/PROP/TYPE51

Block Format Keyword This property set is used to define the sandwich shell property set using the stack and ply approach. Multiple integration points can be defined through the thickness for each ply.

Description

Two possible input:

All elements may have different number of plies by associating a group of elements to the ply in a way similar to OptiStruct.
The layout is described by a sequence of substacks ("SUB"), which are comprised of several plies. The interface between substacks is defined with INT option line.

The input can be either "substack" or by ply, but not both.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)
/PROP/TYPE51/`prop_ID`/`unit_ID`
`prop_title`
`I`_shell	`I`_smstr	`I`_sh3n	`I`_dril	`P_thick`_fail		`Z`₀
`h`_m		`h`_f		`h`_r		`d`_m		`d`_n
	`I`_strain	`A`_shear			`I`_int		`I`_thick	`F`_exp
`V`_X		`V`_Y		`V`_Z		`Skew_ID`	`I`_orth	`I`_pos

By ply (Each ply per two lines, see example)

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
`Pply_ID`_i	$ϕ_{i}$		`Z`_i		`P_thick`_fail		`F_weight`_i
Blank

Or by substack (Each substack per four lines, see example)

(1)	(2)	(3)	(4)	(6)	(8)
`Sub`	`Nsub`	`Sub-plyn`
`Substack Name`
`Pply_ID`_i	$ϕ_{i}$		`Z`_i	`P_thick`_fail	`F_weight`_i
Blank

Optional (Each connection between 2 substacks per line):

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
`INT`	`Pply_ID`_t	`Pply_ID`_b

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. 2 = 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. 3 = 0 Use value in /DEF_SHELL. = 1 Small strain from time =0 (new 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/Eltyp/Keyword3/Iflag). = 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`_dril	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	Percentage of layer thickness that must fail before the element is deleted. 12 13 $0.0 \leq P_t h i c k_{f a i l} \leq 1.0$ (Real)
`Z`₀	Distance from the shell element reference plane to the bottom surface of the shell (Real or blank). 8 It should be considered, if `I`_pos = 2. Default = 0.0 (Real)
`h`_m	Shell membrane hourglass coefficient. 4 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 = 5% for /MAT/LAW25 (COMPSH). Default = 5% for `I`_shell=12 (QBAT) Default = 1.5% for `I`_shell=24 (QEPH) + Laws 36,43 (Real)
`d`_n	Shell numerical damping. 5 It only used for `I`_shell =12 and 24 . Default =1.5% for `I`_shell =24 (QEPH) Default =0.1% for `I`_shell =12 (QBAT) Default =0.01% for `I`_sh3n =30 (DKT18) (Real)
`I`_strain	Compute strains for post-processing flag. = 0 Use value in /DEF_SHELL. = 1 Default, if /DEF_SHELL is not defined Yes = 2 No (Integer)
`A`_shear	Shear factor. Default is Reissner value: 5/6 (Real)
`I`_int	Thickness integration formulation - through layer (ply) thickness. 1 = 0 Set to 1. = 1 (Default) Uniform integration scheme (uniformly distribution of the integration points through ply thickness). = 2 Table 3 (Integer)
`I`_thick	Shell resultant stresses calculation flag. = 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)
`F`_exp	Exponent of the normalization equation used to calculate element suppression criterion. 13 $F_{e x p} \geq 1.0$ Default = 1.0 (Real)
`V`_X	X component for reference vector. 8 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 If the local skew is defined, its X-axis 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. = 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.
`I`_pos	Ply positioning flag for reference vector. 9 = 0 (Default) Ply positions are automatically calculated with regard to ply thicknesses. The coherence of global thickness with the sum of ply thicknesses is automatically checked. = 1 All ply positions in the element thickness are user-defined. Multiple plies may have the same special position. Global thickness is not checked in this case, since it needs to not be equal to sum of ply thicknesses. = 2 The shell element mid-surface is at `Z`₀ from the bottom of the ply layout. = 3 The top of the ply layout is coincident with the element mid-surface. = 4 The bottom of the ply layout is coincident with the element mid-surface. (Integer)
`Sub`	=`Sub`: Indicates the beginning of a substack definition. 10 (must be left justified) (Integer)
`Nsub`	Substack identification number. (Integer)
`Sub-plyn`	Number of plies in substack. (Integer)
`Substack Name`	Name of the substack. (Maximum 100 characters)
`Pply_ID`_i	Ply property identifier for layer `i` . (Integer) `i` = 1, 2, 3 ...200
$ϕ_{i}$	Angle for ply `i`. 8 (Real)	$[\deg]$
`Z`_i	Z position of ply `i` (`Z`_i defines the position of the middle of the ply). Default = 0.0 (Real)	$[m]$
`P_thick`_{fail_i}	Layer failure criterion: Percentage of layer thickness that must fail before the element is deleted. 12 13 $0.0 \leq P_t h i c k l_{f a i l}_{_i} \leq 1.0$ (Real)
`F_weight`_i	Relative failure weight factor for layer `i`. 12 13 Default = 1.0 (Real)
`INT`	Indicates the connection between 2 substacks (must be left justified). (Integer)
`Pply_ID`_t	Ply identification number of the top ply of the bottom substack. One of ply ID in `Pply_ID`_i or `Pply_ID`_j. (Integer)
`Pply_ID`_b	Ply identification number of the bottom ply of the top substack. One of ply ID in `Pply_ID`_i or `Pply_ID`_j. (Integer)

