/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)  (6)  (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_{dril}  P_thick_{fail}  
h_{m}  h_{f}  h_{r}  d_{m}  d_{n}  
N  I_{strain}  Thick  A_{shear}  I_{thick}  I_{plas}  
V_{X}  V_{Y}  V_{Z}  Skew_ID  I_{orth}  I_{pos} 
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

${\varphi}_{i}$  t_{i}  Z_{i}  mat_ID_{i}  F_weight_{i} 
Definitions
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
(Integer) 

I_{smstr}  Shell small strain
formulation flag. 2
(Integer) 

I_{sh3n}  3 node shell element
formulation flag.
(Integer) 

I_{dril}  Drilling degree of freedom
stiffness flag. 8
(Integer) 

P_thick_{fail}  Percentage of layer
thickness that must fail before the element is deleted. 12
13 $0.0\le P\_thic{k}_{fail}\le 1.0$ (Real) 

h_{m}  Shell membrane hourglass
coefficient. Default = 0.01 Default = 0.1 for hourglass type 3 (I_{shell} =3) (Real) 

h_{f}  Shell outofplane
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) 

I_{strain}  Compute strains for
postprocessing flag.
(Integer) 

Thick  Shell thickness. 10 (Real) 
$\left[\text{m}\right]$ 
A_{shear}  Shear factor. Default is Reissner value: 5/6 (Real) 

I_{thick}  Shell resultant stresses
calculation flag.
(Integer) 

I_{plas}  Shell plane stress
plasticity flag.
(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. 9 If the local skew is defined, its Xaxis replaces the global vector $V$ . V_{X}, V_{Y}, and V_{Z} coordinates are ignored. Default = 0 (Integer) 

I_{orth}  Orthotropic system
formulation flag for reference vector.
(Integer) 

I_{pos}  Layer positioning flag for
reference vector. 10
(Integer) 

${\varphi}_{i}$  Angle for layer
i. 9 (Real) 
$\left[\mathrm{deg}\right]$ 
t_{i}  Thickness of layer
i. 10 (Real) 
$\left[\text{m}\right]$ 
Z_{i}  Z position of layer
I
(Z_{i} defines
the position of the middle of the layer). Default = 0.0 (Real) 
$\left[\text{m}\right]$ 
mat_ID_{i}  Material identifier for
layer i. 11 (Integer) 

F_weight_{i}  Relative failure weight factor for layer i. 12 13 
Example
#RADIOSS STARTER
#12345678910
# 1. LOCAL_UNIT_SYSTEM:
#12345678910
/UNIT/2
unit for prop
# MUNIT LUNIT TUNIT
kg mm ms
#12345678910
/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
#12345678910
# 2. GEOMETRICAL SETS:
#12345678910
/PROP/SH_SANDW/2/2
SH_SANDW example
# Ishell Ismstr Ish3n Idril Pthick_fail
12 0 0 0 0
# hm hf hr dm dn
0 0 0 .1 .1
# N Istrain Thick Ashear Ithick Iplas
3 0 1.6 0 1 1
# Vx Vy Vz Skew_ID Iorth Ipos
0 0 0 1 0 0
# Phi t Z mat_ID F_weighti
45 .5 0 1 0
90 .6 0 2 0
45 .5 0 1 0
#12345678910
#enddata
#12345678910
Comments

I_{shell}, I_{sh3n} – 4node and 3node
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 (istotropic + LAW25 shells only).
 I_{shell}=12 (QBAT): modified BATOZ Q4γ24 shell with four Gauss integration points and reduced integration for inplane 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, 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
 d_{n} is only used for I_{shell} =
12 and 24.
 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.
 Output for
postprocessing
 Flag I_{strain} is automatically set to 1 for Material Law 25 and /MAT/LAW27 (PLAS_BRIT).
 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).
 Orthotropy in local
coordinate system.Two different ways to define the orthotropy with this property
 Skew_ID=0:
 Orthotropic direction defined with global vector $V$ (components defined in Line 6) and angle ${\varphi}_{i}$ (angle in degree) for each layer.
 Skew_ID≠0
 Orthotropic direction defined with skew (Xaxis in skew replaces the global vector $V$ ) and angle ${\varphi}_{i}$ (angle in degree) for each layer.
For both ways (with vector $V$ or with skew), Projection of vector $V$ (or xaxis of skew)on shell element plane becomes the vector ${V}^{\prime}$ . Then for each layer, the orthotropic direction (direction 1) is vector ${V}^{\prime}$ turn ${\varphi}_{i}$ degrees (turns positive direction coding to shell normal $n$ ).In case of reference metrics, the orientation for directions of anisotropy must be defined with the reference geometry, not the initial one.
 I_{pos} – Layer position
 I_{pos} = 0: layer
positions are calculated automatically with "Thick". If $Thick\ne {\displaystyle \sum _{i}^{N}{t}_{i}}$
 A warning message is displayed.
 And individual layer thickness will be adjusted to new layer
thickness
${t}_{i}^{new}$
with:
(1) $$Thick={\displaystyle \sum _{i}^{N}{t}_{i}^{new}}$$Here "Thick" and are the shell thickness and layer thickness which specified in input.
 I_{pos} = 1: all layer
positions in the element thickness are userdefined (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.
For more details, refer to “Layer thickness and layer position calculation” in the Property and Elements FAQs.
 I_{pos} = 0: layer
positions are calculated automatically with "Thick".
 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.
 P_thick_{fail} parameter is not compatible with failure defined within the material law itself, such as plastic failure strain in LAW36.
 Element suppression
rules used with /FAIL models:
 Each single layer is turned OFF when all inplane Gauss integration points in the layer are deleted.
 The whole shell element is deleted when the following criterion is
met:
(2) with$${\sum}_{i}Thic{k}_{i}\cdot F\_weigh{t}_{i}}\ge P\_thic{k}_{fail$$(3) $$i=1,{N}_{layers}$$Where, Thick_{i} is relative thickness of failed layer i
 When Ifail_sh parameters are defined locally in failure models associated to each layer material, the P_thick_{fail} value is used by default and local parameter settings are ignored. Local failure model settings are only used when P_thick_{fail} is not defined in the property which allows for backward compatibility with old models.