common to all the hardening laws. You must specify this value regardless of whether you define the elastoplastic material using stress-strain data or by specifying material constants for a selected isotropic hardening law. The default value is zero and it has units of per unit temperature.
When running an analysis, if CTS*(Tmodel-Tref) is greater than 1 the yield stress becomes negative. This indicates that the value you have specified for CTS is too high.