Example (Ply)

There are three plies in this example. Each of the three plies in this example has a different material direction (fiber direction) and a different material (which is defined in each ply with /PROP/TYPE19). Three integration points uniformly distributed throughout each ply.

#RADIOSS STARTER
#---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----|
/PROP/TYPE51/2/2
composite combine by ply
#   Ishell    Ismstr     Ish3n    Idrill                                      Z0
        12         0         0         1                                       0
#                 hm                  hf                  hr                  dm                  dn
                   0                   0                   0                  .1                  .1
#            Istrain              Ashear                Iint              Ithick
                   0                   0                   0                   1
#                 VX                  VY                  VZ   skew_ID     Iorth      Ipos
                   1                   0                   1         0         0         0
# Pply_IDi                PHIi                  Zi       Pthickl_faili           F_weighti
        11                   0                   0                   0                   0
                                                                                                    
# Pply_IDi                PHIi                  Zi       Pthickl_faili           F_weighti
        12                  90                   0                   0                   0
                                                                                                    
# Pply_IDi                PHIi                  Zi       Pthickl_faili           F_weighti
        13                   0                   0                   0                   0
                                                                                                    
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/11/2
PROP number 11
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                  45         0         0         3                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/12/2
PROP number 12
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         2                  .6                   0         0         0         3                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/13/2
PROP number 12
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                 -45         0         0         3                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#enddata
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

Example (Substack)

Substack definition for the ply layout.

#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----|
#-  2. GEOMETRICAL SETS:
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE51/2/2
composite combine by substack
#   Ishell    Ismstr     Ish3n    Idrill         Pthick_fail                  Z0
        12         0         0         1                   0                   0
#                 hm                  hf                  hr                  dm                  dn
                   0                   0                   0                  .1                  .1
#            Istrain               Ashear               Iint              Ithick
                   0                   0                   0                   1
#                 VX                  VY                  VZ   skew_ID     Iorth      Ipos
                   0                   1                   0         0         0         0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#      Sub      Nsub  Sub-plyn
SUB                1         4
Top substack                                                                    
# Pply_IDi                PHIi                  Zi       Pthickl_faili           F_weighti
        11                   0                   0                   0                   0
                                                                                                    
        12                  90                   0                   0                   0
                                                                                                    
        13                   0                   0                   0                   0
                                                                                                    
        14                  90                   0                   0                   0
                                                                                                    
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#      Sub      Nsub  Sub-plyn
SUB                2         4
Left substack                                                                   
# Pply_IDi                PHIi                  Zi       Pthickl_faili           F_weighti
        21                  90                   0                   0                   0
                                                                                                    
