/PROP/TYPE1 (SHELL)

Format

Definitions

Comments

1. I_shell - Shell small strain formulation flag
   • I_shell=1,2,3,4 (Q4): original 4 node Radioss shell with hourglass perturbation stabilization
   • I_shell=24 (QEPH): formulation with hourglass physical stabilization for general use
   • I_shell=12 (QBAT): modified BATOZ Q4γ24 shell with four Gauss integration points and reduced integration for in-plane shear. No hourglass control is needed for this shell
   • I_shell=2 is incompatible with one integration point (through thickness) for shell element
2. I_sh3n - 3 node shell element formulation flag
   • I_sh3n=30 (DKT18): BATOZ DKT18 thin shell with three Hammer integration points
3. I_dril - Drilling degree of freedom stiffness flag
   • Drilling DOF stiffness is recommended for implicit solutions especially for Riks method and bending dominated problems
   • I_dril is available for QEPH, QBAT (I_shell =12, 24), and standard triangle (C0) shell elements (I_sh3n = 1, 2)
4. I_smstr - Small strain formulation
   • Small strain formulation is activated from time t=0, if I_smstr =1 or 3. It may be used for a faster preliminary analysis, but the accuracy of the results is not ensured.
   • Any shell for which $\text{Δt}\text{<}{\text{Δt}}_{\text{min}}$ can be switched to a small strain formulation by Radioss Engine option /DT/SHELL/CST; except if I_smstr =4.
   • If the small strain option is set to 1 or 3, the strains and stresses which are given in material laws, are engineering strains and stresses; otherwise they are true strains and stresses.
   • I_smstr =10 is only compatible with these material laws 42, 62, 69, and 82 that use total strain formulation. Generally, the Left Cauchy-Green strain is used. For User laws, the deformation gradient tensor and the right stretch tensor may be used.
5. h_m, h_f, and h_r - Hourglass coefficients
   • Are only used for Q4 shells (I_shell=1,2,3,4). They must have a value between 0 and 0.05.
   • For I_shell=3, the default values of h_m and h_r are 0.1 with larger values possible.
6. d_n - Shell numerical damping coefficient
   • d_n is only used for I_shell =12, 24 and I_sh3n = 30
     • I_shell =24 (QEPH) d_n is used for hourglass stress calculation
     • I_shell =12 (QBAT) d_n is used for all stress terms, except transvers shear
     • I_sh3n =30 (DKT18) d_n is only used for membrane
7. Default value for numerical damping coefficient d_m.

   	dm
   Ishell= 1, 2, 3, 4 (Q4)	0.05 for LAW27 0.0 for LAW32, 36
   Ishell=12 (QBAT)	0.0 for LAW2, 27, 32, 36
   Ishell=24 (QEPH)	0.015 for all other material
   Ish3n= 1, 2, 31	0.0
   Ish3n=30 (DKT18)	0.0
   Any Ishell, Ish3n	0.05 for LAW65

8. I_thick - Shell resultant stresses calculation flag
   • I_thick is automatically set to 1 for material LAW32
   • I_thick =1, the small strain option is automatically deactivated in the corresponding type of element
9. I_plas - Shell plane stress plasticity flag
   • It is recommended to use I_plas =1, if I_thick =1
   • If I_plas =1, the small strain option is automatically deactivated in the corresponding type of element
10. Global integration, N=0
    • Global integration is only compatible with material LAW1.
    • Failure models are not available with global integration for shells.
    • State files (/STATE/DT which creates /INISHE and /INISH3N) are not compatible with global integration.
    • Automatically set to N=3 for the other material laws.
11. Element deletion rules used with /FAIL models.
    • Under-integrated elements (Belytschko, QEPH, DKT18):
      • If only one /FAIL model with its own P_thick_fail (/FAIL/BIQUAD, /FAIL/TAB1) is applied to the shell material, and P_thick_fail on the /FAIL card is set > 0, the value of P_thick_fail is used regardless of P_thick_fail set on the /PROP/SHELL card. If the value of P_thick_fail on the /FAIL card is set at 0, the P_thick_fail from the property card is used (no default value, so should be set to > 0 to avoid rupture after single integration point failure if that is not desired).
      • If only one /FAIL model without its own P_thick_fail (/FAIL/JOHNSON) is applied to the shell material, and the P_thick_fail value from the /PROP/SHELL property is set to > 0, the property P_thick_fail is taken by default and overwrites I_{fail_sh} settings from the failure model. If P_thick_fail on the property is set = 0 (or blank), then I_{fail_sh} from the failure model is used (for legacy compatibility).
      • If more than one /FAIL failure model is applied to the shell material, the value of P_thick_fail is calculated individually from each of the failure model P_thick_fail or I_{fail_sh} settings and P_thick_fail on the property card is ignored.
        For Example, per failure model:

        • If I_{fail_sh} = 1 (one integration point failure sufficient to delete element) = P_thick_fail= 1.0 e-6
        • If I_{fail_sh} = 2 (all integration points failure is necessary to delete the element) = P_thick_fail = 1.0
        • If P_thick_fail (/FAIL) = 0, = P_thick_fail = 0.0

          In this case on a /FAIL card with P_thick_fail, failure will occur when a single integration point fails, due to this /FAIL (set to > 0 if this is not desired).

    • Fully-integrated shells (Batoz, DKT_S3)

      The rule described for under-integrated shells applies to each Gauss point separately. P_thick_fail ratio is checked for all integration points in thickness for each in-plane Gauss point. The element is deleted only when all Gauss points reach P_thick_fail ratio criteria.

12. I_pinch is used to enable or disable set pinching degree of freedom. Currently, only supported for QBAT shells (I_shell=12).