Block Format Keyword
/DEF_SHELL - Shell Default Values Initialization
Description
This keyword is used to set default values for certain parameters in shell property (/PROP/SHELL).
Format
(1)
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(2)
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(3)
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(4)
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(5)
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(6)
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(7)
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(8)
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(9)
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(10)
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/DEF_SHELL
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Ishell
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Ismstr
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Ithick
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Iplas
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Istrain
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Ish3n
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Idril
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Field
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Contents
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Ishell
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Shell element formulation flag
(Integer)
= 0: default, set to 1
= 1: Q4, visco-elastic hourglass modes orthogonal to deformation and rigid modes (Belytschko)
= 2: Q4, visco-elastic hourglass without orthogonality (Hallquist)
= 3: Q4, elasto-plastic hourglass with orthogonality
= 4: Q4 with improved type 1 formulation (orthogonalization for warped elements)
= 12: QBAT shell formulation
= 24: QEPH shell formulation
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Ismstr
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Shell small strain formulation flag
(Integer)
= 0: default, set to 2.
= 1: small strain from time = 0
(new formulation compatible with all other formulation flags)
= 2: full geometric nonlinearities with possible small strain formulation activation in RADIOSS Engine (option /DT/SHELL/CST)
= 3: old small strain formulation (only compatible with Ishell =2).
= 4: full geometric nonlinearities (in RADIOSS Engine, option /DT/SHELL/CST has no effect)
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Ithick
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Shell resultant stresses calculation flag
(Integer)
= 0: default, set to 2
= 1: thickness change is taken into account
= 2: thickness is constant
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Iplas
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Shell plane stress plasticity flag
(Integer)
= 0: if /IMPLICIT option is used in the input deck, the default value for Iplas is set according to /IMPLICIT, otherwise default = 2 (Radial return)
= 1: iterative projection with three Newton iterations
= 2: radial return (default value if /IMPLICIT is not used in the deck)
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Istrain
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Compute strains for post-processing flag
(Integer)
= 0: default, set to 2
= 1: yes
= 2: no
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Ish3n
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3-node shell element formulation flag
(Integer)
= 0: default, set to 2
= 1: standard triangle (C0)
= 2: standard triangle (C0) with modification for large rotation
= 30: DKT18
= 31: DKT_S3, which based on DTK12 of BATOZ (see Theory Manual)
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Idril
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Drilling DOF stiffness flag
(Integer)
= 0: no
= 1: yes
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| 1. | This card is read only once. Only the first card /DEF_SHELL written in the model is used. The other card /DEF_SHELL are ignored. |
| 2. | Q4: original four node RADIOSS shell with hourglass perturbation stabilization. |
QEPH: formulation with hourglass physical stabilization for general use.
QBAT: modified BATOZ Q4 24 shell with four Gauss integration points and reduced integration for in-plane shear. No hourglass control is needed for this shell.
DKT18: BATOZ DKT18 thin shell with three Hammer integration points.
| 3. | DKT_S3 Sabourin’s triangle shell without rotational DOF. |
| 4. | Flag Ishell can be changed in property set input. |
| 5. | Shell formulation flags are the default values for shells, and can be changed in property set input. |
| 6. | Small strain formulation is activated from time t=0 if Ismstr =1 or 3. It may be used for a faster preliminary analysis, but the accuracy of results is not ensured. Any shell for which  can be switched to a small strain formulation by RADIOSS Engine option /DT/SHELL/CST; except if Ismstr =4. |
| 7. | If Ithick or Iplas are activated, the small strain option is automatically deactivated in the corresponding type of element. |
| 8. | If the small strain option is set to 1 or 3, the strains and stresses given in material laws are engineering strains and stresses. Otherwise, they are true strains and stresses. |
| 9. | Flags Ithick, Iplas and Istrain are global default values that can be changed in shell property set input (/PROP/SHELL); in which case, the later will prevail. |
| 10. | Flag Iplas is available for Material Laws 2, 22, 27 and 36. |
| 11. | Flag Iplas is available for Material Law 2 in case of global integration (N=0 in shell property). The default value for Iplas in case of Law 2 and global integration is Iplas =2: radial return. |
| 12. | Flag Iplas is available for Material Law 36 in case of global integration (N=0 in shell property). The default value for Iplas in case of Law 36 and global integration is Iplas =1: iterative projection. |
| 13. | Flag Ithick is automatically set to 1 for Material Laws 32 and 43. |
| • | Istrain is automatically set to 1 for Material Laws 25 and 27 |
| • | If Ithick =1, then Iplas must be =1; otherwise Ithick =1 is not taken into account |
| 14. | Drilling DOF stiffness is recommended for implicit solution especially for Riks method and bending dominated problems. |
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