/PROP/TYPE20 (TSHELL)

Block Format Keyword This property is used to define the general thick shell property set.

Format

(1)	(2)	(3)	(5)	(6)	(7)	(9)
/PROP/TYPE20/`prop_ID`/`unit_ID` or /PROP/TSHELL/`prop_ID`/`unit_ID`
`prop_title`
`I`_solid	`I`_smstr		`I`_cstr	`I`_npts	`I`_int	`d`_n
`q`_a		`q`_b	`h`
$Δ t_{\min}$		`Vdef_min`	`Vdef_max`		`APS_max`	`COL_min`

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`_solid	Solid elements formulation flag. = 0 Use value /DEF/SOLID. = 14 HA8, 8-node thick shell element, full integration, variable number of Gauss integration points, co-rotational system formulation, shear locking-free. = 15 HSEPH/PA6 thick shell elements (8-node and 6-node respectively). Co-rotational system formulation, under integrated (1 Gauss point in the plane) with physical hourglass stabilization. Variable number of integration points in thickness direction. = 16 Quadratic 16-node thick shell, full integration, variable number of Gauss points in all directions. (Integer)
`I`_smstr	Strain formulation flag. 4 = -1 Automatically define the best value based on element type and material law. = 0 Use value in /DEF_SOLID. = 1 Small strain from time =0. = 2 Full geometric nonlinearities with possible small strain formulation in Radioss Engine (/DT/Eltyp/Keyword3/Iflag). = 3 Simplified small strain formulation from time =0 (non-objective formulation). = 4 Default, if /DEF_SOLID is not defined Full geometric nonlinearities (/DT/BRICK/CST has no effect). (Integer)
`I`_cstr	Constant stress formulation flag to indicate the thickness direction. Only valid for `I`_solid =14. 2 = 001 Reduced stress integration in t direction. = 010 (Default) Reduced stress integration in s direction. = 100 Reduced stress integration in r direction. (Integer)
`I`_npts	Number of integration points. = j 1 ≤ j ≤ 9 for `I`_solid =15 = ijk 2 ≤ i,j,k ≤ 9 for `I`_solid =14 = ijk 2 ≤ i,k ≤ 3, 2 ≤ j ≤ 9 for `I`_solid =16 (Integer) Where: i Number of integration points in r direction. j Number of integration points in s direction. k Number of integration points in t direction.
`I`_int	Thickness integration formulation. Only valid for `I`_solid =16. = 1 (Default) Gauss integration scheme. = 2 Lobatto integration scheme. (Integer)
`d`_n	Numerical damping for stabilization. Only valid for `I`_solid =15. Default = 0.1 (Real)
`q`_a	Quadratic bulk viscosity. Default = 1.10 (Real) Default = 0.0 for /MAT/LAW70 (FOAM_TAB)
`q`_b	Linear bulk viscosity. Default = 0.05 (Real) Default = 0.0 for /MAT/LAW70
`h`	Hourglass viscosity coefficient. Default = 0.10 (Real)
$Δ t_{\min}$	Minimum time step. Default = 10⁶ (Real)	$[s]$
`Vdef_min`	Minimum volume ratio (V/Vo) to delete solid element. Default = 0
`Vdef_max`	Maximum volume ratio (V/Vo) to delete solid element. Used only if different from 0. Default = 0
`ASP_max`	Maximum aspect ratio to delete solid element. Used only if different from 0. Default = 0
`COL_min`	Minimum collapse value to delete solid element. Default = 0

Example

#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/TYPE20/1/2
TSH_ORTH example
#   ISOLID    Ismstr                         Icstr     Inpts      Iint                            Dn
        14         0                           010       222                                       0
#                 qa                  qb                   h                  
                   0                   0                   0
#         deltaT_min            vdef_min            vdef_max             ASP_max             COL_min
                   0                   0                   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

Thickness direction:
- By default, the element must be oriented so that the thickness direction of the thick shell is in the elements "s" direction.
- However, when using I_solid=14 (HA8), a different thickness direction can be specified using the constant stress flag, I_cstr.
  Note: Check the elements local system orientation using a pre-processor.
  
  Figure 1.
  
  r, s, t
  
  Isoparametric frame
  
  r
  
  Center of (1, 2, 6, 5) to center of (4, 3, 7, 8)
  
  s
  
  Center of (1, 2, 3, 4) to center of (5, 6, 7, 8)
  
  t
  
  Center of (1, 4, 8, 5) to center of (2, 3, 7, 6)
I_cstr - for reduced stress integration.
For I_solid=14 (HA8) the reduced integration direction and thus thickness direction of the shell can be set by parameter I_cstr. This parameter represents a 3-digit sequence of "0" and "1", which corresponds to standard r-s-t elemental coordinate system for solid elements.

0

No reduced stress integration is done in corresponding direction.

1

Reduced integration is used in this direction.

For example:

"010" means that reduced integration is used, and the thickness direction corresponds to element axis "s".
When using the automatic setting option I_smstr = I_cpre = I_frame=-1, the values for these options are defined using the best options based on the element formulation, element type, and material. Alternatively, defining I_smstr = I_cpre = I_frame=-2 will overwrite the values for these options defined in this property with the best value (refer to /DEF_SOLID) based on element type and material law. To see the values defined by Radioss, review the “PART ELEMENT/MATERIAL PARAMETER REVIEW” section of the Starter output file.
I_solid - Solid elements formulation flag.
- For I_solid=15, parameter I_cstr has no effect. It is always assumed that elemental direction "s" uses reduced integration and is the thickness direction.
- When property is used with /MAT/LAW1 (ELAST), with I_solid =15 and number of integration points is different from one, number of integration points is set to 2 (enough to compute correct bending).
- When using I_solid=15 with pentahedron elements, /PENTA6 elements are recommended but degenerated /BRICK elements can also be used.

I_smstr - Small strain formulation flag.

If the small strain option is set (I_smstr =1, 3), the strains and stresses used in material laws are engineering strains and stresses. Otherwise, they are true strains and stresses.
The small strain option is available for I_solid =14 (HA8) and I_solid =15 (HSEPH).
The Radioss Engine option /DT/BRICK/CST will only work for brick property sets with I_smstr =2

Starting with version 2017, Lagrangian elements whose volume becomes negative during a simulation will automatically switch strain formulations to allow the simulation to continue. When this occurs, a WARNING message will be printed in the Engine output file. The following options are supported.

Element Type	Element Formulation	Strain Formulation	Negative Volume Handling Method
/BRICK	`I`_solid =14, 15	Full geometric nonlinearities `I`_smstr = 2, 4	Switch to small strain using element shape from cycle before negative volume.

Numerical damping d_n is only used in hourglass stress calculation for HSEPH (I_solid =15).
Hourglass viscosity coefficient h must have a value between 0 and 0.15 and is not active with 8 integration point solids.
Output for post-processing.
- For post-processing solid element stress, refer to /ANIM/BRICK/TENS/STRESS and /H3D/SOLID/TENS/STRESS for animation and /TH/BRICK for plot files.