        22                   0                   0                   0                   0
                                                                                                    
        23                  90                   0                   0                   0
                                                                                                    
        24                   0                   0                   0                   0
                                                                                                    
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#      Sub      Nsub  Sub-plyn
SUB                3         4
Right substack                                                                  
# Pply_IDi                PHIi                  Zi       Pthickl_faili           F_weighti
        31                  90                   0                   0                   0
                                                                                                    
        32                   0                   0                   0                   0
                                                                                                    
        33                  90                   0                   0                   0
                                                                                                    
        34                   0                   0                   0                   0
                                                                                                    
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#      Sub      Nsub  Sub-plyn
SUB                4         3 
Middle substack                                                                 
# Pply_IDi                PHIi                  Zi       Pthickl_faili           F_weighti
        41                  90                   0                   0                   0
                                                                                                    
        42                   0                   0                   0                   0
                                                                                                    
        43                  90                   0                   0                   0
                                                                                                    
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#      Int  Pply_IDt  Pply_IDb
INT               14        21
INT               14        31
INT               43        21
INT               34        41
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/11/2
PROP number 11
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                  45        45         0         0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/12/2
PROP number 12
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                  45        45         0         0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/13/2
PROP number 13
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                  45        45         0         0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/14/2
PROP number 14
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                  45        45         0         0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/21/2
PROP number 21
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                  45        46         0         0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/22/2
PROP number 22
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                  45        46         0         0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/23/2
PROP number 23
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                  45        46         0         0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/24/2
PROP number 24
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                  45        46         0         0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/31/2
PROP number 31
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                  45        47         0         0                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/32/2
PROP number 32
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                  45        47         0         0                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/33/2
PROP number 33
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                  45        47         0         0                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/34/2
PROP number 34
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                  45        47         0         0                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/41/2
PROP number 41
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                  45        44         0         0                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/42/2
PROP number 42
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                  45        44         0         0                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/PROP/TYPE19/43/2
PROP number 43
# mat_ID_i                   t           delta_phi id_grsh4n id_grsh3n   Npt_ply                 A_i
         1                  .5                  45        44         0         0                   0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#enddata
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

Comments

The stack property (TYPE51) is used in combination with /PROP/TYPE19 (PLY) (/PROP/TYPE19) to create composites properties through the ply-based definition.
- Each ply in the stack is defined using Pply_ID_i or Pply_ID_j and can only be referenced once in the stack. If ply ids are used more than once an error message will output.
- Each ply of a shell element can contain a different (≥ 1) number of integration points through its ply thickness. i.e. Npt_ply =3 in /PROP/TYPE19 (PLY)
- Different integration scheme (uniformly distribution or Gauss integration scheme) could be defined with option I_int inside this property.
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.
- 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.
- The hourglass formulation is visco-elastic for Q4 shells.
I_smstr - Small strain formulation
- Small strain formulation is activated from time t = 0, if I_smstr =1. It may be used for a faster preliminary analysis, but the accuracy of results is not ensured. Any shell for which $Δ t < Δ t_{\min}$ can be switched to a small strain formulation by Radioss Engine option /DT/SHELL/CST, except if I_smstr=4.
- If I_smstr =1, 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
It is only used for I_shell =12 or 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_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).
Anisotropy in local coordinate system
Two different ways to define the anisotropy direction with this property

Skew_ID=0

Anisotropic direction defined with global vector $V$ (components defined in Line 6) and angle $ϕ_{i}$ (angle in degree) for each ply.

Skew_ID≠ 0

Anisotropic direction defined with skew (X-axis in skew replaces the global vector $V$ ) and angle $ϕ_{i}$ (angle in degree) for each ply.

For both ways (with vector $V$ or with skew), Projection of vector $V$ or x-axis of skew)on shell element plane becomes the vector $V^{'}$ . Then for each ply, the anisotropic direction (direction 1) is vector $V^{'}$ is turned $ϕ_{i}$ degrees (turns positive direction coding to shell normal $n$ ).

