/MAT/PLAS_ZERIL

Format

Definition

Comments

1. The Zerilli-Armstrong law is applicable only to shells and solids.
2. The equation that describes stress during plastic deformation is:
   $$\sigma =C_0+\left(C_1\exp \left(\left(-C_{3}T+C_{4}T\ln \left(\frac{\dot{\epsilon }}{{\dot{\epsilon }}_0}\right)\right)\right)\right)+C_5{\epsilon }_p{}^n$$
   Where,

   ${\epsilon }_p$

   Plastic strain

   $\dot{\epsilon }$

   Strain rate

   $T$

   Temperature

3. Yield stress should be strictly positive.
4. When ${\overline{\epsilon }}_p$ reaches ${\epsilon }_p^{max}$ in one integration point, then based on the element type:
   • Shell elements:

     The corresponding shell element is deleted.

   • Solid elements:

     The deviatoric stress of the corresponding integral point is permanently set to 0; however, the solid element is not deleted.

5. n must be less than 1.
6. If ${\dot{\epsilon }}_0$ is 0, there is no strain rate effect.
7. ICC is a flag of the strain rate effect on material maximum stress ${\sigma }_{\max }$ :

   
   
   

   $\sigma ={\sigma }_y\left(1+c\text{ln}\left(\frac{\dot{\epsilon }}{{\dot{\epsilon }}_o}\right)\right)$	$\sigma ={\sigma }_y\left(1+c\text{ln}\left(\frac{\dot{\epsilon }}{{\dot{\epsilon }}_o}\right)\right)$
   ${\sigma }_{\max }={\sigma }_{\max 0}\left(1+c\ln \left(\frac{\dot{\epsilon }}{{\dot{\epsilon }}_o}\right)\right)$	${\sigma }_{\max }={\sigma }_{\max 0}$

8. Strain rate filtering input (F_cut) is only available for shell and solid elements.
9. The strain rate filtering is used to smooth strain rates.
10. Temperature is computed assuming adiabatic conditions:
    $${\rm T}={{\rm T}}_r+\frac{E_{int}}{\rho C_{\rho }\left(Volume\right)}$$

    Where, E_int is the internal energy computed by Radioss.

11. When the temperature is not initialized using /HEAT/MAT or /INITEMP, the reference temperature (T_r) is also the initial temperature.