/PROP/TYPE11 (SH_SANDW)

Block Format Keyword This property set is used to define the sandwich shell property set. It is possible to define sandwich composite with several layers and each lay with individual material, thickness, layer position and orthotropic direction.

This property is compatible with XFEM (crack propagation) using /FAIL/JOHNSON, /FAIL/TAB1 and /FAIL/TBUTCHER.

Format


(1)	(2)	(3)	(4)	(5)	(7)	(8)	(9)	(10)
/PROP/TYPE11/`prop_ID`/`unit_ID` or /PROP/SH_SANDW/`prop_ID`/`unit_ID`
`prop_title`
`I`_shell	`I`_smstr	`I`_sh3n	`I`_drill		`P_thick`_fail
`h`_m		`h`_f		`h`_r	`d`_m		`d`_n
`N`		`Thick`		`A`_shear		`I`_thick	`I`_plas
`V`_X		`V`_Y		`V`_Z	`skew_ID`	`I`_orth	`I`_pos	`I`_P

For each layer (integration point) per line


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
$ϕ_{i}$		`t`_i		`Z`_i		`mat_ID`_i		`F_weight`_i

Definition


Field	Contents	SI Unit Example
`prop_ID`	Property identifier. (Integer, maximum 10 digits)
`unit_ID`	Unit identifier. (Integer, maximum 10 digits)
`prop_title`	Property title. (Character, maximum 100 characters)
`I`_shell	Shell element formulation flag. 1 = 0 Use value in /DEF_SHELL. = 1 Default, if /DEF_SHELL is not defined 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. (Integer)
`I`_smstr	Shell small strain formulation flag. 2 = -1 Automatically set the best value according to element type and material law. = 0 Use value in /DEF_SHELL. = 1 Small strain from time = 0 (formulation compatible with all other formulation flags). = 2 Default, if /DEF_SHELL is not defined Full geometric nonlinearities with possible small strain formulation activation in Radioss Engine (option /DT/SHELL/CST). = 3 Old small strain formulation (only compatible with hourglass type 2). = 4 Full geometric nonlinearities (in Radioss Engine, option /DT/SHELL/CST has no effect). (Integer)
`I`_sh3n	3 node shell element formulation flag. = 0 Use value in /DEF_SHELL. = 1 Standard triangle (C0). = 2 Default, if /DEF_SHELL is not defined Standard triangle (C0) with modification for large rotation. = 30 DKT18 = 31 DKT_S3, which based on DTK12 of BATOZ (refer to Element Library in the Theory Manual). (Integer)
`I`_drill	Drilling degree of freedom stiffness flag. 7 = 0 Use value in /DEF_SHELL. = 1 Yes. = 2 Default, if /DEF_SHELL is not defined. No. (Integer)
`P_thick`_fail	Fraction of failed thickness for shell element deletion. 12 -1.0 ≤ `P_thick`_fail ≤ 0 Fraction of failed layers. $0.0 \leq P_t h i c k_{f a i l} \leq 1.0$ Fraction of failed thickness. Default = 1.0 (Real)
`h`_m	Shell membrane hourglass coefficient. Default = 0.01 Default = 0.1 for hourglass type 3 (`I`_shell =3) (Real)
`h`_f	Shell out-of-plane hourglass. Default = 0.01 (Real)
`h`_r	Shell rotation hourglass coefficient. Default = 0.01 Default = 0.1 for hourglass type 3 (`I`_shell =3) (Real)
`d`_m	Shell Membrane Damping. Default = 0.0 Default = 0.015 for `I`_shell =24 (QEPH)+LAW 27 Default = 0.05 for `I`_shell =1,2,3,4,12+LAW25 and 27 Default = 0.05 for LAW65 (Real)
`d`_n	Shell numerical damping. 4 It only used for `I`_shell =12 and 24 Default = 0.015 for `I`_shell =24 (QEPH) Default = 0.001 for `I`_shell =12 (QBAT) Default =0.0001 for `I`_sh3n =30 (DKT18) (Real)
`N`	Number of layers, with 1 ≤ `N` ≤ 100. Default = 1 (Integer)
`Thick`	Shell thickness. 10 (Real)	$[m]$
`A`_shear	Shear factor. Default is Reissner value: 5/6 (Real)
`I`_thick	Shell resultant stresses calculation flag. = -1 Automatically set the best value according to element type and material law. = 0 Use value in /DEF_SHELL. = 1 Thickness change is taken into account. = 2 Default, if /DEF_SHELL is not defined Thickness is constant. (Integer)
`I`_plas	Shell plane stress plasticity flag. = -1 Automatically set the best value according to element type and material law. = 0 Use value in /DEF_SHELL. = 1 Iterative projection with three Newton iterations. = 2 Default, if /DEF_SHELL is not defined Radial return. (Integer)
`V`_X	X component for reference vector. Default = 1.0 (Real)
`V`_Y	Y component for reference vector. Default = 0.0 (Real)
