/PROP/TYPE10 (SH_COMP)

Format

Definition

Comments

1. I_shell, I_sh3n – 4-node and 3-node shell 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_sh3n =30 (DKT18): BATOZ DKT18 thin shell with three Hammer integration points.
   • Flag I_shell =2 is incompatible with one integration point for shell element.
2. 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 $\text{Δ}\text{t<}\text{Δ}{\text{t}}_{\text{min}}$ can be switched to a small strain formulation by Radioss Engine option /DT/SHELL/CST, except if I_smstr = 4.
   • If I_smstr = 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.
3. h_m, h_f, and h_r - Hourglass coefficients
   • h_m, h_f, and h_r 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, default values of h_m and h_r are 0.1 with larger values possible.
4. d_n - Shell numerical damping coefficient
   • d_n is only used for I_shell =12, 24 and I_sh3n = 30:
     • for I_shell =24 (QEPH) d_n is used for hourglass stress calculation.
     • for I_shell =12 (QBAT) d_n is used for all stress terms, except transvers shear
     • for I_sh3n =30 (DKT18) d_n is only used for membrane
5. I_thick - Shell resultant stresses calculation flag
   • Flag I_thick is automatically set to 1 for /MAT/LAW32 (HILL).
   • If I_thick =1, the small strain option is automatically deactivated in the corresponding type of element.
6. 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.
7. I_drill
   • Drilling DOF stiffness is recommended for implicit solutions especially for Riks method and bending dominated problems.
   • I_drill is available for QEPH, QBAT (I_drill =12 and 24), and standard triangle (C0) shell elements (I_sh3n = 1 and 2).
8. Orthotropy direction definition.
   The reference vector $\mathrm{V\text{'}}$ is projection of the input vector $V$ on the shell element surface and defined as following according to the flag I_P:

   • If I_P=0 and skew_ID = 0, the vector $V$ is defined with V_X , V_Y and V_Z.
   • If I_P=0 and skew_ID ≠ 0, the vector $V$ is the first direction (local X) of the local coordinate system skew_ID.
   • If I_P = 20, the vector $V$ is defined with the node N1 and N2 of the shell elements.

     
     
     Figure 2. I_P = 20

   • If I_P = 22, the vector $V$ is the first direction (local X) of the local coordinate system skew_ID. Vector components V_X, V_Y and V_Z are ignored.

     
     
     Figure 3. I_P = 22

   • If I_P = 23, the vector $V$ is defined with V_X, V_Y and V_Z. The reference vector $\mathrm{V\text{'}}$ is the product of vector $V$ and shell element normal direction $n$ Local coordinate system skew_ID is ignored.

     
     
     Figure 4. I_P = 23

   Then for each layer, the 1^st material direction (m1) is vector $V^{\prime }$ turned ${\varphi }_i$ degrees (turns positive direction around shell normal $n$ ).

   
   
   Figure 5.

   The hierarchy order to define the reference vector $V$ is:

   • initial state card (/INISHE/ORTHO)
   • shell property

   In case of reference metrics, the orientation for directions of anisotropy must be defined with the reference geometry, not the initial one.

   The 2^nd material direction m2 is derived from direction m1 rotated 90 degrees (orthotropic).

   Layers are overlaying one by one from bottom to top.

   
   
   Figure 6.

9. The P_thick_fail parameter is not compatible with failure defined within the material law itself, such as plastic failure strain in LAW36.
10. Element deletion rules used with P_thick_fail and failure models:
    • Only P_thick_fail defined in the property is considered to trigger the element failure.
      • P_thick_fail > 0 defines a fraction of failed thickness. This uses the amount of element global thickness assigned to each layer.
      • P_thick_fail < 0 defines a ratio of failed layers. This uses the number of layers.
    • The P_thick_fail defined in failure model(s) (/FAIL) are not used.
    • For fully-integrated shells (I_shell=12), the rules described above for under-integrated shells applies to each Gauss point separately. P_thick_fail criterion is checked for all layers thickness for each in-plane Gauss point. The element is deleted only when all Gauss points reach P_thick_fail criterion.
    • P_thick_fail rules are not used with failure models defined inside the material laws. It is used only for the failure model defined with /FAIL.