/THERM_STRESS/MAT

Format

Definition

Element Compatibility - Part 1

✓ = yes

blank = no

Element Compatibility - Part 2

✓ = yes

blank = no

Comments

1. The /THERM_STRESS/MAT option should be used with thermal material. This option is not compatible with ALE applications (/ALE, /EULER). There is no thermal coupling between an ALE thermal material and a Lagrangian thermal material. /HEAT/MAT should be defined for thermal analysis and temperature change computation.
2. This option is available for all material laws; except for the following:

   LAW0, 5, 6, 11, 21, 26, 37, 41, 46, 51, 54, 97, 108, 113, 151, /MAT/B-K-EPS, /MAT/K-EPS, and /MAT/GAS

3. This option is compatible with equations of state, /EOS, only when used with the following materials: LAW3, 4, 12, and 49
4. This option is not available for implicit analysis.
5. The thermal expansion generates thermal strains which are defined as:
   $$\langle {\epsilon }_{\mathit{th}}\rangle =\langle \alpha \Delta T\alpha \Delta T\alpha \Delta T000\rangle$$

   Where, $\alpha$ is the isotropic thermal expansion coefficient.

   $\text{Δ}T=T-T_{ref}$ is the temperature gradient or temperature increment between current time and reference.

   The total strain is considered as the sum of subsequently mechanical and thermal effect:

   $$\epsilon ={\epsilon }_{th}+{\epsilon }_{meca}$$

   This change in temperature causes stress. The thermal stress can be calculated from Hook's law.

   $${\mathbf{\sigma }}_{\mathit{th}}=H{\mathbf{\epsilon }}_{th}$$

   Where, $H$ is the elasticity matrix.

   It is important to define boundary conditions with particular care for problems involving thermal loading to avoid over-constraining the thermal expansion. Constrained thermal expansion can cause significant stress, and it introduces strain energy that will result in an equivalent increase in the total energy of the model.