`V`_Z	Z component for reference vector. Default = 0.0 (Real)
`skew_ID`	Skew identifier for reference vector. 8 Default = 0 (Integer)
`I`_orth	Orthotropic system formulation flag for reference vector. = 0 (Default) The first axis of orthotropy is maintained at constant angle with respect to the X-axis of an orthonormal co-rotational element coordinate system. = 1 The first orthotropy direction is constant with respect to a non-orthonormal system of deformed element. (Integer)
`I`_pos	Layer positioning flag for reference vector. 10 = 0 (Default) Layer positions `Z`_i are automatically calculated with regard to layer thicknesses. = 1 All layer positions `Z`_i must be user-defined. (Integer)
`I`_P	Reference direction in shell plane. 8 = 0 (Default) Use 1^st direction of `skew_ID` or vector $V$ (if `skew_ID` is not defined) projected on the shell element. = 20 Defined from element connectivity (N1,N2) of the shell element. = 22 Defined from 1^st direction of `skew_ID` projected on the shell element and angle phi. (Vector $V$ is ignored). = 23 Defined from vector product of vector $V$ and the shell element normal direction $n$ (`skew_ID` is ignored). = 25 Defined from the azimuthal direction defined with local cylindrical coordinate system `skew_ID` (2^nd direction). = 26 Defined from 1^st direction of element coordinate system. (Integer)
$ϕ_{i}$	Angle for layer `i`. 8 (Real)	$[\deg]$
`t`_i	Thickness of layer `i`. 10 (Real)	$[m]$
`Z`_i	Z position of layer `I` (`Z`_i defines the position of the middle of the layer). Default = 0.0 (Real)	$[m]$
`mat_ID`_i	Material identifier for layer `i`. 11 (Integer)
`F_weight`_i	Relative failure weight factor for layer `i`. Default = 1.0 (Real)

Example

3 layers (N=3) with different material, different material direction (m1). Reference vector is taken from x-axis of skew.

#RADIOSS STARTER
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#-  1. LOCAL_UNIT_SYSTEm:
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/UNIT/2
unit for prop
#              MUNIT               LUNIT               TUNIT
                  kg                  mm                  ms
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/SKEW/FIX/1
New SKEW 1
#                 OX                  OY                  OZ
                 1.0                   0               100.0
#                 X1                  Y1                  Z1
                   0                   0                   1
#                 X2                  Y2                  Z2
                   0                  -1                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#-  2. GEOMETRICAL SETS:
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/SH_SANDW/2/2
SH_SANDW example
#   Ishell    Ismstr     Ish3n    Idrill                             Pthick_fail 
        12         0         0         0                                       0
#                 hm                  hf                  hr                  dm                  dn
                   0                   0                   0                  .1                  .1
#        N                         Thick              Ashear              Ithick     Iplas
         3                           1.6                   0                   1         1
#                 Vx                  Vy                  Vz   skew_ID     Iorth      Ipos        Ip
                   0                   0                   0         1         0         0         0
#                Phi                   t                   Z    mat_ID                     F_weighti
                  45                  .5                   0         1                             0                              
                  90                  .6                   0         2                             0                              
                 -45                  .5                   0         1                             0                              
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#enddata
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