Figure 3.

$α_{i}$ is the angle between local anisotropic direction 1 and 2 (directions of anisotropy) for each ply which defined in /PROP/TYPE19 (PLY). If $α_{i} = 90 °$ , then ply is in orthotropic.
I_pos - ply position
- In this property, ply position defined with Z_i and option I_pos .
- Z_i values are real ply positions in the local Z axis (negative and positive value are allowed and Z_i defines the position of the middle of the each ply).
- Z₀ only used with I_pos=2, it indicated distance from the shell element reference middle surface to the bottom surface of the whole ply or stack. More info see below I_pos=2.
- I_pos = 0: ply positions are automatically calculated with regard to ply thicknesses.
  - The input thickness “Thick” may be equal to zero as the true shell thickness is always calculated from the ply thicknesses and positions of ply defined by Z_i.
  - If the input thickness “Thick” is different from 0.0, a warning will be displayed if the calculated thickness from the plies is different from the input thickness.
    
    Figure 4.
- I_pos = 1: All ply positions and thickness in the element are user-defined (with in /PROP/PLY and Z_i).
  - Global thickness “Thick” is not checked, as it does not need to be equal to the sum of ply thickness.
  - Multiple plies are allowed to have the same space position.
  - This option is not recommended unless the number of ply is constant for all elements.
- I_pos = 2: the shell element mid-surface is at Z₀ from the bottom of the ply layout.
  
  Figure 5.
- I_pos = 3: the top of the ply layout is coincident with the element mid-surface.
  
  Figure 6.
- I_pos = 4: the bottom of the ply layout is coincident with the element mid-surface.
  
  Figure 7.
Define by substack
- If the substack definition is used, each substack definition begins with the keyword “SUB” and the substack identification number.
- All the plies until the next keyword “SUB” or the keyword “INT” is encountered belong to the same substack.
- All substacks must be defined before defining the “INT connections
- If an element contains plies belonging to several substacks, the connection between the substacks is defined with an INT connection: the ply Pply_ID_t of the first substack is connected to the ply Pply_ID_b of the second substack.
- For more detail, refer to above examples for this property.
Material for each ply
- Material for each ply defined with mat_ID in /PROP/TYPE19 (PLY).
- Different material laws could be defined for each ply.
- The material law number given in /PART will be used to define the mass and the sound speed of the composite, as well as the interface stiffness.
- This property is compatible with XFEM (crack propagation) using /FAIL/JOHNSON and /FAIL/TBUTCHER.
P_thick_fail , P_thickl_{fail_i} and F_weight_i parameters are not compatible with failure defined within the material law itself, such as plastic failure strain in LAW36.
Element suppression rules used with /FAIL models:
- A single Gauss point in each layer is deleted when relative thickness of failed integration points is greater than prescribed value P_thickl_{fail_i} for this layer:
  $\sum_{i} T h i c k l_{i} \geq P_t h i c k l_{f a i l_i}$ with $i = 1, N_{i}$
  
  Where,
  
  $N_{i}$
  
  The number of in-thickness integration points in the layer, defined in corresponding PLY property.
  
  $T h i c k l_{i}$
  
  The ratio of thickness of integration point vs layer thickness.
- Each single layer is turned OFF when all in-plane Gauss integration points in the layer are deleted.
- The shell element is deleted when the following criterion is met:
  ${[{\sum_{i} (T h i c k_{i} \cdot F_w e i g h t_{i})}^{F_{e x p}}]}^{\frac{1}{F_{e x p}}} \geq P_t h i c k_{f a i l}$ with $i = 1, N_{i}$
  
  Where,
  
  $T h i c k_{i}$
  
  Relative thickness of failed layer i over total element thickness.
- By default, the element failure parameters defined in the property are used and local Ifail_sh settings defined at the failure model level are ignored. If the P_thickl_{fail_i} parameters per ply are not defined, the element failure settings defined in the local failure models are applied to the corresponding layer. The P_thick_fail parameter must be defined in the property otherwise the default value is used.