/PROP/TYPE20 (TSHELL)

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

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/PROP/TYPE20/prop_ID/unit_ID or /PROP/TSHELL/prop_ID/unit_ID
prop_title
Isolid Ismstr     Icstr Inpts Iint   dn
qa qb h        
Δ t min MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaqGuoGaam iDamaaBaaaleaaciGGTbGaaiyAaiaac6gaaeqaaaaa@3B70@                

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)

  
Isolid 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)

  
Ismstr 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)

  
Icstr Constant stress formulation flag to indicate the thickness direction. Only valid for Isolid =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)

  
Inpts Number of integration points.
= j
1 < j < 9 for Isolid =15
= ijk
2 < i,j,k < 9 for Isolid =14
= ijk
2 < i,k < 3, 2 < j < 9 for Isolid =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.
  
Iint Thickness integration formulation. Only valid for Isolid =16.
= 1 (Default)
Gauss integration scheme.
= 2
Lobatto integration scheme.

(Integer)

  
dn Numerical damping for stabilization. Only valid for Isolid =15.

Default = 0.1 (Real)

  
qa Quadratic bulk viscosity.

Default = 1.10 (Real)

Default = 0.0 for /MAT/LAW70 (FOAM_TAB)

  
qb Linear bulk viscosity.

Default = 0.05 (Real)

Default = 0.0 for /MAT/LAW70

  
h Hourglass viscosity coefficient.

Default = 0.10 (Real)

  
Δ t min MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9 Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaqGuoGaam iDamaaBaaaleaaciGGTbGaaiyAaiaac6gaaeqaaaaa@3B70@ Minimum time step

Default = 106 (Real)

 [ s ]

Comments

  1. 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 Isolid=14 (HA8), a different thickness direction can be specified using the constant stress flag, Icstr.
      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)
  2. Icstr - for reduced stress integration.
    For Isolid=14 (HA8) the reduced integration direction and thus thickness direction of the shell can be set by parameter Icstr. 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".

  3. When using the automatic setting option Ismstr = Icpre = Iframe=-1, the values for these options are defined using the best options based on the element formulation, element type, and material. Alternatively, defining Ismstr = Icpre = Iframe=-2 will overwrite the values for these options defined in this property with the best value (/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.
  4. Isolid - Solid elements formulation flag.
    • For Isolid=15, parameter Icstr 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 Isolid =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 Isolid=15 with pentahedron elements, /PENTA6 elements are recommended but degenerated /BRICK elements can also be used.
  5. Ismstr - Small strain formulation flag.
    • If the small strain option is set (Ismstr =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 Isolid =14 (HA8) and Isolid =15 (HSEPH).
    • The Radioss Engine option /DT/BRICK/CST will only work for brick property sets with Ismstr =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 Isolid =14, 15 Full geometric nonlinearities

      Ismstr = 2, 4

      		 Switch to small strain using element shape from cycle before negative volume.
  6. Numerical damping dn is only used in hourglass stress calculation for HSEPH (Isolid =15).
  7. Hourglass viscosity coefficient h must have a value between 0 and 0.15 and is not active with 8 integration point solids.
  8. 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.