Comments

I_shell, I_sh3n – 4-node and 3-node shell formulation flag
- I_shell=1,2,3,4 (Q4): original 4 nodes Radioss shell with hourglass perturbation stabilization.
- I_shell=24 (QEPH): formulation with hourglass physical stabilization for general use (isotropic + LAW25 shells only).
- 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.
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 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 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.
h_m, h_f, and h_r - Hourglass coefficients
- h_m, h_f, and h_r are only used for Q4 shells. 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.
d_n - Shell numerical damping coefficient
- d_n is only used for I_shell = 12 and 24.
  - 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 transverse shear
  - for I_sh3n=30 (DKT18), d_n is only used for membrane
I_thick- Shell resultant stresses calculation flag
- If I_thick=1, the small strain option is automatically deactivated in the corresponding type of element.
I_plas- Shell plane stress plasticity flag
- It is recommended to use I_plas =1, if I_thick =1.
- I_plas=1 is available for Material Law 27.
- If I_plas=1, the small strain option is automatically deactivated in the corresponding type of element.
I_drill - Drilling degree of freedom stiffness flag
- Drilling DOF stiffness is recommended for implicit solutions especially for Riks method and bending dominated problems.
- I_drill is available for QEPH, QBAT (I_shell =12, 24), and standard triangle (C0) shell elements (I_sh3n = 1, 2).
The orthotropy angle is defined as following from the reference vector defined in the stack:

$ϕ = ϕ_{s} + ϕ_{i} + ∆ ϕ + θ_{d r a p e}$

Where,

$ϕ_{i}$

is defined per ply in stack

$ϕ_{s}$

is defined on the element

$∆ ϕ$

is defined on the ply

$ϕ_{d r a p e}$

is defined in the drape table
The reference vector $V$ , defined with I_p, skew_ID or vector (V_X, V_Y, V_Z), is described in Composite Properties in the User Guide.
Figure 2.
- Example for I_P = 20:
  Figure 3.
The material direction definition in the initial state card (/INISHE/ORTHO, /INISH3/ORTHO) overwrites the material direction.
In the 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 derived from direction m1 rotated 90 degrees (orthotropic).
I_pos – Layer position
- I_pos = 0: layer positions are calculated automatically with "Thick".
  If $T h i c k \neq \sum_{i}^{N} t_{i}$
  - A warning message is displayed.
  - And individual layer thickness will be adjusted to new layer thickness $t_{i}^{n e w}$ with:
    
    $T h i c k = \sum_{i}^{N} t_{i}^{n e w}$
    
    Here Thick and $t_{i}^{}$ are the shell thickness and layer thickness which are specified in input.
    Figure 4.
- I_pos = 1: all layer positions in the element thickness are user-defined (with $t_{i}$ and $Z_{i}$ ).
  - “Thick” is not checked, as it does not need to be equal to the sum of layer thickness.
  - Multiple layers are allowed to have the same space position.
    Figure 5.
  For more details, refer to “Layer thickness and layer position calculation” in the Property and Elements FAQs.
Mat_ID_i- Material for each layer
- Each layer as well as the corresponding part must use the same material law type. But may have different material properties, hence material IDs. Radioss checks for this condition and errors out if it is not met.
- Global material properties (membrane stiffness, bending stiffness, mass, and inertia) are calculated based on the material properties and layer (thicknesses …). They are used for stability, mass and interface stiffness.
- A material is still required at part definition level but, is only used for pre- and post- (visualization “by material”) and its physical characteristics are ignored.
- The previous formulation where stiffness and mass were calculated from the material associated to the part is still used if the version number of the input file is V13 or earlier.
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 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 integration point 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.